The Mexico City Metropolitan Zone ŽZMCM. population’s exposure to benzene, toluene and xylene was measured at different microenvironments to establish basic indicators of the presence and effects of these characteristic volatile organic compounds ŽVOC.. In particular, VOC personal exposures were measured in different microenviron- ments during a 5-day working week, with 12-h daily periods. We have found a good agreement of our results with the registered VOC levels of the Metropolitan Automated Monitor System ŽRAMA. for the corresponding period. From our results, we expect to generate useful information to evaluate the health effects of these VOCs on exposed people.