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JAMES J. DAVIS, Secretary



B U R E A U OF LABOR S T A T I S T I C S / ............ j
i n d u s t r i a l

a c c i d e n t s

a n d

h y g i e n e




s e r i e s









Description of acute poisoning as given in American and foreign litera­
ture ------------------------------------------------------------------------------------------------------------ 7-16
Aftereffects____________________________________________________________ 10-13
Relapsing form_________________________________________________________
Unusual symptoms_____________________________________________________ 14,15
Effect on child of gassing of mother__________________________________ 15, 16
Individual susceptibility_______________________________________________
Description of chronic poisoning as given in American and foreign
literature_________________________________________________________________ 16-21
Other constituents of industrial gases_______ ■______ _____________________ 22, 23
Sources of carbon-monoxide gas____________________________________________ 24-46
Manufacture of steel________ _________________________________________ 26-31
Coal and metal mining________________________________________________ 31-36
Illuminating g a s_______________________________________________________ 36-38
Smelting and coke by-products--------------------------------------------------------------38, 39
Unusual sources________________________________________________________ 39, 40
Chronic gassing among garage workers_______________________________ 40-44
Chronic gassing among linotypists_____________________________________44-46
Summary___________________________________________________________________ 46, 47




n o . 291.

D ecem ber, 1921.

^Carbon monoxide (CO) is the most widespread and one of the most
important poisons connected with human life and industry. Poison­
ing from this gas has greatly increased in all civilized countries, espe­
cially during recent years. At the First International Congress of
Labor, called in accordance with the provisions of the labor
convention in the Peace Treaty, and held in the fall of 1919
in Washington, D. C., the delegates were instructed to call the at­
tention of their respective Governments to the continued increase of
industrial carbon-monoxide poisoning and to request that investi­
gations be made in each country with a view to its prevention. This
increase has been brought about by the extended use of gas as a
source of heat and power and the increasing use of motor cars and
engines, the exhaust gases of which are more or less rich in carbon
monoxide. These new factors have more than offset the improve­
ments in blast-furnace procedure and in the prevention of mine
explosions, for, although the last two sources of carbon-monoxide
poisoning now yield fewer disastrous cases than they did in former
years, the number of industrial accidents from carbon monoxide
continues to grow from year to year.
The present inquiry was undertaken for the purpose of ascertain­
ing the extent and seriousness of industrial carbon-monoxide poison­
ing in the United States, for, strangely enough, very little is known
about it. It is known that the gas is responsible for many thousands
of deaths each year. According to McNally, chemist to the office of
the coroner of Cook County, 111., carbon-monoxide poisoning as a
cause of death held the fourth place in the death records of that
county in 1916, but the greater number of these cases are not indus­
trial; they are the result of inhaling illuminating gas, either acci­
dentally or with suicidal intent. It is not known how many deaths
from carbon monoxide are caused by industry in the United States,
nor how many cases of severe so-called 6 gassing” occur without a
fatal termination. In foreign countries, as will be seen later, carbonmonoxide gassing from which the victim recovers is often followed
by severe, and sometimes lasting, injury to organs or to the nervous
system. Whether in this country this occurs after gassing in steel
mills, smelters, coal mines, gas works, garages, and so on, is a question
that can not be answered, except with regard to the last. American
medical literature contains a considerable number of instances of men




who were overcome in closed garages by the exhaust gases from motor­
car engines, and who, after recovering consciousness, displayed symp­
toms of distinct mental impairment, the symptoms lasting some­
times for many months. It seems reasonable to suppose that
if gassing in garages has this effect—an effect also noted some­
times after accidental or suicidal illuminating-gas poisoning—
it must also follow other forms o f industrial carbon-monoxide poison­
ing, but there is nothing in American medical literature which fur­
nishes a positive answer to this question. It may be that there is
something in the mode of poisoning in garages, or in the character
of the exhaust gases, which are known to contain other toxic com­
pounds besides carbon monoxide, which will account for these serious
aftereffects, and that these factors are not present in other forms
of industrial carbon-monoxide poisoning; or it may be that the
prominence of the victims of exhaust-gas poisoning and the more
thorough medical examination accorded them have resulted in knowl­
edge concerning the remote effects of the accident, which in the case
of laboring men might fail to be discovered, or, if discovered, fail
to be reported. This is another question to which so far no positive
answer can be given.
It is true of all well-known industrial poisons that however strik­
ing and distressing are the acute effects, they are neither so numerous
nor so permanently crippling as are the injuries caused by long
exposure to small repeated doses of the poison. An acute attack of
lead colic is agonizing, but the man may recover from it completely,
while the results of repeated minute doses of lead, such as a printer
may absorb throughout 20 or 30 years of work, may result in a general
hardening of all the blood vessels, with a consequent slow starvation
o f the organs through an insufficient blood supply. The same thing
is true of benzol poisoning. Acute poisoning may bring a man close
to death’s door, but if he escapes he usually recovers completely. On
the other hand, slow benzol poisoning attacks the tissues on which
he must depend for the formation o f blood and brings about a degree
of anemia that may be fatal. Reasoning from such industrial poisons
as these, whose effects are well known, it is a natural supposition that
the same thing would be true concerning carbon monoxide—that
workers exposed over months and years to air contaminated with
small quantities of this gas would suffer from symptoms less striking
than those of acute gassing but really more serious. Concerning this
also, the evidence, even in foreign literature, is inadequate and un­
satisfactory, white in the United States there is absolutely none.
Yet hundreds of thousands of men and women work in air which
contains small quantities of carbon monoxide, enough, often, to cause
headache and dulling of the intellect. Such conditions are found
in printing shops, in pressing rooms of clothing factories, in bak­
eries and laundries, in soldering, and in new buildings where sala­
manders are used to dry out the walls.
Therefore, in planning a survey of carbon-monoxide poisoning in
the United States, the following problems were considered to be the
ones especially calling for study and solution:
First. The actual extent of acute carbon-monoxide poisoning in
American industry, and its distribution throughout the different
branches of industry.



Second. Does such acute poisoning cause lasting damage to the
victim after the subsidence of the acute symptoms?
Third. Is there any difference in the character of carbon-monoxide
poisoning in the various industries, and, if so, what is the ground for
this difference?
Fourth. Is there any evidence of chronic industrial carbon-monox­
ide poisoning, and if so, what is its character and in what industries
does it occur?
It has been possible to make only a preliminary survey of the
extent and seriousness of industrial carbon-monoxide poisoning in
the United States. The results presented have been gathered from
the following industries: The manufacture of steel; the manufacture
of coke by-products; the smelting of zinc; the production of sublimed
zinc oxide; the smelting of lead; coal mining; metal mining; the
manufacture of illuminating gas; the laying of gas pipes and the
reading of gas meters; the testing of motor cars, repair work, and or­
dinary garage work; and linotype work in printing shops which use
a gas jet under the lead pot. The last two industries were selected as
probable sources of chronic carbon-monoxide poisoning.
In order to have a clear idea of the nature of carbon-monoxide
poisoning, it is necessary to go to foreign sources in part for informa­
tion, although, whenever possible, American authorities have been
used. A great deal of valuable material is furnished by the United
States Bureau of Mines, and, under the auspices of this bureau and
of the Public Health Service, experiments are at present being car­
ried on by experts to solve some of the outstanding problems with
regard to carbon-monoxide gas. In the following section of this
report a brief review is given of the essential facts, so far as they are
known, concerning the mode of action of carbon monoxide, as gath­
ered from German, French, British, and American literature.
According to Haldane,1 a man at rest can breathe an atmosphere
of one part of carbon monoxide per thousand parts of air two
hours and a half before the blood becomes saturated with it to
the extent of 50 per cent; but in a man at active work a like at­
mosphere will cause' unsteady gait and other symptoms in one
hour, an atmosphere of two parts per thousand will cause un­
steady gait and increasing powerlessness in half an hour, and with
three parts per thousand this condition comes on in 20 minutes.
When the amount of carbon monoxide in the air is not more than
one part in a thousand, the symptoms come on slowly if the man is at
rest, but the blood may progressively take up carbon monoxide till
fully 50 per cent of the hemoglobin has been saturated with it. At
that point the man is suffering from the effects so that he is confused,
his intellect dulled, and there is muscular weakness. If he remains
at rest he may escape serious damage, but even at this concentration
of gas, if he makes great exertions to escape from such at­
mosphere, he may lose consciousness. It has often happened
1 Haldane, John S.
p. 89.

Quoted in Occupations, by Thomas Oliver.





that members of a rescuing party have suffered more severely
than the men they came to save, because they were working hard
while the latter were sitting still. With two parts of carbon monox­
ide to a thousand parts of air, utter powerlessness and unconscious­
ness come on, and three parts mean death unless rescue is fairly
The onset of symptoms may be as sudden as a stroke of lightning,
but usually, even in exposure to a high percentage of the gas, the man
has some warning, such as pressure and throbbing in the head,
“ caving in ” of the knees, blurred sight, roaring in the ears, pain
in the stomach, a sweetish taste in the mouth, or nausea. Some men
can tell that an attack of gassing is threatened by the effect on the
throat—a feeling of dryness and constriction. Glaister,2 of England,
says that coal miners have told him of feeling weakness in the legs,
which warned them that they ought to leave the mine, but the gas
had so dulled their minds that they kept on working mechanically till
they fainted. Apfelbach,3 of Chicago, observed some 300 cases of
industrial gas poisoning and found that in about one-third of the
cases there were no warning symptoms at all. It is easy to see> the
reason for this in the steel industry. Blast-furnace gas contains about
30 per cent of carbon monoxide, which is a much higher percentage
than would be encountered in any but an unusual mine accident, and
the effect on the man breathing it would be almost instantaneous.
The cases caused by blast-furnace gas and producer or power gas
usually come on with rapidity. The same thing is true in some cases
of mine accidents, wheh death has apparently occurred almost in­
stantaneously, for the men are found sitting in natural positions,
perhaps with their lunch in their hands, or with their picks as if they
had just paused in their work. The most detailed descriptions of
gradual gassing come from coal mines. The classical one is that
given by Sir Clement LeNeve Foster, who was severely gassed while
engaged in rescue work in the great Sna^fell mine disaster. He
writes: “ I suddenly felt decidedly queer, took out my little brandy
flask, but already my fingers seemed incapable of opening it. Every­
thing seemed to be in a whirl; there seemed to be a dense white fog.
We all sat without trying to escape. The foot of the ladder was
quite near, but none of us made an effort to reach it.” When he
found himself being overcome, he took out his notebook and wrote
a farewell letter to his wife and children. In this letter he would
repeat certain words, even whole sentences, again and again. He
remarks: “ I had absorbed enough of the poison to paralyze me to
a certain extent, but at the same time my reason had not left me.
The general sensation was like a bad dream, and yet I was able to
reason properly and write intelligently, though in a disjointed
When he was rescued and brought to the surface he had a feeling
of exhilaration and was in full possession of his senses, for he asked
the physician to take a sample of his blood. An hour afterwards
he wired to his wife as follows: “ Am perfectly right; do not believe
any report to the contrary. I repeat I am perfectly right. Clement.”
3 Glaister, John, and Logan, David Dale. Gas Poisoning in Mining and Other Indus­
tries. New York, 1914.
3 Apfelbach,. George. In Diseases of Occupation, by Kober and Hanson. Philadelphia,
1916, pp. 43-74.



A few hours later he felt very sick, and afterwards became uncon­
scious and had an epileptiform seizure.
According to many authorities, in carbon-monoxide coma, the lips
should be rosy red and there should be an appearance of perfect
health, but in industrial cases this seems to be rarely true. It is
much more common to find pallor, with red blotches on the skin,
and blue lips. These red spots are areas of distended blood vessels,
but there may be also actual hemorrhages into the skin. The pulse
is slow, strong, and full; then, if the case becomes more serious the
pulse changes and is rapid and weak. A disturbance of the blood
vessels is seen in flushing of the skin, followed by cold sweats. Gil­
man Thompson,4 of New York, has studied the course of 90 cases of
carbon-monoxide poisoning who were taken to hospitals and there­
fore could be carefully observed. Following are the most important
of his findings:
All were unconscious when brought to the hospital. They had
been poisoned by gas containing for the most part 5 to 10 per cent
of carbon monoxide, but in some instances as high as 20 to 30 per
cent. In almost all cases there was fever, sometimes preceded by a
subnormal temperature. The fever lasted from one day to a week;
the maximum duration in any noncomplicated case was 22 days. In
cases which were not fatal the highest temperature, with the excep­
tion of one unusual case in which the temperature reached
108°, was 104.8° F.; in fatal cases, 107°.5 The pulse was’ rapid
and weak, but regular. The respiration was rapid, regardless
of the condition in the lungs, and was labored and jerky, usually
30 to 36 per minute, and in one case as high as 80. The
symptoms in the digestive tract were not severe nor characteristic,
nor was there any characteristic change in the urine. On the other
hand, in the 29 cases in which blood counts were made, an increase
of white cells was found in all but two. Of these 27 cases, 18 had
counts between 18,000 and 44,000 (the normal number is about 7,000),
and all of those who died (17) had counts above 18,000. The increase
in white cells reached its maximum in 24 hours, but sometimes not for
48 hours, and this cpndition subsided slowly, lasting sometimes for
three weeks. It was always a sign of danger to life.
The nervous symptoms were varied. As the patients recovered
consciousness, there was confusion, drowsiness, headache, vertigo,
blueness of the lips, hands, and feet, reddened areas over the body,
and disturbances of sight. Sometimes mental weakness, loss of
memory, dullness, and confusion would last for days; sometimes
muscular weakness or muscular spasms would develop; but usually
there was prompt recovery. It was shown that even if uncon­
sciousness lasted for four or five days the patient might recover.
There were convulsions in 7 per cent of the cases. Pneumonia
seldom occurred, and death was due, not to this complication, but
to the effect of the poison on the brain.
The later consequences of gassing have been described by British,
French, and German writers, and apparently differ somewhat,
according to the character of the accident. Thus, Glaister believes
that the effect on the heart is not so marked in coal-mine gassing as
4 Thompson, W . Gilman. Medical Record, 1904, vol. 66, pp. 4 1 -4 7 .
5 Apfelbach has seen cases with a temperature of 107° F. and even one of 110°
just before death.

