Short- and long-term exposure to air pollution and lack of sunlight are associated with an increased risk of depression: A nested case-control study using meteorological data and national sample cohort data

Previous studies have suggested an increased risk of depression related to air pollutants. This study investigated the relationship of air pollutant exposure and meteorological factors with depression. The Korean National Health Insurance Service-Health Screening Cohort from 2002 to 2013 was analyzed. In total, 25,589 depression participants were 1:4 matched with 102,356 control participants for age, sex, income, and region of residence. Depression was defined based on a diagnosis (ICD-10: F31–33) by a psychiatric physician. Meteorological factors and air pollutants including sulfur dioxide (SO2) (ppm), nitrogen dioxide (NO2) (ppm), ozone (O3) (ppm), carbon monoxide (CO) (ppm), and particulate matter with an aerodynamic diameter <10 μm (PM10) (μg/m3) during the 30 days and 365 days before the index date were analyzed for associations with depression using conditional logistic regression. Subgroup analyses were performed according to age, sex, income, and region of residence. The odds ratios (ORs) for depression were 1.05 (95% CI = 1.02–1.08) at 365 days for 1 h less of sunshine. The ORs for depression were 1.02 (95% CI = 1.01–1.03) and 1.03 (95% CI = 1.00–1.05) at 30 days and 365 days for PM10 (10 μg/m3), respectively. The ORs for depression were 1.18 (95% CI = 1.04–1.35) and 1.25 (95% CI = 1.07–1.47) at 30 days and 365 days for CO (ppm), respectively. In the subgroup analyses, the overall results were consistent. However, statistical significance diminished in the younger, high-income, and urban resident subgroups. Both short- and long-term exposure to PM10 and CO and a reduced duration of sunshine were related to an increased risk of depression.