Table 2.

Hazard ratios (95% confidence intervals) for developing depression for a $10{\text{-}\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$ increase in particulate matter air pollution in the Kangbuk Samsung Health Study (KSHS).

Developing depression assessment method	Exposure	Cases/person-yearsa	Adjustment	12-month per $10{\text{-}\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$ increase		60-month per $10{\text{-}\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$ increase
				HR	95% CI	HR	95% CI
Developing depression ($\text{CES -}\mathrm{D}\ge 16$)	${\mathrm{PM}}_{10}$	11,904/310,075	Model 1b	1.13	1.08, 1.18	1.08	1.03, 1.14
			Model 2c	1.11	1.06, 1.16	1.06	1.01, 1.11
	${\mathrm{PM}}_{2.5}$	2,647/56,719	Model 1	1.01	0.83, 1.22	—	—
			Model 2	1.01	0.83, 1.22	—	—
Developing depression (doctor’s diagnosis or use of medications)	${\mathrm{PM}}_{10}$	1,126/312,334	Model 1	1.21	1.02, 1.45	1.2	1.00, 1.44
			Model 2	1.21	1.01, 1.45	1.2	1.00, 1.43
	${\mathrm{PM}}_{2.5}$	402/56,646	Model 1	0.93	0.63, 1.38	—	—
			Model 2	0.96	0.64, 1.43	—	—

Note: Estimates represent HRs (95% CIs) for $\text{CES -}\mathrm{D}\ge 16$ as a dichotomous outcome. —, data not available; CES-D, Center for Epidemiological Studies Depression scale; CI, confidence interval; HR, hazard ratio; ${\mathrm{PM}}_{10}$, particulate matter with an aerodynamic diameter of $\le 10\mathrm{\mu }\mathrm{m}$; ${\mathrm{PM}}_{2.5}$, particulate matter with an aerodynamic diameter of $\le 2.5\mathrm{\mu }\mathrm{m}$.

^aPerson-years were the total numbers for all subjects and account for missing covariate data. The person-years and number of cases were different between ${\mathrm{PM}}_{10}$ and ${\mathrm{PM}}_{2.5}$ models because the follow-up for ${\mathrm{PM}}_{10}$ model started on 1 January 2011 and the follow-up for ${\mathrm{PM}}_{2.5}$ model started on 1 January 2015.

^bModel 1 was adjusted for age, sex, study center, and year of visit.

^cModel 2 was adjusted as for Model 1 and additionally adjusted for educational level, smoking status, body mass index, alcohol consumption, and physical activity.