Impact of ambient particulate matter on respiratory-related school absence: a case-crossover study in China

School absence was a monitor of temporary and immediate change in the health status of children. Previous studies have focused on the relationship between short-term absent rates and air pollutants, ignoring the number of daily respiratory-related school absence which was a more obvious indicator of children health. To explore the association between the respiratory-related school absence and particulate matter, we implemented this research. The absence data was collected from the symptom monitoring system due to illness. Daily concentrations of pollutants were obtained from the national air quality monitoring stations in Qingdao, China, between January 1, 2014, and December 31, 2018. We used a case-crossover design and conditional logistic regression to investigate whether levels of particulate matter influence the respiratory-related school absence on school children in Qingdao, China. Results showed that the odds ratios (ORs) with 95% confidence intervals (CIs) of the respiratory-related school absence was 1.021 (1.019–1.024) and 1.015 (1.014–1.017) for each 10 μg/m3 increase in PM2.5 and PM10 at lag0 day. Subgroup analyses showed that low age groups between 6 and 12 years have a higher risk of absenting school than higher age groups aged 13–16 years. The risk of absenting school in the warm season was greater, while the gender difference was not significant. In summary, the short-term variation in PM2.5 and PM10 concentrations has a statistically significant positive association impact on respiratory-related school absences in Qingdao, China.