Table 2.

 Odds ratio (95% confidence interval) for 10 µg/m³ increase in exposure to PM_2.5 over multiple averaging periods and high symptoms of anxiety in participants of Nurses’ Health Study

Period	Mean (SD) PM2.5 (µg/m3)	Odds ratio* (95% CI)	P value
1 month	12.74 (4.18)	1.12 (1.06 to 1.19)	0.0001
3 months	12.13 (3.40)	1.13 (1.06 to 1.21)	0.0004
6 months	11.59 (2.77)	1.14 (1.05 to 1.23)	0.002
12 months	11.38 (2.60)	1.15 (1.06 to 1.25)	0.001
1988-2003	13.75 (2.82)	1.09 (1.01 to 1.18)	0.03

PM_2.5=particulate matter <2.5 μm in diameter.

*Adjusted for month of questionnaire return, nurse’s education, husband’s education, age, age squared, whether the nurse has a partner, employment status, physical activity, percent of residential census tract that is white, percent of residential census tract adults who lack a high school education, median home value of residential census tract, geographic region, residence within a metropolitan statistical area, and social support.