Earlier this week, the Public Health Agency of Canada (PHAC) changed its guidance on which kind of mask to wear to prevent the transmission of COVID-19. While it doesn’t say outright that cloth masks should no longer be used, the wording certainly suggests it.
“In general, while non-medical masks can help prevent the spread of COVID-19, medical masks and respirators provide better protection,” PHAC’s website states.
Changing regulations can be frustrating, especially when so many people are dealing with pandemic fatigue. So Healthing turned to an expert to set things straight: Dr. P. Ravi Selvaganapathy, an engineering professor at McMaster University who specializes in biomicrofluidics and protective textiles.
Cloth masks can be effective, but it’s hard to tell which ones
Some cloth masks are great at filtering out air particles, Selvaganapathy says. A well-fitted three-layer mask with a meltblown polypropylene filter “has excellent filtration properties, similar to an N95.”
The problem is that it’s hard to distinguish the good ones from the bad ones since cloth masks aren’t subject to any kind of standardized regulation, unlike medical (sometimes called surgical) masks.
“Medical face masks need to acquire certification,” he says, adding that they can’t be sold as medical masks without adhering to the American Society for Testing and Materials’ ASTM F-2100 rules, which govern their efficiency. Likewise, heavy-duty N95 respirator masks must also meet Health Canada’s qualifications.
But there’s no similar regulation for cloth masks.
“There are a wide range of performance characteristics,” says Selvaganapathy. “The biggest problem is that you don’t have a mechanism by which you can identify which one is good, and which one is not so good, from a ventilation perspective.”
Basically, telling everyone to wear surgical masks ensures the same level of protection against the virus — at least in theory — while telling people to wear cloth masks mean different levels of protection.
If you are set on using cloth masks, look for the ones with three layers — meaning, at least two fabric layers surrounding a polypropylene filter. Filters that are sewn in will be more efficient than those that are simply inserted, because air particles are less likely to get around the filter.
“If the filter material is not fully between the two layers of cloth, then you have more of the air going through the least resistant part of the of the mask,” Selvaganapathy explains.
Double-masking can also be effective, he says — but only to the extent that you’re still able to breathe.
Almost two years in, your masks might be worn out
Cloth masks have been extremely helpful in preventing transmission of the virus. Early in the pandemic, they were suggested to the general public in order to leave medical masks to healthcare staff who needed them the most. Many clothing companies and volunteers stepped up to produce fabric masks when they were most needed.
Now, nearly two years into the pandemic, surgical masks are widely available again. And even though restrictions have been easing as more people get vaccinated, the risk of transmission still exists, continuing to make mask-wearing important.
“I think the timing of why Canada came out for this type of [mask] regulation is that in many jurisdictions, we are opening up restaurants and so on,” says Selvaganapathy. “There are going to be greater opportunities for transmission to happen.”
With this, it’s important to consider the shape that your mask is in. After more than a year and a half of being regularly washed and dried, your cloth mask probably isn’t as effective as it was when you bought it in 2020. “[Cloth masks] tend to lose their filtration properties a little bit,” he says. “I would expect some degradation over time.”
Selvaganapathy recommends washing cloth masks on a gentle cycle and air-drying them rather than putting them in the dryer in order to help them last longer and preserve their effectiveness.
Your mask is useless if it doesn’t fit
Selvaganapathy also says that while there is a lot of focus on what kind of mask to wear, more attention should be focused on the right fit. Many surgical masks tend to be large, which can cause gaping holes by the ears, or open spaces at the top, next to the nose. If that happens — or if a mask slips down under your nose — it doesn’t matter how efficient the mask is at filtering out droplets.
“That gets lost,” he says. “It’s the one thing that an individual can do to get effective filtration.”
To make sure your medical mask fits, squeeze the top around your nose, he says. There are many more tips circulating online, like tying a knot in the ear loops to make the sides more snug.
As for what kind of mask a biomicrofluidics expert wears, Selvaganapathy says he opts for a medical mask.
Maija Kappler is a reporter and editor at Healthing. She can be reached at firstname.lastname@example.org.
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