51863°— 22-------2




in producer-gas poisoning, where the loss of consciousness may
apparently be due to heart failure. Slow, gradual gassing un­
doubtedly causes much more severe permanent damage than does
quick gassing, even though the latter may bring on deep coma and
convulsions, and seem for the time being much more serious. It
is the victims of slower gassing in coal mines and garages who are
most likely to develop pneumonia, weakness of the heart, paralysis,
and mental disturbances, not the victims of sudden gassing at blast

A man who recovers from a fairly severe gassing has a throbbing
headache, a sensation of constriction in his temples, a feeling as if
his head would split, he is dizzy, his legs and sometimes his arms,
back, and neck feel powerless, and he may even not be able to
hold up his head. He is numb, and there are instances in which
a man who has been burned while unconscious does n’ot feel the
pain of the burn after he regains consciousness. He shivers and
can not get warm, he has a feeling of oppression in the chest and
palpitation of the heart, and if he attempts to walk home he may
bring on a cardiac weakness. Pneumonia is a very important
aftereffect, and in countries which grant compensation for occupa­
tional diseases, a very puzzling situation frequently develops in
connection with pneumonia after gassing. The British believe
that carbon monoxide is a more frequent cause of pneumonia in
miners than even nitrogen-oxide fumes, although the latter are very
irritating to the lungs and would seem to do much more damage.
They believe from their experience, not only in England, but in
the mines of South Africa, that carbon monoxide lessens the resist­
ance of the lungs, and therefore prepares the way for pneumonia.
In the mines of the Rand, this is the great occupational disease.
The ore mined there is siliceous, and after some years of work
the men’s lungs are affected with silicosis. These men are said to
be prone to pneumonia after carbon-monoxide poisoning, the condi­
tion of their lungs rendering them less resistant to its effects.
Cases of post-gassing pneumonia usually develop one to three days
after the accident and may be ushered in by a hemorrhage from the
lungs. The characteristics of this form of pneumonia are that it is
lobar in type, caused b the pneumococci, the right lung is mostly
affected, and the disease develops rapidly. The temperature is not
high, but the pulse is disproportionately rapid and thready, the heart
dilates, and if death occurs it is early in the course of the disease,
on the third or fourth day.
For descriptions of the nervous symptoms and the mental symp­
toms following carbon-monoxide poisoning it is necessary to turn
almost exclusively to foreign literature, especially the English and
French, for there is very little in the American, and of the few cases
that have been described in the United States the majority are con­
nected with but one source—the exhaust gases of motor-car engines.
On the other hand, the English have a wealth of material of this sort,
chiefly from their coal mines, and the French also, from a great variety
of industries in which coal gas is used as a source of heat and light.
Glaister finds nervous and mental disorders so common among coal



milkers that he calls them characteristic of colliery accidents in
England and he believes that the action of carbon monoxide is most
marked on nerve tissue. He finds the same thing to be true of
illuminating gas and automobile exhaust gases. He describes many
cases of mental impairment, especially loss of memory, loss of initia­
tive, inability to work hard, depression, dullness, premature senility,
childishness, and change of disposition.
A striking instance given by him was an accident that occurred
about the year 1900 in the Coltness Iron Works. An engineer, 20
years of age, described as being a most intelligent workman, was sent
into an exhauster, a space just large enough for one man, to make some
repairs about the fans. The air inside was tainted with carbon
monoxide. When he came out after finishing his work he complained
of feeling a little giddy, but, remembering that he had left his chisel
behind, he went back to get it and had no sooner entered the exhauster
than he collapsed and sank unconscious to the bottom. There was
no way of getting him out except by taking the exhauster to pieces,
unscrewing bolts, etc., and by the time this was done he had been
about an hour in this confined place, breathing an atmosphere with
an unknown percentage of carbon monoxide. The accident happened
between 11 and 12 in the forenoon. After a long struggle he recov­
ered consciousness, but was dazed and stupid, talked incoherently,
and was very “ heady ” till 5 or 6 in the evening, when he began
to talk quite rationally and could write his name. Except for these
first few hours he had little apparently wrong with him for nearly
three days, when suddenly his mind became a complete blank. He
knew nobody, not even his own mother, and could do nothing on his
own initiative. His powers of speech, sight, and hearing were good.
I f asked to look through a window at a horse he would repeat the word
“ horse,” but if questioned further his answers would be silly and
irrelevant. He had to be tended like a baby. This went on for a
month or two, then there was a slight improvement, and he is described
as being at this stage like a big simple child, who was very easily
managed. After a time he was given lessons by the village school­
teacher, beginning like a child with his alphabet, and soon after he
started work, but here also he had to begin as an apprentice, as he
had forgotten everything, even how to handle his tools. At the end
of ten years he was in the best of health, talking rationally and
intelligently, and seeming to an ordinary observer quite normal,
but those who knew him before his illness said that mentally
he was only a shadow of his former self. He had lost all initiative,
always had to be told what to do, and if a responsible job was given
to him he was sure to get excited. His memory was poor, he was
very easily irritated, losing command of himself, and then was hardly
responsible for what he did. After an attack of anger or excitement
his memory became much worse. He was, however, constantly
Many instances could be given from both English and French lit­
erature of mental deterioration following accidental gassing. The
most important symptom in these cases seems to be loss of memory.
Briand,6 of France, declares it to be quite common. It is not slow
6 Briand.

Annales d’hygiene publique et de m&decine l&gal, 1889, vol. 21, p. 357.



and progressive as in alcoholic dementia, but comes on suddenly.
Usually it is only as to events following the accident, but sometimes
it takes the form known as retrograde amnesia, wiping out the mem­
ories of past life. In a case reported by Sanger Brown, of Chicago,
the events of the three or four days just preceding the accident were
erased along with those of the days just following. Apfelbach, like all
American observers, finds this condition very rare in industry, but
gives the history of one typical case. This man lay in coma for 12
hours, then he was delirious and had involuntary evacuations And
muscular twitchings. After the delirium passed off he was stuporous
or confused and apathetic. When Apfelbach saw him four months
later he had lost memory for places, could not find his way about the
works or find his way home; he could not remember having seen the
doctor before. He had lost the memory of all the events of his life
except his childhood, and could not recollect the happenings of a day
or two previous. His speech was slow and his gait slow and awkward,
but his reasoning powers were good.
The most carefully studied instances of this aftereffect of carbon-monoxide poisoning in American literature are those that come
from exposure to the exhaust gases in garages, probably because the
victims are often educated men, not infrequently physicians, who are
able to describe their own mental symptoms clearly and who are
attended by well-trained physicians. One such case is described by
Dr. C. W. Hitchcock,7 of Detroit. A chemical engineer of college
education was overcome by carbon-monoxide gas in his garage and
was found unconscious on the floor more than an hour later, the
engine of the car running at the time. He was given medical treat­
ment at once and partly recovered consciousness some four or five
hours later. The week following he was very weak and could recog­
nize his friends but would forget that any one of them had been there
as soon as he left the room. About five months later when Dr.
Hitchcock saw him he was lax in his personal appearance, quite un­
like his normal self, and his face had rather a blank expiession.
He lacked initiative for any work, could drive his car only in quiet,
familiar places, was despondent and not so friendly in his attitude
to people as before. He had begun to be able to listen to and follow
short stories. Five months later he was better but still unable to re­
sume work; his memory was still uncertain, especially for the most
recent events. Things happening five or ten minutes back seemed
the hardest to recall. He could remember events of the past eight
months, but the first two months after his accident were almost a
blank. He was still depressed and it would take him a whole after­
noon to do what he would ordinarily have done in 10 minutes. He
lacked his former ambition and energy and was decidedly wanting
in initiative. Fourteen months after the accident his memory was
still poor, but he was gaining somewhat in self-confidence.
Much less common than the above form is delirium or mania fol­
lowing gassing. Cases of this sort have been reported in connec­
tion with a colliery accident in Scotland and the inhalation of char­
coal fumes in France and of coal gas in Germany. Usually the
effect is transient, but a case seen by Thomas Oliver8 was insane
7 Hitchcock, Charles W . Journal American Medical Association, 1918, vol. 71, p. 257.
8 Oliver, Thomas. Diseases of Occupation. London, 1908, p. 60.



for two years. Such cases have sometimes been of medico-legal
importance, for the victims may during the period of excitement
commit a crime, even a murder. According to Dr. Ira Miltimore,
at that time with the Illinois Steel Co., at Gary, Ind., it is not at
all uncommon to have a man who has been gassed while at work
pass through a stage of violent delirium. He described a typical
case as follows: The man is overcome by the gas, but does not lose
consciousness completely. He is hurried by ambulance to the hos­
pital, reaching there usually about 10 or 15 minutes after the oc­
currence of the accident. By this time he is often delirious, even
maniacal, so that he has to be restrained in bed. This stage, how­
ever, lasts only a few hours; then he gradually becomes rational
and complains of intense headache. European authorities say that
excitement, delirium, or hysterical symptoms are more likely to
be seen in women than in men.
Among the nervous aftereffects of severe gassing paralyses of all
kinds, but most often of the legs, are found. Such paralysis may
come on at the time of the accident or develop some days later.
Almost all the motor nerves have been involved in different cases,
and besides this form of paralysis there may be injury to the vaso­
motor nerves or to the optic nerve. Two cases of this kind have
been described by W. J. McGurn,9 of Boston, as cases of multiple
sclerosis due to repeated inhalation of carbon monoxide by men
working over hot-water heaters with leakage of gas. The first had
an acute attack of gassing with a terrible headache, dizziness, vomit­
ing for several hours, bluish lips, and unsteady walk. Four days
later he 'complained of numbness in the legs and difficulty in walk­
ing. Two weeks later he had double vision. All this time he con­
tinued working at the leaky furnace. His condition grew progres­
sively worse, and at the end of two years he was unable -to walk,
there was atrophy of the muscles of the back, legs, and arms, there
were wide areas of anesthesia, and his sight was failing; and his mind
was unimpaired, but he had lost the sense of position of his limbs. He
died six years later, emaciated and helpless from muscular contrac­
tures. The Wassermann test was negative. The second case, also of
a man exposed for some time to gas from a leaky furnace, began in
very much the same way, only the symptoms were even severer, for
he was delirious, with rapid, labored respiration, wide pupils not
reacting to the light, and for several minutes clonic convulsions.
There was loss of strength in the right hand, doss of sensation, and
diminished vision, especially in the right eye. These acute symptoms
cleared up and, though his vision was impaired, he went back to
work. He quickly became much worse, lost strength and weight, his
gait was spastic, he could not coordinate his muscles, and he had
mental depression, loss of memory, and some defect of speech.
Finally he could not stand alone or lift a foot from the floor, or
feed himself. After 16 months in the country, he recovered the use
of his limbs, but typical symptoms of disseminated sclerosis, an
intention tremor, a loss of sense of position, and atrophy of muscles
9 McGurn, W m . J.

Medical Record, 1917, vol. 91, pp. 1 4 9 -1 5 1 .



The relapsing form of carbon-monoxide poisoning is a term used to
indicate those cases which, having apparently recovered from the first
effect of the poison, develop, after a period of fair health, serious
symptoms that may lead to death or insanity. Several instances of
this form are described by McConnell and Spiller,1 of Philadelphia.
One was a man of 69 who had been overcome by carbon monoxide
and had dizziness and headache persisting for a long time. A month
after his apparent return to health he developed paralysis of the
right side, quickly followed by his death. Another was a woman
who, after recovery from acute poisoning, developed mental dis­
turbance, aphasia, convulsions, and rigidity of the muscles. She
had been overcome by coal gas and had seemed to recover, but then
passed into a condition of paralysis with contraction of the muscles,
including those of mastication, so that she had to be fed through a
nasal tube. She died 40 days after her accident.
Lewin,1 of Germany, who has had much to do with the medico­
legal aspect of industrial poisoning, says that these cases present
great difficulty when it comes to deciding questions of compensation.
He mentions a man who’ after severe gassing recovered and at the
end of 36 hours was apparently well except for headache, but 20
days later he had a recurrence with increasing paralysis of the limbs,
which was complete on the 24th day, and on the 25th he died. An­
other victim of gas was able to be up and about for 5 or 6 days after
his accident, then he was seized with convulsions, followed by lockjaw
and death. After lighter poisoning, Lewin has often seen pneumonia
come on some 6 to 14 days later; after severer poisoning there may be
mild or severe nervous symptoms, sometimes no more than what are
usually called “ accident neurosis,” that is, a sense of weariness and
general illness, with pains in the legs, and sometimes much severer
symptoms, such as blindness, deafness, paralysis of various kinds,
or delirium or dementia. This latter class of cases may also develop
pneumonia and bloody urine. The prognosis is always poor in cases
that suffer a relapse.

There are a few special symptoms of gassing which should be
mentioned before leaving this subject. The occurrence of fever has
already been spoken of. It usually comes on during the period of
unconsciousness and may last till consciousness returns or even longer,
while in some cases it appears first several days after the accident.
Sometimes the rise of temperature is very high, especially if there are
convulsions, and this is always an extremely grave sign. The highest
thus far noted was in a case of Apfelbach’s, which reached 110° F.
just before death.
A rapid loss of weight after gassing with carbon monoxide has
been observed frequently and can be produced experimentally in ani­
mals, but it seems probable that in these cases there has been an
injury to the central nervous system; in fact, such cases usually show
paralysis or mental impairment. Diabetes is one of the possible
1 McConnell, J. W ., and Spiller, W illiam G.
Journal American Medical Association,
1912, vol. 59, pp. 2123 and 2124.
1 Lewin, L.
Die Kohlenoxydvergiftung.
Berlin, 1920.



aftereffects, and so are various forms of skin disease, although car­
bon monoxide is not at all irritating to the skin. They, too, are
probably of nervous origin. There may be excessive perspiration,
or dropsy of the skin, or eruptions, blisters, necrosis, and even gan­
The digestive system may undergo a great variety of disturbances,
such as excessive salivation, bleeding from the gums and throat,
gastric and intestinal indigestion, vomiting, and severe abdominal
pain. There are no characteristic changes in the urine. In the
lungs all sorts of inflammatory conditions may be found. The heart
symptoms are among the most constant: Rapid pulse, palpitation,
low blood pressure, and often irregularity. A permanent weakening
of the heart is one of the most frequent aftereffects of accidental
carbon-monoxide poisoning.
The changes in the blood vessels are important from the medico­
legal point of view, for if acute carbon-monoxide poisoning has the
effect of weakening the walls of the blood vessels, then an apoplectic
stroke, which follows (even after a fairly long interval) an acci­
dental gassing, should be regarded as an industrial accident. This
view has been repeatedly held in England and occasionally in the
United States. For instance, recently in one of the large steel towns
in the United States a man was gassed, lost consciousness, was
under medical treatment for several days, then went back to work
and was apparently well for about a month, when he died from
hemorrhage in the brain. The coroner’s office held that since the
man was only 32 years old and not a syphilitic, the damage to the
vessel wall which led to its rupture was to be traced to the effect of
the gas. It has been shown repeatedly in animal experiments that
coal gas causes relaxation of the blood vessels through a sudden
weakening of the muscular fibers. This causes slowing of the circu­
lation and the collection of blood in the smaller vessels, and then
degenerative changes, especially fatty, in the walls of the arteries.
Hemorrhages into the skin from rupture of vessels on the surface
of the body are not at all unusual, causing red blotches on the skin
and purple spots on the lips and the mucous lining of the mouth.
Among the more unusual symptoms which have been attributed
to carbon-monoxide poisoning are paralysis of some of the muscles
of the eyes, leading to the well-known miners’ nystagmus. Affections
of the optic nerve, leading to partial or total blindness, have occurred
after severe gassing, and so have affections of the nerve of hearing.

