As well-intended and carefully executed as the covert mission to China had been, at least some and possibly many of the roughly one-million protective masks on the team plane were not the time-tested, industry-standard N95 masks that medical workers wear when treating coronavirus patients. Rather, they were a Chinese version known as a KN95 mask that some hospitals in Boston and beyond have so far declined to use and remain reluctant about today.

But like so much else in this global pandemic, the ensuing reality has proven to be more complex.

It was a rare moment of celebration in a season of misery: The New England Patriots team plane touching down at Logan Airport April 2 with a massive cargo of scarce respirator masks for front-line health care workers who were trying to save lives.


The state did not respond to questions about what was actually on the plane or how it has been distributed, though one local hospital administrator said he heard that about half the shipment had been sent to area nursing homes.

When KN95 respirator masks are made right, authenticated, and properly tested, they are considered to have most, if not all, of the protective qualities of the N95 masks. The federal Food and Drug Administration on April 3 issued an exception to its strict regulation of respirators, releasing a statement saying it “would not object” to their use “for the duration of the pandemic.” The Centers for Disease Control has also deemed the KN95 mask a suitable alternative when N95 supplies are low.

But while the masks appear to offer similar performance, they are not certified by the National Institute for Occupational Safety and Health. Fears of counterfeit masks run rampant, and many doctors are concerned they would put workers at risk.


“It is not the gold standard,” said Maryanne Bombaugh, president of the Massachusetts Medical Society, in an interview. “We know the N95 masks. We know how well they work, and what they filter, and the safety profile around them.

"We know these [KN95] masks are different,” Bombaugh said.

Ann Scales, a spokeswoman for the Massachusetts Department of Public Health, acknowledged in an e-mail to the Globe last week that the shipment transported by the Patriots’ plane contained KN95 masks, though she declined to say what percentage of the shipment they made up.

“The masks in this shipment, N95 and KN95, were inspected upon arrival and are authorized by the FDA for health care workers," she said in a statement.

Some hospitals and health care workers remain wary, concerned that KN95 masks would require additional testing and may not fit properly.

Shuhan He, an emergency medicine doctor at Mass General, said that while he believes the KN95 mask performs similarly to the N95 and he would be comfortable donning one for personal use — taking care of a relative suffering from COVID-19 at home, for instance — that comfort wouldn’t necessarily extend to the hospital floor.

"I cannot say that a KN95 can be used in the ER,“ said He, who is a cofounder of GetUsPPE, a nationwide organization helping to facilitate personal protective equipment donations for facilities in need. He said he believed the effort to acquire masks and bring them across the world was well-intentioned, but that the KN95 masks are “not gold-standard, and gold-standard really matters when lives are on the line.”


Though the FDA said it won’t object to the use of any KN95 masks under the relaxed rules, its emergency order gives an actual stamp of approval only to those produced by certain authorized manufacturers in China. Scales, of the Department of Public Health, repeatedly declined to say which manufacturer produced the KN95 masks purchased by the state.

It remained unclear Friday whether Governor Charlie Baker, who on multiple occasions has referred to the masks as N95s, was aware that at least some of them were not. In response to a list of questions regarding the masks, Baker’s office offered a one-sentence reply.

“The administration is grateful for the teamwork of the Kraft family and several others to help deliver this generous shipment of FDA-approved masks to Massachusetts, and other states, for our front-line health care workers,” said Baker spokeswoman Elizabeth Guyton in an e-mail.

Peter Slavin, president of Mass. General, said in an interview Sunday evening he had heard many of the masks had been provided to nursing homes throughout the state. He did not know, he added, how many of those masks were KN95s.

“My understanding is, what I was told by two government officials, was that more than half the masks have already been distributed to nursing homes,” he said. “I don’t know any more than that.”

News of the shipment came on a Thursday morning, as Baker, borrowing an oft-repeated Patriots rallying cry, tweeted about the impending arrival of personal protective equipment to the Commonwealth.


