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

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 (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), ozone (O₃), particulate matter ≤ 2.5 µm (PM_2.5), and particulate matter ≤ 10 µm (PM₁₀), on children hospitalized for asthma in Chengdu, China, from 2017-2022.

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.

PM_2.5, PM₁₀, SO₂, NO_2, and CO were significantly associated with an increased risk of hospitalization due to asthma. A 10 μg/m³ 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/m³ increase in SO₂ and NO₂ 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 PM₁₀ and PM_2.5 had a greater impact on children aged 5-6 years old while NO₂ 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.

Our results suggest that increased concentrations of PM_2.5, PM₁₀, SO₂, NO_2, and CO in Chengdu lead to hospitalization for asthma in children and that a lag effect was observed, especially with SO₂. These findings highlight the need for stricter air quality controls to reduce childhood asthma hospitalizations.