An assessment of the health impacts of urban air pollution in the Montpellier metropolitan area was conducted as part of the development of the air quality protection plan. The study, based on the four standardized steps of health risk assessment, serves a dual purpose. The primary objective is to estimate the short-term impact of air pollution on mortality (total, cardiovascular, and respiratory) and on hospital admissions (for respiratory, cardiovascular, and cardiac causes). Furthermore, the long-term health impact is estimated by the number of deaths attributable to air pollution. Additionally, calculating the expected benefits in terms of health gains based on various scenarios for reducing air pollutants can facilitate the planning of measures to improve air quality. The air pollution impact assessment was conducted for eleven municipalities with similar exposure levels within the Montpellier urban area (Castelnau-le-Lez, Clapiers, Le Crès, Grabels, Jacou, Juvignac, Montferrier-sur-Lez, Montpellier, Saint-Clément-de-Rivière, Saint-Jean-de-Védas, Vendargues). It is based on an analysis of mortality data over two years (1999 and 2000) and hospital admissions over four years (1999 to 2002). The study population consists of 288,059 residents. The air pollution indicators analyzed are ozone, nitrogen dioxide, sulfur dioxide, and particulate matter with a diameter of less than 10 μm. Air pollution is directly responsible annually, in the study area, for 34 premature deaths, including 13 due to cardiovascular causes and 4 due to respiratory causes. In terms of morbidity, it causes 79 hospital admissions annually for cardiovascular causes, 15 for cardiac causes, 9 for respiratory causes among those over 65, and 4 among those aged 15–64. People over the age of 65 are proportionally the most affected. These events could theoretically be prevented if pollution levels were similar to those observed on the least polluted days. The health benefits associated with a reduction in pollution were calculated based on two scenarios. Implementing an air pollution reduction scenario aimed at eliminating pollution peaks results in shorter-term health benefits that are less than those achieved by a 25% reduction in background pollution. Long-term health benefits are also greater when average pollution levels are reduced by 25% (40 deaths prevented) or by 5 μg/m³ (37 deaths prevented) rather than through an annual reduction to the 2010 European standard (20 deaths prevented). The impact of air pollution on health, even at low exposure levels, has already been demonstrated elsewhere. The purpose of this study is therefore not to address that objective but to quantify this impact at the local level and to enable policymakers to base their pollution reduction policies on locally established health arguments. In any case, an air pollution reduction policy aimed solely at preventing exceedances of regulatory limits would not yield the expected public health benefits. Greater effectiveness will be achieved by reducing pollutant emissions at the source, on a daily and comprehensive basis. Since air pollution in the Montpellier urban area is primarily caused by road traffic, it is emissions from road transport that should be reduced.