Impact of atmospheric NO2 on pediatric asthma visits in Jinan: effect modification by season and apparent temperature

Background Childhood asthma shows seasonal/Solar terms (STs) patterns, affected by air pollution (notably Nitrogen Dioxide-NO 2, most sensitive to pediatric asthma) and meteorological factors. Apparent temperature (AT) integrates temperature and other meteorological indices. However, joint effects of multiple factors remain unknown. Methods Daily pediatric asthma visits of Children’s Hospital Affiliated to Shandong University, meteorological factors and air pollution concentrations were collected from January 1, 2018 to December 31, 2022. Time-stratified case crossover and conditional logistic regression models were utilized to estimate the odds ratios ( OR s) and 95% confidence intervals ( CI s) of effects of asthma visits. Results 29,906 asthma visits were recorded with age range of 0.8–19 years. Median NO₂ concentration of 33 μg/m 3 and 14 visits recorded per day. NO 2 exposure increased risk of asthma visits in children [ OR = 1.005 (95% CI : 1.003, 1.007), Lag05]. Moreover, the association between NO₂ exposure and the risk of pediatric asthma visits exhibited an approximately parabolic shape, with the nadir of risk at a NO₂ concentration of 33 μg/m 3 . Stratified analysis of demographic characteristics revealed higher effect estimate in females [ OR = 1.006 (95% CI : 1.002, 1.009), Lag05] and the strongest effects of age in children and adolescents aged 10–19 years [ OR = 1.005 (95% CI : 1.001, 1.009), Lag3]. A higher effect estimate was observed during the summer–autumn seasons [ OR = 1.006 (95% CI : 1.002, 1.009), Lag02]. The interaction between atmospheric NO 2 and low (AT) were significant among total visits [ OR = 1.002 (95% CI : 1.001, 1.004)], with a moderate AT used as a reference. Conclusion NO 2 considerably increased pediatric asthma visits, seasons and AT having modifying effects. These findings highlight the urgent need for increased awareness and action from relevant agencies.