Airman 1st Class Jeremy Karcher, a bioenvironmental engineering technician from the 779th Aerospace Medicine Squadron, removes his respirator after a simulated vehicle clearing exercise Jan. 23, 2013 on Joint Base Andrews, Md. Bioenvironmental Engineers wear full protective gear during their exercises when checking for radiation. (U.S. Air Force photo/ Airman 1st Class Erin O’Shea)