Gender in environmental health research stronger associations among women. In the Atherosclerosis Risk in Communities (ARIC) study, Kan et al. (2007) found that living near a major road predicted lower forced expira- tory volume in 1 sec (FEV1) and forced vital capacity (FVC) only among women. The authors pointed to women’s greater airway reactivity, citing stronger responses to smok- ing (Lodrup Carlsen et al. 2006; Vollmer et al. 1994; Yunginger et al. 1992), or better accuracy in residential exposure assessment for homemakers (35% of ARIC women vs. 17% of men). Franklin et al. (2007) studied 130,000 respiratory deaths in 27 U.S. communities, using case–crossover methods and meta- analysis, and found that community air pol- lution better predicted death among women than among men. The authors proposed sex- differing respiratory anatomy and physiology, or PM deposition patterns. In a comprehensive study of daily air pol- lution and respiratory hospitalization among adults and children in Windsor, Ontario, using time-series and case–crossover methods, Luginaah et al. (2005) reported a larger num- ber of significant associations among women Table 1. Studies examining effect modification by sex among adults. Study Population Studies reporting stronger effects among women Franklin et al. 2007 1.3 million deaths, 27 U.S. cities 1997–2002 Exposure metric(s) Outcome(s) Risk among males Risk among females Ito and Thurston 1996 Kan et al. 2007 Kan et al. 2008 Luginaah et al. 2005 Sunyer et al. 2000 Sunyer et al. 2006 Daily deaths in Chicago, IL 1985–1990 15,792 middle-age U.S. adults, 1987–1989 (ARIC cohort) Adult population of Shanghai, China (population, 13.1 million) 1,602 adults (15–64 years) in Windsor, Ontario, Canada 1995–2000 2,305 adults (≥ 35 years of age) Spain, 1985–1989 3,232 men and 3,592 women in Europe Thaller et al. 2008a 142 lifeguards 16–27 years of age (79% male) Studies reporting stronger effects among men Abbey et al. 1998 1,391 nonsmoking U.S. adults Galizia and Kinney 520 nonsmoking 1999 undergraduate students in New Haven, CT Korrick et al. 1998 530 hikers (18–64 years), Mt. Washington, NH Wang et al. 1999 1,075 Chinese adults (35–60 years) Studies reporting or mixed modification Ackermann-Liebrich 9,651 adults et al. 1997 18–60 years of age in Switzerland (SAPALDIA cohort) Chestnut et al. 1991 6,913 adults (25–75 years) (NHANES I) Jedrychowski and 584 men, 830 women Krzyzanowski 1989 in Krakow, Poland Oosterlee et al. 1996 Zeka et al. 2006 1,485 Haarlem, Netherlands, adults 1.9 million deaths in 20 U.S. cities, 1989–2000 Prior day PM2.5 > 10 µg/m3 Daily PM10, O3 at nearest regulatory monitor Quartiles of residential traffic density 10-µg/m3 increase in daily PM10, SO2, NO2, O3 IQR increase in 1-, 2-, 3-day lag NO2, SO2, CO, COH, O3, PM10, TRS 20-µg/m3 increase in same-day ambient black smoke Constant traffic density NO2 > 50 µg/m3 10-µg/m3 increase daily average PM2.5, maximum O3 IQR difference of 54.2 days/year > 100 µg/m3 PM10 Lived ≥ 4 years in U.S. county with summer 1-hr O3 ≥ 80 ppb Ambient O3, PM2.5, aerosol acidity Ambient PM2.5 and SO2 (rural vs. urban area) 10-µg/m3 change in annual mean PM10 1-SD increase in TSP (about 34 µg/m3) Residence in area with higher sulfate or sulfur transformation