Objective: To quantify the short-term effects of air pollution on mortality and hospital admissions due to cardiovascular or respiratory causes in the nine cities (Bordeaux, Le Havre, Lille, Lyon, Marseille, Paris, Rouen, Strasbourg, and Toulouse) participating in the Air and Health Monitoring Program. Methods Mortality and hospitalization data were available from 1990 to 1997 and from 1995 to 1999, respectively. Exposure data included concentrations of sulfur dioxide, particulate matter with a diameter of 10 μm or less, black smoke, nitrogen dioxide, ozone, and carbon monoxide. The analysis linked daily numbers of deaths and hospitalizations in each city with daily pollutant levels, taking into account a set of confounding factors. A combined relative risk was calculated for all cities. The numbers of deaths and hospitalizations attributable to air pollution in each city were estimated based on this relative risk. Results Significant associations were observed for all-cause mortality and for respiratory hospitalizations among children under 15 years of age. If air pollution levels were reduced to 10 μg/m³ across the 9 cities, a total of 2,800 premature deaths and 750 respiratory hospitalizations among children could be prevented each year. Conclusion It is possible to estimate the short-term health impact of pollution reduction. These analyses help provide a health perspective for urban pollution reduction policies at the local and European levels. (R.A.)