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

Background Hand foot and mouth disease (HFMD) is a public health concern. Studies on air pollution and the lengths of hospital stay (LOS) of HFMD are scarce. Methods We characterized the clinic demographic features of 5135 hospitalized HFMD in Nanjing, China from 2012 to 2017, and analyzed the association between short-term exposure to PM2.5 as well as its components (OM, BC, SO42−, NH4+, NIT, SOIL and SS) and the LOS of HFMD. Results Among them 98.62% were aged 0–6 years old, and 3772 (73.46%) were hospitalized for seven days or less. The LOS of HFMD children was different in different ages, illness onset years and illness onset seasons (P2.5 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 7days and lag 14 days, respectively. In addition, per IQR increase of BC, SO42−, NH4+, NIT and SOIL were also significantly associated with the LOS of HFMD. Conclusions Our findings corroborated the hypothesis that short-term PM2.5 exposure was associated with increased the LOS of HFMD, and its components (BC, SO42−, NH4+, NIT and SOIL) of PM2.5 might play a key role in the prolonged LOS of HFMD.