A lab coat is required to be worn by all personnel in a research laboratory whenever there is the potential for exposure to hazardous materials. They must be changed immediately if they become contaminated and they must not be worn outside of the laboratory. Keep coats buttoned to prevent entrapment in equipment. Liquid resistant (vinyl, rubber, depending on particular compound in use) aprons supplement lab coats for activities with an elevated splash potential. Fire-resistant lab coats made from materials such as Nomex or Kevlar are recommended for applications involving pyrophoric materials or very large amounts of flammables. Grossly contaminated lab coats should be bagged and disposed as hazardous, and when appropriate radioactive waste. Lab coats must not be taken home for cleaning.