Long-term exposure to air pollution and mortality in Scotland: A register-based individual-level longitudinal study.

BACKGROUND

Air pollution is associated with several adverse health outcomes. However, heterogeneity in the size of effect estimates between cohort studies for long-term exposures exist and pollutants like SO and mental/behavioural health outcomes are little studied. This study examines the association between long-term exposure to multiple ambient air pollutants and all-cause and cause-specific mortality from both physical and mental illnesses.

METHODS

We used individual-level administrative data from the Scottish-Longitudinal-Study (SLS) on 202,237 individuals aged 17 and older, followed between 2002 and 2017. The SLS dataset was linked to annual concentrations of NO, SO, and particulate-matter (PM10, PM2.5) pollution at 1 km spatial resolution using the individuals' residential postcode. We applied survival analysis to assess the association between air pollution and all-cause, cardiovascular, respiratory, cancer, mental/behavioural disorders/suicides, and other-causes mortality.

RESULTS

Higher all-cause mortality was associated with increasing concentrations of PM2.5, PM10, NO, and SO pollutants. NO PM10, and PM2.5 were also associated with cardiovascular, respiratory, cancer and other-causes mortality. For example, the mortality hazard from respiratory diseases was 1.062 (95%CI = 1.028-1.096), 1.025 (95%CI = 1.005-1.045), and 1.013 (95%CI = 1.007-1.020) per 1 μg/m increase in PM2.5, PM10 and NO pollutants, respectively. In contrast, mortality from mental and behavioural disorders was associated with 1 μg/m higher exposure to SO pollutant (HR = 1.042; 95%CI = 1.015-1.069).

CONCLUSION

This study revealed an association between long-term (16-years) exposure to ambient air pollution and all-cause and cause-specific mortality. The results suggest that policies and interventions to enhance air quality would reduce the mortality hazard from cardio-respiratory, cancer, and mental/behavioural disorders in the long-term.