EDITOR’S NOTE: This story is part of an ongoing investigation by The Associated Press, the PBS series FRONTLINE, and the Global Reporting Centre that examines the deadly consequences of the fragmented worldwide medical supply chain.

WASHINGTON — On a day when COVID-19 cases soared, healthcare supplies were scarce and an anguished doctor warned he was being sent to war without bullets, a cargo plane landed at the Los Angeles International Airport, supposedly loaded with the ammo doctors and nurses were begging for: some of the first N95 medical masks to reach the U.S. in almost six weeks.

Already healthcare workers who lacked the crucial protection had caught COVID-19 after treating patients infected with the highly contagious new coronavirus. That very day, an ER doctor who earlier texted a friend that he felt unsafe in an N95 mask, died of the infection. It was the first such death reported in the U.S., according to the American College of Emergency Physicians.

But the shipment arriving that night in late March wasn’t going to solve the problem. An Associated Press investigation has found those masks were counterfeits – as are millions of medical masks, gloves, gowns and other supplies being used in hospitals across the country, putting lives at risk.

Before the pandemic, federal trade law enforcement agencies focused on busting knockoffs such as luxury goods and computer software, mostly from China. As America fell sick, the mission shifted to medical supplies. To date, Operation Stolen Promise, spearheaded by Immigration and Customs Enforcement’s Homeland Security Investigations, has netted 11 arrests and 519 seizures. And yet counterfeit goods continue to pour in – not just masks, but also mislabeled medicines and fake COVID-19 tests and cures, according to the agency.

“It’s just unprecedented,” said Steve Francis, HSI’s assistant director for global trade investigations. “These are really bad times for people who are out there trying to do the right thing and be helpful and they end up being exploited.”

EAR LOOPS

AP journalists identified the counterfeit masks when reviewing film of the Los Angeles shipment. The telltale sign: these masks had ear loops, while authentic ones have bands that stretch across the back of the head, making for a tighter fit.

The blue and yellow boxes being unloaded in a Southern California warehouse bore the name of the Chinese factory Shanghai Dasheng. The masks inside were stamped as if approved by the U.S. National Institute for Occupational Safety and Health – signifying they had been certified by the U.S. government as safe for workers in health care settings. N95 masks filter out 95 percent of all airborne particles, including ones too tiny to be blocked by looser fitting surgical masks.

But the day before they arrived, the U.S. Centers for Disease Control and Prevention issued a very specific warning: all Shanghai Dasheng N95 masks with ear loops were counterfeit.

Ear loop masks are less expensive to manufacture because the straps are attached with glue to the face covering, while headbands on genuine N95s, also called respirators, must be stitched, stapled or soldered to establish a tighter seal over the nose and mouth.

AP tracked other shipments of Shanghai Dasheng ear loop N95 masks as they entered the vast U.S. medical system. Shipping labels and invoices, certified letters and interviews with more than a dozen buyers, distributors or middlemen pointed to the corporate headquarters and busy factory of Shanghai Dasheng Health Products Manufacture Company.

The company did not respond to AP’s queries about its masks. And AP could not independently verify if they are making their own counterfeits, or, as the CDC said in a published warning, someone is using Shanghai Dasheng’s certification numbers “without their permission.”

The CDC separately told AP it has been in talks with Shanghai Dasheng about authenticity issues.

On their own website, Shanghai Dasheng warns: “WE DON’T HAVE ANY DISTRIBUTORS, DEALERS OR BRANCH FACTORIES. BEWARE OF COUNTERFEIT!”

Shanghai Dasheng is one of the largest manufacturers of authentic N95s in the world and one of only a handful in China certified to make NIOSH approved, U.S. medical-grade N95s.

The company was the gold standard, according to several brokers who work in China. But in the rush of this pandemic, several said cheaper masks are proliferating.

THE FRONT LINES

One recipient of the Shanghai Dasheng ear loop masks was Direct Relief, an international humanitarian aid organization in Southern California.

Like other buyers AP contacted, Direct Relief at first thought the factory inadvertently sent the wrong mask model and set aside the entire shipment. But after reading the CDC’s warnings, CEO Thomas Tighe said they had come to believe they were counterfeit and reported them to the federal government.

“It’s a little scary that it had gone through what we understood was an aggressive customs investigation for export, and an aggressive customs import by the U.S. and still got through,” Tighe said. “It’s been a real lesson.”

Even for those looking out for fakes, it has been difficult to keep up with changing federal guidelines for medical-grade masks.

Citing an acute shortage of N95 masks, government officials relaxed standards in March. The U.S. Food and Drug Administration announced that other, unapproved medical masks with ear loops were appropriate for COVID-19 care.

But government testing of newly arrived models found most were substandard, and on May 7 the agency banned mask imports from 65 Chinese factories.

Shanghai Dasheng is among 14 that remain on the approved list.

For more than four weeks, millions of masks now considered inadequate for medical protection entered the U.S. and are now in use.

Meanwhile state and local governments, hospitals, private caregivers and well-wishers have spent hundreds of millions of dollars on the flawed masks. Before the pandemic, N95 masks sold for about 60 cents each. Today they’re priced as high as $6 apiece.

Some of the masks were purchased by charities or well-intentioned community members who held online fundraisers.

But even experts were caught off guard.

Mount Sinai procurement director Franco Sagliocca was working 18-hour days, seven days a week, to keep enough safety supplies in the hospital system’s emergency rooms and intensive care units as COVID-19 overwhelmed New York. He was searching, ordering and hustling for N95s. And he was planning to buy from Shanghai Dasheng.

“Our sourcing lead said, ‘’Wait a minute guys, this is something we don’t want,’ ” said Sagliocca.