Airman 1st Class Leah Erlandson connects a 8030 Portacount Pro machine to a MCU-2A/P gas mask in order to conduct a gas mask fit test for a Charleston Airman at the bioenvironmental flight building here May 5. The Portacount Pro is designed to measure fit factors of masks with an efficiency of 99 percent or greater by comparing the concentration of microscopic particles outside the gas mask to the concentration of particles that have leaked into the gas mask. Airman Erlandson is a bioenvironmental engineering technician assigned to the 437th Medical Group. (U.S. Air Force photo/Staff Sgt. Marie Cassetty)

Airman 1st Class Leah Erlandson monitors a 8030 Portacount Pro machine during a gas mask fit test for a Charleston Airman at the bioenvironmental flight building here May 5. The Portacount Pro is designed to measure fit factors of a mask with an efficiency of 99 percent or greater. A fit factor of 100 means that the air inside the gas mask is 100 times as clean as the air outside. Airman Erlandson is a bioenvironmental engineering technician assigned to the 437th Medical Group. (U.S. Air Force photo/Staff Sgt. Marie Cassetty)

Airman 1st Class Leah Erlandson adjusts the straps on a MCU-2A/P gas mask for a Charleston Airman prior to administering a gas mask fit test at the bioenvironmental flight building here May 5. Airmen go through a gas mask fit test after receiving their mask or after changing sizes to ensure they have a good seal on their mask, making them more confident in wearing their mask if an adverse situation occurs. Airman Erlandson is a bioenvironmental engineering technician assigned to the 437th Medical Group. (U.S. Air Force photo/Staff Sgt. Marie Cassetty)