The FDA yesterday further relaxed regulations on medical and surgical masks and face shields to ease shortages during the coronavirus pandemic, and invited companies that decontaminate masks to submit proposals for emergency authorizations.

In a new guidance, the agency also gave its blessing to healthcare providers to use improvised masks during the public health emergency when FDA-cleared masks are unavailable. It invited more non-medical product manufacturers to join the effort to produce face masks and respirators, and said it would no longer block the import of  KN95 respirators from China for healthcare workers to use.

Doctors and nurses in hard-hit New York and elsewhere have been reusing masks and respirators and pleading for more, as some have contracted the virus and died. The Centers for Disease Control and Prevention previously added KN95 masks to its list of devices that healthcare providers can use during the coronavirus pandemic. Unlike N95 respirators now in use, the foreign-made masks have not been approved by the National Institute for Occupational Health and Safety (NIOSH).

“Because FDA cannot confirm the authenticity of the respirators… FDA recommends that importers take appropriate steps to verify the authenticity of the products they import,” the agency said.

Separately, President Donald Trump last evening blasted 3M (NYSE:MMM) for selling some of its N95 masks to other countries, hours after invoking the Defense Production Act to prioritize orders from the Federal Emergency Management Agency.

In seeking the aid of more companies that can decontaminate used masks, the new guidance spelled out a long list of requirements that reprocessors would have to meet before submitting proposals for EUAs. The FDA issued an emergency use authorization (EUA) on Wednesday for the Battelle Critical Care Decontamination System, which can decontaminate tens of thousands of respirator masks per day so that health personnel can reuse them.

The Columbus, Ohio-based nonprofit tech development company announced on March 28 that it began rapid manufacturing of its system to decontaminate N95 respirators and other personal protective equipment (PPE). NPR reports that Battelle already had a system on its way to New York City, which is especially hard hit by the pandemic.