Question:
When firefighters go into a burning building, they wear special suits. What are those suits made of, and don't they get hot in them?

Answer:
Firefighter Personal Protective Equipment, or PPE, is specially designed and manufactured to protect firefighters from thermal hazards during structural fire fighting activities - or, simply stated, clothing that protects firefighters' delicate skin from getting burned.

Turnouts (the term commonly used around the fire station for PPE) are constructed to insulate the wearer from a fire's intense heat by utilizing a layering technique. Turnouts insulate so well because they are made up of two separable parts: an outer shell and an inner liner. The outer shell is constructed of Nomex III, or a blend of Nomex and Kevlar, or PBI and Kevlar. The shell has big cargo pockets, hooks, and Velcro fasteners, and are all wrapped up in reflective triple trim.

The inner liner incorporates a layering of three different barriers combined into one component part. The barrier closest to the body is the thermal barrier. This barrier uses Nomex batting sewn into a quilted pattern to achieve an "insulative thickness". The next barrier is the vapor barrier. The vapor barrier protects firefighters from potentially harmful vapors, such as carbon monoxide, that are present during fire as products of combustion. The outermost barrier of the inner liner is the moisture barrier. The moisture barrier is a Goretex type material that has the ability to repel water on one side, but lets it pass through the other. Water used to fight the fire is repelled and moisture generated by the firefighter's body is allowed to dissipate. Repelling outside moisture is important to keep the firefighter dry, of course, but also to prevent steam burns from occurring caused by fire superheating a water soaked turnout coat, turning water to steam.

As you can see, firefighters' turnouts are a complex and important component of structural fire fighting equipment. Without them, we would not be able to enter a burning building. However, they do indeed have one drawback: they do cause the wearer to overheat. In spite of manufacturers' best efforts to enhance their "breathability", heat buildup is inherent. For that reason, firefighters and fire-scene managers must be cognizant of, and watch for, the signs and symptoms of firefighter fatigue and heat stress.