Senior Airman Alexander Phillips, 2nd Maintenance Squadron, dons an M-50 Joint Service General Purpose Mask on Barksdale Air Force Base, La., May 9, 2013. Gas mask fit tests, which are held every Thursday from 8 to 11 a.m. at Bio-Environmental Engineering, ensure Barksdale Airmen have the correct gas mask size to protect them from chemical and biological warfare agents. (U.S. Air Force photo/Airman 1st Class Benjamin Gonsier)
Staff Sgt. Shawn Gallagher, 2nd Aerospace Medical Squadron, connects an M-50 Joint Service General Purpose Mask to a photocount plus machine on Barksdale Air Force Base, La., May 9, 2013. During the test, a photocount plus machine measures the particle readings from the air in the room and compares it to the air found in the gas masks to ensure the masks are sealed properly. (U.S. Air Force photo/Airman 1st Class Benjamin Gonsier)
Staff Sgt. Shawn Gallagher, 2nd Aerospace Medical Squadron, annotates the readings off a photocount plus machine on Barksdale Air Force Base, La., May 9, 2013. During a gas mask fit test, a photocount plus machine measures the particle readings from the air in the room and compares it to the air found in the gas masks to ensure the masks are sealed properly. (U.S. Air Force photo/Airman 1st Class Benjamin Gonsier)
Staff Sgt. Bryan Farley, 96th Aircraft Maintenance Unit Electrical and Environmental Shop, performs a breathing exercise during a gas mask fit test on Barksdale Air Force Base, La., May 9, 2013. Barksdale personnel perform a number of breathing exercises to ensure they have the correct gas mask size and that there is no break in the seal. (U.S. Air Force photo/Airman 1st Class Benjamin Gonsier)
Barksdale Airmen perform a breathing exercise during a gas mask fit test on Barksdale Air Force Base, La., May 9, 2013. Barksdale personnel perform a number of breathing exercises to ensure they have the correct gas mask size and that there is no break in the seal. (U.S. Air Force photo/Airman 1st Class Benjamin Gonsier)
Staff Sgt. Shawn Gallagher, 2nd Aerospace Medical Squadron, reads information off a photocount plus machine during a gas mask fit test on Barksdale Air Force Base, La., May 9, 2013. During the test, a photocount plus machine measures the particle readings from the air in the room and compares it to the air found in the gas masks to ensure the masks are sealed properly. Gas mask fit tests, which are held every Thursday from 8 to 11 a.m. at Bio-Environmental Engineering, ensure Barksdale Airmen have the correct gas mask size to protect them from chemical and biological warfare agents. (U.S. Air Force photo/Airman 1st Class Benjamin Gonsier)