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For almost a year, many Americans have been wearing cloth face coverings to limit the spread of the coronavirus — but without clear guidelines on which types or brands of consumer masks are best. That changed last month with the publication of the first-ever standard for “barrier face coverings,” created through ASTM International, an organization that creates voluntary performance standards for thousands of consumer products.

It will take time for companies to start selling cloth masks labeled with the new ASTM certification, but manufacturers can start taking advantage of the ­standard immediately.

While surgical masks, N95 masks and other medical-grade personal protective equipment have long had established standards in place, this new standard for everyday masks is a first, and is meant to provide a benchmark for both manufacturers and the general public. Manufacturers will be encouraged to comply with the standard, and consumers will be able to have confidence in compliant products, knowing that they are certified.

The new standard, which applies to face coverings worn by the general public and workers outside of health-care settings, will provide guidelines for how well masks should filter out airborne particles, as well as for their breathability, fit and labeling. The standard will also provide guidance on cleaning and how long masks can be used.

To meet the standard, manufacturers need to have their masks tested by an independent third-party lab. The products that pass will be able to note on their labeling that they are certified as ASTM-compliant, which will signal to consumers that those face coverings have been vetted.

The standard will be a big help to consumers, says Linsey Marr, a professor of civil and environmental engineering at Virginia Tech in Blacksburg who studies airborne viruses. Currently, “most people have no idea what to look for or how to judge a mask when shopping for one,” she says. “The No. 1 question I hear from members of the general public [is], ‘How do I know this is a good mask?’ With the new standards, manufacturers can share their mask’s filtration efficiency, fit and breathability, and consumers can easily pick masks with higher numbers.”

The lack of an established standard for consumer face masks “was a gap that we recognized back in the springtime,” says Jonathan Szalajda, deputy director at the National Personal Protective Technology Laboratory at the National Institute for Occupational Safety and Health, and co-chair for the ASTM working group that created the new standard.

While it would have been ideal to have the standard in place sooner, arriving at one was complicated, requiring input from a group of manufacturers, government officials, academics, medical experts and consumers. And compared with the typical ASTM process, “this was lightning-fast,” Szalajda says.

“It’s been a Wild West with regard to these types of products, and there really needed to be a baseline established for identifying some minimum level of performance,” he says. “We understand that not everyone — for instance, small sellers — will be able to meet the ASTM requirement, but the hope is that this standard will provide for better products in the workplace and for the public.”

ASTM came up with two classifications for the mask standard: a lower level 1, which is the minimum level required to meet the ASTM standard, and a higher level 2, for manufacturers that want to produce face coverings that go beyond the ASTM minimum.

Level 1 ASTM-certified masks will have to show via independent testing that they can filter out at least 20 percent of particles smaller than a micron, which is roughly the size of the respiratory droplets that generally carry the coronavirus. Level 2 ASTM-certified masks will have to show that they filter out at least 50 percent of these particles.

By way of comparison, the ASTM-certified masks will be required to filter out far less than an N95 mask but will still offer much more protection than do most consumer face coverings currently on the market, says Jose-Luis Jimenez, professor of chemistry at the University of Colorado in Boulder. Right now, “I can guarantee you that half of what is sold doesn’t meet either level 1 or level 2 of the new standard,” says Jimenez, who studies aerosols. “So as the standard starts to be applied, consumers will have a way to choose.”

Marr agrees that “the new standards are very useful, in that they address the three most important qualities in a mask: filtration, fit and breathability,” she says. “The standards for filtration are a minimum, and people will be able to choose masks that have much higher filtration efficiencies if the manufacturer provides this information.”

Ultimately, having the standard in place is a win for consumers because it should elevate the quality of the face coverings available on the market.

Until ASTM-compliant masks are available, experts say to look for snug-fitting masks that fully cover your nose and mouth, and that don’t have valves or vents, which increase the risk of you breathing in unfiltered air and breathing it out, possibly exposing people around you.

 Copyright 2021, Consumer Reports Inc.

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