INDUSTRIAL A N D ENGINEERING CHEMISTRY
October, 1924
1047
Carbon Monoxide Poisoning in Private Garages‘’z By W. P. Yar~t,~ W. A. J ~ c o ~and s , ~L. B. Berger3 BUREAUOF MINES,PITTSBURGH, PA., AND WASIIINGTON. D.
c.
Mines.6 The values given N SPtTE of the recent I n summing u p the dangers arising from running an automobile in Table I are the averages e x t e n s i v e investigaengine in a closed private garage it can be said that, owing to ( I ) for a representative number t i o n ~on~ the danger of the rapidity with which toxic concentrations can be created. a s shown of cars in each class: poisoning by carbon monby the curves in this report f o r the average automobile; ( 2 ) the fact oxide by inhaling the exthat the gas m a y be more concentrated in the vicinity of the man exTABLE I-CUBIC FEETOF CARBON haust gas of automobiles, posed-say, i n the rear of the cur or under it; (3) the uncertainty MONOXIDE LIBERATED PER HOUR much indifference or ignothat the engine i n question might be adjusted to give off us much as (65’ F . , 29.92 inches Hg) rance still exists concerning 5-pas- 7-pasLight 50 per cent more carbon monoxide than the average; ( 4 ) the varying senger senger trucks the magnitude of the hazard sizes of garages (some being as small as 1000 cubic feet capacity or up to ENQINE auto- autoSPEGD mobiles mobiles 1.5 tons in running engines in small less) and the ventilation; ( 5 ) the digerences in the susceptibility of Idling 35 33 31 p r i v a t e g a r a g e s . The men, together with the increasing egect of exercise on the absorption Racing 65 105 68 public has become so acof carbon monoxide: (6) the lack of warning symptoms-headache. customed to seeing men nausea, etc.- in the case of exposure to these high concentrations, and Taking these figures to w o r k i n g a b o u t engines the possibility of sudden collapses; there seems to be no limit of time r e p r e s e n t t h e average which are running, and to during which the engine m a y be run in a closed private garage with amount of carbon monoxide breathing exhaust gas in low safety to an occupant thereof. liberated by the engines of concentrations, that they The doors should be opened previous to starting the engine, even if the various classes of autohave become more or less it is only intended to fake the car out, because, no matter how careful mobiles that would ordiindifferent to its dangers. people m a y be, a f e w unheeded minutes taken to look at the tires or narily be housed in private Few people have regarded measure the gasoline tank m a y prove disastrous. If it i s necessary garages, the accumulation or thought that the atmosto run the engine f o r any lengthy period. as in making repairs or adof carbon monoxide in a phere they are breathing is justments, the car should by all means be run into the open; and even garage of any size having not exhalist gas in a strict then the direct exhaust should be avoided in order to decrease the any assumed ventilation sense, but an exceedingly possibility of headache and discomfort. can be calculated by use of dilute mtxture of exhaust the following equation:7 gas in air made comparatively safe through natural or artificial ventilation. Also that the volume of air available for dilution of the exhaust from each engine that may be running in these places is many where C = percentage of carbon monoxide in a garage after a given time times greater than that in a private garage a t home. R = ventilation of air changes per unit time The normal hazard that exists through the operation of an t = time automobile engine in a small garage may be determined by V = volume of garage in cubic feet K = cubic feet carbon monoxide liberated by engine per two methods:
I
unit time
(1) From a knowledge of the volume of carbon monoxide liberated by the engine per unit time, together with the ventilation (usually expressed in air changes per hour), the resulting composition of the air in garages after an interval of time can be readily calculated. (2) Analysis can be made of the contaminated air of a garage in which a n engine is actually running.
I n the work described herein both methods were used. More attention is given to the former, because the results can be made applicable to all sizes of garages, types of automobiles, and ventilation conditions; whereas by the latter method the results only pertain to the particular set of conditions under which the tests were made. DETERMIXING
MONOXIDE I N GARAGEBY CALCULATION
CARBON
Data relative to that amount of carbon monoxide liberated by the engines of various types of automobiles were obtained in the course of another investigation made by the Bureau of 1 Presented under the title “Carbon Monoxide Asphyxiation in Private Garages” before the Division oI Petroleum Chemistry at the 67th Meeting of the American Chemical Society, Washington, D. C., April 21 to 26, 1924. 2 Published by permission of the Director, U. S. Bureau of Mines. a Pittsburgh Experiment Station. 4 BureRu of Mines, Washington, D. C. 6 Burrell and Gauger, Bur. Mines, Tech. Paper 216 (1919); Henderson, Boston Med. Sur. J., 187, 180 (1922); Fieldner, Straub, and Jones, THIS JOURNAL, 13, 51 (1921); Henderson and Haggard, Ibid., 14, 229 (1922); J. A m . M e d . Assoc., 81, 385 (1923).
