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 µm (particulate matter, PM(10)/(2.5)) and COPD remains unclear. Our study objective was to examine the association between ambient PM(10)/(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 FEV(1)/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 µg/m(3) and 2.530 (1.280 to 5.001) for >75 µg/m(3) compared with the level of ≤35 µg/m(3) for PM(2.5); adjusted OR 2.442 (95% CI 1.449 to 4.117) for >50 and ≤150 µg/m(3) compared with the level of ≤50 µg/m(3) for PM(1). A 10 µg/m(3) increase in PM(2.5) concentrations was associated with a 26 mL (95% CI −43 to −9) decrease in FEV(1), a 28 mL (−49 to −8) decrease in FVC and a 0.09% decrease (−0.170 to −0.010) in FEV(1)/FVC ratio. The associations of COPD with PM(10) were consistent with PM(2.5) but slightly weaker. CONCLUSIONS: Exposure to higher PM concentrations was strongly associated with increased COPD prevalence and declined respiratory function. TRIAL REGISTRATION NUMBER: ChiCTR-OO-14004264; Post-results.