COVID-19 (coronavirus) Featured Wellness

Everything you need to know about masks

woman wearing mask at store

Natasha Salt, director of infection prevention and control at Sunnybrook, and Dr. Roohi Qureshi, occupational health physician, answer your questions about the effectiveness of cloth versus medical grade masks, whether masks can stop the transmission of COVID-19, and why you shouldn’t leave the house without one.

Wearing a mask

What is the best advice for visiting elderly frail grandparents, even quickly, with a mask?

Natasha: Whether your visit is quick or long, it is important to be safe when visiting the elderly. Don’t visit at all if you are feeling unwell, wear your mask properly, remain physically distant and always perform hand hygiene. If you are visiting them in a care home, be sure to check what the visitor restrictions are before you go.

Do I need to wear a mask while I walk my dog at the park for 3 hours?

Natasha: If you are capable of physically distancing yourself from others not in your social bubble (2 meters/6 feet minimum), there is no need to wear a mask when you walk your dog outdoors.

Do I need to wear a mask in a non-public workplace?

Natasha: The Toronto mask bylaw is applicable to all indoor spaces where access to public is granted. However, the concept is transferable to non-public workspaces. In settings where the office space is not conducive to physical separation, wear a mask to contain your secretions.

How do I wear a mask properly?

View our mask use blog post for step-by-step advice on how to properly wear and remove your non-medical mask.


All about face coverings

Is wearing a face shield better than wearing a mask? Can I just wear a face shield?

Natasha: No, a face shield does not replace the need for a mask. However, if no masks are available or if an individual is not able to wear a mask, a face shield is better than nothing at all.

Is a cloth mask effective in protecting you from COVID-19 or should you stick to a surgical mask?

Natasha: A cloth mask is effective in containing your secretions. If everyone wears a cloth or non-medical grade mask, it helps to prevent secretions from coughs or sneezes from traveling 2 metres/6 feet, which could be inhaled by another person, or contaminate surfaces in that area. By wearing a non-medical mask in situations where physical distancing is challenging, you are protecting others from your secretions, and they are protecting you from theirs.

Medical grade masks, such as surgical masks and N95s, contain the wearer’s secretions, and protect the wearer against the transmission of COVID-19 and other respiratory pathogens. Medical grade masks continue to be in critical supply, and should be reserved for health-care workers, who work in close contact with people who may be ill with COVID-19.

Are non-medical masks effective at slowing down the spread of COVID-19?

Natasha: COVID-19 is predominantly spread from person-to-person, through respiratory droplets that are produced when someone coughs, sneezes, talks or raises their voice. Non-medical masks are good for containing these droplets that would otherwise contaminate surfaces and the area within 2 metres/6 feet of a cough or sneeze. When everyone wears a cloth/non-medical mask, we are reducing our risk of passing our secretions, including those that cause COVID-19, along to others.

Use of non-medical grade masks is important as part of a bundle of activities we should be doing: cleaning your hands often, physically distancing, staying home when you are feeling ill, not socializing with sick friends/family and avoiding touching our eyes, mouth and nose.

Does wearing a mask/cloth mask cause carbon dioxide (CO2) poisoning?

Dr. Qureshi: Wearing a surgical mask or face mask is an important element in the public health effort to limit the spread of COVID-19. Despite misinformation regarding adverse health effects of wearing masks, it is safe to wear a mask.

Wearing a mask will not in any way interfere with your ability to breathe in enough oxygen. The mask materials and design allow oxygen to flow into the lungs without any obstacle. Oxygen molecules can flow in through the mask fabric or through the openings around the mask if the mask is not tight fitting. There is no risk of reduced levels of oxygen in the blood or in the brain or other body tissues.

Wearing a mask cannot cause elevated levels of carbon dioxide in your blood. When you breathe out carbon dioxide, it will pass through the mask fabric and around any openings. As long as it can flow in this way, carbon dioxide will not build up inside the mask and it will not lead to too much carbon dioxide in your blood.

COVID-19 virus travels through via respiratory droplets which are produced when people breathe, speak or cough. Masks are designed to stop these droplets. Oxygen and carbon dioxide molecules are tiny compared to these respiratory droplets, and they are able to pass easily through the mask fabric.

Any tips for preventing eyeglasses from fogging up when wearing a mask?

Natasha: When selecting non-medical grade masks, look for a type that has a snug fit or is tailored to fit over the bridge of the nose. If your mask has a wire over the bridge of your nose, make sure it’s securely molded to your nose and cheeks. Another tip that may work is to clean your glasses with dish soap and water, rinse with warm water and then dry with an approved lens cloth.


Making and washing cloth masks

Is there a recommended type of fabric or thread count I should use when making a cloth face mask?

Natasha: Fabric with high thread counts is recommended. If possible, use two different fabrics or colours for each side of the face covering, so that you know which side faces your mouth and which side faces out. The Public Health Agency of Canada (PHAC) provides some guidance on how to make and maintain fabric masks.

How often do cloth face masks need to be washed?

Natasha: The Public Health Agency of Canada (PHAC) recommends washing cloth masks daily. However, be sure to follow safety measures to avoid self-contaminating as you don and doff (put on and take off) your mask throughout the day.

What’s the best way to wash my cloth mask? I don’t want to ruin it in the laundry!

Natasha: If you have a mesh bag to help protect your cloth mask from damage, don’t be afraid to wash it in the washing machine. You can also hand wash your cloth mask using warm water and soap. Just be sure to let it dry completely before wearing it again. PHAC has some helpful tips on mask care.

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Sunnybrook