The Airliner Cabin Environment Air Quality and Safety (1986) / Chapter Skim
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5 Cabin Air Pollutants: Sources and Exposures
5 Cabin Air Pollutants: Sources and Exposures
Pages 113-189
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From page 113... ...
Lacking a repository of the existing information, the Committee searched the published literature to obtain relevant material on pollutants known to be potentially hazardous or to cause acute irritation and on physical factors that affect comfort. On the basis of the results of the searches, this chapter discusses ozone, cosmic radiation, ground fumes, tobacco smoke and carbon monoxide, biologic aerosols, relative humidity, cabin pressure, carbon dioxide, volatile organic chemicals, and pesticides.
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From page 114... ...
In 1980, Nastrom et al.107 reported that over 5,600 observations were made in this project in a B-747-100 and a B-747-SP. The ozone concentrations measured in the outside air and in the cabin of an unmodified B-747-SP are shown in Figure 5-1.
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From page 115... ...
· It initiated a study of available data on ozone concentrations at flight altitudes to provide an estimate of average atmospheric ozone at flight altitudes. On the basis of these efforts, FAA established a standard for cabin ozone concentration.
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From page 116... ...
5 0 ~ ~ ~ 7 Lategola and associates attempted more quantitative evaluation of problems associated with ozone exposures of flight attendants and passengers. Lategola et al.
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From page 117... ...
Pulmonary function and subjective responses were recorded near sea level before and 10 min after the altitude exposures. Other studies -- on vision, hand steadiness, and memory -- were conducted during the high-altitude exposures.
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From page 118... ...
studier were, however, generally lower than those reported to occur in some aircraft at high altitudes. Determination of the effects of known aircraft cabin ozone concentrations on passengers and flight attendants will require additional information from studies conducted on board, as well as immediately after flights, with continuous measurements of the cabin environment.
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From page 119... ...
COSMIC RADIATION We are exposed to ionizing radiation from several sources. Some is natural, such as cosmic radiation and terrestrial radiation, and some is from man-made sources, such as medical x rays, radioisotope drugs, nuclear fallout, nuclear power-plant emission, uranium and phosphate mine tailings, and nuclear waste materials.
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From page 120... ...
, muons and associated decay electrons are the dominant components of the cosmic-ray particle flux. Figure 5-2 illustrates the components of cosmic-radiation dose equivalent rates as a function of altitude.
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From page 121... ...
The flux rates for fast neutrons at various altitudes are shown in Figure 5-3. The dose equivalent rate of cosmic radiation in millirems per hour as a function of altitude is illustrated in Figure 5-4.
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From page 122... ...
, the cosmic-ray dose equivalent rate is approximately 100 times the rate at sea level. The newer, higher-performance aircraft are certified to 46,000 ft (14 km)
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From page 123... ...
In general, the hourly dose rate at a jet cruising altitude is approximately 100 times the groundlevel rate. A person who lived near sea level would have to spend about 200-600 h/yr at cruising altitude to double his or her exposure to cosmic radiation.
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From page 124... ...
Matrices were developed for neutron and secondary chargedparticle densities according to latitude, altitude, and solar conditions. The Aircraft Radiation Exposure (ACRE)
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From page 125... ...
commercial air travel industry. Passenger miles grew rather slowly more than 7%/yr between in the early 1980s, but grew at 1983 and 1985.
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From page 126... ...
populatlon,e mrems/person per year 2,991,000 8,194 156 1,281,000 468,000,000 16,803 22,996 581,000,000,000 9,372,000,000 13,000,000,000 736,000,000 12,100,000 16,600,000 164, 300,000 2,650,000 3,690,000 9.47 1,084 1.41 0.20 0.28 2.82 158 160 769,000 281,000,000 349,000,000,000 442,000,000 98,580,000 0.47 a Reprinted with permission from Wallace and Sondhaus.165 b Assuming a limit of 720 h per [till-time equivalent crew member at altitude per year, this number of crew members would be required. "Flight crew" refers to flight-deck crew, and "cabin crew" refers to flight attendants.
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From page 127... ...
Bramlitt25 2 6 argued that these changes render the Wallace and Sondhaus calculations of cosmic radiation exposure of 160 mremsfyr for flight and cabin crew members inappropriate for 1986. Crew and passengers flying more hours at higher latitudes and altitudes can receive substantially more radiation than 160 and 3 mrems/yr, respectively.