ratio Living on heavy (vs. light) trafficked streets 10-µg/m3 change in daily PM10 concentrations Percent increase in respiratory mortality All-cause mortality RR for respiratory mortality Lung function: FEV1 FVC Percent increase in respiratory mortality Risk of respiratory hospitalization Prevalence of chronic phlegm FVC FEV1/FVC PPFEV1 FEV1/FVC Percent change in FEV1 FEF25–75 FEF75 symptoms Percent change in FEV1 FVC Mean change FEV1 FVC Lung function, symptoms Wheeze (ever) Wheeze (2-year) Percent increase in respiratory mortality 1.90 (0.14–3.65) 1.06% (0.07–2.6) RR = 1.10 (0.97–1.26) β (Q4, age adjusted) = 19.6 (–34.9 to 74.1); p-trend = 0.66 β (Q4, multivariate) = 11.7 (–40.2 to 63.5); p-trend = 0.86 β (PM10) = 0.17% (0.03 to 0.32) β (SO2) = 0.85% (0.43 to 1.28) β (NO2) = 0.88% (0.49 to 1.28) β (O3) = 0.19% (–0.16 to 0.55) RR (2-day COH) = 1.04 (0.82–1.32) RR (3-day COH) = 0.95 (0.80–1.13) β (traffic) = 6.13% (4.37–8.32); p-trend = 0.47 β (NO2) = 6.67% (3.49–11.36); p-trend = 0.98 β (PM2.5) = –0.1% (–0.8 to 0.5) β (O3) = –0.006% (–0.2 to 0.05) β = –7.2 (–11.5 to –2.7) (males w/parental respiratory illness) β = –1.5 (–2.7 to –0.4) β = –4.7% (–0.7 to –8.8) β = –13.0% (–4.9 to –21.1) β = –10.0% (1.3 to –21.3) OR = 2.30 (1.15–3.46) β = –0.055 (SE = 0.025) β = –0.051 (SE = 0.016) 199 mL (SE = 50 mL) β = 3.4% (p < 0.05)b 1.57% (–0.22 to –3.35) 1.34% (0.40–2.27) RR = 1.17 (1.02–1.35) β (Q4, age adjusted) = –34.8 (–66.5 to –3.1); p-trend = 0.01 β (Q4, multivariate) = –34.8 (–66.5 to –3.1); p-trend = 0.01 β (PM10) = 0.33% (0.18–0.48) β (SO2) = 1.06% (0.62–1.51) β (NO2) = 1.10% (0.69–1.51) β (O3) = 0.40% (0.03–0.76) RR (2-day COH) = 1.20 (1.00–1.43), by case crossover RR (3-day COH) = 1.15 (1.02–1.30), by time series OR = 1.52 (0.99, 2.31) β (traffic) = 7.69% (5.95–9.75); p-trend = 0.002 β (NO2) = 8.68% (5.30–13.22); p-trend = 0.05 β (PM2.5) = –2.1% (–3.2 to –1.0) β (O3) = –0.3% (–0.4 to –0.6) β = 0.9 (–0.8 to 2.5) β = –0.2 (–0.9 to 0.5) β = –0.26% (3.79 to –4.31) β = –1.96% (5.39 to –10.30) β = –2.08% (9.94 to –13.9) OR = 1.79 (0.83–3.89) β = –0.039 (SE = 0.039) β = –0.019 (SE = 0.025) 87 mL (SE = 30 mL) Effects did not differ by sex Percent change in FVC β = 2.25% (p < 0.05) Effects did not differ by sex (p > 0.75) FEV1 decline faster by 11 mL/year in high- vs. low-sulfate areas High-sulfate area predicted symptoms, not lung function OR = 1.1 (0.8–1.3) OR = 1.1 (0.6–1.8) β = 0.71 (0.004–1.42) Effects did not differ by sex β = 1.04 (0.33–1.75) Respiratory mortality OR = 1.14 (0.98–1.33) Abbreviations: IQR, interquartile range; NHANES, National Health and Nutrition Examination Survey; NR, not reported; OR, odds ratio; PPFEV1, percent predicted FEV1; RR, relative risk; Q, quartile; SAPALDIA, Study on Air Pollution and Lung Diseases in Adults; TRS, total reduced sulfur; VC%, vital capacity percent. Key results demonstrate observed effect modification, and are not exhaustive of results reported for each study. Values in parentheses are 95% confidence intervals, unless otherwise indicated. aOther outcomes showed no significant effect modification by sex. bEffects did not differ by sex, and therefore are reported here in only one column. Environmental Health Perspectives • volume 118 | number 2 | February 2010 169