The impact of ozone pollution on hospitalizations

This paper estimates the impacts of ozone pollution on hospitalizations, medical expenditure, and in-hospital mortality using inpatient admission records from 1,087 hospitals in China between 2017 and 2021. Leveraging an instrumental variable based on ozone concentrations in nearby upwind cities, we find that ozone significantly increases all-cause hospitalizations and medical expenditure. Ozone elevates hospital admissions across a broader range of diseases than previously documented, and the hospitalization cost of 1-standard deviation increase in ozone is larger than that of PM2.5. Ozone reduces the average number of doctors per inpatient and increases the all-cause in-hospital mortality rate in emergency departments, suggesting that ozone-induced surges in healthcare demand generate hospital crowding, which lowers the quality of care and worsens patient outcomes.