Smoke exposure measurements among firefighters at wildfires in the Western United States between 1992 and 1995 showed that although most exposures were not significant, between 3 and 5 percent of the shift-average exposures exceeded occupational exposure limits for carbon monoxide and respiratory irritants. Exposure to benzene and total suspended particulate was not significant, although the data for the latter were limited in scope. The highest short-term exposures to smoke occurred during initial attack of small wildfires, but the shift-average exposures were less during initial attack than those at extended (project) fire assignments because of unexposed time during the shift. Among workers involved in direct attack of actively burning areas and maintaining fireline boundaries, peak exposure situations could be severral times greater than recommended occupational exposure limits for short-term exposures. The study found that exposure to acrolein, benzene, formaldehyde, and respirable particulate matter could be predicted from measurements of carbon monoxide. Electrochemical dosimeters for carbon monoxide were the best tool for routinely assessing smoke exposure, so long as quality assurance provisions were included in the monitoring program. Suggested procedures for reducing overexposure to smoke include (1) hazard awareness training, (2) routinely monitoring smoke exposure, (3) evaluating health risks and applicable exposure criteria, (4) improving health surveillance and injury recordkeeping, (5) limiting use of respiratory protection when other mitigation is not feasible, and (6) involving workers, managers, and regulators to develop a smoke exposure management strategy.