Research objective and content of these pollutants at fixed monitoring sites, but instead by the personal exposures of individuals in their daily activities, in urban microenvironments and in commuting between them. The general objectives of this study are: * To measure the exposures of European adult urban populations to major air pol and personal and communal parameters that affect these exposures. * To improve the possibilities for environmental health risk management by developing a technique for assessing and predicting the air pollution exposure consequences of alternative industrial and urban development policies. This is achieved by the measurement of; * frequency distributions and other basic statistics of the exposures to air po volatile organic compounds (VOC), carbon monoxide (CO) and respirable particula matter (RPM), and * distributions of the timing and amounts of time spent by adult urban populati different microenvironments, and by further analysis of; * the roles of the geographic, housing and commuting related, behavioral and socioeconomic risk factors of air pollution exposures, and * the roles of different air pollution sources in the air pollution exposures, practical results; * European databases for simulation of air pollution exposures of the urban pop and subpopulations in alternative future exposure scenarios by Monte Carlo tech The study is performed with a probability sample of 240 individuals, 25 - 55 years of age, in Helsinki (to determine the roles of the above mentioned risk factors), and with probability or selected samples of 50 individuals in Milan, Athens, Basel, Prague and Grenoble (to determine the air pollution exposure, microenvironmental air pollution concentration and time-activity distributions), by measuring, for 48 h for each subject, the personal air pollution exposures, and microenvironmental concentrations of the mentioned air pollutants. All questionnaire and environmental sampling, analysis and data management is done according to strict common protocols to assure interchangeability and comparability of the data.