The effects of traffic-related air pollutants on chronic obstructive pulmonary disease in the community-based general population.

BACKGROUND Previous studies have shown inconsistent results regarding the impact of traffic pollution on the prevalence of chronic obstructive pulmonary disease (COPD). Therefore, using frequency matching and propensity scores, we explored the association between traffic pollution and COPD in a cohort of 8284 residents in a major agricultural county in Taiwan. METHODS All subjects completed a structured questionnaire interview and health checkups. Subjects with COPD were identified using Taiwan National Health Insurance Research Databases. A hybrid kriging/LUR model was used to identify levels of traffic-related air pollutants (PM2.5 and O3). Multiple logistic regression models were used to calculate the prevalence ratios (PRs) of COPD and evaluate the role played by traffic-related indices between air pollutants and COPD. The distributed lag nonlinear model was applied in the analysis; we excluded current or ever smokers to perform the sensitivity analysis. RESULTS Increased PRs of COPD per SD increment of PM2.5 were 1.10 (95% CI 1.05-1.15) and 1.25 (95% CI 1.13-1.40) in the population with age and sex matching as well as propensity-score matching, respectively. The results of the sensitivity analysis were similar between the single and two pollutant models. PM2.5 concentrations were significantly associated with traffic flow including sedans, buses, and trucks (p < 0.01). The higher road area and the higher PM2.5 concentrations near the subject's residence correlated with a greater risk of developing COPD (p for interaction < 0.01). CONCLUSIONS Our results suggest that long-term exposure to traffic-related air pollution may be positively associated with the prevalence of COPD.