Association between screening myopia and mixed exposure to air pollution among primary school children in four cities in China

Objective To investigate the association between screening myopia in school-age children and combined exposure to air pollutants, thereby providing scientific evidence for myopia prevention and control measures among children and adolescents.Methods Between May and July 2023, a cluster random sampling method was employed to select 15,102 primary school pupils in grades 3 to 6 from four cities: Hefei, Zhongshan, Shenyang, and Nanchang. Data were collected through questionnaires, distance visual acuity screening, and computerised refraction. Annual average pollutant concentrations for school-aged children were calculated using monthly mean concentrations of PM10, PM2.5, NO₂, and SO₂. A quantile g calculation model was employed to analyse the association between combined exposure to air pollutants and screening myopia.Results Within the overall sample, mixed exposure to air pollutants showed a positive trend with myopia risk, though the difference was not statistically significant.(β = 0.033, 95% CI: -0.004 to 0.072, P = 0.08). Stratified analysis revealed that among children with ≤1 hour of outdoor activity, combined pollutant exposure was significantly positively associated with myopia risk (β = 0.050, 95% CI: 0.002–0.099, P = 0.04); After stratification by city, mixed pollutant exposure was significantly associated with myopia risk among children in Nanchang and Shenyang (P < 0.05), whereas no significant association was observed in Hefei and Zhongshan.Conclusions Exposure to multiple air pollutants may increase the risk of myopia in school-aged children, with this risk influenced by time spent outdoors and geographical location. It is recommended that outdoor activity management for children be strengthened in areas with higher air pollution levels, and that environmental factors be incorporated into comprehensive myopia prevention and control strategies.