[Air pollution and myocardial infarction. Strasbourg France, 1984-89]

Many studies have shown positive associations between urban air pollution, mortality and hospitalizations for cardiovascular diseases. This study tried to estimate short term effects of ambient air pollution on myocardial infarction on the basis of data collected in a morbidity registry.

The daily number of myocardial infarctions between 1984 and 1989 was supplied by the Monica registry (Bas-Rhin). The pollution variables were daily mean and maximum of hourly measures of carbon monoxyde (CO), sulfur dioxide (SO(2)), particles (PM13), nitrogen monoxyde (NO) and nitrogen dioxide (NO(2)), mean and maximum of hourly measures of ozone (O(3)) between 10 a.m. and 6 p.m. Other data were influenza epidemics, daily temperature and humidity. The analysis was a Poisson regression controlling for trend, season, meteorological factors and pollutant, using non parametric smoothing. Influence of day of week and influenza were controlled through dummy variables.

For the hourly maximum of NO with a 5 day lag the association was statistically significant (square root relation): for an increase from percentile 25 (63 microg/m(3)) to percentile 75 (189 microg/m(3)), the RR was 1.087 (95% CI: 1.014-1.166). The association was significant during winter with a RR of 1.129 (95% CI: 1.028-1.241) for a percentile 25 (101 microg/m(3)) to percentile 75 (265 microg/m(3)) increase. A positive linear association was found with daily maximum of NO(2) during winter with a 5 day lag: the RR, for an increase from percentile 25 (59 microg/m(3)) to percentile 75 (107 microg/m(3)) was 1.095 (95% CI: 1.015-1.181). For the daily mean and maximum of O(3), a positive association was found but it was not robust. For other pollutants, no association was found.

The association between NO(2) and coronary events, hospitalizations and mortality, has been shown in several studies but not in all. This secondary pollutant could be a proxy for small particles.