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TAATFS AR°J FIGURES CHAPTER 3 1 m ~ -35 ~ d ~

TABLES IL*M FIGURES CEAB'PER 3 tJ h

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