Carbon monoxide can pass from the mother’s blood into the blood
of the fetus, and, according to Nicloux,1 the latter may contain an
equal quantity of gas. Lewin describes the case of a woman who,
toward the end of her pregnancy, attempted suicide with illuminat­
ing: gas. She was found unconscious in the morning and 11 hours
later gave birth to a dead child, which was, however, so rosy that the
midwife attempted artificial respiration, unable to believe that it
was dead. It was found that one-fifth of the baby’s hemoglobin
had taken up carbon monoxide. In another case the mother’s blood
1 Nicloux, M.

Comptes rendus de la Societe de Biologie, 1901, vol. 53, p. 120.



contained 18 per cent carbon monoxide and the blood of the fetus
only 4.07 per cent. It has long been believed, since Roman days in
fact, that the smoke from extinguished candles would bring about
premature labor, and Lewin believes that there is evidence to show
that while slight carbon-monoxide poisoning in the mother may
produce no symptoms striking enough to arouse attention, it may be
quite enough to kill the child in utero, and that such poisoning is
probably fairly common in industries where women are employed
and where the air is vitiated with carbon monoxide. He has known
of an instance of this sort, a pregnant woman working on a print­
ing press which was driven by a gas motor. Some accident allowed
gas to escape, she was seized with symptoms of carbon-monoxide
poisoning, and aborted.

Every student of carbon-monoxide poisoning is impressed with
the great variety of injuries which it may set up. In this respect
carbon monoxide differs from every other known poison. Even the
symptoms of acute poisoning vary more than is usual, and when
it comes to the aftereffects, it seems that any organ or tissue of the
body may show injury, and it is impossible to predict what the
course of any individual case will be. To begin with, there is a
great difference in individual susceptibility, and although it seems
plain that drunkards succumb soonest, still that is not nearly enough
to account for the varying effects of the gas on different victims
who, apparently, have been exposed to the same amount. For in­
stance, in the greatest mine disaster on record, the one in the Courrieres district in France, 1,100 men died from carbon-monoxide
poisoning and 13 escaped. It has been said by some that women
are less susceptible than men, and that in cases of family poisoning
it is more likely to be the woman who escapes with her life than
the man, but in such cases the source of the gas is usually some leak
from the domestic supply, and it is quite possible that the woman,
employed in the house for most of the time, has acquired a partial
immunity by breathing small quantities of gas for many days. The
Zola case was cited in proof of the theory that women resist gas­
sing better than men. Madame Zola lived while her husband died,
but he was found dead on the floor, having gotten up from bed, and
it may be that the exertion he had made was the last straw.
According to Glaister, experienced foremen in industrial estab­
lishments in England believe that vigorous young men are espe­
cially liable to be gassed, and that middle-aged men should always
be selected for a piece of work which involves exposure. Glaister
agrees with this and considers that the young and the old are both
oversusceptible, the former probably because of their deeper in­
spirations and greater chest capacity.
When chronic carbon-monoxide poisoning is considered the situa­
tion is not nearly so clear, The symptoms which may be attributed
to long exposure to small quantities of this gas are not character-



istic and might be explained on other grounds, especially as they
are usually found in working people, in whose environment and
mode of life there are many features besides the exposure to gas
which could be held responsible for ill health and for the more or
less vague symptoms of which they complain. It is in European
countries, especially in France, that we find the theory held most
generally as to the injury caused by chronic carbon-monoxide poi­
soning. In 1869, Moreau,1 of Tours, proposed to call the mental
disorders of carbon-monoxide poisoning “ the insanity of cooks ”
( folie des cuisiniers ), because so many cooks were subject to it. Illventilated gas stoves, devoid of flues, such as are found in poor
dwellings, are looked upon by the French as the probable source of
many unrecognized cases of poisoning. Even more frequent in
France is the escape of gas from the slow combustion coal stoves
so common on the Continent. Landouzy1 emphasized this at the
meeting of the International Congress of Tuberculosis in 1905, and
said that the disappearance of anemia and headache in poor people
who were sent to the country could be explained by their escape from
carbon-monoxide poisoned air to pure air.
See,3 in 1873, wrote about “ The dizziness of cooks,” and de­
scribed a condition which he said was very common among them,
consisting in severe headache, sometimes intolerable, dizziness, mus­
cular weakness, sense of weariness, staggering gait, and sometimes
nausea and vomiting. Usually the attack began after leaving work
and going out into the fresh air, or on waking in the morning, or
at the end of the day’s work. Some men never experienced it;
others seemed to acquire a tolerance which could, however, be upset
by an unusually long exposure. These men practically always
suffered from digestive disturbances.
From the British it is learned that the most serious symptoms of
chronic carbon-monoxide poisoning consist in disturbance of thenervous mechanism of the heart, palpitation, distress over the heart,
a feeling of oppression, and irregular pulse, which on very slight
exertion becomes rapid. Observations were made on steel workers.
Glynn,1 in 1895, described chronic poisoning in a boy of 16 who
was employed in a shop where the air was contaminated with carbon
monoxide. He suffered, from pain in the calves of the legs, loss of
power affecting especially the extensor muscles, tenderness on pres­
sure, and sensations of crawling and pricking. He recovered on re­
moval from work. Glaister believes that women feel the effects of
chronic poisoning more than men; that in factories where the air is
contaminated with gas the women suffer more from nervous symp­
toms than do the men.
The changes in the blood which are caused by carbon monoxide have
been studied in connection with chronic carbon-monoxide poisoning,
with varying results. The effect of saturating some of the red cor­
puscles with carbon monoxide instead of oxygen is to cause a number
of fresh corpuscles to be thrown into the circulation in an effort to
1 Moreau. Quoted by Glaister and Logan in Gas Poisoning in Mining and Other In­
dustries, p. 276.
1 Landouzy, L. London Lancet, 1905, Vol. II, p. 1433.
1 SSe.
Quoted by Glaister and Logan in Gas Poisoning in Mining and Other Indus­
tries, p. 312.
1 Glynn, T. R. British Medical Journal, 1895, vol. 1, p. 759.

51863°— 22-------3



keep up a normal supply of oxygen. This means that the red-blood­
cell count may be high in a man who is continually exposed to car­
bon monoxide. Yon Jaksch reports a blood count of 6,390,000
per cubic millimeter (the normal number is five to five and
one-half million). Glaister examined a stoker in a gas works who was
suffering severely from loss of motor power, pain in his abdomen and
in the left side of the head, loss of appetite, and weakness. Three
counts of the blood showed, respectively 8,200,000, 9,500,000, and
11.200.000 red cells, but the hemoglobin was only 62, 76, and 90 per
cent. 'H e was sent to the mountains and gained in weight but was
otherwise unimproved, and four months later the count was still
between 9,400,000 and 11,000,000, with hemoglobin of 90 per cent.
This increase in red corpuscles is found both in experimental animals
and in human beings without any symptoms of ill-health at all.
Nasmith and Graham1 succeeded in keeping the blood of guinea
pigs 25 per cent saturated with carbon monoxide for days at a time.
The animals were lively and continued to gain weight normally and
their blood showed a decided increase of red blood corpuscles. An
examination of the blood of steel workers was made by Apfelbach
and Karasek for the Illinois occupational disease investigation in
1910. Sixty-eight men, all steel workers who had either been recently
gassed or subject to frequent gassings, were selected, and the blood
examined for hemoglobin and red and white cell counts. They found
that there was an increased number of red cells which ran from
5.500.000 to 9,676,000, more than half, or 66 per cent, being over
6,000,000, but no immature red cells were found. The hemoglobin
ran from 95 to 125 per cent, more of them being over than under 100
per cent. No abnormality was found in the white corpuscles.
Apfelbach later presented the results of 5 examinations made of
people suffering from acute carbon-monoxide poisoning, and 11 of
men and women employed in work exposing them to chronic poison­
ing. The first series of examinations may be briefly summarized as
showing that after severe gassing the blood has on the third day
and still more on the sixth day an increased number of red cor­
puscles, from 100,000 to more than 1,000,000 over the normal. The
second series of examinations is more interesting and is reproduced



LFrom Kober and Hanson, Diseases of Occupation, Philadelphia, 1916, p. 72.]



Tailor shop.........................................
Male . . . ___ Can manufacturer..............................
.. do...................................................
. . . . do...................................................
Do ........
D o .........
.. ..d o ...................................................
Do . . ..

1 Nasmith and Graham.

How long

Journal o f P hysiology.

cell count.

5,280, 710

Symptoms noted.

Headache, anorexia.
Headaches, anorexia.

London, 1906— vol. 35, p. 32.



Some years later, in 1917, the Illinois Steel Co. undertook an
examination of 176 blast-furnace and open-hearth men at the Gary
and South Chicago plants. These employees were given physical
examination, analysis was made of the urine, and the blood ex­
amined for percentage of hemoglobin and for the red-cell and white­
cell count. The men had all been employed for several years in
work which exposed them continually to small quantities of carbon
monoxide and the majority of them had suffered from acute gas
poisoning. The records of the examination were furnished by the
chief surgeon.
The men who had suffered from acute gas poisoning, in describing
their experience, said that usually they noticed first a severe head­
ache, dizziness, ringing in the ears, weakness of the legs, nausea and
vomiting, and in some cases loss of consciousness. After regaining
consciousness a severe frontal headache would persist for from a few
hours to a few days. None of the men were at that time suffering
from any nervous disorders nor were the findings from the blood
examination or from the urine analysis of any particular significance.
The red blood-cell count was as follows:






of men.

Red blood cells per cubic millimeter.

O P E N -H E A R T H


Per cent
of total.

Under 4,500,000.............................................................
4,500,000 to 5,000,000.....................................................
Over 5,000,000 to 5,300,000...........................................
Over 5,300,000 to 5,600,000...........................................
Over 5,600,000 to 6,000,000...........................................
Over 6,000,000........... .....................................................
N ot examined...............................................................






This shows that only 15 per cent of the men had red-cell counts
much above the average and only 2.2 per cent had counts which
woirld be called strikingly high. The white-cell count showed noth­
ing of interest, nor did the urine analysis or blood-pressure esti­
mations. It must be remembered in discussing such results as these
that a group of men who have worked for years at blast furnaces
and open hearths, many of them working a 12-hour shift regularly,
can not be regarded as average men—they are a selected group, they
represent the survival of the fittest, for no man of only average
physique could endure the strain. I f one were really to seek an
accurate picture of the effect of such work as this on ordinary men,
one would have to examine not only those still employed but those
who have been obliged to drop out.
In works on chronic carbon-monoxide poisoning Grawitz1 is
always quoted, and sometimes the quotation is much more emphatic
than Grawitz’s original statement. What he says is that anemia of
profound degree, resembling pernicious anemia in type, may be
found as a result of continual breathing of carbon monoxide in
coal gas, such as he saw in a woman who did pressing in a tailor shop
and in whom this seemed to be the cause. Lewin speaks of pro1 Grawitz, E.

Klinische Pathologie des Blutes.

Leipzig, 1911, p. 416.



found anemia with a red-blood-cell count as low as 1,500,000 as a result
o f chronic poisoning. On the other hand, there are some observa­
tions o f a high red-cell count with low color index; that is, a low
percentage of hemoglobin. One of these was reported by Rein­
hold.1 The man was employed in a gas factory, working for two
years on a 12-hour shift and exposed to a good deal of gas. After
nine months he began to suffer from a sense of weariness and weak­
ness, left-sided headache, loss of appetite, alternating with rave&ous
appetite, and pains in the abdomen. No carbon monoxide was
shown by the spectroscope, but a count of the red cells gave 9,500,000,
but only 76 per cent hemoglobin, and later on 11,200,000 with 90 per
cent hemoglobin. A similar though not so striking a case is reported
by Apfelbach, of Chicago. This man was working for certain
periods every day over a burning soldering machine, during which
time it was possible to inhale carbon-monoxide fumes. His symptoms
pointed to profound anemia. Apfelbach ruled out tuberculosis, lead
poisoning, and nephritis, and, finding that the man had a red-cell
count of about 7,(X)0,000, he made the diagnosis of chronic carbonmonoxide poisoning. The man improved on changing his work.
An interesting finding and one which, if confirmed, would be of
decided economic importance, was that made by Karasek and Apfel­
bach in the course of an investigation of carbon-monoxide poisoning
for the Illinois Cpmmission on Occupational Diseases in 1910. They
examined 400 workers, half of them employed in the steel works of
South Chicago, the other group employed in plants where there was
no possibility of carbon-monoxide poisoning. The two groups were
of the same nationalities and the character of their work was similar,
as were also their home conditions. A comparison was made of the
muscular strength of the hand, using the ordinary hand d3mamometer, and, as shown below, it appeared that the steel workers ex­
posed to carbon monoxide had decidedly less muscular strength than
working men of the same age not so exposed.
Ages 20 to 40 :
Steel workers_________
Car-company workers.
Other trades.
Ages over 40:
Steel workers________
Car-company workers
Other trades.

Average strength.

134. 48
127. 25
113. 01

The whole question of chronic carbon-monoxide poisoning is very
obscure as to its nature, its prevalence, and its diagnosis. It can not
be regarded as caused by an accumulation of carbon monoxide in
the body, which reaches a certain degree and then produces symp­
toms, because that could occur only if a person were breathing
carbon-monoxide contaminated air all the time, and this is never
true. During the hours when pure air is being taken in, the carbon
monoxide is pretty quickly discharged. However, it is possible
that, although the gas does not accumulate in the blood, there may be
a piling up of the slight injuries produced by its presence until the
point is reached when the effect on the health becomes noticeable.
This effect may be simply a slow starvation of the tissues, but if
1 Reinhold.

