Wildland firefighters work on wildfire incidents all over the United States and perform arduous work under extreme work conditions, including exposure to smoke. Wildland fire smoke is a mixture of hazardous air pollutants. For assessing wildland firefighter exposure to smoke, most studies measured carbon monoixde (CO) and particulate matter and reported changes in lung health by measured lung function, airway responsiveness, and respiratory symptoms across individual work shifts and single fire seasons. All fire personnel should understand the hazards of smoke and develop ways to mitigate exposure to smoke.