The health impact assessment (HIA) of air pollution in the Pau metropolitan area is consistent with the guidelines of the Aquitaine Region’s Regional Air Quality Plan, which sets out strategies aimed at preventing, reducing, or mitigating the effects of air pollution. This study is based on the four stages of the HIA process for air pollution defined by the InVS. The short-term health impact of air pollution was calculated in terms of morbidity (hospital admissions) and premature mortality. The study area consisted of 29 municipalities where the population’s exposure to air pollution could be considered homogeneous, representing a total of approximately 150,000 residents. The pollution indicators selected were calculated for three pollutants routinely measured in the area: NO2, O3, and PM10. The total number of premature deaths attributable to air pollution in 2001 was 17, including 9 due to cardiovascular disease and 2 due to respiratory disease. Regarding morbidity, 20 hospital admissions for cardiovascular causes were attributable to pollution in 2002, 11 for cardiac reasons and 7 for respiratory reasons among people aged 65 and older. Calculations of health benefits associated with various air pollution reduction scenarios show that the most effective scenarios are those involving a 25% reduction in the annual average of the pollutant in question. Regarding long-term health benefits, compliance with the European standard scheduled for 2010 is expected to prevent 12 deaths per year. This study shows that, even though the relative risks associated with air pollution are low, the large number of people exposed results in a significant collective impact. It also shows that health effects are already evident at pollution levels well below those for which measures are currently being taken, and that the most effective actions would therefore be those that combine daily reductions in emissions at the source with a significant decrease in the number of annual pollution peaks. (R.A.)