Relationship between Air Pollution and Hospital Admissions for Chronic Obstructive Pulmonary Disease in Changchun, China: A Season-Stratified Case-Cross Study

Background. This study aimed to explore the relationship between air pollution and hospital admissions for COPD in Changchun, a northeast city of China, in different seasons. Methods. The data on a total of 1,733 hospitalized patients living in Changchun with acute exacerbation of COPD from September 2013 to April 2018 were collected from a comprehensive 3A hospital of Changchun. Daily average concentrations of PM2.5, PM10, SO2, NO2, CO, and O3 were collected from the Department of Ecology and Environment of Jilin Province. The conditional logistic regression model was adopted to analyze the effect of air pollutant concentration on the number of hospitalized patients with COPD in different seasons. Results. The maximum OR value for most air pollutants emitted in spring was on lag day 4, in summer and autumn on lag day 3, and in winter on lag day 2. In spring, SO2 and NO2 were entered into the regression equation, and the OR (95%CI) was 0.992 (0.986-0.998) and 1.009 (1.002-1.017); in autumn, PM2.5, PM10, and SO2 were entered into the regression equation, and the OR (95%CI) was 1.005 (1.000-1.011), 0.995 (0.991-1.000), and 1.006 (1.001-1.011), respectively; and in winter, PM2.5 and PM10 were entered into the regression equation, and the OR (95%CI) was 1.008 (1.002-1.015) and 0.994 (0.988-0.999), respectively. Conclusion. The relationship between air pollution and hospital admission for COPD in Northeast China varies with different seasons. In spring, NO2 is likely to be the major risk factor for hospital admissions for COPD; in autumn, PM2.5 and SO2 are the major risk factors; and in winter, PM2.5 is the major risk factor.