Do I Need a Three-Layer Mask Now?

The Public Health Agency of Canada recently advised that people wear non-medical masks with three layers, but does that mean we need to toss our old masks? An infectious disease specialist explains

An important reminder off the top—while more layers offer added protection, any mask is always better than no mask when it comes to preventing the spread of COVID-19. And masks are just part of an overall strategy that also includes physical distancing and reducing close contacts. Now, here’s what you need to know about three-layer masks.

What’s the new mask recommendation?

Earlier this month the Public Health Agency of Canada advised Canadians to up their mask game and use non-medical face masks that have three layers—two layers that are made of a tightly woven fabric like cotton, and a third layer that is made of a synthetic water-repelling material that can act as a filter to trap infectious particles. (Alternatively, you can choose masks that have a pocket in which you insert a removable filter.) Previously, PHAC had been telling Canadians to use a non-medical mask or face covering with two layers.

Canada’s Chief Public Health Officer Dr. Theresa Tam stressed the importance of the new recommendation given the fact that we are moving into winter and likely to spend more time indoors.

Why now?

Most likely for two reasons. One, as Dr. Tam points out, we are headed into winter, and two, COVID-19 numbers in Canada are rising.

While this recommendation is new from PHAC, the World Health Organization has been recommending people choose three-layer masks with a filter for months, says Susy Hota, an infectious disease specialist and the medical director of prevention and control at the University Health Network in Toronto.

PHAC does seem to be doing a little catching up. The change to its face-covering guidance comes at the same time that it has updated its guidelines on how the virus that causes COVID-19 can be transmitted, saying that coronavirus can spread as an aerosol, too, i.e. microscopic particles that linger in the air for some time after an infected person talks, sings, coughs, sneezes or shouts. This change also now falls in line with what the WHO and other countries have been saying about transmission for a few months. WHO updated transmission information in July, while the CDC in the U.S. did in October. (Previously PHAC only acknowledged its transmission via respiratory droplets, which are larger particles emitted when an infected person talks, sings, coughs or sneezes.)

Read this next: What’s Going On with a COVID-19 Vaccine?

What’s the difference between the old two-layer mask PHAC recommended before and the new three-layer style it is recommending now?

That third, extra layer just offers slightly more protection for yourself and those around you. COVID-19 travels in the saliva and mucus of an infected person and the particles they expel, which can linger in the air for some time after. Research indicates that a non-medical mask can offer “source control,” i.e. significantly reduce the chances that an infected person who is wearing a mask will transmit the virus through their mucus or saliva. Mandatory mask policies have also been associated with a reduction in case loads. For people who aren’t infected, however, a mask acts as a form of personal protective equipment. It can provide a barrier against the virus from entering your airway and reduce the viral load you are exposed to, which can lessen symptoms or result in asymptomatic cases.

Basically—the more barriers you’ve got, the better.

A mask with two layers is good, says Hota, but a third filter layer made of a water-repelling material or that consists of a removable filter (also, ideally, made of a water-repelling fabric) offers just that little bit extra, says Hota.

“The extra layer is just adding barrier protection for yourself and others, it may help to filter out a bit more [particles] as well.”

None of those layers are worth much, however, if you’re not wearing the mask properly, so it should be fitted to your face and cover your mouth and nose.

Where can you find this kind of mask?

You can make one—both the WHO and PHAC offer instructions for doing so and provide guidance on the kind of material that works best.

The first two layers of a face-covering or non-medical mask should ideally be made of a tightly-woven, absorptive material like cotton or linen and the third layer should be made of a “filter-type fabric such as a non-woven polypropylene.”

Alternatively, PHAC says you can make a disposable filter out of the same material or even a piece of folded paper towel.

Read this next: I Spoke Out About Feeling Unsafe At Work During COVID—And Got Fired

What the heck is non-woven polypropylene—and why is it a better filter?

It’s a synthetic material in which the plastic is bonded rather than woven. This kind of material repels water, says Hota, which makes it a good material for helping “filter” particles. (A lot of reusable tote and shopping bags are made of the material, and PHAC even suggests you use one to make your filter layer.) One important caveat: PHAC underlines “filters should not interfere with your breathing. Plastic films or pieces of non-breathable plastic are not a suitable filter material.”

If you have the cash to spare, you can also simply buy some new masks. There are a range of options—whether it’s three-layer masks or two-layer masks with removable filters—for sale on Etsy, Amazon and, among others. (Just have a look at the materials used to make the masks and the filter, being sure to look for filters that are made of water repelling materials like polypropylene or a non-woven cotton.)

Do paper towel or coffee filters work as an added filter layer, too?

Not every filter layer needs to be made of non-woven polypropylene—PHAC also says you can use a folded paper towel. But Hota isn’t convinced that paper towel is as effective as a non-woven synthetic material.

“I don’t think that they necessarily provide any filtration that would protect people from the virus.”

She thinks it’s best to follow the primary advice from the WHO and choose a filter made of a non-woven synthetic material or fabric. The filter is supposed to repel particles, and synthetics do a good job of that.

Read this next: What To Watch Out for When Buying Hand Sanitizer

Can I still use my old two-layer masks?

Yes, says Hota. Any level of protection is important. A mask that has a third filter layer simply confers slightly better protection, which isn’t a bad idea as we head into winter, but you don’t need to turf your two-layer masks or rush out and buy three-layer masks in a panic. Your two-layer mask is still going to give you an important degree of protection.

What’s most important, however, is not to assume any one thing is going to work as well as doing the things that, when followed together, reduce the risk of both infection and increased transmission.

“There’s still lots of COVID-19 out there,” says Hota. “Having a mask is not going to get rid of the necessity of continuing to physically distance and reduce your close contacts.”

“All the same messages we’ve been saying are incredibly important now.”