A gas mask fit-test monitor collects examination data in the bioenvironmental office at Langley Air Force Base, Va., Aug. 18, 2015. During the test, U.S. Service members must demonstrate several breathing techniques to find the accurate mask fitting. (U.S. Air Force photo by Senior Airman Kimberly Nagle/Released)

A U.S. Air Force Airman annotates gas mask fit-test scores at the bioenvironmental office at Langley Air Force Base, Va., Aug. 18, 2015. The technicians observe Service members performing the test while annotating the scores of the breathing techniques with the mask on. (U.S. Air Force photo by Senior Airman Kimberly Nagle/Released)

U.S. Air Force Airman 1st Class Danielle, 30th Intelligence Squadron imagery analyst, demonstrates breathing techniques during a gas mask fit-test at Langley Air Force Base, Va., Aug. 18, 2015. Airmen at the bioenvironmental office administer the test to ensure Service members’ masks properly function in case of an emergency situation. (U.S. Air Force photo by Senior Airman Kimberly Nagle/Released) (Last name withheld for operational security purposes)

U.S. Air Force Airman 1st Class Danielle, 30th Intelligence Squadron imagery analyst, dons a gas mask during a fit-test at Langley Air Force Base, Va., Aug. 18, 2015. The test is a requirement of all Service members prior to deployment. (U.S. Air Force photo by Senior Airman Kimberly Nagle/Released)(Last name withheld for operational security purposes)

A gas mask fit-test monitor collects examination data in the bioenvironmental office at Langley Air Force Base, Va., Aug. 18, 2015. During the test, U.S. Service members must demonstrate several breathing techniques to find the accurate mask fitting. (U.S. Air Force photo by Senior Airman Kimberly Nagle/Released)

A U.S. Air Force Airman annotates gas mask fit-test scores at the bioenvironmental office at Langley Air Force Base, Va., Aug. 18, 2015. The technicians observe Service members performing the test while annotating the scores of the breathing techniques with the mask on. (U.S. Air Force photo by Senior Airman Kimberly Nagle/Released)

U.S. Air Force Airman 1st Class Danielle, 30th Intelligence Squadron imagery analyst, demonstrates breathing techniques during a gas mask fit-test at Langley Air Force Base, Va., Aug. 18, 2015. Airmen at the bioenvironmental office administer the test to ensure Service members’ masks properly function in case of an emergency situation. (U.S. Air Force photo by Senior Airman Kimberly Nagle/Released) (Last name withheld for operational security purposes)

U.S. Air Force Airman 1st Class Danielle, 30th Intelligence Squadron imagery analyst, dons a gas mask during a fit-test at Langley Air Force Base, Va., Aug. 18, 2015. The test is a requirement of all Service members prior to deployment. (U.S. Air Force photo by Senior Airman Kimberly Nagle/Released)(Last name withheld for operational security purposes)