Abstract
What is already known about this topic? Few studies have elucidated the relationships between ambient ozone and respiratory morbidity, especially in developing countries. What is added by this report? This study involved 5 cities in China with a wide variation in ozone concentrations and therefore could add credible evidence for the associations between short-term ozone exposure and increased respiratory morbidity. What are the implications for public health practice? The results could be used to better assess disease burden of short-term exposure to ozone and further guide policymaking for reducing ozone air pollution and improving public health.