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Physical work limits for Toronto firefighters in warm environments.
J Occup Environ Hyg. 2004 Apr; 1(4):199-212.JO

Abstract

This study examined the relationship between time to reach critical end points (tolerance time [TT] and metabolic rate for three different environmental temperatures (25 degrees C, 30 degrees C, and 35 degrees C, 50% relative humidity), while wearing firefighting protective clothing (FPC) and self-contained breathing apparatus (SCBA). Thirty-seven Toronto firefighters (33 male and 4 female) were divided into four work groups defined as Heavy (H, n = 9), Moderate (M, n = 9), Light (L, n = 10), and Very Light (VL, n = 9). At 25 degrees C, 30 degrees C, and 35 degrees C, TT (min) decreased from 56 to 47 to 41 for H, 92 to 65 to 54 for M, 134 to 77 to 67 for L, and 196 to 121 to 87 for VL. Significant differences in TT were observed across all group comparisons, excluding M versus L at 30 degrees C and 35 degrees C, and H versus M at 35 degrees C. Comparing 25 degrees C to 30 degrees C, M, L, and VL had significant decreases in TT, whereas only VL had a significant decrease when 30 degrees C was compared to 35 degrees C. For 25 degrees C to 30 degrees C, the relative change in TT was significantly greater for L (37%) and VL (41%) compared with H (16%) and M (26%). For 30 degrees C to 35 degrees C, the relative change among the groups was similar and approximately 17%. During passive recovery at 35 degrees C, rectal temperature (T(re)) continued to increase 0.5 degrees C above T(re final), whereas heart rate declined significantly. These findings show the differential impact of environmental conditions at various metabolic rates on TT while wearing FPC and SCBA. Furthermore, these findings reveal passive recovery may not be sufficient to reduce T(re) below pre-recovery levels when working at higher metabolic rates in hot environments.

Authors+Show Affiliations

Operational Medicine Section, Defence R&D Canada--Toronto, Toronto, Ontario, Canada.No affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15204859

Citation

Selkirk, G A., and T M. McLellan. "Physical Work Limits for Toronto Firefighters in Warm Environments." Journal of Occupational and Environmental Hygiene, vol. 1, no. 4, 2004, pp. 199-212.
Selkirk GA, McLellan TM. Physical work limits for Toronto firefighters in warm environments. J Occup Environ Hyg. 2004;1(4):199-212.
Selkirk, G. A., & McLellan, T. M. (2004). Physical work limits for Toronto firefighters in warm environments. Journal of Occupational and Environmental Hygiene, 1(4), 199-212.
Selkirk GA, McLellan TM. Physical Work Limits for Toronto Firefighters in Warm Environments. J Occup Environ Hyg. 2004;1(4):199-212. PubMed PMID: 15204859.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Physical work limits for Toronto firefighters in warm environments. AU - Selkirk,G A, AU - McLellan,T M, PY - 2004/6/19/pubmed PY - 2004/7/9/medline PY - 2004/6/19/entrez SP - 199 EP - 212 JF - Journal of occupational and environmental hygiene JO - J Occup Environ Hyg VL - 1 IS - 4 N2 - This study examined the relationship between time to reach critical end points (tolerance time [TT] and metabolic rate for three different environmental temperatures (25 degrees C, 30 degrees C, and 35 degrees C, 50% relative humidity), while wearing firefighting protective clothing (FPC) and self-contained breathing apparatus (SCBA). Thirty-seven Toronto firefighters (33 male and 4 female) were divided into four work groups defined as Heavy (H, n = 9), Moderate (M, n = 9), Light (L, n = 10), and Very Light (VL, n = 9). At 25 degrees C, 30 degrees C, and 35 degrees C, TT (min) decreased from 56 to 47 to 41 for H, 92 to 65 to 54 for M, 134 to 77 to 67 for L, and 196 to 121 to 87 for VL. Significant differences in TT were observed across all group comparisons, excluding M versus L at 30 degrees C and 35 degrees C, and H versus M at 35 degrees C. Comparing 25 degrees C to 30 degrees C, M, L, and VL had significant decreases in TT, whereas only VL had a significant decrease when 30 degrees C was compared to 35 degrees C. For 25 degrees C to 30 degrees C, the relative change in TT was significantly greater for L (37%) and VL (41%) compared with H (16%) and M (26%). For 30 degrees C to 35 degrees C, the relative change among the groups was similar and approximately 17%. During passive recovery at 35 degrees C, rectal temperature (T(re)) continued to increase 0.5 degrees C above T(re final), whereas heart rate declined significantly. These findings show the differential impact of environmental conditions at various metabolic rates on TT while wearing FPC and SCBA. Furthermore, these findings reveal passive recovery may not be sufficient to reduce T(re) below pre-recovery levels when working at higher metabolic rates in hot environments. SN - 1545-9624 UR - https://www.unboundmedicine.com/medline/citation/15204859/Physical_work_limits_for_Toronto_firefighters_in_warm_environments_ L2 - https://www.tandfonline.com/doi/full/10.1080/15459620490432114 DB - PRIME DP - Unbound Medicine ER -