M iinchener m edizinische W ochenschrift, 1904, vol. 51, p. 739.



such starvation results in impairment of function of an organ, the
secondary effects of that may be decidedly harmful. There is a
marked variation in the way different individuals are affected by long
exposure to small quantities of carbon monoxide. One person will
suffer from ill-health, constant headache, neuralgic pains, perhaps
albumen in the urine, after a few months’ work in a room where
others have passed several years with no trouble at all. An interest­
ing report from France by Courmont2 'describes the effect on 35
individuals of working for periods up to three years in a room with
leaking gas pipes. It was found that the air had contained from
time to time 1 part of carbon monoxide in 1,000 parts of air to 1 in
10,000 parts of air. Twelve of the 35 had albuminuria and three had
sugar in the urine, but none had any symptoms of heart weakness or
of damage to the blood vessels. They complained of headache in
the forehead or temples, less often in the back of the head. Thirtytwo out of the 35 had neuralgic pains in the lower part of the back
or in the intercostal nerves, and in some cases there were areas of
great tenderness on the skin and sensation of crawling or pricking.
There is great difficulty in diagnosing this form of occupational
poisoning, because so rarely are the symptoms at all characteristic.
Usually there is only complaint of headache, palpitation of the
heart, breathlessness, general nervousness, ana disturbed sleep.
Indigestion (especially for solid food), loss of appetite, and acid
eructations two or three hours after meals are very common. There
may be sleeplessness at night and drowsiness in the daytime. Often
this drowsiness is so great as to lead to the taking of stimulants.
The French attribute the alcoholism of male cooks to the effect of
gas from the stoves, and say that they suffer from loss of energy and
great irritability.
A great number of industrial workers are exposed to small quan­
tities of carbon monoxide in the course of their work, and may
suffer from poisoning, although there is almost no positive evidence
that this is actually the cause of the ill-health so often complained
of in these trades. Those who are most in danger are thought to
be the following:
Laundry workers, especially ironers.
Pressers in tailor shops.
Furnace tenders.
Gas workers, especially men making connections and reading
Painters working in rooms in which salamanders are kept burning
to dry the walls.
Printers, especially linotypists, and men working at melting kettles
heated with gas.
Molders of metal where gas is used for heat.
Men working in canneries on soldering machines.
Miners, especially in mines where blasting is done continuously.
Garage workers, especially repairers.
The results of tests made on garage workers and linotypists to
determine the presence of carbon monoxide in their blood are given
in the final sections of this report.
2 Courmont, Jules.

Bulletin de l’Academie de M6decine, 1910, vol. 64, pp. 491-503.



Although the effect of these industrial gases is always attributed
to the carbon monoxide which they contain, it must not be forgotten
that there are dangerous substances present besides carbon monoxide.
Analysis of coal gas shows the presence not only of large propor­
tions of carbon dioxide, nitrogen, and hydrogen, but such toxic
gases as benzol and toluol* sulphureted hydrogen, hydrocyanic acid,
and a small quantity of ethylene. The most important constituent
next to carbon monoxide is undoubtedly benzol. This is a wellknown poison, for it is used largely in industry as a solvent for
gums, resins, fats, and rubber. It is obtained in the distillation of
coal in the production of coke, as one of the'by-products, together
with toluol and some xylol. These three compounds all have the
same effect on human beings, but toluol is weaker than benzol and
xylol distinctly weaker than toluol.
Benzol attacks the central nervous system, causing loss of con­
sciousness, muscular twitching, sometimes convulsions, and death
from respiratory failure. I f the dose is not so large, there is dizzi­
ness, confusion, roaring in the ears, impairment of vision, headache,
and nausea. I f benzol is inhaled in small quantities for a long
period of time, a chronic poisoning is set up which shows itself in
very profound anemia, loss of both red and white blood cells, and
in hemorrhages into the tissues under the skin and through the
mucous membranes, the skin shows purpuric spots like bruises,
there is bleeding from the gums and throat and sometimes from
the stomach and the intestines. Hemorrhages into such tissues as
the brain and spinal cord cause symptoms of paralysis and mental
It is quite possible that some of the puzzling features of carbonmonoxide poisoning will be found to belong not to carbon monoxide
but to benzol. The chronic anemia of slow gassing and the nervous
and mental symptoms which follow both rapid and slow gassing
are possibly referable to the benzol present in the gas. Illuminating
gas practically always contains benzol and in greater proportion
as the proportion of water gas increases. Gases from motor engines
contain benzol, especially when the fuel is composed of coal-tar oils
as well as petroleum oils. It is possible that this is the explanation
of the puzzling fact that paralysis and mental disease seem to occur
so much oftener after gassing accidents in garages than after any
other form of industrial carbon-monoxide poisoning.
Experimenters have found that if they use coal gas as a substitute
for pure carbon monoxide their experiments will not come out the
same. An interesting observation was made by Staehelin, who was
experimenting on frogs with carbon monoxide. Having no more pure
gas he tried to use ordinary illuminating gas instead, but found that
he got quite different results—rigidity of the muscles, and con­
vulsions, which had never followed the use of pure carbon monoxide.
Then he tested the other constituents of illuminating gas and found
that benzol in the same proportion as that found in the gas would
get up convulsions and muscular rigidity.
In the early days of motor cars the cases of gassing that occurred
from breathing the exhaust gases o f engines were attributed to



gasoline fumes and the name “ petromortis ” was given to accidents
of this sort. Later on all these came to be regarded as caused by
carbon monoxide, and yet there are some clear instances on record
of very much the same form of poisoning which were clearly due
to the fumes of gasoline. For instance, there were 42 cases of gaso­
line poisoning in a tunnel in Montreal in 1913. The men were
asphyxiated, unconscious, with flushed faces; rapid and deep breath­
ing, and in two instances, in convulsions. They recovered conscious­
ness, complaining of severe frontal headache, and the next day they
seemed all right. The air of the tunnel was analyzed and gasoline
fumes were found but not carbon monoxide, nor did a spectroscopic
examination of the men’s blood show any carbon monoxide.
Potts described in 1914 a case of poisoning which closely re­
sembled those caused by carbon monoxide, but here too gasoline
fumes were responsible. This man worked for four months filling
automobile tanks with gasoline. He was ill for about two months
with intense headache, vomiting, and sometimes double vision. One
day while at work he fell to the ground in a faint and when aroused
he complained of headache, his left side was weak, and there was
some incoordination in his left arm. He improved but did not re­
cover the strength of his left arm nor of the muscles of the eye.
The other gases which may be present are probably of far slighter
importance. Sulphureted hydrogen begins to produce a toxic effect
when present in the proportion of 1.5 parts to 10,000 of air and is
dangerous when the quantity reaches 5 parts, but it is doubtful
whether this gas plays an important part in coal-gas poisoning ex­
cept perhaps in the manufacture of illuminating gas or in the gas
from coke by-products or in certain conditions in coal mining.
Ethylene has been regarded as possibly an important element in coal
gas because it is extremely destructive to plant life, but the evidence
seems to show that it is fairly harmless to man.
Hydrocyanic acid, or cyanogen, is present in the gas from coke
by-products and may be present in illuminating gas and in blast­
furnace gas. A recent report from Germany2 is interesting as
pointing to the presence of some unknown poisonous fumes in blast­
furnace gas. In a plant situated in the Saar Yalley dry scrubbing
of the furnace gases had been substituted for wet. The report, which
is made by a factory inspector, states that after this change was
made several men were overcome by gas from the scrubbers, but
although the acute symptoms were quite like those of ordinary
carbon-monoxide gassing, the men did not recover completely, but
there was very decided mental impairment which necessitated treat­
ment in the insane asylum. The report was made some three months
after the accident, and during that time there had been no improve­
ment in their condition. No cases of this kind had ever been observed
at the plant while the wet scrubbing was used, showing that some com­
pound or compounds which were formerly removed by the wet process
remained after the dry scrubbing. The management suggested that
possibly some arsenical or cyanogen compound might be responsible.
2 Derdack.

Zentralblatt fur Gewerbehygiene, 1920, vol. 8, p. 90.



The sources of carbon-monoxide gas in human environment are
very numerous, but by far the most important is the burning of car­
bon-containing material with an insufficient supply of oxygen.
Much the largest number of cases of carbon-monoxide poisoning
occur as the result of breathing air in which the products of such
combustion are present. ’ Coal gas, which is a product of incomplete
combustion, consists essentially of carbon monoxide and carbon
dioxide, the mixture of which is heavier than atmospheric air.
These two gases are odorless, but almost always they carry with them
enough odorous bodies to give warning of their presence. The actual
composition of coal gas varies greatly according to its source. The
following are a few analyses given by Lewin:
Glowing anthracite coal (results of seven analyses) : Per cent of carbon
monoxide, 0.16, 0.19, 0.26, 0.3, 0.44, 0.56, 0.62.
Coal from burning wood (average of eight analyses) : Carbon monoxide, 0.34
per cent; carbon dioxide, 6.75 per cent; oxygen, 13.19 per cent; nitrogen, 79.72
per cent.
Brown coal in the form of briquettes, burning slowly, yielded the following:
Carbon monoxide, 10 per cent; carbon dioxide, 90 per cent.

In the course of coking coal the percentage of carbon monoxide
produced varies according to the character of the coal, the per­
centages in German coke works running from 8.9 to 7.1.
Blast-furnace gas is very rich in carbon monoxide, resulting from
reduction of the oxide ores by means of glowing coke, and in addi­
tion there is the carbon monoxide formed by the burning of the coke.
German blast-furnace gas contains from 24 to 25.97 per cent.
American analyses usually demonstrate about 26 per cent, though
sometimes as high as 30 per cent.
Power, producer, and generator gas contain different amounts of
carbon monoxide, according to the source and method of production,
the limits being from about 22.8 to 26 per cent.
The detonation of explosives produces large quantities of carbon
monoxide, the burning of explosives a smaller quantity. German
experiments have shown that the explosion of celluloid forms n gas
containing 45.7 per cent carbon monoxide, while the burning of cellu­
loid films has been known to give off gas containing 26.3 per cent.
The explosion of gunpowder results in a gas containing only 3.6 to
9.26 per cent carbon monoxide, but the gas from the explosion of
pyroxylin contains 46.87 per cent, of dynamite 34 per cent, of
trinitrotoluol 57 per cent, and of picric acid (lyddite, melinite)
61 per cent. The gases that are found in mines and tunnels after
explosions produce their effect chiefly through their carbon-monoxide
content, although if there is much hydrogen sulphide present this
may also have a toxic action.
Several analyses have been made of the gas from open braziers
filled with glowing coke, and it was found that in a well-ventilated
room the air 15 to 25 centimeters (5.9 to 9.8 inches) above the burning
coke contained 0.83 to 1.4 parts of carbon monoxide per thousand
parts of air; in a poorly ventilated room, 1.3 to 1.6 per thousand. It
was found that the highest percentage of carbon monoxide in a room
heated with a brazier of coke was to be found up under the ceiling



because the heat carried the gas up. The amount found at this height
was sometimes six times as great as that near the floor. This fact is
important in connection with the use of salamanders by painters to
dry out the walls of new buildings while painting is going on, for a
painter may breathe enough carbon monoxide while up on a scaffold
to make him dizzy so that he falls to the floor.
The smoke from locomotives that collects in tunnels has been
analyzed and in one Italian tunnel a large amount of carbon monoxide
was found. This was the Ronco Tunnel on the Turin-Genoa line,
where an average of 1.9 per cent carbon monoxide was found, with
3.6 per cent as the maximum. Two analyses ^fiade in American tun­
nels showed far less carbon monoxide. The Fulton Tunnel of the
Pennsylvania Railroad yielded an average of only 59 parts of carbon
monoxide per million parts of air and a maximum of 267 per million
(0.0059 and 0.0267 per cent). The tunnel of the Baltimore & Ohio
Railroad under the city of Baltimore yielded only 25 parts of carbon
monoxide per million parts of air.
Illuminating gas varies in composition in different cities, the pro­
portion of carbon monoxide depending on the amount of water gas
which is added to the coal gas (see p. 36). When made from
cannel coal, illuminating gas oontains about 4.5 per cent carbon
monoxide. The gas used in London has from 4 to 7.5 per cent;
that in Paris, 5 to 6.6 per cent; that in Bordeaux, 10 to 12 per cent;
and the gas used in German cities averages about 7.3 per cent. The
addition of water gas and the consequent increase in the carbonmonoxide content are more common in this country than in any other,
the average amount of carbon monoxide in the gas in American cities
being usually between 27 and 30 per cent, far higher than in any other
country. Pittsburgh uses natural gas, which is said to have not more
than 13.25 per cent carbon monoxide.
The most conspicuous cause of death from carbon-monoxide gassing
at present is connected with the testing, repairing, and use of auto­
mobile vehicles, for the exhaust gases from their engines contain
fairly large proportions of carbon monoxide (see p. 41). Analyses
of these gases made by J. N. Schumacher, chemist for the city of
Chicago, gave an average of 9.3 per cent carbon monoxide. German
reports give from 3.7 to 7.0 per cent.
The principal sources of industrial poisoning from carbon mon­
oxide, with the per cent found in each, are as follows:
Per cent.

Steel manufacture, blast furnaces---------------------------------Making illuminating gas:
Coal g a s _____________________________________________
5 to 8
Water g a s ___________________________________________Up to 30
Making coke (by-products)______________________________
6 to 40
Use of producer or power gas (for smelting zinc, lead,
etc.; metallurgical plants of all kinds; foundries;
glass works; laundries; bakeries; brick and cement
kilns; enameling porcelain; enameling sanitary ware;
heating and steam power plants)______________________
9. 3
Exhaust gases from motor engines______________________
Mining explosions and mine fires________________________ 2. 7 to 47. 4



The British statistics2 divide the industries in which carbon
monoxide is a danger into four groups. Their reports for six years,
from 1908 to 1913, inclusive, give the following figures:


of cases.


Per cent

Blast-furnace gas.........................
Power, producer, and suction
gas.......... f ...........................
Coal gas.........................................
Other gases...................................











During the years 1914, 1917, 1918, and 1919 the. number of cases
increased and the severity also increased, as shown by the higher
mortality rate. While in the earlier years the average number of
cases per year had been 62.5, in the later period it was 75. The
mortality in the earlier period was 46 out of 375 cases, or 12.3 per cent,
while in the later period it was 52 out of 300 cases, or 17.3 per cent.
Gassing from blast-furnace gas furnished the highest mortality, no
less than 22.8 per cent for the later period, while the cases caused by
coal gas had a mortality of only 10.6 per cent and by power gas of
12.9 per cent.
There are no statistics in the United States at all comparable to
these, but the information that is available has been collected and
is presented under the industries in which the gassing occurred,
namely, the steel works, manufacture of illuminating gas, and
metal and coal mining.

