Associations between daily cause-specific mortality and concentrations of ground-level ozone in Montreal, Quebec

The authors investigated the association between daily variations in ozone and cause-specific mortality. Fixed-site air pollution monitors in Montreal , Quebec, provided daily mean levels of ozone, particles, and other gaseous pollutants. Information on the date and underlying cause of death was obta ined for residents of Montreal who died in the city between 1984 and 1993. The authors regressed the logarithm of daily counts of cause-specific morta lity on mean levels of ozone, after accounting for seasonal and subseasonal fluctuations in the mortality time series, non-Poisson dispersion, and wea ther variables. The effect of ozone on mortality was generally higher in th e warm season and among persons aged 65 years or over. For an increase in t he 3-day running mean concentration of ozone of 21.3 mug /m(3), the percent age of increase in daily deaths in the warm season was the following: nonac cidental deaths, 3.3% (95% confidence interval (Cl): 1.7, 5.0); cancer, 3.9 % (95% Cl: 1.0, 6.91); cardiovascular diseases, 2.5% (95% Cl: 0.2, 5.0); an d respiratory diseases, 6.6% (95% Cl: 1.8, 11.8). These results were indepe ndent of the effects of other pollutants and were consistent with a log-lin ear response function.