Association of PM2.5 and its components with lengths of hospital stay for hand foot and mouth disease in children.

Hand foot and mouth disease (HFMD) is a widespread public health concern but the studies on air pollution and the lengths of hospital stay (LOS) of HFMD are scarce nevertheless. Clinic demographic features among 5135 hospitalized HFMD cases in Nanjing, China, had been characterized from 2012 to 2017. Then, we had analyzed the association between PM2.5 short-term exposure as well as its components (OM, BC, SO42-, NH4+, NIT, SOIL, and SS) and the LOS of HFMD. Among these cases that were involved in our study, 98.62% were aged 0-6 years old, and 3772 (73.46%) were hospitalized within 1 week or less. The LOS of HFMD patients was different in various age ranges, illness onset years, and illness onset seasons (P < 0.01). For per IQR increase in PM2.5 concentrations, LOS of HFMD increased by 0.52 (0.33, 0.71), 0.50 (95% CI, 0.31-0.69) and 0.46 (95% CI, 0.28-0.65) day in adjusted models at lag 3 days, lag 7 days, and lag 14 days, respectively. In addition, per IQR increase of BC, SO42-, NH4+, NIT, and SOIL was also significantly associated with the LOS of HFMD. Our findings corroborated that short-term PM2.5 exposure was associated with the increased LOS of HFMD, and its components (BC, SO42-, NH4+, NIT, and SOIL) of PM2.5 might play a key role in prolonged LOS of HFMD.