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From page 128... ...
population, a person receives 44 mrems/yr from cosmic radiation and 40 mrems/yr from terrestrial radiation. 20 to to z o ~ 10 o cow 15 l ol l L I I I I I ~ n I 40 60 80 1 00 1 20 1 40 1 60 1 80 0 20 DOSE EQUIVALENT, mrems/yr FIGURE S-6 Population distribution vs.
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From page 129... ...
Both the National Council on Radiation Protection and Measurements and the International Commission on Radiological Protection recommend that exposure of the fetus during the entire gestation period from occupational exposures of the expectant mother not exceed 0.5 rem. 68 Boa Stewart and co-workers, 144 - ~ 46 MacMahon, 95 and MacMahon and Hutchison9 6 have determined that fetuses are at high risk.
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From page 130... ...
There is relatively little information on actual exposures in aircraft during these periods, but some information on potential exposure to various substances can be obtained from a review of aircraft engine emission. Aircraft jet engines emit a variety of potentially toxic substances,92 93 \~8 \36 including carbon monoxide, oxides of nitrogen, hydrocarbons, aldehydes (especially
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From page 131... ...
ENVIRONMENTAL TOBACCO SMOKE The air contaminant in an aircraft cabin that is most apparent to the passengers and crew is cigarette smoke. Cigarette-smoking contributes to environmental tobacco smoke (ETS)
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From page 132... ...
This pattern of smoking results in higher transient concentrations of cigarette smoke than occur in other public places where smoking is permitted. High transient concentrations occur not only in the smoking section, but also in other parts of the cabin.
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From page 133... ...
AIRCRAFT VENTILATION AND SMOKE CONCENTRATIONS Table 5-2 is a partial list of compounds in cigarette smoke. Many of these are more heavily concentrated in the sidestream.
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From page 134... ...
As discussed in Chapter 7, measurements of carbon monoxide, nitrogen oxides, respirable suspended particles (RSP) , and light-scattering are all used as surrogates to detect ETS.
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From page 135... ...
TABLE 5-2 Distribution of Compounds in Nonfilter-Cigarette Undiluted Mainstream and Diluted Sidestream Smokea Total Emission in Sidestream-to Mainstream Smoke, Mainstream Total Compound p~/cizarette Emission Ratio Vapor Chase . Carbon monoxide 10,000-23,000 2.~:1-4.7:1 Carbon dioxide 20,000-40,000 8:1-11:1 Carbonyl sulfide 18-42 0.03:1-0.13:1 Benzene 12-48 10:1 Toluene 160 6:1 Formaldehyde 70-100 0.1:1-50:1 Acrolein 60-100 8:1-15:1 Acetone 100-250 2:1-5:1 Pyridine 16-40 6.5:1-20:1 3-Methylpyridine 12-36 3:1-13:1 3-Vinylpyridine 11-30 20:1-40:1 Hydrogen cyanide 400-500 0.1:1-0.25:1 Hydrazine 0.032 3:1 Ammonia 50-130 40:1-170:1 Methylamine 11.5-28.7 4.2:1-6.4:1 Dimethylamine 7.8-10 3.7:1-5.1:1 Nitrogen oxide 100-600 4:1-10:1 N-Nitrosodimethyl- 0.01-0.04 20:1-100:1 amine N-Nitrosopyrrolidine 0.006-0.03 6:1-30:1 Formic acid 210-490 1.4:1-1.6:1 Acetic acid 330-810 1.9:1-3.6:1
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From page 136... ...
136 TABLE 5-2 (continued) Total Emission in Sidestream-to Mainstream Smoke, Mainstream Total Compound ~g/cizarette Emission Ratio Particulate chase: Particulate matter 15,000-40,000 1.3:1-1.9:1 Hico tine 1,000-2,500 2.6:1-3.3:1 Anatabine 2-20 <0.1:1-0.5:1 Phenol 60-140 1.6:1-3.0:1 Catechol 100-360 0.6:1-0.9:1 Hydroquinone 110-300 0.7:1-0.9:1 Aniline 0.36 30:1 2-Toluidine 0.16 19:1 2-Naphthylamine 0.0017 30:1 4-Aminobiphenyl 0.0046 31:1 Benz~ajanthracene 0.02-0.07 2:1-4:1 Benzo~a~pyrene 0.02-0.04 2.5:1-3.5:1 Cholesterol 22 0.9:1 y-Butyrolactone 10-22 3.6:1-5.0:1 Quinoline 0.5-2 8:1-11:1 Harman 1.7-3.1 0.7:1-1.7:1 N'-Nitrosonornicotine 0.2-3 0.5:1-3:1 NNKb 0.1-1 1:1-4:1 N-Nitrosodiethanolamine 0.02-0.07 1.2:1 Cadmium 0.1 7.2:1 Nickel 0.02-0.08 13:1-30:1 Zinc 0.06 6.7:1 Polonium-210 0.04-0.1 psi 1.0:1-4.0:1 Benzoic acid 14-28 0.67:1-0.95:1 Lactic acid 63-174 0.5:1-0.7:1 Glycolin acid 37-126 0.6:1-0.95:1 Succinic acid 110-140 0.43:1-0.62:1 a Total emissions are given for fresh, undiluted mainstream smoke generated by a smoking machine under conditions of 1 puff/min of 2-s duration and 35-ml volume, i.e.
