If you work a job that requires FR clothing, it may feel like the outer shell is enough to protect you, but remember nothing is 100% safe when working with flash fire and electrical arc hazards. It’s important to understand how layers under your FR garment can provide additional protection or be dangerous.

When it’s necessary to perform a job or work on a job site where fire, electric, and other hazards exist to necessitate FR clothing, you don’t want to be caught up wearing one of these innocent-seeming articles of clothing that could be potentially deadly.

1. Performance Sport-style Undershirts

These garments are synthetic and they not only can hold heat in, creating much higher body heat within the FR outer shell than necessary, but the possibility of them melting to the skin at high heat or igniting within the outer shell are great.

2. Yoga Pants

It’s fashionable these days for women to wear yoga pants and other skin-tight leggings for comfort. While women have a variety of FR choices to stay comfortable, fashionable, and safer (even while pregnant), yoga pants are not a good idea to wear under FR clothing.

Like synthetic under shirts, synthetic yoga pants can become a fire hazard and are difficult to remove in an emergency situation. Synthetic fibers and fabrics not properly tested for flame and electrical arc hazards can react in unpredictable ways and may melt onto your skin if overheated.

3. Panty Hose

Nylon, like any other synthetic fabric not specifically designed and tested for FR and electrical arc ratings, can combust and/or melt to your skin. While it may be fashionable to wear nylons outside, on the job site, they need to be banned.

4. Thick Cotton/Wool

Cotton and wool are accepted under layers but in high-heat conditions, cotton can keep moisture near the skin, making it clammy and heavy reducing your comfort and increasing your potential for heat stress. Like synthetic fabrics, cotton and wool don’t provide proper FR protection on their own, and FR-engineered clothing is best to wear underneath any FR clothing.

While a lot of clothing seems great for different situations, it’s important to focus on what you’re wearing underneath FR clothing on the job site. If an accident occurs, you don’t want to be wearing that new pair of satin boxers as a tattoo on your skin.