Acute effects of multi-pollutant exposure on pediatric epistaxis: evidence from a distributed lag nonlinear model in Chongqing, China

Although short-term exposure to air pollutants has been associated with pediatric respiratory diseases, evidence on its impact on childhood epistaxis remains limited, particularly in regions with severe air pollution such as Chongqing. To investigate the association between short-term air pollution exposure and epistaxis incidence in children, and to characterize population-specific susceptibility based on age, gender, and allergen sensitization status. We analyzed 87,733 epistaxis cases (aged 0–18 years) from a tertiary pediatric hospital in Chongqing (2016–2022). A distributed lag nonlinear model (DLNM) with quasi-Poisson regression was applied to quantify exposure-response relationships between six criteria pollutants (PM₂.₅, PM₁₀, SO₂, NO₂, CO, O₃) and daily outpatient visits, adjusting for meteorological factors and long-term trends. Stratified analyses were conducted by age group, sex, and allergen positivity. Significant associations were observed between all pollutants (except CO at lag0) and epistaxis risk, with O₃ demonstrating the strongest cumulative effect (cumulative relative risk: CRR = 1.245, 95%CI:1.202–1.289 over 0–21 lag days). Seasonal patterns showed summer peaks in both epistaxis visits and O₃ concentrations (mean:40.83 µg/m³). Stratified analyses revealed an age-dependent susceptibility, with older individuals exhibiting higher relative risks (RR) associated with gaseous pollutants. A sex-related disparity was observed, as females showed elevated risks for SO₂ (RRR = 1.020) and NO₂ (RRR = 1.010) compared to males. No significant effect modification was detected based on allergen sensitization status. Short-term exposure to air pollution, particularly O₃, is significantly associated with childhood epistaxis in Chongqing, with distinct seasonal patterns and demographic susceptibility. Our findings underscore the need for targeted air quality interventions and season-specific prevention strategies, especially for school-aged children and females. These results offer an evidence base for pediatric environmental health policies in pollution-prone urban regions.