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From page 137... ...
In 1970 and 1971, in one of the earliest studies, FAA and the U.S. Public Health Services 60 measured carbon monoxide, aromatic hydrocarbons, aldehydes, ketones, and total particulate mass on 20 military flights and 14 domestic civilian flights.
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From page 138... ...
nonsmoking RSP 50-500 ~g/m3 in smoking section;3 peak, 1,000 ~g/m DC-lOa RSP 10-40 ~g/m3 in nonsmoking aft cabin with no cigarette odor 100~20 ~g/m3 in nonsmoking forward cabin with cigarette odor RSP a Load factor, 40-60X. 300~200 ~g/m3 in smoking section; peak, 750 ~g/m 550-1,200 ppm
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From page 139... ...
. An additional indoor air standard for particle density in office buildings is the Japanese standard of 150 ~g/m5.9 For carbon monoxide, the EPA and ASHRAE standards of total l-h concentration of 35 ppm and 8-h concentration of 9 ppm appear unlikely to be violated in typical airliner cabins.
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From page 140... ...
On commercial aircraft, the people with the greatest exposure are the cabin crew, who are exposed to ETS regularly. In some aircraft, the galley is in the smoking section, so cabin crew are exposed to ETS at the same concentrations and for the same durations as passengers in the smoking section.
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From page 141... ...
This was true when smoke concentrations were low, as determined by measurement of surrogate carbon monoxide concentrations at 5 ppm and even as low as 1 ppm. Filtration of 80~o of particles with Cambridge filters, which are currently in use on aircraft that have recirculation systems, has reduced irritation substantially i68 (see Chapter 2~.
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From page 142... ...
were observed after flights of 8 h.49 However, Duncan and Greaney44 found no increase in carbon monoxide in exhaled breath of 16 flight attendants after 10 h of flying (Los Angeles to Honolulu and back)
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From page 143... ...
They found that odor sensitivity to ETS increased as relative humidity was increased from 50% to 75%. Tobacco smoke odor does not decay rapidly.
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From page 144... ...
Cain et al. 32 determined that, with as few as lox of the occupants in a space smoking at any time, a ventilation rate of 5.3 cfm/occupant was required to make the air acceptable to at least 80% of the occupants, especially nonsmokers, who are more sensitive to the odor than smokers.32 Kerka and Humphreys77 demonstrated that, although perceived tobacco smoke odor in reduced over time owing to olfactory adaptation while the person stays in the chamber, the degree of sensory irritation increases.
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From page 145... ...
To evaluate the relevance of occupational exposures to ETS for the cabin crew in aircraft, we assumed that a flight attendant worked 800 h/yr in the smoking section of an airplane, where the average concentration of total particles might be 250 ~g/m3. Assuming a breathing rate consistent with modest exercise -- i.e., 15 L/mine-under these circumstances the integrated exposure to ETS would be 1.8 x 105 ~g/yr.
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From page 146... ...
Many studies of chronic exposure of children indicate that the prevalences of respiratory symptoms and illness are increased and pulmonary function can be decreased.16, However, there have been relatively few studies in adults. White and Phoebe 7 4 reported that nonsmoking healthy adults exposed to tobacco smoke at work had lower forced expiratory flow rates than nonsmokers not so exposed.
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From page 147... ...
}62 A recent comprehensive review of laboratory and clinical data on animals and humans with respect to nicotine and carbon monoxide uptake in passive smoking and its potential effect on the cardiovascular systems 3 3 concluded that passive smoking should have no cardiovascular effects in humans. However, the reports of cardiovascular complications in previously normal people exposed to ETS raise the possibility of deleterious effects associated with exposure .
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From page 148... ...
PREVENTION OF EXPOSURE TO ETS Occupational exposure of flight attendants to ETS could be limited by configuring aircraft without any work stations (galleys) in the smoking section.
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From page 149... ...
