Fig. 2From: The effects of traffic-related air pollutants on chronic obstructive pulmonary disease in the community-based general populationAssociations between exposure to air pollution (PM2.5 and O3) and prevalence ratios of COPD in population with frequency matching (Black square) and with propensity-score matching (Black diamond) analyzed by single-pollutant model and two-pollutant model. A all population (B) non-smokers in the sensitivity analysisBack to article page