As a protective garment, FR clothing is usually worn as long pants and long sleeves, no matter how hot the environment is. The garments could be in the form of pants and shirts or coveralls as full body protection is required. This may not provide the best comfort when working in such environment but it provides safety by separating the person from the flame . Air is an efficient insulator between the body and the environment when it comes to protection against electrical arc flash or flash fire. Therefore a loosely fitting FR garment where air can flow freely between the clothing and the skin is not only more comfortable but can also improve protection. The looseness of the fit should take into consideration the issue that the garment may be caught in moving parts of any machinery or running equipment. FR garments will shrink like any standard work clothes so sizes should be chosen accordingly. As a general rule flame resistant cotton clothing will shrink more than Nomex.