Seattle, Washington – Dozens of hospitals in Washington state have learned that N95 respirator masks believed to be purchased from 3M are knockoffs and were not manufactured by the company.

After receiving notice from 3M about the possibility that some masks were counterfeit, the Washington State Hospital Association on Friday alerted the state’s hospitals and asked them to pull potentially affected masks from their supplies.

WSHA asked the state’s 115 hospitals to sort through their mask supplies and several have sent masks to 3M for testing. This weekend, the company confirmed that some were counterfeit.

WSHA officials said they’re unsure how 3M originally discovered the fraud. And it’s unclear where the masks originated or how many masks are fakes, since hospitals around the state are still sending samples in for testing. But the issue affects the supply of somewhere between hundreds of thousands to more than a million N95 masks, said Cassie Sauer, president and CEO of WSHA.

"We are having hospitals go through all their masks and look for what they can find," she said. She estimates the state’s hospitals spent $5 million to $8 million on the fakes.

She said it’s unclear whether the counterfeit masks are less safe than those manufactured by 3M.