Air pollutants have a short-term impact on respiratory health and children are more sensitive to air pollutants.

This study investigates the associations between six routine monitoring pollutantscoarse particulate matters (PM₁₀), fine particulate matters (PM_2.5), ozone (O₃), carbon dioxide (CO), sulfur dioxide (SO₂), and nitrogen dioxide (NO₂) and daily hospital visits for childhood respiratory disorders in Shanghai.

We collected outpatient visits for childhood respiratory disorders from Children's Hospital of Fudan University, and air pollutant concentration data and meteorological data of Shanghai from January 1, 2014 to May 31, 2016. We used generalized additive model with Poisson regression to quantify the associations between six air pollutants and daily hospital visits for respiratory disorders after adjusting for secular trend, day-of-the-week effect, holiday effect, and meteorological variables. The effects of pollutants on children of different genders were compared as well.

During the study period, the daily average concentrations of PM₁₀, PM_2.5, O₃, CO, SO₂, and NO₂ were 70.5, 53.2, 101.8, 812.7, 17.2, and 46.2 μg·m^-3, respectively; the unqualified rates of PM₁₀, PM_2.5, O₃, NO₂ were 4.20%, 20.09%, 11.58%, and 7.04%, respectively, and SO₂ and CO did not exceed the national limits. The single-pollutant model results showed that with every 10 μg·m^-3 increase of PM₁₀, PM_2.5, O₃, and SO₂, the RRs of children's respiratory outpatient visits were 1.002 2 (lag4, 95%CI:1.0017-1.0026), 1.0019 (lag4, 95%CI:1.0014-1.0024), 1.001 9 (lag2, 95% CI:1.001 4-1.002 5), and 1.005 2 (lag4, 95% CI:1.003 2-1.007 2), respectively. With every 10 μg·m^-3 increase of NO₂, the outpatient visits of boys increased by 0.12% (lag2, RR=1.001 2, 95% CI:1.000 1-1.002 4). Girls (lag4, RR=1.002 7, 95% CI:1.001 9-1.003 5) were found slightly more sensitive to O₃ exposure than boys (lag2, RR=1.001 8, 95% CI:1.001 1-1.002 5) in outpatient visits. The effect of CO on boys was statistically significant at lag1 and lag2 (P < 0.05), while that of girls was statistically significant at lag1, lag2, and lag3 (P < 0.05). The effect of SO₂ on boys was statistically significant at lag2, lag3, and lag4 (P < 0.05), but only at lag4 for girls (P < 0.05). The results of double-pollutant model showed that the RR of O₃ did not change significantly after the other five pollutants were introduced into the model; when PM_2.5 and PM₁₀ were introduced into the model, the effects of all pollutants except O₃ changed greatly.

The increase of SO₂, O₃, PM₁₀, and PM_2.5 concentrations in Shanghai may lead to the increase of daily hospital visits for childhood respiratory disorders with lag effects. NO₂, O₃, CO, and SO₂ have different effects on boys and girls. Air pollutants may have complex effects on children's respiratory health due to their possible interactions.