Studies have shown over and over again: wearing a face mask can help slow the spread of COVID-19. While there are many options on the market, some scientists are now recommending masks with three layers, as opposed to two.

Recently, the Public Health Agency of Canada updated its recommendations accordingly.

“To improve the level of protection that can be provided by non-medical masks or face coverings, we are recommending that you consider a three-layer nonmedical mask,” said Chief Public Health Officer Dr. Theresa Tam during a pandemic briefing.

The World Health Organization has recommended three layers for non-medical masks since June. Tam said Canada’s new guidance simply reflects the evolving nature of Covid-19 science.

“This is an additional recommendation just to add another layer of protection,” Tam explained of the change. “The science of masks has really accelerated during this particular pandemic. So we’re just learning again as we go,” she said.

So does that mean you should throw away your two-layer masks?

Not at all.

First, any layer of protection is better than none. If you only have access to a one or two-layer mask, use it.

Secondly, you can improve your existing mask by placing a folded tissue or coffee filter inside the mask. That extra layer will help filter droplets.

And this is what the Canadian government is actually recommending. They’re not advocating for masks with three cotton layers. Instead, they’re urging people to pick up masks with two cotton layers and a breathable, filter-type middle layer.

Studies show that the filter layer can help trap smaller infectious particles.

The CDC currently recommends wearing masks of “two or more” layers. So, if you want to follow the new advice from our neighbor to the north, you would still be following the CDC’s recommendations, too.

If you’d like to try your hand at making new masks for your family, the Canadian government offers several tutorials and methods.