We have heard a lot from the field that wearing FR clothing is just too hot specially when you are working outdoor and direct exposure to the sun. Which makes everyone worry about the potential heat stress that this may cause.
Fact is, single layer breathable clothing either FR or regular non-FR work wear does not typically cause heat stress. Here are the main causes of heat stress:
- Lack of hydration
- Lack of rest breaks or cool-down time.
- Lack of shade
- Health of the worker
Some medication can also trigger heat stress because it can interfere with the body’s natural reaction of cooling process. The human body dissipates heat first by radiation and then by sweating.
Note: About 70% of radiant heat loss is from the head and neck. Which is part of our body that is not generally covered by FR clothing.
The remaining 30% of heat is easily transmitted through any breathable fabric. When radiation alone is not sufficient cooling, our body begins to sweat which provides significant cooling. It is important that the fabric that the FR clothing is made from is breathable and can move the seat from the skin to the surface of the fabric which wear it can evaporate. But the fact that the fabric is FR, compared to not being FR, in itself does not increase heat stress.
Other clothing issues that may contribute to comfort and hot environments are lighter fabric colors, the weight of the fabric and a loose fit.