This study investigates the association between short-term exposure to ambient ozone and mortality in 95 large US urban communities from 1987 to 2000. Using distributed-lag models and hierarchical models, the researchers estimated a national average relative rate of mortality associated with short-term exposure to ambient ozone. A 10-ppb increase in the previous week’s ozone concentration was linked to a 0.52% increase in daily mortality (95% posterior interval: 0.27%-0.77%) and a 0.64% increase in cardiovascular and respiratory mortality (95% PI: 0.31%-0.98%). The results were robust to adjustments for particulate matter, weather, seasonality, and long-term trends. The findings suggest that short-term exposure to ozone has a significant adverse impact on public health, with potential implications for regulatory policies and public health interventions.This study investigates the association between short-term exposure to ambient ozone and mortality in 95 large US urban communities from 1987 to 2000. Using distributed-lag models and hierarchical models, the researchers estimated a national average relative rate of mortality associated with short-term exposure to ambient ozone. A 10-ppb increase in the previous week’s ozone concentration was linked to a 0.52% increase in daily mortality (95% posterior interval: 0.27%-0.77%) and a 0.64% increase in cardiovascular and respiratory mortality (95% PI: 0.31%-0.98%). The results were robust to adjustments for particulate matter, weather, seasonality, and long-term trends. The findings suggest that short-term exposure to ozone has a significant adverse impact on public health, with potential implications for regulatory policies and public health interventions.