Owing to the large number of types of cars, the many different sizes of garages, and the various conditions of ventilation, it would be confusing to attempt to give results specific to each case. However, it is possible to represent the magnitude of the danger, which is the point on which emphasis is desired to be placed, by giving average results which, within practical limits, can be considered as the danger that will exist, not in the exceptional, but in the majority of cases. From Table I it will be noted that the carbon monoxide liberated per hour by 5 and 7-passenger cars and light trucks is practically the same, especially when idling. Also, these three classes of automobiles, being of approximately the same dimensions, would be housed in garages of approximately the same size. The average of the data of their liberation of carbon monoxide was taken as a basis of calculation for representing the condition that would obtain for these types after certain intervals of running in a garage of 1500 cubic feet capacity and a ventilation of quarter and one air change per hour. The condition of quarter air change per hour would be applicable to a very tight garage, while one air change would be considered as fair ventilation. These results are shown graphically in Fig. 1, which will be discussed later. 8 Fieldner, “Tunnel Gas Investigations-Amount and Composition of Automobile Exhaust Gas,” Report of New York State Bridge and Tunnel Commission, 1921, p. 91. 7 For derivation of the formula see Jones, Berger, and Holbrook, Bur. Mines, Tech. Paper 831 (1823).
INDUSTRIAL A'ND ENGINEERING CHEMISTRY
1048
TESTSMADEBY RUNNING ENGINES IN A G ~ R A G E I n the second method of determining the dangers arising from the operation of an automobile engine in a closed garage -namely, that of actually running an engine in a garage and making analyses of the atmosphere-two tests were made in a garage a t the Pittsburgh Experiment Station of. the Bureau of Mines. This garage had a capacity of 2950 cubic feet, this being made larger than the average. It is an intermediate one of a series of brick garages, has two windows in the rear, 2 feet 6 inches by 5 feet, and a folding door which opens the entire front, but which fits rather tightly when closed. The type of automobile used and the conditions of operation for each test are given in the test data.
Curves showhg anounf o f cur+nmonox/de found by onu/vs/sof atmos@ere M e r runnwq Ou/OiRGb//e Vgu7er ma dosed goruye of 2950 cu./f: volume. Eflqmeesrunning upprox/mu&//y ZOO r p m.
Curves showing.amounf o f curban rnonox/de present offer running otwnnq cor o r
iight truck enpne in f f c/ased garage of.iM0 cu. fl: vo/umej co/cu/ffhd from uverageomour?,+of cffrbon monoxide hberutedper h o u r
FIG.1
I n addition to the data obtained through sampling the gas in Test I, a dog was placed on the driver's seat and his symptoms were noted. In each case the engine was allowed to run until it stopped owing to the lowering of the oxy en content of the garage, this being planned in view of the ghelief of some people that the air is not exceedingly dangerous to life as long as the engine continues to operate. The results of these tests are given in Table 11. TABLE11-ACCUMULATION O F CARBON MONOXIDE AFTER RUNNINGAN ENGINEI N A CLOSEDGARAGEOF 2980 CUBICFEET CAPACITY Gas analysis, Time Per cent by volume Minutes Con On CO REMARKS Test I--5-pasrenger louring car, speed approximately 200 r. p . m . 12 Dog unconscious 25 Or80 1 8 . 6 4 1 : 3 l Dogdead;b!oodanalysis = 80% CO-Hb 60 1 , l O 1 7 , 4 2 1 . 9 7 Engjne missing 112 1 . 0 7 1 7 . 4 0 2 . 1 0 Engine stopped due to low oxygen Test 11--1.5-ton truck, speed approximately 200 r. p . m. 10 0.42 19.8 0.42 30 1 . 1 3 18.11 1 . 1 8 60 1 . 4 4 17.13 1 . 9 1 90 1 . 5 3 1 6 . 7 6 2 . 1 7 Engine missing 120 1 . 5 0 1 6 . 7 4 2 . 2 4 Engine missing 175 1 33 1 6 . 5 0 2 . 4 3 F;egir?estopped due t o low oxygen I
Vol. 16, No. 10