The material for this study was obtained in the steel towns of
the Chicago and Pittsburgh districts and in South Bethlehem.
The modern blast furnace gives off 150,000 to 200,000 cubic feet
of gas per ton of fuel consumed. The charging is done automati­
cally and the gases are no longer allowed to escape into the air,
but are utilized for fuel, having about one-half the heating value
of coke. They pass through “ downcomers5 and mains to be freed
of dust and on into scrubbers and washers, where a stream of
water removes various by-products, of which benzol is the most
Since the purpose of the blast furnace is to bring about reduction
of iron ores by means of carbon monoxide formed by the burning
of coal or coke, the quantity of this gas in the blast furnace may be
large. When the heat in the furnace is between 600° and 700° C
(1112° and 1292° F.) combustion with air results chiefly in the
formation of carbon dioxide, but from that point up to *1000° C.
(1832° F.) carbon monoxide is produced in increasingly large
proportions, and above this point practically all the carbon is given
off in this form. As the zone of fusion is at a temperature of from

22 Annual Reports, Chief Inspector of Factories and Workshops. London, 1913 and




1200° to 1600° C., (2192° to 2912° F.) it is easy to see how much
risk of gassing there is at the top of the furnace and how much
more dangerous is the old type of top-filler furnace, some of which
are still in use in the larger plants, and many in the smaller ones.
Two statements concerning the composition of blast-furnace gas
were given by men connected with large plants in Illinois and in
Pennsylvania, essentially the same though varying slightly in the
proportions :

Plant -1.

Carbon monoxide...................................
Carbon dioxide........................................
Metnane or marsh gas............................

Plant 2.

Per cent.

P er cent.



Another company official from an Ohio plant said that the escap­
ing blast-furnace gas might run as high as 50 per cent carbon
Figures as to carbon-monoxide gassing have been furnished by the
Illinois Steel Co., which has three large plants near Chicago. The
records of this company show the following number of cases of
gassing during two periods. The first period was from 1912 to
1915, inclusive. Among 1,112 men employed at the blast furnaces
and in the boiler house the average number of cases of carbonmonoxide gassing per year, cases severe enough to require medical
care, was 66, and the average number of deaths per year 3.25, making
a mortality of only 5 per cent, which is decidedly lower than the
British rate.
During the five years 1916 to 1920, inclusive, the records of the
large plants of the Illinois Steel Co. were as follows:



South Chicago.


gassed. deaths.
ber Deaths. num­
ber Deaths. ber

1916.............. 8,684
1917 . . .
1919.............. 9,618
1920.............. 10,825


Total. 51,019

















1 No deaths up to June 4.

The grand total, 271 cases in five years with 13 deaths, or a mortal­
ity of 4.8 per cent, is far lower than the mortality in Great Britain
from blast-furnace gas—22.8 per cent for the period 1914-1919.



Nevertheless, extensive and disastrous accidents do still occur from
the escape of carbon-monoxide gas in various parts of American steel
plants. A wholesale poisoning of some 55 men during the fall of
1919 in a plant in Pennsylvania illustrates very strikingly what may
occur when gas with this composition pours without warning into the
air of an inclosed space in which men are working. For the details
we are indebted to Dr. Francis D. Patterson, of the Pennsylvania De­
partment of Labor and Industry.
The men were engaged in relining a blast furnace which had been
cut off for 22 days from the gas mains while the repairs were in
progress. In order to prevent the gas which was passing through the
mains from reaching this particular furnace, water seals were used,
although the company had been warned not to place entire depend­
ence on water seals, but to use goggle valves. The men in charge,
however, believed that they had an entirely efficient system of water
sealing, for instead of the usual depth of 3 feet of water they used
approximately 5 feet. This apparently was efficient as long as the
water was maintained at that level. A watchman was placed at the
water seal to see that everything was working properly by watching
the overflow pipe, for as long as the water continued to flow from the
overflow pipe the seal was full and there was no danger of the gases
surging through. If, however, the supply of water failed or leaked
out, an excessive gas pressure, as high as 26 inches for instance, might
allow the gases to burst through, and once the water seal was broken
the gas might continue to flow through the seal.
On this particular day water seals had been placed in the main line
which was in operation, on either side of the line leading to the fur­
nace under repair, in order that the water seal at this furnace could
also be repaired. The latter was drained after the seals on the two
neighboring furnaces had been filled, and a watchman was placed
on guard at each seal. At about the lunch hour the man on one of
these seals went to the foreman and asked to be allowed to go and get
some tobacco. The foreman sent another workman in his place to
guard the seal, an ignorant man, who, as was shown at the inquest,
could not speak English intelligently and who was quite ignorant of
the extremely dangerous nature of blast-furnace gas and the grave
responsibility with which he was charged. He noticed at once that
the seal was not working properly, as water was not running from
the overflow pipe, but not realizing the danger he did not give any
warning to the men working in the furnace; instead, he went first to
the pump house and then to the boiler house to see what was the
trouble with the water seal. Examination made subsequent to the
accident showed that the water in the seal had fallen and the gas
had broken through. The concentration of carbon monoxide in the
gas when it forced its way through the water seal to the top of the
furnace through the downcomer pipe was estimated at 10 to 15 per
cent at the very least. The result was the gassing of some 55 men
and the death of 25. It was possible to secure the records of the sur­
viving 30, who were incapacitated for varying periods, as follows:
111 for 3 days 6 men, 4 days 8 men, 5 days 3 men, 6 days 1 man, 7 days
1 man, 8 days 1 man, 9 days 6 men, 10 days 2 men, 11 days 1 man, 15
days, 1 man.
Eighteen months later inquiry was made as to the condition of
these men, and although it was not possible to secure personal inttfr-



views with them it was found that they were at that time in the em­
ploy of the same company, and according to the statement of the
company physician none showed any effect of the gassing. Even
•if a careful examination of the nervous system had not been made
in these cases, it was evident that the survivors of the accident did
not suffer enough injury to impair their working powers.
In 1916 the United States Bureau of Mines made a study of the
danger spots in the steel industry, so far as gassing accidents were
concerned. Their report describes some 120 cases of asphyxia, usu­
ally fatal, either from the direct effect of the gas itself or from an
accident which occurred because of the loss of consciousness brought
on by the gas. The sources of the gas in these accidents are the
Bustle pipes_______________________
Furnace stacks____________________
Blast-furnace tops_________________
Hot-blast furnaces________________
Cleaning boilers___________________


Gas outside of boilers--------------------Downcomers______________________
Mains________________ ____________
Holders and washers______________


Some of the more interesting instances have been selected from
this report. A man was overcome with gas on the bustle-pipe plat­
form and was drowned by falling into a water trough. An elec­
trician was asphyxiated while changing carbons on an arc light on
the sheave-wheel platform. An oiler was killed by falling from the
sheave-wheel platform to the changing platform when partially over­
come by gas. Seven men were gassed while attempting to make
repairs on the small bell rod inside a receiving hopper. A rigger, sit­
ting in a boatswain’s chair and tearing down the skin wall in a well,
was overcome with gas which was being drawn in from a leaky
burner through an open burner door, and he was killed by falling to
the bottom of the well. A stove cleaner entered the dome of a
stove the hot-well doors of which had been opened to cool the stove,
but the burner door had not been closed, and gas from the burner,
which was leaking badly, killed him. A boiler cleaner also was
fatally gassed on entering a dust chamber before the leaks had been
stopped. Another fatal case was attributed to the leakage of gas
into a coal boiler from another boiler through cracks in the partition
walls. Two boiler-house men were enveloped in a cloud of steam
on the top of the boiler. Becoming bewildered, they tried to escape
the steam by retreating to the front of the boiler, where there were
no steps down, and by the time other men had succeeded in closing
off the steam and had come to look for them one had been fatally
gassed from the leaky burners beneath. In attempting to close an
explosion door beneath a boiler-house roof blown open by a slip
12 men were overcome and 2 of them died.
The largest number from any one department in this list came
from the work in the mains (34). This is found in all statistics
of blast-furnace gas poisoning. Apfelbach found more cases among
cleaners of cold mains than in any other one department, and 23
out of 68 cases reported by the British factory inspectors for 1918
were of men cleaning mains. The dust in the mains holds the
carbon monoxide, and it is released as soon as the dust is disturbed.
All of the cases given above are o f acute severe poisoning. In
many instances it is not possible to ascertain whether loss of con­
sciousness was instantaneous, although sometimes, even when the



accident has been fatal, there are evidences that the man made some
effort to escape. Apfelbach was able to interview 300 American
steel workers who had been acutely gassed, and found that in about
one-third of them loss of consciousness came on without warning.*
In the others the prodromal symptoms were throbbing and pressure
in the temples, ringing in the ears, weakness in the legs, a feeling of
“ caving in ” at the knees, or sluggishness of movement, or even a
feeling of being glued to the spot. Less often a sweetish taste acted
as a warning, or dry throat, or palpitation of the heart, or distress
in the stomach, or nausea. According to this same observer, the
breathing of blast-furnace gas does not cause coma as often as does
illuminating gas. He saw only 65 cases of typical coma in 261 cases
of gassing in steel workers. The others had only stupor or mental
confusion. Glaister also says that there is more serious coma in
men who are gradually poisoned by gas in mines or by producer gas
than in steel men who are suddenly exposed to enormous doses.
A physician in charge of one of the great American steel mills, a
man who had had many years’ experience with this sort of work,
described a typical case of gassing as follows: The first stage, which
comes on quickly, is one of confusion or stupor or actual loss of con­
sciousness. The physician does not see the man till some 5 or 10
minutes later, when he has been hurried in a motor ambulance to
the hospital, which is on the grounds of the plant. By this time the
stupor, unless it is very deep, has begun to pass off, and the man is
often slightly delirious. This increases after he has been put to bed,
and it is sometimes necessary to put him under restraint because of
his maniacal excitement. This condition lasts for a few hours, rarely
over night, and he then recovers consciousness with an intense throb­
bing headache, nausea, and more or less gastric pain. In the experi­
ence of this physician such cases recover with varying promptness,
but always completely. He has never observed any aftereffects.
It is easy to obtain histories of acute gassing in the steel works, but
impossible to discover anything further, either from the physicians
or from the men themselves. Every effort was made to cover this
part of the investigation thoroughly, for it was believed that since
the reports from Great Britain, Germany, and France showed that
permanent damage to the heart or the nervous system sometimes fol­
lowed gassing in steel works in other countries, although not nearly
so often as gassing in coal mines, it must be possible to discover some
such instances in American steel towns where many thousand work­
men are employed and where instances of gassing are not uncommon.
The physicians connected with steel works in the Chicago district,
the Pittsburgh district, and in South Bethlehem were interviewed,
but although they were all quite frank as to the occurrence of very
severe and even fatal gassing, they had none of them anything to
say about remoter effects from such an accident—pneumonia or
cardiac weakness or loss of memory or paralysis. Then the inquiry
was extended to the other physicians in these towns, men not con­
nected with the steel works and not bound by loyalty to the com­
panies. It was supposed that through them some such cases would
come to light, but their testimony was quite as negative as that of the
company doctors. It was not easy to approach the workmen them­
selves, for the great strike was only recently over and they were in



a very timid and suspicious state, unwilling to answer questions of
any kind. South Chicago was the only one of these towns which
still openly maintained union headquarters and where it was possible
to talk to some of the blast-furnace men. They, too, stated that no
matter how badly a man was gassed, if he did not die he recovered
completely. The^ had never heard of an instance of loss of memory
or mental aberration or paralysis resulting from a gassing accident.
In all these steel towns the clergymen and the charity workers were
visited and questioned, for it seemed more than probable that they
would be able to tell of cases of this sort if any had occurred, but no
history was obtained from any of them. That this was not due to a
desire to conceal facts was evident by the frankly prolabor attitude
of several of them, who freely denounced the policy o f the companies
with regard to the 12-hour day, the 7-day week, the working condi­
tions, and the personal relations between employers and men, but even
they did not believe that gassing accidents ever resulted in permanent
damage of any kind.
Now, this evidence is, of course, purely negative, but it seems
convincing. I f one goes into a lead smelting community, one
can always get histories of cases of lead palsy, and lead colic, and
sometimes lead convulsions simply by talking to townspeople, drug­
gists, clergymen, and shopkeepers, to say nothing of the non­
industrial physicians. Such cases become matters of ordinary
gossip. It seems impossible that anything so conspicuous and unusual
as a mental breakdown, after a gassing accident to a steel worker,
should occur in a fairly small community without anyone hearing
of it and spreading the tale. For some reason, probably because of
the sudden excessive exposure to carbon-monoxide gas, such as is
found in the steel works, the damage to the central nervous system
that comes from oxygen starvation does not take place. The acci­
dent occurs suddenly, and the man is quickly removed from the
poisonous atmosphere, so that the duration of oxygen deprivation is
very short and his blood rids itself of carbon monoxide very rapidly.
A longer exposure means death. Only one instance of damage to
the brain as a result of an accident of this kind has come under
observation, and that was Apfelbach’s which has been already
described. Watkins, of the Public Health Service, has found that
the air where furnace men are working may easily contain as
much as 0.01 per cent of carbon monoxide. He would regard 0.01
per cent as the limit of danger, but the usual view is that anything
less than 0.03 per cent is harmless.

The material concerning carbon-monoxide poisoning in mining
was gathered in the copper regions of Arizona and Montana, and
in the coal regions of Illinois and Pennsylvania. All available
data from the United States Bureau of Mines were also utilized.
The gaseous impurities in the air of coal mines and metal mines
come from the use of explosives in blasting; from mine fires, due
not only to the burning of the wood used in construction, but also to
the combustion of the pyrite ores or native sulphur; from acci­
dental explosions, especially of coal dust; from the gases given off
by shale; from the exhalations of men and animals.



