Master Sgt. William Catton, the 189th Airlift Wing emergency management superintendent, instructs Airmen on the proper procedures for donning and checking a protective mask and hood during a chemical, biological, radiological or nuclear training session. The class is a requirement for all Air National Guard members regardless of their mobility status, and is required every three years.(U.S. Air National Guard photo by Tech. Sgt. Jessica Condit)