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I Ventilation Rate (elm per occupant) F•gu:e 1 eo 60 40 20 GD ~ 00 O m N N ~A

40 Recommendations from ASHRAE Standard 15 20 25 30 35 40 45 50 55 60 Ventilation (cfm per occupant) Figure 2 35 b

v d 80 60 5 2 3 4 5 6 7 8 910 Odor Intensity (cm) Figure 5 35 e

r ) Ventilation Rate per Occupant (c 50 5 10 ) 100 200 500 1000 2000 5000 Ventilation Rate per Cigarette (ft3) FiSure 4 35 d m -1 O ~ N N 4~

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dissatisfaction would occur at a concentration of 3.8 ppm carbon monoxide. A comparison with the odor judgments of visitors in Fig. 6 reveals that only smokers would find such a level tolerable at the 20% rule. Clausen et al. estimated that the ventilation rate necessary to control irritation of occupants to a dissatisfaction of 204 would equal only one-tenth of that needed to control odor perceived by visitors to the same level of dissatisfaction. Although Clausen et al. did not argue in favor of lowering ventilation to meet only the dissatisfaction of occupants, there -could exist some temptation to do so (see Winneke, Plischke, Roscovanu, and Schlipkoeter, 1984). Cain et al. cautioned against the temptation to see irritation and odor in the same light: Apart from the issue of whether visitors or occupants are more sensitive, there exists a question regarding whether the '20t rule' should govern dissatisfaction based on irritation just as it governs dissatisfaction based on odor alone. Whereas odor may be interpretable narrowly on grounds of comfort, irritation would seem interpretable on grounds of health. Some people may find themselves quite neutral with respect to one or another odor, but no one could plausibly argue neutrality with respect to burning eyes. It could be argued, therefore, that any consistent irritation above baseline should be deemed unacceptable. [p.352] Alternatives to Ventilation It might seem intuitively reasonable that the odor of ETS should come from its vapor phase and the irritation from its particulate phase. At one time this seemed likely, but recent investigations that have employed electrostatic air cleaning have shown clearly that the gas phase accounts for most of both odor and irritation (cf. Hugod, *1984; Weber, 1984). Comparison of the right and left sides of Fig. 7 will reveal that elimination of the particulate phase had only a trivial effect on the eye irritation caused ETS at 2 and 5 ppm carbon monoxide (Cain, Tosun, See, and Leaderer, 1987). The same held true for judgments of odor and of nose and throat irritation. Clausen, Nielsen, Sahin, and Fanger (1987) confirmed these results. In finding that particles played essentially no role in odor, both investigations also confirmed Clausen et al.'s (1985) earlier experiments with visitors. Hence, particle filtration holds no promise for immediate elimination of the discomfort of ETS. The major advantage of such air.cleaning will derive from reduction of haze and collection of 'tar' that would otherwise adsorb elsewhere in the space. Although both the odor and irritation of ETS come from the ~ 34 CD O CD N N 47

vapor phase, the chemical constituents that give rise to the one, probably do not give rise to the other. Undoubtedly, the odor comes from a very large number of constituents. The sense of smell will respond to almost all airborne organic materials present in sufficient concentration (Cain, 1988). For one substance, however, a 'sufficient concentration' may fall a millionfold below that of another. Furthermore, individual constituents will combine perceptually in mixtures in complicated, nonlinear ways. Although one or a few materials could in principle dominate the odor, it seems unlikely. Many fewer materials can cause irritation at the concentrations present in ETS and its irritation could realistically arise from a few or perhaps even one constituent. Little is known about how irritants combine with each other perceptually though it is known that odor and irritation interact (Cain and Murphy, 1980). Irritation can surpress the perception of odor and vice versa (Cain, See, and Tosun, 1986). In so far as irritation may have less complex origin than odor, it may offer easier opportunities for control through filtration. As yet, however, experiments on the origin of ETS have told more about what fails to cause irritation than about what causes it (Weber, Jermini, and Grandjean, 1976; Weber-Tschopp, Fischer, and Grandjean, 1977; Weber-Tschopp, Fischer, Gierer, and Grandjean, 1977; Hugod, Hawkins, and Astrup, 1978). The complexity of ETS more or less guarantees that almost any means of air cleaning will eliminate part of it, even though no simple procedure will eliminate all of it. Through the use of air washing that presumably eliminated some water-soluble constituents, Clausen, Moller, and Fanger (1979) achieved some reduction in level of dissatisfaction though not in the perceived intensity of ETS. The air-washed ETS smelled fresher. The results offered little encouragement for the use air-washing alone, but, showed that the odor character of ETS can play some role in degree of acceptance. Undoubtedly, a combination of particulate air cleaning and vapor-phase cleaning via adsorption on activated carbon or via chemisorption on oxidant-impregnated alumina can control both the irritation and odor of ETS to some degree. Unfortunately, there exist no standards to assess the efficacy of vapor-phase filtration media. The installation of such media occurs more commonly in special environments, e.g., libraries and computer facilities, under expert guidance than in spaces designed for genera*l occupancy. In the overwhelming majority of cases, attempts to control ETS rely on ventilation (dilution). As we have seen, however, ventilation has its limitations. m ~ 35 OD O GD N N ~

