What type of clothing is prohibited when wearing flame-resistant (FR) clothing?

Flame-resistant (FR) clothing is designed to protect against fire hazards by resisting ignition and burning when exposed to flames or high heat. Synthetic materials, such as acetate, nylon, polyester, and rayon, are prohibited when wearing FR clothing because these fabrics can melt when exposed to high temperatures or flames. This melting can cause severe burns to the skin, compromising the protective purpose of the FR clothing.

In contrast, cotton, denim, and wool clothing, while not inherently flame-resistant, do not have the same melting characteristics as synthetic fibers. Cotton and denim can char upon exposure to flames but will not melt onto the skin, making them less hazardous in fire situations compared to synthetic fabrics. Wool, known for its natural flame-resistant properties, does not ignite easily and tends to self-extinguish when the flame source is removed. Therefore, the prohibition of synthetic clothing while wearing FR clothing is a critical safety measure to prevent injuries in environments where fire hazards exist.