The causal relationship between exposure to urban air pollution and health, both in the short and long term, is now widely accepted. The existence of epidemiological studies quantifying the relationship between the level of an air pollution exposure indicator and the risk of a health event makes it possible to assess the health impacts of air pollution at the metropolitan area level. This approach was applied for the 2004–2006 period to nine cities in metropolitan France as part of the European Aphekom project. Air pollution exposure indicators were constructed based on pollutant levels measured by background stations in air quality monitoring networks. Health indicators were derived from data from the PMSI (hospitalizations) and CépiDc (deaths). Relevant exposure-risk relationships were selected based on a literature review. Standard methods for calculating health impacts were used to assess, under various scenarios for reducing pollutant levels, the number of preventable cases (short- and long-term impacts) and the gain in life expectancy (long-term impacts). A monetary valuation of these potential health benefits was performed using a willingness-to-pay approach for mortality and a disease cost approach for hospitalizations. For the nine metropolitan areas with a combined population of 12 million, compliance with WHO guideline values for ozone levels would have prevented 69 deaths per year and avoided 62 respiratory hospitalizations. For particulate matter (PM10) levels, 360 hospitalizations per year due to cardiac causes and 673 due to respiratory causes could have been avoided. For fine particulate matter, in the long term, compliance with WHO guideline values would have resulted in an average increase in life expectancy at age 30 of 3.6 to 7.5 months depending on the city, representing a total of over 2,900 deaths per year averted on average. These long-term impacts have the highest economic value, with an estimated annual cost of €4.9 billion. These results highlight the continued substantial impact of air pollution on health in French cities. They are thus likely to encourage the implementation of public policies to improve air quality at the local level. (R.A.)