Using a physiological manikin to evaluate the effect of foam thermal reinforcement in firefighter turnout construction on heat strain

Firefighter turnout gear is a significant contributor to firefighter heat stress. This study uses a physiological manikin procedure to show how adding impermeable foam reinforcement in a firefighter suit construction can detrimentally affect firefighter heat strain. It shows that singular reliance on the THL (total heat loss) requirement called for by the NFPA (National Fire Protection Association) 1971 performance standard for firefighter gear leaves a critical gap in information needed to evaluate the heat strain contribution of reinforced turnout suit constructions. This is because THL test only measures heat loss through flat swatches of fabric used in the main body of the turnout suit construction. It does not account for the additional insulation and moisture vapor resistance of reinforcement or the overwhelming effects of garment air layers. This study demonstrates instrumented manikin testing procedures can supply the missing information in laboratory based heat strain performance testing of firefighter turnout suits.