Chronic exposure to fine particles (PM2.5) and mortality: Evidence from Chile.

Many Chilean cities suffer from high air pollution from industrial, mobile, and residential wood-burning sources. Several studies have linked PM_2.5 air pollution exposure to higher mortality risk from cardiovascular, pulmonary, and lung cancer causes. In recent years, Chile has developed an extensive air pollution monitoring network to enforce air quality standards for PM_2.5, allowing the study of the medium-term association between PM_2.5 and mortality.

Methods: A negative binomial regression model was used to study the association between 3-year average PM_2.5 concentrations and age-adjusted mortality rates for 105 of the 345 municipalities in Chile. Models were fitted for all (ICD10 A to Q codes), cardiopulmonary (I and J), cardiovascular (I), pulmonary (J), cancer (C), and lung cancer (C33-C34) causes; controlling for meteorological, socioeconomic, and demographic characteristics.

Results: A significant association of PM_2.5 exposure with cardiopulmonary (relative risk for 10 µg/m³ PM_2.5: 1.06; 95% confidence interval = 1.00, 1.13) and pulmonary (1.11; 1.02, 1.20) age-adjusted mortality rates was found. Cardiovascular (1.06; 0.99, 1.13) and all causes (1.02; 0.98, 1.07) were positive, but not significant. No significant association was found between cancer and lung cancer. The positive associations remained even when controlling for multiple confounding factors, model specifications, and when considering different methods for exposure characterization. These estimates are in line with results from cohort studies from the United States and European studies.

Conclusion: Three-year average PM_2.5 exposure is positively associated with the age-adjusted mortality rate for cardiopulmonary and cardiovascular causes in Chile. This provides evidence of the medium-term exposure effect of fine particles on long-term mortality rates.