2nd Lt. Charles Heim, 47th Civil Engineer Squadron officer in charge of emergency management, inspects his gas mask prior to donning his gear at Laughlin Air Force Base, Texas, Sept. 12, 2013. Heim was part of a chemical, biological, radiological and nuclear training course here that dealt mostly with hands-on use of chemical protective equipment. (U.S. Air Force photo/Senior Airman John D. Partlow)