NO FCTRATION I FLTRATION N 2 PPM } I _ • 5 PPw. U W p.~+ o . . ~ . i. ~T r- ° NO R-1 RATION FCTAAT10N W L In ~C N SC ° r i0 Z • ZPPM .5PPM. C I + ^m I -_ W C4• •13 SC U f0 0 SS L T I M E (minutes) FiS. 7 3C 0 CC 35 g

into a space in order to satisfy visitors to that space? Will the amount of air required by smokers differ from that required by nonsmokers? Does ETS-odor decay spontaneously after smoking ceases? Do occupants accustomed to the environment impose less stringent criteria for ventilation than visitors fresh from a nonsmoking space? Does the odor and irritation of ETS come from the smoke particles or from the vapors that accompany the particles? Does filtration offer opportunities for control? Ventilation Reauirements Based on Responses of the Visitor The usual setting to explore how indoor contaminants affect the senses is a climate-controlled environmental chamber with relatively inert surfaces, e.g.,, aluminum or stainless steel, and variable ventilation. In the case of occupancy odor, human beings occupy the chamber in order to generate the odor of interest. Judges may enter the chamber briefly or may place their faces into a box fed with the atmosphere of the chamber. (In their manner of sampling the atmosphere, the judges essentially the space.) The odor judgment may comprise a mark on an annotated rating scale (e.g., 'no odor' to 'overpowering odor') or the choice of a matching odor intensity. The latter judgment generally entails the use of a device called an olfactometer that delivers the vapor of some standard odorant, such as n-butyl alcohol (1 -butanol), at various concentrations. A matching odor has the advantage of reproducibility from lab to lab. Many modern investigations also obtain judgments of acceptability in order to 'calibrate' intensity judgments. Acceptability._judqments address the question: How many people will object to any given level of odor (or irritation)? The answer will depend on individual differences in olfactory sensitivity and on esthetic criteria. Whereas we can expect average intensity judgments to remain constant through the decades for any fixed stimulus, we can expect acceptability judgments to shift somewhat with prevailing standards. A comment by N. W. Downes following the presentation of a classic study of ventilation requirements for occupancy odor by Riley, Yaglou, and Coggins (1936) illustrates the matter of shifting standards: - This paper brings to mind an experience we had in Kansas City some years ago. we built a 30-room elementary school... equipped with a ..fan system...so dampered that not only outside air in toto could be used but air cou*ld be recirculated on a basis of one-third, two-thirds or in toto, the air supplied remaining constant at 30 cfm per pupil. We soon found we were getting no place on a recirculation basis on account of odors which were at times nauseating. Even the use of outside air in toto failed to eliminate the objections. The Principal on investigation soon found that a 30

