Master Sgt. Paul Lewis (right), 926th Force Support Squadron education and training manager, ingests water from a canteen through his M-50 gas mask during a Chemical Biological Radiological and Nuclear Defense training class, Nov. 8, 2017, at Nellis Air Force Base, Nev. CBRNE is a protective measure taken in situations in which chemical, biological, radiological or nuclear warfare (including terrorism) hazards may be present.