Fire departments must use caution when purchasing respirators to avoid counterfeit and altered respirators.
USFA specified these resources from the U.S. Center for Disease Control and Prevention, Occupational Safety and Health Administration, and National Parks Service as importance guidance:
Counterfeit Respirators / Misrepresentation of NIOSH-Approval (CDC)
Counterfeit & Altered Respirators: The Importance of Checking for NIOSH Certification (OSHA)
NIOSH-Approved Particulate Filtering Facepiece Respirators (CDC)
Safety Alert - Counterfeit N95 Masks (National Park Service)