Associations of prenatal and postnatal exposure to air pollution with hand, foot, and mouth disease: Key pollutants and sensitive exposure windows.

BACKGROUND

The long-term association between exposure to air pollution-particularly during early life-and hand, foot, and mouth disease (HFMD) remains unclear. Moreover, evidence is lacking regarding the potentially differential effects of PM2.5 constituents on HFMD.

METHODS

We included 41,256 children aged 0-6 years from a nationwide survey covering 15 Chinese provinces in 2013. Using satellite-based exposure models, we estimated the levels of air pollutants at each child's residence. Logistic regression models were used to assess the long-term associations between exposure to criteria air pollutants and PM2.5 constituents during different time windows and HFMD.

RESULTS

Early-life exposure to fine particulate matter (PM2.5), coarse particulate matter (PM2.5-10), nitrogen dioxide (NO2), and ozone (O3) was linked to increased odds of HFMD. During pregnancy as well as the first two years are critical exposure windows. PM2.5-10 presented the largest effects on HFMD, followed by O3. Odds ratios with 95 % confidence intervals of HFMD per interquartile range increase during the entire pregnancy were 1.19 (1.09-1.29), 1.44 (1.32-1.57), and 1.26 (1.14-1.39) for PM2.5, PM2.5-10, and O3, respectively. During the first year after birth, odds ratios were 1.16 (1.07-1.26), 1.37 (1.26-1.49), 1.12 (1.03-1.22), and 1.31 (1.20-1.43) for PM2.5, PM2.5-10, NO2, and O3, respectively. Among constituents, nitrate presented the strongest association with HFMD, followed by ammonium, and sulfate. Children 3 years and under, those who spend more time outdoors and those in rural settings were more susceptible. The exposure response curves demonstrated an approximately linear relationship between air pollutants and HFMD.

CONCLUSIONS

Our findings provided first-hand evidence linking early-life air pollution exposure with heightened HFMD risk in children, highlighting the need for air quality interventions to mitigate pediatric health impacts, particularly during pregnancy and the first two years of life.