Senior Airman Doug Rish, 779th Aerospace Medical Squadron bioenvironmental engineer, takes off his self contained breathing apparatus mask during a hazardous material exercise Feb. 1, 2010, at Joint Base Andrews, Md. The exercise helped Joint Base Andrews Airmen stay proficient in HAZMAT and decontamination procedures. (U.S. Air Force photo by Airman 1st Class Perry Aston) (Released)