Association between long-term exposure to traffic-related air pollution and COPD

Abstract

Background: Current evidence suggests that ambient air pollution results in adverse acute respiratory effects in populations of all ages. The role of air pollution in the development of Chronic Obstructive Pulmonary Disease (COPD) remains uncertain. We aimed to assess the impact of long-term exposure to traffic related air pollution on the prevalence and incidence of COPD in four existing European cohorts (ECRHS, NSHD, SALIA, SAPALDIA) using the newly developed fully standardized ESCAPE exposure estimates. Method: Annual concentrations of NO2, NOx, PM2.5, PM10 at the home addresses were estimated using land-use regression models. GOLD stage 1+ COPD was defined as a pre-bronchodilator of FEV1/FVC<0.70 in non-asthmatics. The main regression model was adjusted for age, sex, BMI, education and smoking. Results: In total, we included 7,023 subjects with NO2 and 3,580 with PM10 exposure measures. COPD prevalence and incidence was not significantly associated with NO2 or PM10 in any of the cohorts. The associations were strongest in ECRHS (OR: 1.07 (95%CI: 0.93,1.24) and NSHD (OR: 1.17 (95%CI: 0.73,1.87)) with NO2 (per 10µg/m³) and incidence of COPD. In the meta-analyses, all markers of pollution, with exception of PM2.5, were positively but not significantly associated with COPD. The meta-analyses for COPD incidence showed an overall estimate of 1.03 (95%CI: 0.91,1.15) for a 10µg/m³ increase in NO2 and 1.08 (95%CI: 0.70, 1.65) for a 10µg/m³ increase in PM10. The effect estimates were slightly stronger in females and in non-movers. Conclusion: Our findings indicate an inconsistent association between long-term exposure to air pollution and COPD prevalence and incidence. Further investigation will be needed to address the reasons for these inconsistencies, such as the rather substantial time difference between exposure measurements taken as part of ESCAPE and the health assessment of the original studies, limitations in exposure contrasts or precision in the exposure models.