Book excerpt: Personal protective equipment (PPE) is critical for those dealing with toxic, infectious, and radioactive materials. An easily accessible guide for professionals and researchers in all PPE fields, this book takes a fresh look at how PPE is designed, selected, and used in today's emergency response environment where users may need to be protected against deliberately used chemical, biological, or radiological agents in terrorism or warfare scenarios as well as more traditional hazards. Covering the physics, chemistry, and physiology of these hazards, the book explains how PPE protects from various forms of hazards as well as how to use this information to select PPE against these highly hazardous substances for first responder or military users. The design of PPE and components plus relevant performance and evaluation standards are also discussed.