Short-term traffic-related gaseous pollutant exposure is associated with childhood bronchopneumonia hospitalization: a 10-year time-series study from Guangzhou, China

Short-term exposure to traffic-related gaseous pollutants [nitrogen dioxide (NO 2 ) and sulfur dioxide (SO 2 )] may increase childhood bronchopneumonia risk, but evidence from megacities with high pollution levels remains limited. This study aimed to evaluate the association between short-term exposure to NO 2 and SO 2 and pediatric bronchopneumonia hospitalization in Guangzhou. We collected all pediatric inpatient records with a primary discharge diagnosis of bronchopneumonia (International Classification of Diseases, Tenth Revision: J18) among children aged 0 to 14 years from a tertiary hospital in the Huadu District, between 1 January 2014 and 31 December 2023. Daily air pollutant and meteorological data were integrated with admission records and analyzed using a generalized additive model with quasi-Poisson distribution. A total of 20,623 hospitalisations were included, of which 60.6% were male and 68.4% were aged <6 years. Both NO 2 and SO 2 were positively associated with bronchopneumonia hospitalization. Per 5 μg/m 3 increase in pollutant concentration, for single-day exposure, the peak excess risks (ERs) occurred at lag 4 (NO 2 : 2.74% [95% confidence interval (CI): 1.73–3.75]; SO 2 : 8.81% [95% CI: 4.94–12.82]); For the 0-7 day moving average, the ERs increased to 6.83% (95% CI 4.93–8.77) for NO 2 and 17.21% (95% CI 10.18–24.70) for SO 2 . Children aged 6–14 years and boys showed consistently higher susceptibility. These findings provide the first long-term evidence from Guangzhou that short-term NO 2 and SO 2 exposure is positively associated with childhood bronchopneumonia hospitalization, with older children and boys being the susceptible subgroups. Public health authorities should consider developing targeted air pollution alert thresholds and intervention strategies for school-aged children and boys.