Senior Airman Matthew Hung, and Airman 1st Class Ricky Schutter, 28th Civil Engineer Squadron emergency management technicians, survey simulated unknown substances during a training exercise at Ellsworth Air Force Base, S.D., Jan. 23, 2014. Responders don protective masks under their level A hazardous material suits to guarantee that they remain unharmed from any chemical or biological attacks. (U.S. Air Force photo by Senior Airman Zachary Hada/Released)