An evaluation of the thermal protective clothing used by six Australian fire brigades

Individuals working in hot environments experience an increase in body core temperature due to the combined influences of physical activity, which elevates metabolic heat production, and external heat sources, which impede heat loss. Since dry heat exchanges are dependent upon thermal gradients, then hotter environments restrict heat dissipation, particularly when the air temperature approaches and exceeds that of the skin. Heat loss will now become progressively more reliant upon the evaporation of sweat, which is also gradient dependent.