Figure 3 87808225 )000 F 4 CiporNles/Ar 900F 8 Clyoie/Ies/Ar Malching la'Ywc cf./.cc. ~ 16 Clporelles/Ar U tn M 300F 200 100 30 smoklnq-] 60 90 120 30 60 90 120 30 - 60 90 120 Time (min)

both occupancy odor and tobacco smoke odor (Fig. 5). Stronger odors meant greater dissatisfaction irrespective of odor type. How well does the higher rate implied by the investigation compare with the ASHRAE standard? As indicated above, the standard recommends 60 cfm per occupant in a smoking lounge, where presumably most or all occupants will be smoking. If 100% rather than 10% were smoking simultaneously, then the rate would need exceed an unachievable 500 cfm per occupant. If 50% were smoking, perhaps a more realistic expectation, then the rate would need to exceed a still unachievable 250 cfm per occupant. (The maximum achievable rate for typical design occupancy in a mechanically-ventilated space will usually equal about 60 cfm per occupant, though a generous allotment of space per person can increase that value.) Fortunately, however, the smoker seems less concerned about the odor of ETS than the nonsmoker. As it turns out, smokers as a group seem satifisfied with about one quarter the ventilation air of a mixed group containing a typical proportion of smokers and nonsmokers. Hence, a rate of 60 cfm per occupant may actually almost meet the customary ASHRAE criterion of a maximum of 20% dissatisfaction. How about nonsmokers? Just as a group of smokers will hold a less stringent criterion than the mixed group, a group of nonsmokers will hold a more stringent criterion. The data from the investigation suggest that under typical conditions of smoking occupancy (10% smoking at any given time) nonsmokers would need over 100 cfm per occupant to hold dissatisfaction at only 20% . At the present time, we do not know whether the difference between smokers and nonsmokers derives from olfactory sensitivity to ETS or to esthetic criteria. Nevertheless, it would appear that where smoking occurs none of the recommendations of the ASHRAE standard will do for the nonsmoker. Clausen (1986) confirmed differences in tolerance of ETS odor between smokers and nonsmokers. For any given level cf odor (expressed as concentration of butanol), a group of nonsmokers expressed much more dissatisfaction than smokers (Fig. 6). Both groups exhibited a lawful relation between odor intensity and dissatisfaction, but the difference between the groups grew as odor level increased. At the point where 20% of smokers expressed 'dissatisfaction, the majority of nonsmokers did so. As ETS enters the atmosphere, its many chemical constituents react with each other and with surrounding materials both chemically and physically. Does this behavior change the nature of the contaminant over time? Yes and no. Irrespective of whatever chemical changes occur, the odor of ETS behaves in the short run like a stable contaminant. After the source has been removed, ETS odor decays in a manner entirely predictable from ventilation rate (Clausen, Fanger, Cain, and Leaderer, 1985). In this respect, it differs from occupancy odor which has a (Z 32 m O C7 ~ »'a

References American Society of Heating, Refrigerating, and Air-Conditioning, Engineers (ASHRAE) (1986). Ventilation for Accentable Indoor Air Oualitv. ANSI/ASHRAE 62-1981R. Atlanta: ASHRAE. Cain, W. S. (1979). Ventilation and odor control: prospects for energy savings. ASHRAE Transactions, 85 (11. 784-792. Cain, W. S. (1988). Olfaction. In R. C. Atkinson, R. J. Herrnstein, G. Lindzey, and R. D. Luce (Eds.), Stevens' Handbook of Exnerimental pavcholoav. Vol 1: Perceotion and Motivation, rev. ed. New York: Wiley. Pp. 409-459. Cain, W. S. and.Murphy, C. L. (*1980). Interaction between chemoreceptive modalities of odour and irritation, Nature. 284 *1 255-257. Cain, yS., See;-Leaderer, B., and Tosun, T. (1986). Irritation and odor from formaldehyde: chamber studies. In tA0 '86: Managing Indoor Air for Health and Enerav Conservation. Atlanta: ASHRAE. Pp. 126-137. Cain, W. S., Tosun, T., See, L.-C., and Leaderer, B. (1987). Environmental tobacco smoke: sensory reactions of occupants. Atmosoheric Environment. 21. 347-353. Cain, yS., Leaderer, B. P., Isseroff, R., Berglund, L. G., Huey, R. J., Lipsitt, E. D., and Perlman, D. (1983). Ventilation requirements in buildings - 1. Control of occupancy odor and tobacco smoke odor. Atmosoheric Environment. 17. 1183-1197. Clausen, G. H. (1986). Tobaksrog - *lugtgener og ventilationsbehov. Doctoral thesis, Technical University of Denmark. Clausen, G. H., Fanger, P. 0., Cain, W. S., and Leaderer, B. P. (1985). The influence of aging, particle filtration and humidity on tobacco smoke odor. In P. 0. Fanger (Ed.), Clima 2000, Volume 4: Indoor Climate. Copenhagen: -VVS Kongres - VVS Masse. Pp. 345-349. Clausen, G. H., Fanger, P. 0., Cain, W. S., and Leaderer,- B: P. (1986). Stability of body odor in enclosed spaces. Environment International. 12. 201-205. Clausen, G. H., Moller, S. B., Fanger, P. 0., Leaderer, B. P., and Dietz, R. (1986). Background odor caused by previous tobacco smoking. In jgQ '86. Managing Indoor Air for Health and Energy Conservation. Atlanta: ASHRAE. Pp. 119-125. 36

