Wildland firefighting presents many hazards to fireline workers, including inhalation exposure to smoke (Sharkey 1998; Reinhardt and Ottmar 1997; Sharkey 1997). Many experienced fireline personnel consider this to be only an inconvenience, occasionally causing acute cases of eye and respiratory irritation, nausea, and headache. Others express concern about long-term health impacts, especially when large-scale fires occur in terrain and atmospheric conditions that force fireline workers to work for many days in smoky conditions. At the present time, no one can say whether there are long-term adverse health effects from occupational smoke exposure. This is because there have been no epidemiological studies to track the health of fireline personnel and compare it with other workers to see if fireline personnel have more or fewer health problems during and after their careers. Until such long-term data are examined to tell us if a problem exists, we can only assess the occurrence of relatively short-term adverse health effects. We can measure fireline worker's exposure to particles and individual chemicals found in smoke and compare these exposures to standards established to protect worker health (Reinhardt and Ottmar 2000; Reinhardt and others 2000; Reinhardt and others 1999). We can evaluate the relative risk of disease among fireline workers based on the exposure data and the potency of the health hazards (Booze and Reinhardt 1996).