Blowin’ in the wind of an invisible killer: long-term exposure to ozone and respiratory mortality in the USA

In light of the lower public awareness of ozone pollution than other forms of pollution and the potential health threats posed by long-term ozone exposure, this study estimates the causal effect of long-term ozone exposure on respiratory mortality. By employing an instrumental variable approach based on the transmission of ozone from upwind neighbor counties, we discover that an increase in the average concentrations of ozone in the preceding 5 years significantly increases respiratory mortality. The findings show that long-term ozone exposure increases mortality from both acute and chronic respiratory diseases and has significant adverse effects on vulnerable groups. Our bootstrap simulation results suggest that if ozone concentrations in the preceding 5 years decrease by 10%, 11,498 annual deaths from respiratory diseases could be avoided in the USA, accruing health benefits valued at around $75.50–80.32 billion. Our further estimates suggest that, consistent with general respiratory diseases, long-term ozone exposure also contributes to deaths from COVID-19 during the pandemic.