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i Vl I L, accuracy of the=original assumption..or-,the representativeness- of the measurements made.- That is why.- -measurement--methods- development for ETS is so important. Unfortunately, much of James Repace's,exposure estimations are riot based on realistic original data or assumptions. This critique will demonstrate areas of this chapter where this is the case. A prime example of this poorly conceived initial assumption is found on page 85. Repace picks measurements from 42 "smoking" buildings; a substantiaLl number of which are those bowling alleys, casinos, bars, barbecue restaurants and cocktail lounges referenced to in the previous chapter we reviewed, and compares them with twenty-one non-smoking buildings (such as churches and libraries) and concludes that about 85% of the indoor RSP is due to ETS. Reference to Eatough's work where he reviews exposure assessment methods shows he estimates about 50% of indoor RSP due to ETS. The difference is explained because Repace did not compare like buildings with similar activities in each, which generated equivalent amounts of non-ETS derived RSP. In Section D, in support of hi:; modelling assumptions, he states, "Field studies of` RSP in buildings where smoking occurs suggest that RSP from ETS contributes 80 to 90 percent of the particulate load during the period of smoking,-and that it persists for long pe!riods after smoking ends at typidal building air exchange rat:es, thus prolonging nonsmokers' exposures." Of course he is referring once more to his-unique collection=of bui-ldings., and-the statement---

, fl concerning the pers-istenc.e, of ETS -is - in--di-rect_- contrast with our -own work on the topic •of office_ environments-. - In Section C he also mentions t:hat exposures on aircraft can be considerable. This contrasts with the FAA and NIOSH findings of mean RSP levels of only 40 µg/m3, and maximum of 120 µg/m3. Measurements by Drake found a mean level of 14 µg/m3 and a maximum of 41 µgfm3. . Repace goes on to explore the concept of cigarette equivalents. This concept has to be used with care -- the basis on which such estimations are made must be carefully stated. For instance, based on his assurnptions, he estimates nicotine uptake in non-smokers to be equivalent to between 1/6 and 1/3 of a cigarette per day. However, in our previous studies of approximately 600 offices sampled on a worldwide basis where smoking was allowed, the ave::age airborne concentration of nicotine was 4.0 µg/m3. Using breathing rates as publi;3hed by ASHRAE, the average individual in an office inhales 3.6 liters of air per minute or 4.13 cubic meters of air per eight hour day. If the average nicotine content of that air was 4.0 µg/m3, each individual could inhale 16.52 micrograms of nicotine through- out the course of each day. Since the average smoker in the USA inhales 880 micrograms of nicotine per cigarette, the non- smoker exposed to 16.52 micrograms per day could inhale 0.019 QC "cigarette equivalents" per eight hour day, in contrast to ~ -IT Repace's estimates of 0.17 to 0.33 nicotine cigarette equiva- ~ lents.' ~

Finally, RSP is defined early on in this•chapter--as that portion of the particles below -2.5 um:. For reasons-_ discussed in the review of chapter 6, this figure should be 3.5 um. The piezobalance used for Repace's own work to which he refers is equipped with a size selectiv.e inlet of 3.5 um. In sui~mary, the assumptions on which exposure assessment models are based must be carefully examined since they will have such a strong influence on the outcome of such an exercise, and the policy decisions on which they are based. In our opinion, much of the data from which Repace's assumptions are derived are unrealistic, and not representative of the typical workplace environment, yet the workplace is where much of the smoking policy decision making is currently taking place.