U.S. Air Force Airmen from the 702nd Munitions Support Squadron don their M50 gas masks as part of a timed Mission Oriented Protective Posture gear exercise at the 702nd MUNSS, April 13, 2021. Airmen must have their masks on and properly sealed in nine seconds or fewer, before a chemical, biological, radiological or nuclear attack begins to affect the body. (U.S. Air Force photo by Senior Airman Ali Stewart)