The approach to any potentially hazardous environment, including chemical and biological hazards, must be made according to a plan that includes an assessment of hazard and exposure potential, protective clothing and respiratory protection equipment requirements, entry conditions, exit routes, and decontamination strategies. Any plan involving chemical or biological hazards should be based on infectious disease or safety recommendations issued by the Centers for Disease Control and Prevention and other expert resources including emergency first responders, law enforcement, and public health officials. The Environmental Protection Agency classifies protective clothing in four categories: Fully Encapsulating Vapor Protective; Chemical Liquid Splash Protective; Air Purifying Respirators (the minimum level of protection recommended for response to potential biological hazards); and Normal Work Clothing. The article describes clothing at each level and possible uses. It also describes decontamination procedures for clothing and equipment used at each level of protection. The article emphasizes that the decision concerning level and type of protective clothing required for a particular assignment is based on the results of a hazard and risk assessment, which must be completed before any decisions are made.