Background Both domestic and foreign studies have shown that ambient air pollutant concentrations are closely related to the decrease of lung function and the occurrence of respiratory diseases and symptoms in children.

Objective The study aims to evaluate the association between daily air pollutant concentrations and hospital pediatric respiratory disease outpatients in Shanghai.

Methods Generalized linear models (GLM) were used to evaluate the lag effects (lag0 to lag7) and cumulative lag effects (lag01 to lag07) between daily outpatients of pediatric respiratory diseases in a general hospital and daily air pollutant concentrationsincluding fine particulate matters (PM_2.5), inhalable particulate matters (PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), and carbon monoxide (CO) from a nearest air quality monitoring station in Shanghai in 2013-2018. Daily meteorological variables were also collected.

Results Per 10 μg·m^-3 increase of the six pollutants at different lag time points had different effect sizes on pediatric respiratory disease outpatients. Per 10 μg·m^-3 increase in concentrations of PM_2.5 at lag4excess risk (ER)=0.32%, 95% CI:0.12%-0.53% and lag07 (ER=0.59%, 95% CI:0.15%-1.03%), PM₁₀ at lag3 (ER=0.19%, 95% CI:0.00%-0.37%), NO₂ at lag 3 (ER=1.11%, 95% CI:0.71%-1.51%) and lag07 (ER=3.05%, 95% CI:2.24%-3.87%), SO₂ at lag4 (ER=1.86%, 95% CI:1.08%-2.65%) and lag07 (ER=4.90%, 95% CI:3.31%-6.51%), O₃ at lag6 (ER=-0.21%, 95% CI:-0.38%--0.05%) and lag07 (ER=-0.56%, 95% CI:-0.93%--0.20%), and CO at lag4 (ER=0.30%, 95% CI:0.07%-0.53%), and lag5 (ER=0.24%, 95% CI:0.01%-0.47%) showed the largest effects among the respective categories (P < 0.05 or P < 0.01). The results of multi-pollutant model analysis showed that SO₂ and NO₂ had more stable and significant impacts on the pediatric respiratory disease outpatients when they coexisted with PM_2.5, O₃, and CO, and the related ERs (95% CIs) were 1.54% (0.49%-2.60%) and 1.21% (0.67%-1.74%), respectively; NO₂ showed the strongest effect when it coexisted with PM₁₀, O₃, and CO, and the related ER (95% CIs) was 1.41% (0.88%-1.95%) (P < 0.01).

Conclusion The ambient PM_2.5, PM₁₀, NO₂, SO₂, and CO concentrations are positively and O₃ concentration is negatively associated with daily hospital pediatric outpatients due to respiratory diseases in Shanghai. The ambient NO₂ and SO₂ have more significant and stable synergistic effects in multi-pollutant model analysis compared with single-pollutant model analysis.