Clausen, G. H., Moller, S. B., and Fanger, P. 0. (1987). The impact of air washing on environmental tobacco smoke odor. In-B. *Seifert, H. Esdorn, M. Fischer, H. Roden, and J. Wegner (Eds.), Indoor Air '87. Volume 2. Berlin: Institute for Water, Soil and Air Hygiene. Pp. 4751. Clausen, G. H., Nielsen, K. S., Sahin, F., and Fanger, P. 0. (1987). Sensory irritation from exposure to environmental tobacco smoke. In B. Seifert, H. Esdorn, M. Fischer, H. *ROden, and J. Wegner (Eds.), Indoor Air '87. Volume 2. Berlin: Institute for Water, Soil, and Air Hygiene. Pp. 52-56. Hugod, C. (1984). Indoor air pollution with smoke constituents - an experimental investigation. Preventive Medicine. 13. 582-588. Hugod, C., Hawkins, L. H., and Astrup, P. (1978). Exposure of passive smokers to tobacco smoke constituents. International Archives of Occunational and Environmental Health. 42. 21-29. Weber, A. (1984). Annoyance and irritation by passive smoking. Preventive Medicine. 13. 618-625. Weber, A., Jermini, C., Grandjean, E. (1976). Irritating effects on man of air pollution due to cigarette smoke. American Journal 21 Public Health. 66. 672-676. Weber-Tschopp, A., Fischer, T., Grandjean, E. (1977). Reizwirkungen des Formaldehyds (HCHO) auf den Menschen. (Irritating effects of formaldehyde on men.) International Archives of *OccuDational and Environmental Health. 39. 207-218. Weber-Tschopp, A., Fischer, T., Gierer, R., and Grandjean, E. (1977). Experimenteile Reizwirkungen von Akrolein auf den Menschen.(Experimentally induced irritating effects of acrolein on men.) Archives of Occuoational and Environmental Health. 40. 117-130. Winneke, G., Plischke, K., Roscovanu, A., and Schlipkoeter, H.-W. (1984). Patterns and determinants of reaction to tobacco smoke in an experimental exposure setting. In B. Berglund, T. Lindvall, and J. Sundell (Eds.), Indoor Air. Vol. 2. Stockholm: Swedish Council for Building Research. Pp. 351-356. Yaglou, C. P., Riley, E. C., and Coggins, E. (1936). Ventilation requirements. ASHVE Transactions. 42. 133-162. 37

