Chronic obstructive pulmonary disease patients have a higher risk of occurrence of pneumonia by air pollution.

Epidemiological evidence has shown that air pollution is associated with chronic obstructive pulmonary disease (COPD). The objective of this study was to investigate the effects of air pollution on patients with COPD and pneumonia. A case-control study of patients who had undergone thoracentesis for pleural effusion drainage in a hospital was recruited for this study. COPD and non-COPD patients with pneumonia respectively served as the case and control groups. Increases in particulate matter of <2.5 μm in aerodynamic diameter (PM2.5) and NO2 increased the risk of pneumonia in COPD patients (adjusted odd ratio (OR) = 4.136, 95% confidence interval (CI) = 1.740-9.832 for PM2.5; adjusted OR = 1.841, 95% CI = 1.117-3.036 for NO2). COPD patients with pneumonia had higher levels of CD14 in pleural effusion than did non-COPD with pneumonia (p < 0.05). An increase in CD14 of the pleural effusion increased the risk of pneumonia in COPD patients (adjusted OR = 1.126, 95% CI = 1.009-1.256). We further observed that an increase in Cu and a decrease in Zn in the pleural effusion increased the risk of pneumonia in COPD patients (adjusted OR = 1.005, 95% CI = 1.000-1.010 for Cu; adjusted OR = 0.988, 95% CI = 0.978-0.997 for Zn). In conclusion, our results suggest that COPD patients had a high risk of pneumonia occurring due to air pollution exposure.