The normal proportion of oxygen in the atmosphere is 20.93 per
cent. In the air o f good mines it is rarely lower than 19 per cent,
but in certain mines where the coal and shale is of such a
character as to oxidize quickly, it may fall to 18 per cent. Oxygen
is also taken up by decaying timber, and in the neighborhood of
crushed timber the air may be impoverished to such an extent as
to cause discomfort to the men. Another cause of oxygen dis­
appearance is the burning of lamps. The following gases are
found at times in mine air, the first two practically always in small
proportions even under normal conditions: Carbon dioxide, which
is produced in excess by blasting, by mine fires, by oxidation of organic
matter, coal, and shale, and by animal breath; carbon monoxide,
caused by blasting and by mine fires; nitrogen oxides, N 0 2 and N20 3,
produced when explosives are incompletely detonated and burn
instead of discharging; ethane, C2
H6, from natural gas; sulphureted hydrogen, from heating of sulphurous coal in mine fires,
and, rarely, from natural sources, such as sulphur springs or the
action of acid waters on sulphite ore, or by the reducing action of
bacteria on sulphates in water, so that dangerous quantities may be
liberated by stirring up stagnant water in old mine workings; sulphur
dioxide, from the burning of pyrite ores or native sulphur; and
hydrogen, formed by fires and by explosions.2
Since blasting is a normal process of mining, the gases formed by
the explosion of the different substances used are of greater im­
portance than those formed by any accidental occurrence. The tests
made by the Bureau of Mines of different compositions used in
blasting show that the following poisonous gases (the nonpoisonous
are omitted) are produced in widely varying proportions. The
column showing the percentages of carbon monoxide is the most


Per cent of—
c o 2.
30 per cent nitroglycerin dynamite....................................................
40 per cent nitroglycerin dynamite. . . . . . .......................................
50 per cent nitroglycerin dynamite....................................................
60 per cent nitroglycerin dynamite. . . . . ...............................
60 per cent low freezing dynamite. . . . . ...........................................
40 per cent ammonia dynamite...........................................................
40 per cent gelatin dynamite...............................................................
40 per cent burned gelatin dynam ite...............................................
5 per cent granulated nitroglycerin powder ............. ....................
FFF black blasting powder, tested in gauge...................................
FFF black powder when used in coal
. ..................



N 0 2.

h 2s .


It is obvious that since these gases are formed by the ordinary
processes of blasting, there is far more danger in mines where blast­
ing goes on all day than in those where the firing of the shot comes
at the end of the shift and the men do not have to return to the gal­
lery for some hours. I f the blasting is continuous, the gases from

23 Rice George S. In Mining Engineers’ Handbook, sec. 23. New York, 1918, pp. 13861391.
24 Idem, p. 1390.



one explosion may affect the men working at quite a distance from it.
According to Bureau of Mines’ tests, carbon monoxide in propor­
tions running from 3.23 to 9.59 per cent has been found as much as
350 feet away from the site of the blasting. After an explosion in an
Alabama mine2 a gang sent in to do recovering was waiting at a base.
The whole party was almost overcome by carbon monoxide and was
saved only by a stream of fresh air, yet the men’s lamps were burning
brightly and nobody had noticed anything wrong till suddenly sev­
eral of the men sank down unconscious.
In the instructions issued by the Bureau of Mines, the following
statements are made: Anything above 0.15 per cent carbon monoxide
is dangerous and 0.4 per cent may be fatal. For continuous exposure,
0.03 per cent is to be considered unsafe, as the action is cumulative.
In an atmosphere with 0.04 per cent carbon monoxide 4he blood
finally reaches one-third saturation with carbon monoxide. In an
atmosphere of 0.08 per cent it reaches one-half saturation, and in one
of 0.16 per cent it reaches two-thirds saturation. But in all these
cases the accumulation of carbon monoxide in the blood is slow. In
one experiment in which 0.2 per cent carbon monoxide was used, 50
per cent saturation was not reached till after 70 minutes. When the
blood has reached 20 per cent saturation, there is a tendency to dizzi­
ness and shortness of breath on exertion. At 50 per cent the man can
hardly stand and slight exertion causes unconsciousness.
A few words must be said as to the other gases formed in blasting.
Carbon dioxide is toxic in its effect, although its action is produced
partly by the lack of oxygen when carbon dioxide is present in large
quantities. A change in respiration is said by Haldane to begin when
there is 3 per cent carbon dioxide in the air. Breathing changes to
panting at 6 to 7 per cent; the face is flushed and the pulse rapid. At
10 per cent breathing is very difficult and after that the narcotic effect
begins, with confusion of mind. Animals die sometimes when the
proportion of 25 per cent has been reached, but they may survive
even 50 per cent. The miner’s candle goes out when the percentage
of oxygen has fallen to 17 per cent with 2 per cent carbon dioxide.
Such an atmosphere is not dangerous. Death comes when the oxygen
has fallen to 5 per cent and is due to this, not to carbon dioxide
Death from nitrogen oxide fumes is said to be a not uncommon
occurrence in the mines of the Rand in South Africa. According to
Irvine,2 many cases occur each year in these mines from the custom,
which still generally exists, of blasting a second time shortly after
the first blasting. This practice is very dangerous, as it exposes the
miner to an atmosphere highly charged with dust and with the fumes
of carbon monoxide and other gases. Exposure to 0.05 per cent of
nitrous fumes was found by Haldane to cause death in mice, but not
till after 24 hours. The gas does not produce any startling effects at
first, so that the man has little warning of danger. An illustration of
its effect was given by Johnson2 in the Colorado Journal of Medicine.
In a western tunnel the air was filled with nitrous fumes by a change
in the tentilating current. The men experienced choking, nausea,
2 Rice, George S. In M ining Engineers’ Handbook, sec. 23. New York, 1918.
« - Irvine. Transvaal Medical Journal, 1912—
13, vol. 8, p. 30.
Quoted by Rice, George S. Mining Engineers’ Handbook, sec. 23. New York, 19 IS,
p. 1401.



profuse perspiration, and headache. They revived in the open air,
but later began to cough blood and mucus. Nine of the 13 died
within three days and the others, including some of the rescuers,
were ill for months.
Sulphureted hydrogen is poisonous in small quantities. Lehmann
says that 0.07 per cent is deadly to man in one hour. In larger
quantities it produces unconsciousness, and death comes on very
rapidly from paralysis of respiration.
The next commonest source of carbon monoxide and other gases
in mines is fire from the burning of coal dust or of timbers, or the slow
combustion of the coal itself, the gas seeping into the working part
of the mine because it has been incompletely walled off. Slowburning fires, without explosion, are common in the coal mines of
Illinois, Jowa, and Missouri, which are nongaseous mines. The
burning areas are often shut off and ignored, and then carbon mon­
oxide finds its way through leaks. These fires also occur in aban­
doned mines in the thick-bed anthracite region. Fires may start
spontaneously in the Arizona and Montana copper sulphide mines
also, in old stopes, and the gases formed consist not only of carbon
monoxide and carbon dioxide from the burning timber, but also of
sulphur dioxide from the sulphide ore. In fighting mine fires carbon
monoxide is the great danger, and these fires are most common in
coal mines where gob fires are always occurring.
The spontaneous explosion of coal dust results in the formation
of carbon monoxide in dangerous quantities. Another source of
this gas is the internal combustion engine, such as is used for gasolinedriven pumps and locomotives. The exhaust from these contain
carbon monoxide and dioxide according to the carburetor adjustment
and the size of the engine. Tests made by the Bureau of Mines show
that under the worst conditions the carbon monoxide in these exhaust
gases is about 13.5 per cent, but under normal running conditions
rarely over 6 per cent. However, even under normal conditions it
would be necessary to have a current of air sufficient to dilute this
down to 0.02 per cent, the safety limit.
Mine gas is an increasing danger in the United States as the
mines grow deeper, for the deeper the mine the more the gas accumu­
lates, the greater the difficulty of maintaining adequate ventilation, and*
the greater t]ie possibility of men being trapped in inaccessible places.
Statistics of the Bureau of Mines contain the fatalities which have
occurred since 1870, but it is not possible to discover how many of
these were due to the effect of gas. Bulletin 115 of the Bureau of
Mines contains the fatalities between 1870 and 1914, and there are
two headings under which deaths by gassing are grouped. Suffoca­
tion from mine gases caused 263 out of the 52,187 total fatalities
between 1870 and 1914 (49,733 from 1870 to 1913 and 2,454 during
1914). Suffocation by powder gas caused 127 deaths between 1870
and 1913. The other headings under which it is reasonable to sup­
pose are included deaths from gases are gas explosions and burn­
ing gas, coal-dust explosions, and gas and dust explosions combined,
and mine fires, burned, "suffocated, etc. Under these headings, to­
gether with the heading “ suffocation from mine gases,” we find in
Bulletin 196 the cases which occurred between 1914 and 1919, inclusive.
The men killed by gas explosions and burning gas made up from



3.68 to 13.53 per cent; coal dust and gas explosions were responsible
for 0.69 to 6.66 per cent; suffocation from mine gases from 0.48 to
0.71 per cent; mine fires from 0.05 to 1.01 per cent. The number
of employees during these years was between 720,000 and 763,000.
So far as one can discover from these reports, the deaths are
attributed to the principal factor in the accident. Thus, in Bulletin
115, it is stated that mine fires were responsible for 1,053 deaths
between 1867 and 1912, but no statement is made as to what actually
killed the men, whether it was burning or gassing from the products
of combustion. In all probability the latter is the more important
of the two. Naturally nonfatal accidents are described in even less
detail. The statement is made that between 1911 and 1914 about 30
men in a thousand suffered from accidents incapacitating them for
20 days or more, and about 150 were incapacitated from 1 to 20 days,
but there is no way of knowing how many of these were gassing
According to Hayhurst,2 who made a thorough study of the
health of coal miners in Illinois and Ohio, there is not so much
carbon monoxide in American coal mines as in the English, because
our mines are not so deep nor are they so dry, and dryness leads to
dust explosions resulting in the production of 4.5 to 5 per cent car­
bon monoxide. In Illinois coal mines blasting is not continuous, the
shooting being done at the end of the shift. The same thing is true
in the Arizona copper mines, but in Montana copper mines blasting
is continuous, and according to the Bureau of Mines there is much
more carbon monoxide in these mines. There are some coal mines
in Ohio where blasting is continuous, and the miners often complain
of daily headache.
Gassing in mines is usually gradual, although in serious accidents
it may be rapid, almost instantaneous. Men have been found dead
with placid expression and no evidence of suffering or struggle, some­
times even with their picks in their hands, or their luncheon. Glais­
ter says that even after the miner has had warning of disaster by
the feeling of weakness in his legs and arms, he may sometimes keep
on working because his intellect is so much dulled that he has not the
will to stop. Lewin tells of three miners who were killed by the gas
following blasting, even though the mine ventilator was going.
They went into a stope soon after blasting with dynamite and were
found dead on the floor. Examination showed that carbon monoxide
mixed with the dioxide had settled heavily near the floor.
These facts, scanty as they are, cover the available information on
gassing in American mines. Visits to coal-mining regions in Illi­
nois, Pennsylvania, arid Alabama did not result in any important
addition to the facts gained from the reports of the Bureau of Mines
and from Hayhurst’s study. Just as in the steel towns, it was easy
in these coal regions to hear of cases of severe gassing, although they
seemed to be not nearly so frequent as in steel work. It was also
easy to find men who complained of headache and general discomfort
and misery at the end of their day’s work, but it was not possible to
get any histories of cases of pneumonia or mental disease or paralysis
or heart weakness or any other organic disease which was attributed
by the physicians or by the men themselves to the effects of the gas.
28 Hayhurst, E. R.

Journal of Industrial Hygiene, 1 9 1 9 -2 0 , Vol. I, p. 360.



We do not know how to explain this. The English literature is full
of such histories and so is the German and French, and there seems
110 reason why similar cases should not occur among American
miners. Even if it is true that there are not so many accidents from
gas in American mines, still it seems incomprehensible that none of
those which do occur should cause the damage which like accidents
have been shown to cause in European mines. The slow absorption
of the gas, the long-continued exposure which is usually charac­
teristic of mine gassing, is supposed to set up just those changes in
the cells of the brain and spinal cord which result in loss of memory
and of mental power and various kinds of neuritis and paralysis.
This brief survey of gassing in the coal mines does not make it
possible to explain why the situation that was found differs so much
from the situation as described by Glaister and Logan in England
and by Lewin in Germany.
In the copper mines of Arizona carbon-monoxide poisoning is un­
known. The custom in that region is to have all the blasting or shot
firing done at the end of the shift, so that the miner leaves as soon
as he has lighted the fuse, and before the next shift comes on the
gas has been carried off by the ventilators. In Montana not only
are the mines deeper and the ventilation more difficult, but it is cus­
tomary to have blasting going on continuously. In this region gas­
sing is perfectly well known, but here also it is held by miners,
as well as by physicians and managers, that no effects of the accident
persist after the man has recovered from the acute symptoms.
In comparing the results of studies in this country with the studies
made by the British in collieries it must be remembered that men of
foreign birth and language are dealt with here, while the British
deal with men of their own nation and language. It is excessively
difficult to get information concerning possible psychical symptoms
in a miner who speaks English imperfectly or not at all, who has
no family or intimates, and who passes muster as entirely normal
provided he can carry on his day’s work as well as he did before the
accident. A lawyer with many years’ experience under the Illinois
compensation law told of the difficulty he had in determining injury
of this kind in Slavic miners whose English was restricted to a few
words necessary for the performance of their day’s work. Even when
he could convince himself that the victim of an accident was in a
condition of mental dullness, was slow to respond, was easily con­
fused and upset, and was unable to make a decision promptly, he
could not get enough evidence as to the man’s mentality before the
accident to make it possible for him to prove that this condition was
of recent origin. This may really be the explanation of the failure
to discover in the coal and metal mining districts visited the sort of
injury following gassing accidents which the British find common
enough to call “ characteristic of colliery accidents.”

There is great variety in the composition of illuminating gas as
used in different cities in the United States and at different times of
the year. For many years past the gas used for illuminating in this
country has been what is known as “ enriched coal gas,” containing
from two-thirds to three-fourths of water gas. The water gas is



added from motives of economy, and the proportion is larger during
the winter months. Coal gas, made by the destructive distillation
o f coal, less often petroleum or wood, is luminous because of the
large proportion of methane and of hydrogen it contains. Water
gas is made by passing steam over incandescent coke; and as it con­
tains far more carbon monoxide and less hydrogen and methane, it
is rich in heating power but poor in illuminating power. The flame
is blue, and in order to render it luminous it must be carbureted,
that is, enriched with gases derived from hydrocarbons and burning
with a yellow flame. These hydrocarbons are ethane (C2
H6) ethylene
(C2H4), acetylene (C2 2), and benzol (C6 6). Carbureted water
gas, then, is much more poisonous than ordinary coal gas, because it
contains a decidedly higher proportion of carbon monoxide, and also
a larger proportion of light oils, the most dangerous of which is
The composition of coal gas and of carbureted water gas is usually
given as follows:


Carbon monoxide...................................
Carbon dioxide........................................
Light oils..................................................
Methane - -......................................

Coal gas.

Water gas.