I FiQure Captions Figure 1. Showing the relation between level of occupancy odor (indicated by concentration of 1-butanol matched to the odor) and ventilation rate per occupant when 4 to 12 persons occupied a climate chamber for an hour. Judgments of odor were made by visitors who sampled the air of the chamber at a remote sampling box. Also shown is the frequency of dissatisfaction expressed by the visitors in response to the question, Is the air acceptable or unacceptable? Data from Cain et al. (1983). Figure 2. Frequency distribution of ventilation rates i. recommended for various types of spaces (e.g., offices, auditoriums, ticket booths, waiting rooms) by the ASHRAE standard on ventilation and indoor air quality. Figure 3. Showing the intensity of ETS odor perceived by visitors to the sampling box during and after intermittent (4 :cig/hr) or continuous (8 and 16 cig/hr) smoking in the climate chamber. Results are expressed relative to level of butanol matched to odor during presmoking occupancy. The open squares in. the left panel show a function for nonsmoking occupancy for comparison. Ventilation rate per occupant under smoking conditions refers to smokers, who were the only occupants in the chamber. From Cain et al. (1983). Figure 4. Percent dissatisfaction among visitors vs ventilation during the last 15 min of smoking in the experiment shown in Fig. 3. Ventilation rate per cigarette based on 7.5-min smoking time per cigarette. Ventilation rate per occupant adjusted to typical conditions of smoking occupancy where 10t of occupants will be smoking at any give time. Modified from Cain et al. (1983). Figure 5. Percent dissatisfaction vs odor intensity (graphic rating) during smoking and nonsmoking occupancy. Data from Cain et al. (1983). Figure 6. Left: Percent dissatisfaction vs odor intensity (matched level of butanol) judged by smokers and nonsmokers. Right: Percent dissatisfaction vs increment in concentration of airborne carbon monoxide. Modified from Clausen (1986). Figure 7. Perceived magnitude of eye irritation and degree of dissatisfaction expressed by occupants exposed to ETS for an hour. Concentrations of carbon monoxide were held constant throughout the exposures and indicate severity of exposure. Filtration refers to elimination of particles via electrostatic precipitation. Filtration had little effect on irritation. From Cain et al. (1987). GG 38 .l ~ O ~ N N O

CHAPTER 3 THE ODOR AND IRRITATION OF ENVIROWMENTAL TOBACCO sMOKE Rilliam s. Cain, PhD John B. Pierce Foundation Laboratory and Yale University New Haven, CT 06519 Introduction The atmosphere inside buildings contains many chemicals generated by the presence and activities of people. People's bodies give off small quantities of organic materials in the breath and from the skin and alimentary tract. Although a chemical analysis may reveal hundreds or even thousands of materials, we usually perceive them in the aggregate as what we call body odor or sometimes occupancy odor. We often notice it consciously when we enter a hot, muggy room. Nevertheless, body odor exists in occupied spaces at essentially all other times, but remains at a low level because of ventilation with outside air. When engineers and public health specialists began to study ventilation requirements for buildings quantitatively, they started with the smell of occupancy (Cain, 1979). The fresh-air requirements so derived exceeded those based on metabolically-relevant gases (oxygen, carbon dioxide) several- fold. In general, occupancy odor poses a mild challenge to the HVAC engineer. (HVAC refers to heating, ventilating, and air- conditioning.) This odor constitutes the baseline case. Anything else that people do in the space will increase ventilation requirements. This would include cooking, painting, operating machines (e.g., mimeo, photocopier), woodworking, smoking, and so on. Of these various activities, smoking has traditionally been pervasive and has accordingly received specific attention (Yaglou, 1955; Kerka and Humphreys, 1956; Weber, Jermini, and Grandjean, 1976). As with occupancy odor, the HVAC engineer has confronted environmental tobacco smoke (ETS) via its sensory characteristics, i.e., its odor and irritation, rather than via its chemical or physical complexity. The chemical complexity of ETS likely exceeds that of emissions from bodies and a chemical analysis of ETS-containing air offers little of practical significance regarding the origin of its, odor or irritation. In what follows, we shall review how human beings perceive ETS. We shall ask: How much ventilation air must we introduce 29

