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Firefighters wear structural turnout gear and other components of personal protective equipment (PPE) to provide protection against multiple hazards, most notably thermal injury. The use of such protection is absolutely necessary, but it also imposes a physiological burden. Specifically, the weight and insulative properties of the gear increase the cardiovascular and thermoregulatory strain of performing work.
National Fire Protection Association (NFPA) 1971, Standard on Protective Ensembles for Structural Firefighting and Proximity Firefighting, includes a thermal protection performance (TPP) test to ensure a minimum amount of thermal protection as well as a total heat loss (THL) test to ensure minimum level of heat dissipation.
However, current NFPA standards for TPP and THL consider only the turnout gear worn during emergency operations. In fact, the clothing worn under the turnout gear (including base layers and station uniform) may also contribute to thermal protection and may limit heat dissipation.
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