Per cent.
Per cen t.
0.5 1

The large proportion of carbon monoxide in American illuminat­
ing gas is usually taken as the explanation of the frequency of
illuminating-gas poisoning, which, according to McNally* held the
fourth place in the death records of Cook County, 111., for 1916, being
responsible for no less than 501 deaths. But the large proportion of
hydrocarbon illuminants in water gas is also of great significance.
In one of the cities visited in the course of this inquiry the statement
was made that in manufacturing the illuminating gas, 2 gallons of
light oils were added to 10,000 cubic feet of gas, and that this oil
consisted of three parts benzol and one part toluol. The resulting
gas was said to contain benzol in the proportion of five parts per
thousand parts of gas.
In another city the coal gas used contains from 0.5 per cent to 1.0
per cent of benzol, one-third as much toluol, and one-fifth as much
xylol. This coal gas is mixed with water gas in varying proportions,
but usually sufficient to bring its carbon-monoxide content up to from
27 to 29 per cent, probably about one part of coal gas to two or two
and a half of water gas, which would dilute the benzol decidedly, for
water gas does not contain benzol. Still, even one-third or one-fourth
of the above quantity of benzol is enough to constitute a menace.
According to the experiments made by Rambousek,2 as small an
amount of benzol as 1.5 parts in 100,000 parts of air is poisonous to
animals, and 5.5 parts per 100,000 is enough to render them uncon­

p. 29 Rambousek, J. Industrial Poisoning. Translated by T. M. Legge. London, 1912,



scious. The above analyses show a proportion of 500 patts per 100,000
parts of gas. The accidents caused by illuminating-gas poisoning,
the unconsciousness and delirium, and the nervous symptoms which
follow may be due, not to the carbon monoxide, but to the benzol and
toluol. Lewin found that even a slight poisoning with benzol might
be followed by aftereffects such as giddiness, nausea, headache, dis­
tress in breathing, and a sense of oppression in the heart. For­
tunately, the increasing expense of hydrocarbon oils promises to
bring about a return to the use of coal gas, which is so much safer,
having both a lower carbon-monoxide content and a smaller quantity
of benzol than water gas.
The manufacture of illuminating gas is seldom attended with
accidental gassing. Fatal accidents are almost unknown. The em­
ployees of gas companies who suffer most from gassing are the testers
of meters and the men doing extension work; that is, making connec­
tions for new lines and working in ditches and trenches and man­
holes. In one city an official of the gas company said that they ex­
pected the men in extension work to get gassed, but that the only
thing to do was to have someone watch at the top of the ditch, and
when the man staggered and fell, pull him out and send another in.
The American Gas Institute has a committee on accident preven­
tion and this committee has reported some 11,000 accidents in the
industry between 1915 and 1919. There were 30 deaths, only 4 of
which were caused by gas. The records for 1919 cover about 1,000
accidents occurring in 77 plants. Thirty of these were men overcome
with gas, but none of them died. The opinion held by this commit­
tee is that practically all cases of gassing recover within 48 hours,
with no permanent effects.

In one of the industrial towns of northeastern New Jersey a large
copper works uses producer gas, and cases of carbon-monoxide gassing
are not uncommon. Of seven physicians interviewed there, three
had had such cases. One of them told of an accident involving three
men, all overcome by the gas fumes, but while two recovered com­
pletely the third suffered from mental impairment and great ex­
haustion for some days. When he had regained his mental powers
and his strength he went back to work, was overcome again, and de­
veloped the same symptoms. He was then transferred to other work.
This was the only case of such aftereffects noted in that town.
In a town in La Salle County, 111., a visit was made to a great
zinc smelter, where metallic zinc is produced and also sublimed zinc
oxide, the latter being obtained from the fumes of the furnaces, which
pass through flues to a bag house and there deposit the white oxide.
With the zinc oxide there passes a varying quantity of carbon
monoxide, but the bag house is equipped with a mechanical shaking
apparatus and the men do not have to go in to do this. When bags
must be repaired the current is shut off. Apparently carbon-mon­
oxide gassing does not constitute a danger there, although there is a
rumor to the effect that birds flying through the openings in the
walls of the building and coming out on the other side sometimes
fall to the ground overcome by the gas.



In the making of coke the by-products are tar, naphthalene,
benzol, and toluol; the gases given off are carbon monoxide, carbon
dioxide, cyanogen, hydrogen sulphide, sulphur dioxide, and marsh
gas or methane. This is according to the superintendent of a large
plant near Pittsburgh. Here the great danger is benzol, and car­
bon monoxide is relatively negligible. The gases carrying tar and
the lighter distillates pass to furnaces where the tar is condensed,
then sulphuric acid is added to form ammonium sulphate, and then
oil “ scrubbers” catch in heavy oils the light distillates, benzol,
toluol, and xylol. The danger points for carbon monoxide are prob­
ably, as in steel manufacture, at the feed door, which in this plantwas at the top of the furnace, and in cleaning and repairing work.

It would be impossible to describe all the many ways in which
accidental carbon-monoxide poisoning may take place in industry,
for dozens of instances could be given. A few have been selected,
especially from American literature, in order to give an idea of the
way in which these disasters may occur. Dr. Louis I. Harris,3 of
the occupational disease clinic of the New York City Department of
Health, has seen about 220 cases of acute gassing in New York in­
dustrial establishments which could be traced to gas flames or
furnace gas. An unusually striking instance was the following: In
three lofts devoted to clothing manufacture there were 125 em­
ployees. At about 2 o’clock in the afternoon on a certain day some
of the employees in each shop became suddenly ill with nausea and
vomiting, headache, dizziness, and weakness, especially in the legs;
several were actually overcome, and three were sent to hospitals,
but the greater number recovered in a few hours, although two were
very weak for several days. The department of health, suspecting
carbon monoxide as the cause, found that all of the 73 cases were
working in the rear of the three lofts near the back doors, which
had been left open into a hallway leading to the roof. The skylight
also had been left open and a shift in the wind had blown gas from
the chimneys down into the hall and the workrooms.
Dr. R. P. Albaugh,3 while director of the division of industrial
hygiene of the Ohio State Department of Health, relates a very
unusual occurrence in a construction camp. Thirty white and 30
colored men were living in a bunk house constructed on an old dump
where dirt, slag, scrap, mill waste, ashes, and cinders had been de­
posited for a period of about five years. In December, 1916, during
a week’s time, 14 men were severely gassed and 3 died. After it
had been shown that these were not cases of food poisoning, but that
some gas was present in the air of the bunk house, affecting even the
physicians and rescuers, a search was made for the source of the gas.
It was found that about 10 days before a little steam seemed to be
rising from the edge of the dump about 50 feet from the bunk house.
It was thought that the dump might be on fire, although no ashes or
cinders had been deposited there for the last six months. A trench


Harris, L. I. Paper read before American Medical Association, Atlantic City, 1919.
See extract f r o m this paper in M o n t h l y L a b o r R e v i e w ,, November, 1919, p. 263.
Albaugh, R. P. Journal American Medical Association, 1917, vol. 68, pp. 1 0 3 3 -1 0 3 5 .



was dug around the part thought to be on fire, and it Was found that
the dump was frozen to a depth of about 2 feet, but at 5 feet red hot
cinders were encountered. Other trenches were dug, and one of them,
which extended under the camp building, also contained hot cinders.
While working in one of these trenches six men suffered from head­
ache, dizziness, and weakness of the knees to such an extent that they
had to be helped out of the trench and two were taken to the plant
The deaths and prostrations could undoubtedly be traced to the
carbon monoxide formed by the incomplete combustion of cinders
and other material in the dump. Because the surface of the ground
was frozen the gas found its only outlet under the camp buildings
where the ground was not frozen and where the cinders were soft
and porous, especially under the kitchen sink where the hot water
ran down.
Two other instances of carbon monoxide from ashes and cinders
have come to light and, singularly enough, both occurred out of
doors, where one would suppose the.gas would be rapidly diluted
beyond the fatal point. One was a man who was raking hot ashes
from a copper works in Perth Amboy, N. J. He died in the city
hospital, supposedly of “ marsh-gas poisoning,” and when inquiry
was made as to this diagnosis, marsh gas (methane) being quite non­
toxic, the explanation given was that the man was working in a marsh
and was killed by gas, therefore it must be marsh gas. Two men
who died from gassing while raking cinders were reported by Apfelbach,3 and they also were working out of doors.
McNally3 tells of two carpenters who went into a burning cooper
shop to get their tools and 20 minutes after were found dead, killed
by the carbon monoxide from the smoldering wood. Carbon mon­
oxide was demonstrated in the blood.
Cases of carbon-monoxide poisoning have been reported from
copper smelting in which producer gas is used, in lead smelting,
and in the smelting of zinc and the production of zinc oxide, which
is obtained from fumes carried through pipes and which is deposited
in long cotton bags. The carbon monoxide from the furnaces passes
along with the zinc and is encountered both in the mains and in the
bag house.
The explosion or burning of celluloid in factories or in movingpicture houses when the films catch fire gives rise to large quan­
tities of carbon monoxide and is responsible for the greater number
of deaths in such accidents.

It has already been shown that the exhaust gases from motor­
car engines contain on the average about 9 per cent of carbon mon­
oxide. Apfelbach made five analyses of the carbon-monoxide con­
tent of the air in motor garages and found an average of 0.042 per
cent. It must be remembered in this connection that the Bureau
of Mines places the safety limit at 0.15 per cent. Schumacher gives

82 Apfelbach, George. Personal communication.
33 M cNally, W m . B. Journal American Medical Association,

1917, vol. 69, p. 1588.



the composition of gas collected from the exhaust pipes of motor
cars as follows:
Carbon monoxide, 9.3 per cent; carbon dioxide, 6.7 per cent; oxy­
gen, 1.4 per cent; nitrogen, 82.2 per cent; illuminants, 0.3 per cent.
These analyses, made more than five years ago, probably do not
represent the composition of the gases at present, for there has
been an increasing use of coal-tar benzol as motor fuel, and it is
probable that the amount of benzol vapor is at times very con­
siderable, since some of the cheaper gasolines contain fairly large
quantities of benzol.
An effort was made to determine how much chronic gassing could
be discovered in employees of storage and of repair garages. It
was not possible to subject these men to a physical examination
nor even to make an examination of the blood which would include
an estimation of the number of red blood corpuscles. The method
chosen was to examine the blood for carbon-monoxide gas. I f it
were present, the conclusion would be inevitable that the men were
absorbing while at work an appreciable amount of this gas, and
also of the other constituents which are known to be present along
with the carbon monoxide but which can not be detected in the
blood. The test that was adopted is simple. It is the so-called
tannin precipitation test. A drop of blood from the ear is diluted
with three parts of distilled water, which at once lakes it—that is,
dissolves the red corpuscles, producing a clear red fluid. This is
then dropped into a small glass tube containing three times as
much of a 1 per cent solution of tannic acid. A precipitate forms,
and after a few hours this flocculent precipitate, if the blood contains
carbon-monoxide gas, is a pinkish color, while if the blood is normal
the precipitate is brown. It is easy to detect this difference in color,
and the test is therefore simple, rapid, and accurate.
The examinations were made in Boston garages during the months
of January and February when the thermometer ranged from 25° to
50° F. The conditions in the garages varied according to the ven­
tilation and according to whether the plants were for storage only or
for repair work. As a rule, repairing involved decidedly more con­
tamination of the air than storage, but one storage garage proved to be
quite as full of fumes as any of the repairing plants because it was
unventilated and not only were cars going in and out continually but
one to three cars were “ running idle ” all the time.
The effect of the gas was well known to every man interviewed,
although not all had personally suffered from it. The symptoms de­
scribed were headache, weakness in the legs, sometimes constipation,
less often nausea and dizziness, and sometimes vomiting. Some of the
drivers complained of headache if they were obliged to remain in the
garage for several hours. The symptoms were always aggravated by
cold weather because then windows and doors were kept closed.
Even in the better-ventilated shops, where the men experienced no
discomfort from the gases, positive evidence of carbon monoxide
was obtained. In garage No. 17 approved methods for carrying off
the exhaust gas from engines were in use, but every man in the place
gave a positive test for carbon monoxide.



The following are the results obtained in 17 storage and repair
No. 1. Repair garage. Cloudy, damp day, 55° F. Ventilation from windows
in ceiling and walls.
A. F. H. Mechanic 8 years. Suffers from headache and constipation, espe­
cially in cold weather, even if window is open, for the gas does not escape.
Negative test.
K. F. H. Mechanic 5 years. Occipital headache and gastric distress in cold
weather. Negative test.
No. 2. Storage garage. Rainy, muggy day, 50° F. Windows closed, door
opened part of the time. Two or three cars running idle and several going
in and out all the time so that the air was smoky.
A. T. Eight years employed. No symptoms except when the gas is very
heavy; none at present. Positive test.
I. W. Only one hour inside the garage. No symptoms at the moment but he
has headache when the gas is heavy. Doubtful test.
J. J. M. Seven months in this garage. He has no chronic symptoms but two
weeks before during a cold spell the gas came into his office from the adjoining
storage room. He had an attack of dizziness, weakness of the legs, headache,
and was sick at his stomach. He could barely reach home, but was all right
after about three hours. Positive test.
No. 3. Repair and storage. Damp, cloudy weather, 40° F. Windows closed,
swinging doors open part of the time, air slightly smoky.
F. A. H. Mechanic for 13 years. He complains of stomach trouble with occa­
sional vomiting and nausea, weakness in the knees, sometimes headache. He
has these symptoms more or less every day, especially when the smoke is heavy
and toward the end of the day’s work. Positive test.
D. Mechanic for 10 years. He has occasionally a splittting headache and
weakness in the legs. Positive test.
H. Twelve years in auto work. He has no complaint of ill health. Nega­
tive test.
No. 4. Storage garage. Clear and cool, 40° F. All the windows and doors are
kept closed because the heating system is poor.
J. G. H. Employed for 6 weeks. He has headaches, especially at the end of
the day, and in cold and moist weather attacks of nausea. Positive test.
L. M. P . Twenty years in auto work. He has headaches and weakness in
the legs when the smoke is even moderately bad. He had not been working on
this day. Negative test.
No. 5. Storage garage. Clear and cool, 40° F. The ceiling is high but the ven­
tilation insufficient and the air .smoky.
W. M. Employed for 3 years. He complains of headaches. Positive test.
R. C. R. Employed 10 days. No symptoms. Positive test.
J. A. Driver.^ Negative test.
W. D. H. Driver. Negative test.
No. 6. Repair garage. Warm and damp, 60° F. The ventilation was good at
the time, air clear.
H. Mechanic 12 years. On duty only half an hour when test was made.
Negative test.
No. 6. Storage garage. Weather cloudy and damp, 45° F. Modern garage
with ventilation from side windows and skylight, but the air is smoky.
W . H. Only one hour inside the garage this morning. Negative test.
J. H. M. Only one hour inside the garage this morning. Negative test.
No. 7. Storage garage. Moderately low rooms. Ventilation through one win­
dow, skylight, and open doors. Air slightly smoky.
S. H. Fifteen years employed. He has headaches occasionally, especially on
cold days. Positive test.
J. B. Fifteen years employed. Never has suffered from the gas, no matter
how much there is in the air. Positive test.
R. S. Eight years employed. Complains of headache. Positive test.
No. 8. Storage garage. Weather clear and cold, 30° F. Ventilation through
one window, large open elevator shaft, and doors. Very little smoke in
the air.
E. F. A. Seven years employed. No symptoms. Positive test.



