Air pollution increases depression risk among young women: possible natural world resiliencies

Air pollution may contribute to depression risk, but prospective incidence studies of risks and resiliencies for young women have not been undertaken. We analyzed prospective cohort data from the Australian Longitudinal Study on Women's Health combined with air pollution exposure data from the National Pollutant Inventory. We followed 7804 women without baseline depression who were aged 21-26 years at baseline for up to 14 years. Cox proportional hazards regression models were used to examine associations between greater air pollution exposures and incident depression controlling for covariates. Air pollutants included carbon monoxide, nitrogen oxides, particulate matter (PM2.5 and PM10), and sulfur dioxide, measured in inverse distance weighted exposures in kilograms occurring within 10 km of participants' residences. Results showed that total air pollution exposure decile was significantly associated with incident depression (hazards ratio = 1.039, 95% confidence interval 1.018-1.060). Exposures were also significantly related to depression when total exposure, and each of the five individual air pollutants, was measured in quartile. Multiple other sociodemographic and behavioral variables were independently associated with depression. Women who possessed behavioral resiliencies (nonsmokers and nonobese) or socioeconomic resiliencies (higher education and adequate income) were not at elevated depression risk when exposed to high amounts of air pollution. Multiple depression risks, and the presence of behavioral and socioeconomic resiliencies, suggest multiple leverage points to reduce depression risk among young women with air pollution exposures, including effects to improve air quality and improve human connection to the natural environment, especially for women who experience lifestyle or socioeconomic disadvantages.