N95s and KN95s Offer the Most Protection. But Some Cloth Masks Come Close. – The New York Times

My home has masks aplenty: some with nose-bridge wires and filters, others with adjustable ear loops or silicone gaskets, a few with dubious “antimicrobial” claims, and one with giraffes on it. As the writer of Wirecutter’s guide to the best cloth and disposable face masks for kids, I’ve spent the past year and a half scoping out more than a hundred kids masks—with my three children (ages 2, 4, and 7) trying on about 40 of them.

The fast-spreading Omicron variant led us to revisit our mask choices. The Centers for Disease Control and Prevention now recommends that people “wear the most protective mask you can that fits well,” acknowledging that basic cloth masks may not protect as well as surgical masks and respirators. Many adults have switched to disposable N95s or KN95s, which are made with high-efficiency filter layers. Parents and caregivers may be wondering whether they should do the same for their kids.

If you want a high-performing disposable mask for kids, N95s (designed to meet US standards) are made only for adults, but kid-size KN95 (Chinese standards) or KF94 (Korean standards) are available. We recommend the WellBefore Kids KN95, Children’s Sized Powecom KN95, Harley Children’s HL001 KN95-style mask, and the WellBefore Kids surgical-style mask. These masks are lightweight, block around 99% of aerosol-sized particles, and are sized to fit small faces.

But for some kids, medical masks are a hard sell. These masks can have a funny smell, at least until they air out a bit—something our kid testers (from preschoolers through tweens) complained about. They can also be expensive for daily use. Although you can reuse KN95s several times, they aren’t washable, and once they become visibly soiled, you’ll need to toss them.

There’s also another mask category to consider: cloth masks with incorporated filters. These masks, which Wirecutter has been recommending for nearly a year, have the ability to be washed and reworn. They also have ear loops (to aid with fit) and a breathable, structured shape that we’ve found many kids find more comfortable.

In terms of protection, these filter-incorporated masks are a significant step above a basic cloth mask. For example, independent lab tests we commissioned found that the Enro and Happy Masks Pro masks blocked 94% to 99% of the smallest particles tested—performance that is on a par with that of N95 and KN95 masks. By contrast, many of the basic cloth masks without filters blocked only about 20% of the smallest particles.

It’s important to note that other independent—and early—tests have shown a wider gap in performance. Linsey Marr, PhD—an aerosol expert and professor of Civil and Environmental Engineering at Virginia Tech—and her team have run preliminary experiments by fitting two children with masks that have measurement devices installed in them (these devices measure the mask’s filtration while it is worn). They found that KN95s blocked 90% of aerosol-sized particles, whereas masks with built-in filters blocked 60% to 80% of aerosols.

Aaron Collins, a mechanical engineer and aerosol expert known as the “mask nerd,” has conducted similar experiments on himself and his 5-year-old son. In his tests of adult-size and kid-size masks, he found that the adult-size Enro filtered about 70% of aerosols, the adult-size Happy Masks Pro filtered 80%, and the kid-size KN95s filtered over 97%. One reason for the differences in results may be how the masks were tested: Wirecutter’s lab tests examined only the ability of the mask’s material to block aerosols and particles assuming a perfect fit (because all faces are different). Marr’s and Collins’s tests accounted for how the mask fit a particular face in their experiments.

Fit is one of the most crucial factors when picking a mask. If there are gaps around the mask, air (and potentially the virus) will flow around the material rather than through it. “If it doesn’t seal to your face tightly, then it doesn’t really offer that much protection,” Collins said.

Anything that can make a mask fit better on an individual’s face, including adjustable ear loops and nose-bridge wires, will improve its performance. And that’s why Marr speculates that cloth masks with built-in filters may perform better than an average surgical-style mask, which tends to leave gaps. (You can adjust the fit of surgical-style masks by employing certain methods, such as knotting and tucking the ties, purchasing masks with adjustable ear loops, or layering a cloth mask over them.)

It’s also important to know that not all masks with filters perform equally, so you should choose a mask that has been independently tested for filtration. In Wirecutter’s independent lab tests, we found that the Space Mask, for instance, didn’t perform much better than a regular cloth mask, even though it has a built-in “antimicrobial cloud filter.” It’s also important for the filter to span the entire mask. (Our picks, the Enro and Happy Masks Pro, have this feature.) Adding a filter into a mask with a filter pocket is less effective, since the filter is often smaller than the mask, so some air will go around the filter rather than through it, according to both Collins and Marr.

How you wash your cloth mask can also affect its performance. After wearing and washing the Enro and Happy Masks Pro for six months, we sent them back to the lab for testing in fall of 2021. The much-used, much-washed Enro mask, which went in the dryer on high heat a few times (it isn’t supposed to), showed about 44% filtration efficiency for 0.5-micron particles, a significant reduction from the 99% efficiency measured with a brand new Enro. The Happy Masks Pro, which is supposed to be hand-washed (but was sent through the washing machine on occasion), filtered about 30% of 0.5-micron particles, compared with 94% with a new mask. In his research, Collins also observed that washing masks with incorporated filters can diminish their performance.

What if your kid doesn’t want to give up their favorite basic cloth mask? These masks still offer some protection. Research (by the CDC and others) has found that cloth masks block droplets and aerosols, just not to the extent of a tight-fitting mask with a medical-grade filter. Ultimately, a simple yet comfy cloth mask that your kid keeps on their face all day will block more droplets than a KN95 that they’re constantly pulling at or wearing under their nose.

My 4-year-old and 7-year-old both now prefer KN95s or well-fitting surgical-style masks to cloth masks. They like that these disposable masks are lightweight, and after all that testing, we’ve found the specific brands that fit them best. (Collins said his son also prefers a KN95 to a cloth mask.) My 2-year-old’s go-to is a cloth mask with a built-in filter that has adjustable ear loops, so it fits his small face better than most disposable masks. But even though my children’s preferred masks have changed in the past year, one thing hasn’t: They’ve gotten so used to them that they forget they’re wearing them much of the time.

Sources

1. Aaron Collins, mechanical engineer and aerosol expert, phone interview January 24, 2022

2. Linsey Marr, PhD, aerosol expert, professor of Civil and Environmental Engineering at Virginia Tech, phone interview August 12, 2021, follow-up emails January 2022

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