Senior Airman Thomas Hollingsworth, 779th Aerospace Medicine Squadron bioenvironmental technician, demonstrates putting on a gas mask with the help of Airman 1st Class Ashton McLaughlin, 779th AMS bioenvironmental technician, March 16, 2015, on Joint Base Andrews, Md. The flight conducts approximately 1,400 gas mask fit tests and tests more than 140 water samples per year. (U.S. Air Force photo/Senior Airman Mariah Haddenham)