Association with Ambient Air Pollutants and School Absence Due to Sickness in Schoolchildren: A Case-Crossover Study in a Provincial Town of Japan

The effect of ambient air pollutants and Asian dust (AD) on absence from school due to sickness has not been well researched. By conducting a case-crossover study, this study investigated the influence of ambient air pollutants and desert sand dust particles from East Asia on absence from school due to sickness. From November 2016 to July 2018, the daily cases of absence due to sickness were recorded in five elementary schools in Matsue, Japan. During the study period, a total of 16,915 absence cases were recorded, which included 4865 fever cases and 2458 cough cases. The relative risk of overall absence in a 10-μg/m(3) increment of PM(2.5) and a 0.1-km(−1) of desert sand dust particles from East Asia were found with 1.28 (95%CI: 1.15–1.42) and 2.15 (1.04–4.45) at lag0, respectively. The significant influence of PM(2.5) persisted at lag5 and that of desert sand dust particles at lag2. NO(2) had statistically significant effects at lag2, lag3, and lag4. However, there was no evidence of a positive association of O(x) and SO(2) with absence from school. These results suggested that PM(2.5), NO(2), and AD increased the risk of absence due to sickness in schoolchildren.