Ambient Air Pollution and Daily Mortality Among Survivors of Myocardial Infarction

Background: Certain subgroups in the general population, such as persons with existing cardiovascular or respiratory disease, may be more likely to experience adverse health effects from air pollution. Methods: In this European multicenter study, 25,006 myocardial infarction (MI) survivors in 5 cities were recruited from 1992 to 2002 via registers, and daily mortality was followed for 6 to 12 years in relation to ambient particulate and gaseous air pollution exposure. Daily air pollution levels were obtained from central monitor sites, and particle number concentrations were measured in 2001 and estimated retrospectively based on measured pollutants and meteorology. City-specific effect estimates from time-series analyses with Poisson regression were pooled over all 5 cities. Results: Particle number concentrations and PM, averaged over 2 days (lag 0-1) were associated with increased total nontrauma mortality for patients of age 35 to 74 (5.6% [95% confidence interval, 2.8%-8.5%] per 10,000/cm(3) and 5.1% [1.6%-9.3%] per 10 mu g/m(3), respectively). For longer averaging times (5 and 15 days), carbon monoxide and nitrogen dioxide were also associated with mortality. There were no clear associations with ozone or sulfur dioxide. Conclusion: Exposure to traffic-related air pollution was associated with daily mortality in M1 survivors. Point estimates suggest a stronger effect of air pollution in MI survivors than among the general population.