U.S Air Force Airman Alex McClendon, 633rd Aerospace Medicine Squadron bioenvironmental engineer technician, dons a Mine Safety Appliances FireHawk mask at Langley Air Force Base, Va., Feb. 9, 2016. Bioenvironmental Airmen use these masks when going on supplied air to respond to an emergency, such as entering contaminated areas. (U.S. Air Force photo by Senior Airman Brittany E. N. Murphy)