Fig. 2

Percent change (95% confidence interval) in cardiovascular mortality associated with a 10 μg/m³ increase in 2-day average of 8-h maximum O₃ concentrations in individuals with prior hospitalization for acute myocardial infarction. Individuals were stratified according to the time period between their last hospitalization and death. Strata included month 0 (0–28 days before death) divided into 4 separate weeks, and preceding months (1–36) grouped into 6-month periods. All strata are mutually exclusive and results are from time series analysis