average annual exposure in their city of residence. In the Seventh-Day Adventist study, geostatistical interpolation of annual fixed-site monitor data was assigned to the address of each subject. In the Dutch study, a complicated exposure-assessment algorithm based on regional and local pollution and accounting for land use was used to estimate annual exposure of each subject. In the Norwegian study, dispersion models coupled with emission data were used to estimate annual sulfur dioxide (SO2) and NOx at each subject’s residence.

Table 4.20 shows that in the Harvard Six Cities study and in the Dutch study, RRs of lung cancer were increased with exposure to fine particulate matter (PM) although the CIs included the null. In the Harvard Six Cities study, the RR associated with an increase in PM2.5 of 18.5 µg/m3 was 1.17 (95% CI 0.67–2.04). In the Dutch study, the RRs associated with an increase in air pollution from the 5th to the 95th percentile were 1.1 (95% CI 0.4–2.6) for black smoke (a measure of PM2.5 and elemental carbon) and 1.3 (95% CI 0.4–3.7) for nitrogen dioxide (NO2). In the ACS study, the RR associated with a 10 µg/m3 increase in fine PM was 1.14 (95% CI 1.04–1.23). In the Seventh-Day Adventist Study, RRs increased with increasing exposure: with an increase in PM10 of 24.8 µg/m3, men had an RR of 3.36 (95% CI 1.57–7.19), and women an RR of 1.33 (95% CI 0.60–2.96); with an increase in SO2 of 3.72 ppb, men had an RR of 1.99 (95% CI 1.24–3.20), and women an RR of 3.01 (95% CI 1.88–4.84); and with an increase in NO2 of 19.78 ppb, men had an RR of 1.82 (95% CI 0.93–3.57), and women an RR of 2.81 (95% CI 1.15–6.89). Finally, an association with NOx (a marker of traffic-related combustion products) was found in the Norwegian study: for an increase in NOx of 10 µg/m3, the adjusted hazard ratio was 1.08 (95% CI 1.02–1.15). No associations were found with exposure to SO2.

A number of case-control studies of the association between lung cancer and air pollution have been published. After adjusting for age, smoking, and occupation, Vena (1982) found a 26% increase in risk in persons living for at least 50 years in areas of Erie County, New York, that had high concentrations of total suspended particles (TSP). In a mortality case-control study in Krakow, Poland, an association was found among men living in areas with high concentrations of SO2 and TSP (OR 1.46, 95% CI 1.06–1.99), but no excess risks were found among women (OR for medium or high concentrations 1.17) (Jedrychowski et al. 1990). A study in Trieste, Italy, found lung cancer to be associated with high estimated concentrations of deposited of particles (OR for over 0.298 g/m2 per day compared with less than 0.175 g/m2 per day 1.4, 95% CI 1.1–1.8) (Barbone et al. 1995; Biggeri et al. 1996). Lung-cancer risk was also associated with living near an incinerator in the city (OR 2.6, 95% CI 1.3–5.1). (Alarie et al. 1972; Xu et al. 1996a) found that in northeastern China ORs in men increased with perceived smokiness in the outdoor environment (OR for “somewhat smoky” 1.5, 95% CI 1.2–2.0; OR for “smoky” 2.3, 95% CI 1.7–2.9). Similar results were found in women. In a small study among women living in Athens, Katsouyanni et al. (1991) investigated the association between lung cancer and ambient concentrations of soot. They did not find an association among nonsmoking women (smoking-adjusted, comparing highest quartile with lowest quartile OR 0.7), but found a strong association among women who smoked for long durations (30 years of smoking, comparing highest quartile with lowest quartile OR of 2.23). Nyberg et al. (2000) conducted a case-control study of lung cancer and traffic-related pollution in Stockholm, Sweden, and estimated traffic-related concentrations of NO2 and heating-related concentrations of SO2, using patterns of traffic density and dispersion models. After adjusting for smoking, occupation, exposure to radon, and other risk factors, they found little evidence of an association when they used exposures to NO2 averaged over a 30-year period. A trend in risk was observed with a 20-



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