[Individual exposure to air pollution in urban areas: the example of Marseille].

We examined the exposure of an urban population to the following air pollutants, in the home and outdoors: nitrogen dioxide, benzene and its derivative BTXE, carbon monoxide, ozone, aldehydes and particulate matter (PM)2,5. Measurements were made continuously during 48-hour periods in summer and in winter, in non-smoking volunteers, using passive and active samplers and appropriate analytical methods. NO2 concentrations were relatively low (lower in summer than in winter). Individual overall exposure correlated strongly with levels in the home. Benzene levels were high both outdoors and in the home, and were higher in winter than in summer; 47% of the volunteers were exposed to mean values up to 5 microg x m(-3) (annual mean value outdoors). Benzene derivative levels were also higher in winter than in summer. Personal exposure to CO was low and related to determinants such as trafic and environmental tobacco smoke (ETS). Mean concentrations of O3 were low in winter and higher in summer, owing to higher outdoor photochemical pollution. The most abundant aldehydes were formaldehyde, acetaldehyde and acrolein ; personal exposure was low. Overall personal exposure to formaldehyde correlated with concentrations in the home. PM2,5 reached high levels in the home in winter and outdoors in summer.