title: Heat stress while wearing long pants or shorts under firefighting protective clothing.
abstract: It was the purpose of this study to examine whether replacing long pants (P) with shorts (S) would reduce the heat stress of wearing firefighting protective clothing during exercise in a warm environment. Twenty-four Toronto Firefighters were allocated to one of four groups that performed heavy (H, 4.8 km x h(-1), 5% grade), moderate (M, 4.5 km x h(-1), 2.5% grade), light (L, 4.5 km x h(-1)) or very light (VL, 2.5 km x h(-1)) exercise while wearing their full protective ensemble and self-contained breathing apparatus. Participants performed a familiarization trial followed by two experimental trials at 35 degrees C and 50% relative humidity wearing either P or S under their protective overpants. Replacing P with S had no impact on the rectal temperature (Tre) or heart rate response during heavy or moderate exercise where exposure times were less than 1 h (40.8 +/- 5.8 and 53.5 +/- 9.2 min for H and M, respectively while wearing P, and 43.5 +/- 5.3 and 54.2 +/- 8.4 min, respectively while wearing S). In contrast, as exposure times were extended during lighter exercise Tre was reduced by as much as 0.4 degrees C after 80 min of exercise while wearing S. Exposure times were significantly increased from 65.8 +/- 9.6 and 83.5 +/- 11.6 min during L and VL, respectively while wearing P to 73.3 +/- 8.4 and 97.0 +/- 12.5 min, respectively while wearing S. It was concluded that replacing P with S under the firefighting protective clothing reduced the heat stress associated with wearing the protective ensemble and extended exposure times approximately 10 - 15% during light exercise. However, during heavier exercise where exposure times were less than 1 h replacing P with S was of little benefit.
authors.affiliation: Operational Medicine Section, Defence R&D Canada--Toronto, 1133 Sheppard Avenue West, Toronto, ON, M3M 3B9, Canada. tom.Mclellan@drdc-rddc.gc.ca
authors.forename: T M
authors.initials: TM
authors.lastname: McLellan
authors.forename: G A
authors.initials: GA
authors.lastname: Selkirk
mesh_terms: D001831:Body Temperature; D005260:Female; D005390:Fires; D006339:Heart Rate; D018882:Heat Stress Disorders / Q000175:diagnosis / Q000209:etiology*; D006801:Humans; D008297:Male; D009784:Occupational Diseases / Q000175:diagnosis / Q000209:etiology*; D005082:Physical Exertion / Q000502:physiology; D011481:Protective Clothing / Q000009:adverse effects*; D018635:Rescue Work; D013997:Time Factors