Critical exposure windows of PM2.5-Meteorological interactions triggering pediatric mycoplasma pneumoniae epidemics: An age-stratified distributed lag nonlinear modeling approach.

BACKGROUND

The rising prevalence of Mycoplasma pneumoniae infection (MPI) in children, a leading cause of severe pneumonia and mortality, highlights the need to clarify impacts of air pollution and meteorological factors.

METHODS

This study analyzed associations of PM2.5, temperature, and humidity with outpatient MPI, inpatient MPP, and severe MPP (SMPP). Data on 391,559 children from 15 Northeast China hospitals (2017-2023) were analyzed using a distributed lag nonlinear model, with sensitivity analysis after 2020 (COVID-19 onset).

RESULTS

PM2.5 (60-100 μg/m3) showed nonlinear associations with outpatient MPI (7-15-day lag, RR = 2.28 at 100 μg/m3, 10-day lag), especially in preschoolers. Temperature correlated positively with outpatient MPI (peaks at 20 °C/30 °C, 7-10-day lag; RR = 1.82 at 30 °C, 10-day lag), with high temperatures increasing female MPP/SMPP risk. Humidity had a U-shaped association with outpatient MPI (20 %/100 % humidity increased risk 2.75/2.18-fold at 15-day lag), with high humidity elevating female/school-age SMPP risk (RR = 5.32). Trends were consistent pre/post-COVID-19.

CONCLUSION

High PM2.5, high temperature, and extreme humidity correlate with increased childhood MPI cases and severity, emphasizing targeted strategies for extreme conditions.