Four testing days included baseline examination on Day 1 (informed consent, PARQ, hydrostatic weighing, and VO2max) followed by 3 days of identical exercise during the three smoke exposure conditions (“Clean Air” 0 μg/m3; Low Exposure 250 μg/m3; High Exposure 500 μg/m3`) Episodic woodsmoke exposures were introduced in a randomized crossover design with trials separated by 1 week. In all three trials participants performed an identical treadmill session for 1.5 hours. Blood samples were taken Pre-, Post-, and 1Hr Post exercise for subsequent examination of blood oxidative stress biomarkers.