We conclude on balance that the limited benefits are outweighed by the difficulties associated with the proposal. In the judgment of the Committee, the potential health effects of passive smoking are of more concern than effects of withdrawal, and more people are at risk.
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From page 150... ...
ambient or workplace carbon monoxide standards, but do violate a Japanese standard for indoor air quality. Cigarette smoke contains known human and animal carcinogens that would be strictly regulated if the source were something other than tobacco.
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From page 151... ...
A return to the random distribution of smokers throughout the cabin would decrease the peak concentrations of contaminants, but the Committee feels that this probably would be unacceptable to a majority of the traveling public. The Committee recommends a ban on smoking on all domestic commercial flights, for four major reasons: to lessen irritation and discomfort to passengers and crew to reduce potential health hazards to cabin crew associated with ETS, to eliminate the possibility of fires caused by cigarettes (see Chapter 1)
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From page 152... ...
Many of these fungi can grow and reproduce on surfaces within man-made structures and, when disturbed9 produce dense biologic aerosols that accumulate within an enclosed space and cause hypersensitivity diseases -- such as hypersensitivity pneumonitis, allergic rhinitis, and allergic asthma -- and rarely invasive diseases in susceptible people. 30 Many infectious fungal diseases (including coccidioidomycosis, histoplasmosis, blastomycosis, and cryptococcosis)
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From page 153... ...
, as well as transmit serious diseases.~39 \66 }75 Finally, animal dander and human dander accumulate in any occupied space, and both can be allergenic. SOURCES OF BIOLOGIC POLLUTANTS Potential sources of biologic aerosols in cabin air include outside air, the cargo compartment, passengers and crew, and structural contamination of the aircraft.
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From page 154... ...
Barriers to air circulation between passenger and cargo compartments can range from structural and excellent (Class D) to virtually nonexistent and dependent entirely on airflow patterns (Class B)
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From page 155... ...
Fungi and actinomycetes, in particular, can withstand repeated wet-dry cycles and temperature extremes. FACTORS AFFECTING AIRBORNE CONCENTRATIONS OF_BIOLOGIC POLLUTANTS AND THEIR HEALTH EFFECTS Factors that can affect airborne concentrations of biologically derived particles include source strength, methods of aerosolization, viability, stability, and ventilation.
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From page 156... ...
The outside air supplied to aircraft cabins during flight is essentially clean. Enough outside air needs to be supplied to dilute the inevitably produced bacterial aerosols to the point where the risk of infection is minimized.
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From page 157... ...
Submarine and spacecraft environments are most nearly like the commercial aircraft environment, except that all their air must be recirculated, because outside air is unavailable. In both, recirculation systems are designed with that in mind, and the quality of air filtration far exceeds that in commercial airliners.
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From page 158... ...
These data are only marginally relevant to the aircraft environment, because there are major differences in ventilation, air filtration, and passenger load. Data from doctors' offices and schools clearly indicate that viruses can be circulated through ventilation systems, remain viable, and infect people who have had no physical contact with the source.22 '21 In aircraft cabins, this effect might be augmented by the low relative humidity, which would prolong the life of airborne viruses.
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From page 159... ...
The risk of contracting epidemic disease on a grounded aircraft is emphasized by ~ report of an epidemic of influenza directly traceable to a passenger aboard a plane grounded for 4 h in Alaska; 72% of the passengers became ill from the exposure. i04 The absence of other such reports in the literature does not lessen the danger implicit in conditions in a crowded airplane with little or no outside ventilation.
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From page 160... ...
If the risk of infection is to be minimized, the amount of outside air supplied to each passenger during flight should be maximized, because outside air at cruise altitude is essentially clean. The dangers of extensive use of unfiltered, untreated recirculated air should be carefully considered.
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From page 161... ...
Moisture from the passengers themselves will cause relative humidity to increase, depending on the outside-air ventilation rate and the load factor, and it will decrease as rate of outside ventilation increases. MEASURED RELATIVE HUMIDITY IN AIRCRAFT Humidity measurements that have been made in aircraft cabins are summarized in Table 5-~.
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From page 162... ...
Corneal ulcerations have been reported in wearers of contact lenses after long flights, possibly owing to low oxygen partial pressure, as well as low relative humidity. Hydrophilic contact lenses tend to lose water, but not to the detriment of vision.
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From page 163... ...
