Association of short-term ozone exposure with pulmonary function and respiratory symptoms in schoolchildren : A panel study in a western Japanese city

The average annual ozone levels have been increasing in Japan, even though the high ozone levels have decreased in recent years. There is limited information on the relationship between ozone exposure, pulmonary function, and respiratory symptoms in schoolchildren in Japan. The aim of this study was to investigate the effects of short-term ozone exposure on pulmonary function and respiratory symptoms in Japanese schoolchildren. Afternoon peak expiratory flow (PEF) values and respiratory symptom scores were recorded daily in 276 schoolchildren from September to October 2016 and from January to February 2017. The association of daily ozone levels with PEF was assessed using a linear mixed model and that with respiratory symptoms was evaluated by generalized estimating equations logistic regression analysis. There was a significant association of daily ozone levels with PEF values. A 13.6-ppb increment in the interquartile range for ozone exposure was significantly associated with a decrease in PEF of −3.67 L/min (95% confidence interval −4.73, −2.61). However, increased ozone levels were not associated with an increased risk of respiratory symptoms. Our present findings suggest that more attention should be paid to the potential adverse effects of short-term ozone exposure on pulmonary function in schoolchildren.