The links between exposure to air pollution and its health effects in terms of morbidity and mortality are now well established and documented in numerous French and international epidemiological studies. The health impacts of air pollution can be broadly divided into the effects of short-term exposure (acute clinical, functional, or biological “manifestations” occurring within a few days or weeks of exposure) and the effects of long-term exposure (the development of long-term pathogenic processes). (R.A.)