U.S. Air Force Airmen with the 633rd Civil Engineer Squadron Emergency Management flight, perform a hot swap in a gas chamber at Joint Base Langley-Eustis, Virginia, Aug. 29, 2019. The gas masks are designed to function properly with one filter. This feature enables Airmen in contaminated zones to swap filters on their masks for new ones when necessary. (U.S. Air Force photo by Senior Airman Delaney Gonzales)