The majority of N95-type respirator masks made in China are not effective and should not be used to protect health care workers from COVID-19 exposure, the nation’s largest patient safety organization warned in a high priority alert earlier this week.

These imported masks, known as KN95s, may put both patients and providers at risk and should only be used as a “last resort” in COVID-19 settings, according to ECRI, a more than half century old nonprofit.

ECRI researchers found that between 60% and 70% of KN95s failed to provide the same protection as N95s, which filter at least 95% of aerosol particles. Their independent analysis included nearly 200 masks representing 15 different KN95 models used by some of the nation’s largest health care systems.

"Because of the dire situation, U.S. hospitals bought hundreds of thousands of masks produced in China over the past six months and we're finding that many aren't safe and effective against the spread of COVID-19," Dr. Marcus Schabacker, ECRI president and chief executive officer, said in an announcement Tuesday. "Using masks that don't meet U.S. standards puts patients and frontline healthcare workers at risk of infection.”

ECRI urged thorough testing and evaluation of respirator masks from China prior to their use with COVID-19 patients. In particular, the masks must filter at least 95% of aerosol particles and seal tightly against the wearer's face.

The ECRI report cautions against trusting verification efforts from KN95 manufacturers, such as certificates and test results, even though Chinese filtration efficiency requirements are described as “nearly identical” to those of the U.S. National Institute for Occupational Safety and Health. 

“We strongly recommend that healthcare providers going forward do more due diligence before purchasing masks that aren't made or certified in America,” Schabacker said.

NIOSH found that 9 out of 10 KN95 respirator masks featured ear loops instead of straps that wrap around the head and neck. According to public health experts, respirator masks with ear loops do not create the proper seal against the face, as reported by The Philadelphia Inquirer. All of the KN95s tested by ECRI used the less-effective ear loops.