DuPont™ Nomex® for Heat Stress Protection

Heat stress is a dangerous condition in any situation, but for firefighters it can be especially life threatening. In fact, heat stress is the number-one cause of casualties among firefighters. Nomex® fibre helps reduce heat stress due to its higher air permeability.

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Comfortable garments in order to reduce heat stress
Statistics from the United States of America (Firefighter Fatalities and Injuries: The Role of Heat Stress and PPE, July 2008) show that the principal reason for injuries and fatalities among firefighters is heat stress, caused by a rise in the body’s core temperature through exposure to heat combined with physical exertion.

At DuPont, we understand that the same garment that protects firefighters must also allow for the release of metabolic heat that can contribute to heat stress. For this reason, Nomex® fibres are blended with an optimised percentage of para-aramid fibres. The resulting fabrics are constructed for maximum air permeability (breathability); together with the lightweight Nomex® fibre, they help to reduce heat stress.

Dangerous body temperature
In callouts involving proximity to fire, millions of the body’s sweat glands work overtime to regulate core body temperature and keep the firefighter cool. Garments with high insulating properties only compound the problem. Moisture build-up means damp clothes, more effort and more body heat. And if a firefighter’s core body temperature rises too much, it can lead to impaired judgment, mistakes and accidents. Evaporation helps draw heat away from the body. But this process only works when the sweat can escape away from the skin. With multilayer garments, it’s essential that the outer shell is permeable. Otherwise vapour cannot move to the outside, and remains trapped near the body.

Outstanding permeability
Nomex® fibre helps give outershell fabrics their outstanding air permeability, helping the membrane to function as it should.
Under intense heat, such as from a flash fire, Nomex® fibre thickens instantly, creating an expanded barrier to reduce heat transfer. Fabric blends made of Nomex® help offer ideal comfort, breathability and protection – all in a lightweight fabric that makes it an apparel of choice for many firefighters.

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