DISCUSSION OF TESTS The results of these tests have also been plotted in Fig. 1. I n interpreting them, however, it must be remembered that they were obtained in a garage of 2950 cubic feet capacity, while the other curves shown are for one of but 1500 cubic feet capacity. As will be noted, the curves representing the two garage tests are more flat than those obtained by the use of the equation. This is due to. the engine missing considerably, and it also slowed down as the oxygen became lowered, thus burning less gasoline. But, on the other hand, it should be observed that the decrease in oxygen gradually affected the carburetor adjustment, making it richer, which in turn caused a less proportion of carbon dioxide and an increased liberation of carbon monoxide. At 17.40 and 16.50 per cent of oxygen the engines automatically stopped. I n inspecting these curves the striking point to be noted is the rapidity with which a very toxic concentration of carbon monoxide is created. From the curve representing an engine idling, a condition under which the minimum amount of carbon monoxide would be liberated, and allowing one complete air change per hour, which is considered fair ventilation for a living room, it will be noted that in but 6 to 7 minutes the average concentration of carbon monoxide is 0.20 per centan amount sufficient, should the engine be stopped a t that time, to cause unconsciousness in 30 to 45 minutes. If the engine continued to operate but 12 to 15 minutes, an occupant of the garage would be rendered unconscious a t the end of that time. At the other extreme, that of an engine racing, a condition that might prevail in warming up, after 6 minutes' operation with but a quarter air change, which might easily be the condition in very tight construction, the concentration of carbon monoxide would be 0.50 per centan amount sufficient to cause unconsciousness in the time taken to produce it. The only significance of the upper portions of the curves is to show the concentrations produced after certain intervals of time, and to give evidence as to the disastrous results should the engine be started and left in operation while the driver went elsewhere. It is seen that a concentration of 2 per cent may easily be built u p in a short time, and on his return but a couple of minutes would be required to asphyxiate him. Although these higher concentrations are of importance and interest, they should not detract from the fact that the matter of first importance is the rapidity with which the minimum concentration and exposure that will render a man helpless, not necessarily a t the time unconscious, will be formed. Carbon monoxide is in many cases, especially in these relatively high concentrations, very insidious in its action, and the victim will often suddenly collapse and be entirely helpless-although conscious for a time of his condition yet unable to make an escape or give alarm. This state will quite rapidly develop into unconsciousness and death, especially if the engine continues to operate, which in all probability will be the case. The second point of importance shown by the curves is that ordinary ventilation has but little effect on the rapidity with which acutely toxic concentrations are produced. This is to be expected, however, since the accumulation of carbon monoxide is so rapid that the ventilation effected in that time does not materially alter the condition of the resulting atmosphere. After a time the ventilating effect is quite noticeable, but in all cases tthe corresponding concentration of carbon monoxide has reached a value that is no longer of consideration, any exposed victim having previously succumbed. It should be remembered that these results represent the
October, 1924
INDUSTRIAL A N D ENGINEERING CHEMISTRY
average for all automobiles. It is quite possible that certain engines whose carburetors are adjusted for a rich mixture will give off as much as 50 per cent more carbon monoxide, especially in starting during cold weather. With these the concentrations and effects described above would be produced in a great deal less time. An amelioration of this condition in the form of a vertical exhaust pipe extending a few inches above the tap line has been suggested by Henderson.6 Further, in practice the gas will not be evenly distributed throughout the garage, there being a lag in the dilution, and a much
1049
higher concentration will be present in the vicinity of the exhaust outlet. The time necessary to render a man unconscious will be further dependent upon the amount of exercise. The limitations described were made on the basis of moderate activity, whereas, should the occupant be doing strenuous work, his respiration would be increased and he would absorb a great deal more carbonmonoxideina giventime;hisneedforoxygenwould likewise increase with exercise. Both of these factors tend to decrease the time necessary to produce serious symptoms.
