HHS is publishing this proposed rule to propose a new performance standard designed to allow the National Institute for Occupational Safety and Health (NIOSH) to test the fit characteristics of non-powered, air-purifying, particulate-only half-facepiece respirators during the approval process. The new respirator fit capability standard, developed by ASTM International in collaboration with the NIOSH National Personal Protective Technology Laboratory, would be incorporated by reference into the existing respirator regulations for both filtering facepiece respirators and elastomeric respirators equipped with any type of particulate filter. The intent of the new standard is to ensure that an approved non-powered, air-purifying respirator is capable of fitting its intended population. The proposed rule would also require that approval holders identify the shelf life (i.e., the product’s use-by date) of particulate filters, including Filtering Facepiece Respirators (FFRs), on product packaging and in user instructions. Finally, the rule would require manufacturers to provide NIOSH with a description of FFR product packaging in order to aid NIOSH in better identifying counterfeit respirators being sold on the market. HHS expects that this action will result in improved respiratory protection for healthcare workers, emergency responders, and other workers who may be exposed to particulate and aerosol hazards.