R. S. V. Driver for 10 years. If he remains in the garage long he gets a
headache. He had just come into the garage when the test was made. Nega­
tive test.
No. 9. Storage and repair. Cloudy, moderately cold weather. Storage rooms
on two floors, large, with good window ventilation and only slightly smoky.
Two small repair rooms.
G. M. H. Employed 14 years, but in the office. Negative test.
O. A. Mechanic in repair room, 4 years. He often has headache and
dizziness. Positive test.
C. W. W. Foreman of repair room, 4 years employed. Very rarely any
symptoms. Negative test.
C. Mechanic, 5 years employed. Occasionally has attacks of dizziness.
Positive test.
R. R. G. Mechanic for 20 years. He is, according to his own account, very
susceptible to the gas, suffering from headaches and dizziness. Positive test.
G. Mechanic, employed a year and a half. No complaint. Positive test.
F. J. G. Mechanic for 20 years. He has indigestion and headache, but does
not attribute them to the gas. Positive test.
No. 10. Small storage garage. Cloudy, moderately cold weather. Ventilation
from door and large open elevator shaft. There is only a little smoke in
the air.
B. F. Fourteen months employed. No complaint. Positive test.
J. M. Three years employed. Occasional headache. Positive test.
No. 11. Storage garage. Clear, dry, windy day, 60° F. Ventilation good; doors
open; no smoke.
W. B. Ten years employed. Occasional headache on cold days when the
doors are closed. Doubtful test.
No. 12. Storage garage. Weather as under No. 11. Well ventilated from win­
dow, skylight, and open doors. Very little smoke.
W. R. Three years employed. He occasionally has headaches. Just before
the test was made he had been working outside for half an hour. Negative test.
W. F. Employed 12 years. He has headaches and dizziness sometimes. He
had been outside for several hours just before the test was made. Negative
No. IS. Storage and repair. Weather cool, foggy, cloudy, and very damp. The
repair shop in the second floor is large, but with a lowT ceiling. There are
windows on two sides, but only one is partly open. An open elevator shaft
communicates freely w ith the first floor, which is used for storage. An
ozone machine, with a small fan, was placed in the center of the room.
Cars running; air very smoky.
E. ,T D. Fifteen years. Complains of headaches. Positive test.
W. F. R. Mechanic 7 years. Complains of headaches. Positive test.
A. P. Mechanic 8 years. Headaches and indigestion. Positive test.
S. M. Mechanic 1| years. Headaches and dizziness. Positive test.
A. G. B. Mechanic 3 years. Headaches. Positive test.
R. B. Mechanic 8 years. Headaches and dizziness. Positive test.
M. L. H. Mechanic 10 years. Headaches and dizziness. Negative test.
O. ,T G. Mechanic 6 months. Headaches occasionally. Positive test.
W. G. Mechanic 3 weeks. Headaches. Doubtful test.
P. J. R. Mechanic 3£ years.' Headaches. Negative test.
The symptoms reported by this group of men were more marked and more
general than in any other garage. All the men complained of headache, which
came on usually toward the end of the afternoon, and most of them suffered
daily from headache, except in summer, when the weather is clear and all
windows and doors open. Cold and damp days are especially bad. The owner
said that the ozone machine had made a decided improvement in the efficiency
of the men, but this was not borne out by the evidence of the men themselves,
who thought that there was no improvement after the installation of the
machine. *
No. 14. Basement repair shop. Weather cold and clear. The air was fairly
thick with smoke and odor of exhaust gas.
W. D. Headache when the weather is cold and damp. Positive test.
J. N. Headache when the weather is cold and damp. Positive test.
T. M. Headache when the weather is cold and damp. Positive test.



No. 15. Storage garage. Weather cold and cloudy. Air in the garage seems clear.
All work had been over for three-fourths of an hour when the test was made.
T. M. Positive test.
No. 16. Repair garage. Clear, dry weather, 20° F. The ventilation is poor, all
windows and doors being closed, and the “ smoke ” is fairly thick.
F. G. Mechanic 7 months. He has headache followed by gastric distress and
nausea, and when he is working on his back under the car he sometimes vomits.
Positive test.
A. Mechanic 7 months. He has headache, and when the smoke is bad he
has nausea and pain in the stomach. Positive test.
No. 17. Repair and storage shop. W^eather clear and windy, 40° F. Large,
moderately high repair room with all windows and skylight closed but
with open doors into well-ventilated storage room. There is not much
smoke, for flexible tubes are used to attach to exhaust and carry off gas
through holes in walls.
W. L. D. Mechanic 7 years. Headaches and stomach trouble. Positive test.
H. G. D. Mechanic 7 years. Headaches. Positive test.
P. Mechanic 15 years. Headaches. Positive test.
C. A. R- Mechanic 6 years. Headaches and stomach trouble. Positive test.
L. J. D. Mechanic 5 years. “ Gas headaches ” and stomach trouble. Positive

The above records give the results of 55 tests on garage workers
and show that 36 had absorbed carbon monoxide from the exhaust
gases in the air. This number, equal to about two-thirds, does not
tell the whole story, for if the records of those that gave dubious
or negative tests are examined it is found that several of them had
not been exposed to the gases for more than an hour before the
tests were made. Thus of the 3 with doubtful results, 1 had been
inside the garage only an hour. Of the 16 with negative tests, 1
had been at work only half an hour, and 2 for only one hour, 3 were
drivers, who were in and out of the garage all the time, 1 worked in
the office, 1 had just been outside for half an hour and another for
several hours. This means that of the 19 who failed to give clearly
positive tests, only 9 were employed in garage work and had been
inside for more than an hour just prior to making the test.

The two industries which seem to offer the greatest opportunity
for constant absorption of small quantities of carbon-monoxide gas
are the tailoring trades and the printing trades. In the former it is
the pressers using gas-heated irons who are exposed; in the latter,
the linotypists, on whose machines the lead pots are heated by
gas flames, unless an adequate system of ventilation carries off the
gas fumes. It was planned to include in this study both pressers
and linotypists, but conditions in the clothing industry were too
unsettled to permit of such an inquiry at the time, and it had to be
confined to the linotypists. The study was carried on in Boston
and covered three newspaper plants. It was made* possible by the
cordial cooperation of the Typographical Union officials and the
chairmen of the various chapels. The results which are given below
show that the contamination of the air in machine composing rooms
is demonstrable although slight. In no case did the investigator
fail to find at least one positive test, although the proportion of
positives was nothing like so high as it was among the garage workers.
Probably no two days would yield exactly the same results in any one
plant, for the condition of the air in the different parts of the room



would undoubtedly vary from day to day. It seems safe to conclude
from these tests that the ill health complained of by many printers
may be in some part due to the gas in the air and that the discom­
fort, headache, dullness, loss of appetite, especially at the end of
the day’s work, and the chronic constipation—a frequent complaint
of printers—may be aggravated by the small quantities of carbon
monoxide in the air they breathe.
The following results were obtained in these newspaper plants:
No. 1. 12.30 to 2 a. m. Weather warm and rainy. Composing room high and
well ventilated, but no exhaust system for the lead pots.
F. H. T. Five years employed. Complains of gastric trouble and headaches.
Negative test.
J. T. P. Nine years. No complaint. Negative test.
J. C. S. Eight and a half years. No symptoms. Negative test.
D. S. Nine years. No symptoms. Negative test.
A. E. W. Ten years. No symptoms. Negative test.
M. C. H. Seven years. Headaches and gastric trouble. Negative test.
C. W. A. Twenty years. No symptoms.. Negative test.
E. F. S. Twenty-five years. No symptoms. Negative test.
P. J. S. Twenty-six years. No symptoms. Negative test.
F. B. Five and a half years. No symptoms. Negative test.
R. B. Five years. Indigestion. Negative test.
L. C. Ten years. Indigestion. Negative test.
C. W. Thirty years. No symptoms. Negative test.
H. E. H. Ten years. No symptoms. Negative test.
E. F. B. Twenty-five years. No symptoms. Negative test.
S. J. O. Twenty-five years. No symptoms. Negative test.
J. H. G. Thirty-five years. Gastric ulcer. Negative test.
E. F. N. Eight years. Lead poisoning. Doubtful test.
L. D. Eighteen years. No symptoms. Doubtful test.
F. A. B. Thirty-seven years. Lead poisoning. Doubtful test.
W. C. Five years. No symptoms. Doubtful test.
D. J. L. Thirteen years. No symptoms. Positive test.
No. 2. 2 p. m. Weather clear and cool, 25° F. Room not very high, windows
all closed, but there were three electric fans. No odor of gas in the air.
M. J. C. Five to six years. No symptoms. Positive test.
J. J. T. Twenty-eight years. No symptoms. Negative test.
B. J. T. Ten years. Severe headache at times when the air is bad. Negative
W. P. B. Twenty-five to 30 years. Headache and constipation. Negative test.
W. J. S. Fifteen years. Headaches. Negative test.
H. L. A. Twenty-seven years. Negative test.
A. G. Fifteen years. No symptoms. Negative test.
J. S. Seventeen years. No symptoms. Negative test.
No. 3. 3 p. m. Clear day, temperature 40° F. There are two small low rooms
communicating with each other. The lower room contains 15 linotype
machines, the upper room is the composing room, and in one corner is a
large gas-heated melting pot which runs for a few hours in the morning. A
draft ventilator is attached, but is reported as out of order most of the time.
There is no exhaust system for the linotype pots. The linotype room has
several windows partly open.
W. H. Thirty years. No symptoms. Negative test.
W . T. Thirty-five years. No symptoms. Negative test.
W. G. Thirteen years. No symptoms. Negative test.
F. H. M. Sixteen years. No symptoms. Negative test.
F. W. B. Thirty years. No symptoms. Negative test.
G. W. S. Thirty years. No symptoms. Negative test.
H. R. S. Two years. No symptoms. Negative test.
T. J. W. Two years. No symptoms. Negative test.
H. F. C. Forty years. No symptoms. Negative test.
J. C. G. Twelve years. No symptoms. Negative test.
J. B. Thirty-eight years. No symptoms. Negative test.
J. H. R. Thirty-five years. No symptoms. Positive test.



W. F. R. Six years. No symptoms. Positive test.
O. C. Two months. No symptoms. Positive test.
J. A. M. Twelve years. No symptoms. Positive test.
D. M. Twenty-four years. Headaches, lead poisoning. Positive test.
T. J. F. Thirty years. Headaches and stomach trouble. Positive test.

The total figures for the linotypists are 8 positive out of 47 tested,
or 17 per cent. This does not include the 4 doubtful cases, which are
classed with the negative.
Industrial carbon-monoxide poisoning is said to be increasing in
all civilized countries because of the increasing use of power and
producer gas, the increasing use of motor engines, and the increasing
depth of mines with the consequent difficulty of ventilation and seri­
ousness of accidents. British statistics show that the average num­
ber of cases per year increased during the last quinquennium from
62.5 to 75 and the mortality from 12.3 to 17.3 per cent.
Studies in European countries, especially Great Britain and
France, show that industrial carbon-monoxide poisoning when not
fatal is sometimes followed by serious effects, such as pneumonia,
cardiac weakness, mental disease, or paralysis. Such aftereffects are
seen most often in coal miners.
Chronic carbon-monoxide poisoning is described, though not
clearly, by the French, English, and Germans. It is supposed that
the ill health complained of by cooks, bakers, laundresses, ironers,
pressers in tailor shops, painters working in rooms dried by sala­
manders, etc., is caused by the coal gas in the air.
Inquiries made in the United States show that acute carbon-mon­
oxide poisoning occurs in steel manufacture, in making illuminating
gas, in making coke (by-products), in using producer gas for indus­
trial processes (especially in smelting), in coal mining, metal mining,
zinc smelting, and in garages when the exhaust gases from engines
American statistics as to the number of cases and of fatalities are
available only to a very slight extent. The figures from one of the
steel companies show a decidedly lower mortality (4.8 per cent for
1916 to 1920) than the British mortality from blast-furnace gas (22.8
per cent for 1914 to 1919). The figures from the American Gas Insti­
tute show that among some thousand accidents during 1919 only 30
were due to gas and none was fatal.
No statistics are available for carbon-monoxide poisoning in coal
mines or in metal mines, the reports of the Bureau of Mines not
distinguishing this cause of death and disability from others.
A careful search in steel towns and in coal mining and metal
mining towns failed to confirm the statements made by foreign
authorities as to serious aftereffects from gassing accidents. Only
very rare instances of sucli a character were discovered. It is not
possible in our present state of knowledge to explain why experience
in this country differs so much from that of European observers. A
more thorough study should be made of this aspect of industrial
carbon-monoxide poisoning.
The suggestion is made that some of the obscure features of
poisoning by this gas may be cleared up when it is known just what



other constituents besides carbon monoxide are present in a given
industrial gas, and just what effects might be produced by these
other gaseous bodies. It is especially suggested that small quanti­
ties of benzol may be really the active agent in cases attributed to
carbon monoxide.
Chronic carbon-monoxide poisoning may be looked for in indus­
tries in which small quantities of the gas are more or less con­
tinuously present in the air.
Of 55 garage employees, mechanics and storage men, 36, or about
two-thirds, were shown to have absorbed in their blood carbon mon­
oxide in demonstrable quantities. Of the remaining 19 only 9 had
been at work inside the garage for more than an hour when the test
was made.
Of 47 linotypists in newspaper plants where the gas from the lead
pots is not carried off by an adequate suction apparatus, 8, or over
one-sixth, showed the presence of carbon monoxide in their blood.
The actual effect of such constant absorption of small quantities of
this gas should be studied further.



Federal Reserve Bank of St. Louis, One Federal Reserve Bank Plaza, St. Louis, MO 63102