The Department of Homeland Security’s Center for Domestic Preparedness Mobile Training Unit has selected the OHD FitTester 3000 as the instrument to use for training respirator fit testing in the United States. The Center for Domestic Preparedness prepares response teams all over the U.S. to address public dangers dealing with weapons of mass destruction (WMD) events. Such events include those involving chemical, biological, radiological, and to a lesser degree, explosive devices. The Center for Domestic Preparedness teaches the use and implementation of a respirator program, including requirements for annual fit testing using the OHD FitTester 3000.