Air Pollution and Childhood Asthma Hospitalizations in Chengdu, China: A Time-Series Study

Purpose: Research on the relationship between air pollutants and hospitalization for asthma in children in developing countries remains inadequate. This study aimed to assess the short-term effects of air pollutants, including sulfur dioxide (SO 2 ), nitrogen dioxide (NO 2 ), carbon monoxide (CO), ozone (O 3 ), particulate matter ≤ 2.5 μm (PM 2.5 ), and particulate matter ≤ 10 μm (PM 10 ), on children hospitalized for asthma in Chengdu, China, from 2017– 2022. Patients and Methods: During the study period, 5592 children were hospitalized for asthma. A generalized additive model was used to control for seasonality, long-term trends, weather, day of the week, and holidays. The analysis was further stratified by age, sex, and season to estimate the associations. Results: PM 2.5 , PM 10 , SO 2 , NO 2, and CO were significantly associated with an increased risk of hospitalization due to asthma. A 10 μg/m 3 increase in PM 2.5 , PM 10, and CO at lag04 corresponded to an increase of 2.07%, 1.56%, and 0.33% in daily hospital admissions for asthma, respectively. A 10 μg/m 3 increase in SO 2 and NO 2 at lag05 corresponded to an increase of 45.69% and 8.16% in daily hospital admissions for asthma, respectively. Further analysis by age found that PM 10 and PM 2.5 had a greater impact on children aged 5– 6 years old while NO 2 and CO mainly affected children under 7 years old. Analysis by by sex found that pollutants had a greater impact on hospital admissions in girls. Seasonal analysis revealed that pollutants had a more significant effect on admission during the winter. Conclusion: Our results suggest that increased concentrations of PM 2.5 , PM 10 , SO 2 , NO 2, and CO in Chengdu lead to hospitalization for asthma in children and that a lag effect was observed, especially with SO 2 . These findings highlight the need for stricter air quality controls to reduce childhood asthma hospitalizations. Plain Language Summary: • Exposure to air pollutants increases the risk of hospitalization for children with asthma. • The effect of each studied air pollutant varies according to the age and sex of the child. • The effect of air pollutants on children with asthma was stronger in the winter. • Air quality control standards are needed to reduce hospitalizations for asthma in children. Keywords: pediatric asthma, air pollutants, stratified analysis, in-patient