Economy through Smoke Abatement’ By H. B. Meller’ MELLONINSTITUTE OF INDUSTRIAL RESEARCH, PITTSBURGH, PA.
i
UCH antismoke agitation has taken place in the United States during the past ten or twelve years. Surveys have been made and ordinances passed. The net result has been a decided decrease in the amount of dense smoke in city air, without a corresponding abatement of the dirt and acid evils. In 1912-13 Mellon Institute of Industrial Research of the University of Pittsburgh made a survey of the City of Pittsburgh to determine the amount of “soot fall,” its effects, and possible methods of minimizing it. The results were published in nine bulletins. Data have been collected in Great Britain since 1914, under the auspices of the Advisory Committee on Atmospheric Pollution, attached to the Meteorological Office. “Soot-fall” studies were made in St. Louis, Cincinnati, and Pittsburgh in 1916, and Mellon Institute has just completed an eleven months’ survey of Pittsburgh. In all these investigations all solid matter that was deposited was considered, while in legislative action, taken with a view toward abatement, dense smoke only has been prohibited. Excellent results have been attained in combating this nuisance, but dense smoke is responsible for only a small percentage of the precipitate.
manufacturers would be given a reasonable time t o meet. There is now a tendency toward this restriction and manufacturers are showing a commendable willingness t o cooperate. 2-Permit is required beEore any work of installation, repair, or alteration of fuel-burning apparatus. From August 5, 1914, t o July I , 1924, the Bureau of Smoke Regulation of the City oi Pittsburgh issued 1695 permits under t h e ordinance. All new installations, of course, were required to be such as could be operated within the limits set. The person charged with the enforcement of an antismoke ordinance is therefore in a position t o assure himself t h a t plants are so designed and constructed t h a t reasonable care will prevent violation. 3-Penalty for violation. 4-In Pittsburgh and in some other cities private dwellings and t h e smaller apartment houses are exempt. The reason for this exemption in Pittsburgh was that, a t the time the ordinance was adopted in 1914, the customary domestic fuel was natural gas. The diminishing supply of this fuel has caused many t o change t o bituminous coal in t h e last few years.
When fuel is fired, the moisture is driven off first, then the volatile constituents. If the fuel is high-volatile bituminous coal, this expulsion may amount to 35 or 40 per cent by weight of the total; and if, as in hand-fired furnaces, the injection of fuel is intermittent, large volumes of volatile matter are distilled off in a very short space of time. It is during this period of distillation that dense smoke usually is emitted. PRESENT-DAY CONDITIONS RESPECTING SMOKE ABATEMENTIf the furnace temperature is sufficiently high and a sufficient volume of oxygen is present, the volatile matter will be burned A statement of the salient points in the antismoke ordi- above the fuel bed. The fixed carbon is then burned. nance of Pittsburgh and a brief description of the methods For complete combustion it is necessary that a sufficient used to minimize dense smoke will be pertinent in considering temperature be maintained in the furnace, that the furnace present-day conditions. have sufficient volume to permit the gases to be held long enough for completion of combustion, and that there be 1-Smoke of No. 3 density, Ringlemann chart (60 per cent black) for 2 minutes or more (aggregate) in any period of 15 proper provision for the admission of a sufficient volume of minutes, except in t h e case of locomotives or steamboats, where air, the internal construction being such that the gases from t h e allowable period is 1 minute in 8 minutes, is prohibited. No. the fuel will be thoroughly mixed with the air provided. I t 3 on t h e I2inglemann chart is equivalent t o smoke of such density is obvious that in hand-fired furnaces the volume shall be t h a t it is not possible t o see through it at the point of emission from the stack. Smoke of less density t h a n this is permissible adequate for the distillation period. It is necessary, also, at all times. that provision be made for the large proportion of air necesIt may seem t h a t this provision is too lenient, in t h a t it permits t h e production and emission of a n y quantity of light smoke sary during this period. In a large percentage of the plants in existence a t the time and a considerable volume of dense smoke; but, because of t h e present state of development of fuel-burning devices, it really of the passage of Pittsburgh’s antismoke ordinance in 1914, is fair. The fault has been t h a t t h e comparatively small number one or more of these necessary factors were missing. A of persons engaged actively in t h e work of smoke abatement have been more or less constrained t o follow t h e lead of the manu- number of methods, most of them quite simple, were used to make it possible to operate these plants within the limits facturers, tightening u p o n requirements as improvements were made in design, rather than t o set a high standard which t h e set by the ordinance. It should be remembered that only dense smoke was prohibited and that no attempt was made 1 Received August 1, 1924. to regulate by legal procedure the emission of any solid ma2 Chief, Bureau of Smoke Regulation, Department of Public Health terial that would not color the issuing stream. o f the City of Pittsburgh; and president of the Smoke Prevention AssociaIn cases where boilers were operated a t more than 50 pounds tion. Formerly Senior Industrial Fellow of Mellon Institute of Industrial Research, in charge of Air-Pollution Investigation. steam pressure, and where the supply of air was insufficient
