U.S. Air Force Airman Marquis’ Henry, 97th Civil Engineer Squadron emergency management apprentice, explains the basic pieces of equipment used to detect chemical and radioactive threats during the career fair at the Freedom Community Center, March 17, 2015. Some of the equipment on display is used to detect chemical threats or radioactive materials that would be dispersed in explosions, and another machine helps monitor oxygen levels and potential air contaminants. (U.S. Air Force photo by Airman 1st Class Megan E. Acs/Released)