On only three flights were there complaints of "dry air".15 Mendez Martin9 9 and Kohler81 showed that urinary calculosis was common among flight personnel, possibly because of low relative humidity, but the Committee found no corroboration of this finding (see Chapter 6~. REPORTED HEALTH EFFECTS OF LOW RELATIVE HUMIDITY IN OTHER ENVIRONMENTS Water loss from airways might be an important stimulus of exercise-induced asthma under dry conditions,7 s7 and a slight reduction in lung capacity has been noted in asthmatics at rest in dry environments.
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From page 164... ...
2 3 It has been shown that people overwintering at the Antarctic station, where indoor relative humidities approach those in aircraft cabins, are not at increased risk of respiratory infections after their return to a more temperate environment.72 These data are only marginally relevant to cabin air quality, because there are major differences in conditions and patterns of exposure. Lidwell et al.89 demonstrated that increased incidence of respiratory infection in winter is related to temperature, not to relative humidity, and stated that this analysis "contradicts any arguments based on virus survival in relation to indoor humidity or on a postulated damaging effect, due to drying, on the mucous membranes, predisposing to the initiation of infection when the indoor humidity falls in cold weather." However, after a less extensive study, Gelperin54 reported that the rate of upper respiratory infection was 5-10% lower in humid barracks (relative humidity, 40%)
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From page 165... ...
SUMMARY The health risks associated with clean, dry air appear quite low, especially for normal people, and probably do not justify the cost and potential microbiologic complications that would attend installation of active humidification systems in aircraft. PRESSURIZATION The Committee recognizes that pressurization of the cabin to an equivalent altitude of 5,000-8,000 ft is physiologically safe -- no supplemental oxygen is needed to maintain sufficient arterial oxygen saturation.
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From page 166... ...
Cabin crew members should be advised as to the symptoms and procedures to alleviate them. The Committee sought evidence of operating practices in which an aircraft was pressurized at altitudes above 8,000 ft.
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From page 167... ...
CARBON DIOXIDE Carbon dioxide is the product of normal human metabolism, which is the predominant source in aircraft cabins. The carbon dioxide concentration in the cabin depends on the ventilation rate, the number of people present, and their individual rates of carbon dioxide production, which vary with activity and (to a smaller degree)
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From page 168... ...
the reduced pressure has no significant effect on the symptoms or other response to increased carbon dioxide concentrations. In discussing federal regulations, Chapter 3 pointed out that the current FAR concerning acceptable cabin concentrations of carbon dioxide is several decades old.
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From page 169... ...
The Committee could find no monitoring data on the concentrations of volatile organic chemicals in aircraft cabins during operation. Insecticides can be used on aircraft to control pests of public-health or agricultural importance.
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From page 170... ...
2. American Conference of Governmental Industrial Hygienists.
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From page 171... ...
S Effect of carbon monoxide on cardiovascular disease.
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From page 172... ...
Carbon monoxide effect on exercise-induced angina pectoris.
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From page 173... ...
III. Passive smoking and pulmonary function.
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From page 174... ...
Stability of tobacco smoke odor in enclosed spaces, pp.
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From page 175... ...
Passive smoking and uptake of carbon monoxide in flight attendants.
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From page 176... ...
Boyle. The effect of environmental tobacco smoke in two urban communities in the west of Scotland.
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From page 177... ...
Bone. Deposition of sidestream cigarette smoke in the human respiratory tract.
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From page 178... ...
The influence of passive smoking on pulmonary function: A study of 1,351 office workers.
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From page 179... ...
Saw. Is passive smoking an added risk factor for lung cancer in Chinese women?
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From page 180... ...
Passive smoking. Lanced 1: 791, 1982.
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From page 181... ...
Federal Aviation Administration, Office of Aviation Medicine, 1970.
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From page 182... ...
National Council on Radiation Protection and Measurements. A Review of NCRP Radiation Dose Limit for Embryo and Fetus in Occupationally-Exposed Women.
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From page 183... ...
Aircraft cabin ozone measurements on B747-100 and B747-SP aircraft: Correlations with atmospheric ozone and ozone encounter statistics.
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From page 184... ...
J WilcOxe Passive smoking in adulthood and cancer risk.
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From page 185... ...
Richter. The influence of passive smoking on the cardiovascular system Prev.
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From page 186... ...
W Tobacco smoke dilution recommendations for comfortable ventilation.
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From page 187... ...
Revised Evaluation of Health Effects Associated with Carbon Monoxide Exposure: An Addendum to the 1979 EPA Air Quality Criteria Document for Carbon Monoxide.
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From page 188... ...
Characteristics in the atmosphere of long-range transport aircraft cabins. Aviat.
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From page 189... ...
Fischer. Passive smoking at work.
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