Personal exposures to various metals in airborne particulates in Mexico City were measured over a seven consecutive-day period. Subjects were divided into two groups, Group A, whose work required them to spend considerable time outdoors and in traffic (messengers, delivery men, taxi drivers, salesmen), and Group B who spent most of their time indoors (university professors, consultants, managers and research workers). Group A spent 32 +/- 8.5% of their time outdoors, while Group B spent 10.7 +/- 6.7% of their time outdoors. Group A had higher exposures to airborne lead, zinc, vanadium, manganese and chromium than did Group B. There was no difference between the groups with respect to airborne copper exposures. Overall exposures to the various airborne metals were: lead, 435 +/- 220 ng m-3; zinc, 361 +/- 253 ng m-3; vanadium, 23 +/- 12 ng m-3; manganese, < or = 30 +/- 25 ng m-3; chromium, < or = 8.5 +/- 5.5 ng m-3; and copper, < or = 45 +/- 32 ng m-3. A significant number of samples were below the analytical limits of detection for manganese and copper.