The Association Between Air Pollutants and Hospitalizations for Asthma: an Evidence from Chengdu, China

Background:Exposure to air pollutants has been linked to the exacerbation of asthma, and it has become a risk to human welfare and health throughout the globe. Previous works did not achieve a systematic study by considering interactive effects of age, gender, and meteorological factors on the exposure-effect relationship between air pollutants and asthma. We aimed to quantitatively investigate the effects of air pollutants on hospitalizations for asthma in Chengdu, China.Methods:This is a retrospective and population-based study. Data of asthma hospitalization records for residents, the average daily concentrations of air pollutants including SO2, CO, NO2, O3, PM10, and PM2.5, and meteorological variables from 1 January 2014 to 31 December 2014 in Chengdu, China, were obtained from several government departments. A generalized additive model (GAM) was used to analyze the exposure-effect relationship between air pollutants and daily asthma hospitalizations after controlling the long-time seasonal trend, "day-of-week (DOW)" effect, holiday effect, and confounding meteorological factors.Results:A total of 7,503 hospitalizations were assessed. Significant associations between hospitalizations and air pollutants were found. The relative risk (RR) for hospitalizations for every 10 µg/m3 increase in PM2.5 and PM10 for the male group were 1.0121 [95% confidence interval (CI): 1.0012-1.0232] and 1.0075 (95% CI: 1.0001-1.015), respectively. The elderly (≥65 years old) tended to have a higher RR (1.0022; 95% CI: 1.0001-1.0043) for each 10 mg/m3 increase in CO than the other age groups. All pollutants had slightly protective effects on the younger age group (≤14 years old). O3 had more significant effects in cold season, whereas SO2 impacted more significantly in warm seasons, particularly for females and adults (14-65 years old).Conclusions:Adverse effects of ambient concentrations of air pollutants on hospitalizations for asthma are evident, especially in specific population groups. Male patients were more susceptible to PM2.5 and PM10, and the elderly were more sensitive to CO. The effects of O3 in China were significant in the cold season, whereas SO2 impacted more significantly in the warm season particularly on females and adults. The study would be meaningful for asthma intervention and corresponding healthcare resource management.