TORONTO -- Amid a global shortage of personal protective equipment, more people are mobilizing to make homemade face masks.

While there is limited evidence to support the effectiveness of homemade masks at preventing the spread of a virus, some studies have shown that everything from vacuum bags to tea towels can provide some protection.

A surgical mask is ideal, says infectious disease specialist Dr. Abdu Sharkawy, but the appetite for creative solutions amid the COVID-19 pandemic is growing, and there are options.

“Really anything that covers your nose and your mouth with a reasonable seal,” he told CTV National News on Sunday. “You can fashion (a mask) out of cloth, you can fashion (a mask) even out of a vacuum bag,” he said.

Currently, the Public Health Agency of Canada says that it is not necessary for healthy people to wear face masks. “Wearing a mask when you are not ill may give a false sense of security,” the agency says online.

Last week, Health Canada released a warning about homemade masks, advising Canadians that they should be used with caution and have several limitations that surgical masks and respirators do not. Homemade masks have not been tested “to recognized standards.” They may not provide “complete protection” against viruses. They may be difficult to breathe through and made with ineffective fabric. They may also be loose-fitting and require frequent adjustments that would increase hand-to-face contact.

“Homemade masks are not medical devices and consequently are not regulated, like medical masks and respirators,” the agency wrote. “These types of masks may not be effective in blocking virus particles that may be transmitted by coughing, sneezing or certain medical procedures. They do not provide complete protection from the coronavirus because of a potential loose fit and the materials used.”

But an increasing number of health professionals are recommending more people wear them in public.

If making a mask at home, there are a variety of materials recommended for use, but some factors to consider are the breathability, reusability and durability.

“As long as it can stand a little bit of humidity, that’s very useful,” said Sharkawy. “If it’s something that’s reusable… that’s also very reasonable.”

One of the most common materials for homemade masks is cotton. In 2006, a group of University of Pittsburgh researchers shared their method of making face masks with a Hanes Heavyweight 100 per cent pre-shrunk cotton T-shirt. It involved cutting the shirt into one outer layer and eight inner layers, then tying the pieces together and around the wearer’s head.

Other groups have called for sewers to help produce more intricate masks and have shared detailed instructions online.

Last week, the Michael Garron Hospital in Toronto asked sewers to help produce 1,000 two-layered masks every week. They recommended cutting two rectangular pieces of cotton about 23 centimetres by 16 centimetres for the outer layer and 21 centimetres by 14 centimetres for the inner layer, depending on the person. The sewers can use tea towels or T-shirts for the cotton pieces, but polyester is preferred for the outer layer, they said.

Pillowcases are another common recommendation for at-home masks, particularly anti-microbial pillowcases, which are often used to fight acne and other skin conditions. The hospital’s instructions show that the two rectangular pieces are pleated at the sides and sewn together with elastic ear loops in between the layers. You can find full instructions here.

Vacuum bags are an unconventional option for at-home masks, but were found to perform the strongest compared to other household alternatives in a 2013 study. Still, the group of Cambridge University researchers determined that pillowcases and 100 per cent cotton T-shirts were the best alternatives to surgical masks. They were particularly better than dish towels and vacuum bags for the material’s breathability factor.

One study from 2008 compared surgical and respirator masks with homemade masks made from tea towels. The research, published in the journal PLoS One found that homemade masks were not as effective, but might still provide “a significant degree of protection.”

The homemade variety also provide another benefit: they won’t run out: “Home made masks however would not suffer from limited supplies,” it continued, “and would not need additional resources to provide at large scale.”