Certain N95 masks produced in China should not be reused by health care workers, the Food and Drug Administration announced Sunday. Shortages of N95 masks had prompted the FDA to loosen restrictions on mask usage via emergency use authorizations, allowing health care workers to reuse the masks after decontamination. Masks that had not been approved by the National Institute for Occupational Safety and Health but were being used in other countries were allowed to meet mask demands. These masks are still allowed for emergency use but are not permitted to be reused. Testing on the masks by the NIOSH indicated that some of the N95 masks made in China may “vary in their design and performance.”

Last month, the agency banned masks from medical use that failed to meet safety standards.