Association between exposure to ambient particulate matter and chronic obstructive pulmonary disease: results from a cross-sectional study in China

Objective The association between exposure to ambient particles with a median aerodynamic diameter less than 10/2.5 mu m (particulate matter, PM10/(2.5)) and COPD remains unclear. Our study objective was to examine the association between ambient PM10/(2.5) concentrations and lung functions in adults. Methods A cross-sectional study was conducted in southern China. Seven clusters were randomly selected from four cities across Guangdong province. Residents aged >= 20 years in the participating clusters were randomly recruited; all eligible participants were examined with a standardised questionnaire and spirometry. COPD was defined as a post-bronchodilator FEV1/FVC less than 70%. Atmosphere PM sampling was conducted across the clusters along with our survey. Results Of the subjects initially recruited, 84.4% (n=5993) were included for analysis. COPD prevalence and atmosphere PM concentration varied significantly among the seven clusters. COPD prevalence was significantly associated with elevated PM concentration levels: adjusted OR 2.416 (95% CI 1.417 to 4.118) for >35 and <= 75 mu g/m(3) and 2.530 (1.280 to 5.001) for >75 mu g/m(3) compared with the level of <= 35 mu g/m(3) for PM2.5; adjusted OR 2.442 (95% CI 1.449 to 4.117) for >50 and <= 150 mu g/m(3) compared with the level of <= 50 mu g/m(3) for PM1. A 10 mu g/m(3) increase in PM2.5 concentrations was associated with a 26 mL (95% CI -43 to -9) decrease in FEV1, a 28 mL (-49 to -8) decrease in FVC and a 0.09% decrease (-0.170 to -0.010) in FEV1/FVC ratio. The associations of COPD with PM10 were consistent with PM2.5 but slightly weaker. Conclusions Exposure to higher PM concentrations was strongly associated with increased COPD prevalence and declined respiratory function.