A U.S. Air Force airman from the 99th Civil Engineer Squadron fire protection element shuts down a building's ventilation system during a chemical, biological, radiological and nuclear exercise July 12, 2012, at Nellis Air Force Base, Nev. Shutting the ventilation system down limits the exposure of a contaminated area during a incident involving contaminants.
Airman 1st Class Daniel Hughes
Taken on 12 July 2012
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