Objective To investigate the association between air pollutant exposure and outpatient visit risk for community-acquired pneumonia (CAP) among children and adolescents, and to further evaluate its lagged effects and seasonal characteristics.

Methods Clinical data from children and adolescents diagnosed with CAP at the First People's Hospital of Tianmen between 2021 and 2024 were collected, along with concurrent air pollutant and meteorological data. Descriptive statistics and Spearman correlation analysis were employed to evaluate the relationships among environmental variables and their associations with daily hospital visits. Generalized additive models were constructed to estimate the lagged effects of both single- and multi-pollutant models at optimal lag days. Distributed lag non-linear models (DLNM) were utilized to explore the lag-exposure-response relationship of pollutant.

Results A total of 7,939 patients were included. The monthly average number of visits showed obvious seasonal variation, with high incidence in winter and spring, mainly in children aged ≤ 2 years and male patients. Spearman correlation analysis showed that temperature (r=0.291), humidity (r=0.149), and CO (r=0.106) were weakly positively correlated with daily CAP visits (P < 0.001), whereas O₃ showed a weak negative correlation (r=-0.058, P=0.032). Single-pollutant models showed that CO [RR=26.508,95%CI (5.096,137.897)], SO₂ [RR=1.361, 95%CI (1.125, 1.648)] and PM₁₀ [RR=1.016, 95%CI(1.008, 1.023)] were significantly associated with increased CAP outpatient risk. In multi-pollutant models, PM₁₀ maintained a relatively stable positive association with CAP visits, whereas the association for CO was less robust. DLNM analysis revealed that the association between PM₁₀ exposure and CAP visits increased at lag 2-5 days, with stronger associations during the mid-to-late lag period, while CO showed a relatively weak lagged effect.

Conclusion Exposure to ambient air pollutants was associated with an increased risk of CAP-related outpatient visits among children and adolescents. Among the pollutants examined, PM₁₀ demonstrated a relatively stable lagged effect, suggesting that air pollution may contribute to the development and progression of pediatric respiratory diseases.

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