FBI ERT in HAZMAT suit during training exercise at the Washington Field Office. The ERT program supports teams in all 56 FBI field offices. These highly trained and equipped teams operate at an exceptional level of competence to ensure evidence is collected in such a manner that it can be introduced in courts throughout the U.S. and the world. A hazmat suit is a piece of personal protective equipment that consists of an impermeable whole-body garment worn as protection against hazardous materials. Such suits are often combined with self-contained breathing apparatus (SCBA) to ensure a supply of breathable air. The US Department of Homeland Security defines a hazmat suit as "an overall garment worn to protect people from hazardous materials or substances, including chemicals, biological agents, or radioactive materials." More generally, hazmat suits may provide protection from: chemical agents, nuclear agents, biological agents, and fire/high temperatures. Hazmat protective clothing is classified as either Level A, B, C, or D, based upon the degree of protection they provide. Washington D.C., 2012.