half-life of 55 min, presumably dictated by slow oxidation of its chemical constituents into less odorous products (Clausen, Fanger, Cain, and Leaderer, 1986). ETS odor offers no such easy benefit to the engineer. Indeed, when ventilation fails to eliminate the contaminant entirely, ETS carries a penalty derived from its physical interaction with surfaces. Because the liquid aerosol of ETS, known in the aggregate as 'tar,' adsorbs strongly to walls, fabrics, and so on, it becomes a source of odor later. The background odor of the emitted products carries its own demands for ventilation, predictable in Dart from the typical amount of smoking in a space (Clausen, Moller, Fanger, Leaderer, and Dietz, 1986). jn_a laboratory situation where other sources of combustion can be eliminated, carbon monoxide can offer a gross index of level of ETS. Figure 6 shows that Clausen could relate dissatisfaction to concentration of carbon monoxide in ETS as well as to matehed level of butanol. This occurred because of a strong correlation (r>0.90) between odor intensity and incremental carbon monoxide due to smoking. Such a relationship makes it possib*le to compare one study to another. We can ask, At what concentration of carbon monoxide will ETS reach a given level of dissatisfaction in one or another group? As Fig. 6 revealed, the concentration at which 20% of nonsmokers will express dissatisfaction falls about eight times below that at which 20% of smokers will express dissatisfaction. Responses of Occunants Up to this point, we have concerned ourselves only with the reactions of visitors. Standards for ventilation have focused on the reactions of the visitor, rather than those of the occupant, because the visitor will have a more sensitive, and hence more critical, nose than the person adapted to the contaminant. on the other hand, a focus on the visitor sidesteps another important time-dependent sensory response of the occupant, irritation. Whereas air containing an irritant may seem only barely irritating at first, it may become intolerably so over time. Figure 7 illustrates the time-course of eye irritation experienced by occupants exposed to ETS at constant concentrations of 2 or 5 ppm carbon monoxide, used here as a tracer in the manner mentioned above (Cain, Tosun, See, and Leaderer, 1987). The lower concentration led to slight, though statistically significant, irritation above pre-smoking baseline. The higher concentration led to irritation that increased over time in sensory magnitude and caused an increasing degree of dissatisfaction. Whereas essentially none of the occupants found the irritation objectionable at first, by the end of an hour about 30% found it so. In an extension, Clausen, Nielsen, Sahin, and Fanger (1987) found that an asymptotic level of 20% 33

large number of these youngsters were sent to school by their parents literally sewed up for the winter. He immediately took it upon himself to change the situation by requiring each chi*ld to take a warm shower bath once a week at the school, although encountering vigorous opposition from some of the parents. The objectionable odors soon disappeared as did the objections from the parents. [p. 158] Figure 1 depicts how occupancy odor varied with ventilation rate per occupant under nonsmoking occupancy in a recent study conducted in a climate chamber (Cain, Leaderer, Isseroff, Berglund, Huey, Lipsitt, and Perlman, 1983). Visitors made judgments of air circulated through an outside sampling-box and were therefore naive to the conditions of occupancy. The scale refers to the concentration of 1-butanol matched to the occupancy odor present after one hour of occupancy. Just as odor level decreased with increases in ventilation rate, so also did dissatisfaction. The point of 20% dissatisfaction holds special interest. The ventilation standard of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) (1986) recommends a maximum of 20% dissatisfaction among visitors to a space. By this criterion, the data from the investigation imply the need for 17.5 cfm per occupant. The ASHRAE standard suggests 15 cfm or more per occupant for most spaces, e.g., 15 cfm for classrooms, libraries, auditoriums, dormitories; 20 cfm for offices, conference rooms, dining rooms, lobbies; 25 cfm for discos, beauty shops; 30 cfm for bars, casinos; 60 cfm for smoking lounges (see Fig. 2). Hence, practice coincides with the experimental data about as well as could be expected regarding the baseline case. When cigarettes were smoked in the climate chamber, odor level increased markedly. Figure 3 displays ETS odor for various conditions of smoking: intermittent (4 cig per hr) or continuous (8 or 16 cig per hr). As Fig. 4 shows, the degree of dissatisfaction mirrored the higher odor level. Based on the rule of 20% maximum dissatisfaction, the ventilation rate required per cigarette during active smoking exceeded 4,000 ft3. In order to convert ventilation per cigarette into ventilation rate per person for typical conditions of occupancy in a 'smoking-permitted' space, we assumed that 10% of occupants would be smoking at any given time. The resulting rate equalled 53 cfm, more than three times that for nonsmoking occupancy. Does the higher ventilation rate for smoking imply that the judges in the investigation showed a special aversion to the odor of cigarettes? Apparently not. The judges, one-third of whom were smokers and two-thirds of whom were not, seemed to base their dissatisfaction strictly on odor intensity. Degree of dissatisfaction varied with odor intensity in the same way for 31 W