Effect of heat on firefighters' work performance and physiology

Larsen, Brianna and Snow, Rodney and Aisbett, Brad (2015) Effect of heat on firefighters' work performance and physiology. Journal of Thermal Biology, 53. pp. 1-8. ISSN 0306-4565


Abstract

Wildland firefighters often perform their duties under both hot and mild ambient temperatures. However, the direct impact of different ambient temperatures on firefighters' work performance has not been quantified. This study compared firefighters' work performance and physiology during simulated wildland firefighting work in hot (HOT; 32 °C, 43% RH) and temperate (CON; 19 °C, 56% RH) conditions. Firefighters (n=38), matched and allocated to either the CON (n=18) or HOT (n=20) condition, performed simulated self-paced wildland fire suppression tasks (e.g., hose rolling/dragging, raking) in firefighting clothing for six hours, separated by dedicated rest breaks. Task repetitions were counted (and converted to distance or area). Core temperature (Tc), skin temperature (Tsk), and heart rate were recorded continuously throughout the protocol. Urine output was measured before and during the protocol, and urine specific gravity (USG) analysed, to estimate hydration. Ad libitum fluid intake was also recorded. There were no differences in overall work output between conditions for any physical task. Heart rate was higher in the HOT (55±2% HRmax) compared to the CON condition (51±2% HRmax) for the rest periods between bouts, and for the static hose hold task (69±3% HRmax versus 65±3% HRmax). Tc and Tsk were 0.3±0.1 °C and 3.1±0.2 °C higher in the HOT compared to the CON trial. Both pre- and within- shift fluid intake were increased two-fold in the heat, and participants in the heat recorded lower USG results than their CON counterparts. There was no difference between the CON and HOT conditions in terms of their work performance, and firefighters in both experimental groups increased their work output over the course of the simulated shift. Though significantly hotter, participants in the heat also managed to avoid excessive cardiovascular and thermal strain, likely aided by the frequent rest breaks in the protocol, and through doubling their fluid intake. Therefore, it can be concluded that wildland firefighters are able to safely and efficiently perform their duties under hot conditions, at least over six hours.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published version in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 21 Sep 2020 23:50
Last Modified: 22 Sep 2020 02:35
Uncontrolled Keywords: firefighting, work output, hydration
Fields of Research (2008): 11 Medical and Health Sciences > 1106 Human Movement and Sports Science > 110602 Exercise Physiology
11 Medical and Health Sciences > 1117 Public Health and Health Services > 111705 Environmental and Occupational Health and Safety
Socio-Economic Objectives (2008): C Society > 92 Health > 9205 Specific Population Health (excl. Indigenous Health) > 920505 Occupational Health
Identification Number or DOI: 10.1016/j.jtherbio.2015.07.008
URI: http://eprints.usq.edu.au/id/eprint/39608

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