Long-term exposure to low levels of air pollution and mortality adjusting for road traffic noise: A Danish Nurse Cohort study

•Long-term exposure to PM2.5 was associated with mortality in the Danish Nurse Cohort.•Associations were strongest with diabetes, hypertension, and ischemic heart disease mortality.•Associations were even stronger at the PM2.5 levels below EU limit value of 25 µg/m3.•Associations were independent of road traffic noise. The association between air pollution and mortality is well established, yet some uncertainties remain: there are few studies that account for road traffic noise exposure or that consider in detail the shape of the exposure–response function for cause-specific mortality outcomes, especially at low-levels of exposure. We examined the association between long-term exposure to particulate matter [(PM) with a diameter of