“No days off,” Baker wrote. “Thanks to some serious teamwork, Massachusetts is set to receive over 1 million N95 masks for our front-line workers. Huge thanks to the Krafts and several dedicated partners for making this happen.”

The tweet included a photo of the Patriots’ team plane being loaded on Chinese soil, where it was granted only three hours to remain on the ground.

The story quickly ricocheted around the world as hospitals and state and local governments tried to overcome a dire shortage of protective gear. Baker, whose administration procured the masks for Massachusetts hospitals, had sought the help of Patriots owner Robert Kraft, who readily offered to dispatch the team plane to China to pick up the cargo and deliver it to Logan. Kraft donated $2 million toward the purchase and also donated an additional 300,000 masks to the state of New York.

Even the New York Post took a brief break from snark to offer up a compliment: “Something we thought we’d never say . . . Thank you, Pats.”

But even as the spread of COVID-19 has left some cities facing shortages of personal protective gear, the KN95 mask had emerged as a divisive topic in the medical world.

Mass. General, for example, doesn’t use KN95 masks and has instead implemented policies of "extended use and reuse” of the hospital’s N95 masks during the crisis, according to Erica S. Shenoy, associate chief of the hospital’s infection control unit. But the hospital, she said in an e-mail, is “interested in exploring the potential” of using KN95 masks as a way to increase supply.


“Introducing them into our hospitals would likely entail assessment of both quality of the product and, as with all respirators, how they fit the end users,” she said.

Partners HealthCare, the parent organization to Mass. General and Brigham and Women’s Hospital, also procured a massive mask-sanitizing machine from an Ohio-based nonprofit that will disinfect N95 masks, allowing for multiple uses. The machine is expected to significantly address the shortage of N95 masks across the region.

State Senator Becca Rausch, a Democrat who represents Norfolk, Bristol, and Middlesex counties and is a former attorney with the state’s Health and Human Services Department, said she has been hearing from health care professionals both inside and outside her district who say masks they have received from the shipment don’t fit properly and aren’t safe for use with COVID-19 patients.

“When I heard this, I was floored,” she said. “The whole Commonwealth — the whole world — sort of breathed a sigh of relief when these masks showed up. And they’re useless for the purpose for which they were brought here."

Christine Pontus, associate director of health and safety for the Massachusetts Nurses Association, said that the fit of the KN95 has been an issue. And in an interview earlier this month with CNN, Steven Corwin, CEO of New York-Presbyterian Hospital, one of the country’s largest health care systems, offered a stark rebuke of the KN95 masks following testing, calling them “too porous” and “just not good.”

“They don’t work," Corwin told the outlet.

He softened his stance in a more recent CNN interview, saying, “We were worried about the KN95 masks, because there were so many that were counterfeit. We think that a number of those are now being certified, so that’s now better.”

It is believed that the Baker administration arranged for the purchase of the state’s masks, and the Kraft family supplied the transportation. Asked about the masks, a spokesman for the Krafts issued a statement to the Globe saying, “The governor has shown great leadership in helping our courageous health care heroes with the acquisition of 1.4 million FDA and CDC approved medical masks. We were privileged to have partnered with him to provide the logistical support to expedite the delivery of the masks and we are happy to split the cost to lessen the Commonwealth’s financial obligation in these unthinkable times.”

Jonathan Kraft, the oldest of Robert Kraft’s four children, is also the chair of the Mass. General board of trustees.

It is yet unclear how many of the masks from the Commonwealth’s shipment have reached local facilities. As of midweek, Mass. General, Brigham and Women’s, and Boston Children’s had not received any N95 masks from the shipment.

Jeremy Lechan, a spokesman for Tufts Medical Center, said the hospital had received 2,000 KN95 masks from the shipment but that none is currently being used by hospital employees.

“We are assessing the masks, and determining how best to utilize them moving forward,” he said.

Globe reporter Victoria McGrane contributed to this report.

Dugan Arnett can be reached at dugan.arnett@globe.com.