On April 7, 2020, Canada’s public health authorities added the use of homemade masks to the pandemic response1. A few months later, masks became mandatory in some regions in indoor public spaces and on public transit. This recommendation was also meant for patients with underlying lung disease. Let’s take a look at the issue of masks and try to answer some of the most common questions received about them.
Can wearing a mask be dangerous to your health?
The simple answer is NO.
The circulating ideology that wearing a mask reduces the amount of oxygen you breathe is FALSE. Everyone can agree that wearing a mask is unpleasant and uncomfortable and that it is even worse on hot days. However, it will never lead to a lack of oxygen.
The good news is that this is also true for people with underlying lung disease. There is no evidence that wearing a face mask causes an exacerbation (a “flare-up”) of an underlying lung condition. The Canadian Thoracic Society also supports this recommendation2 and issued a position statement in June.
Still have doubts? Doctors have shared their experiences by measuring their oxygen saturation in various scenarios while wearing a mask: Doctor wears six face masks to debunk oxygen deprivation myth
How does the face mask protect against COVID-19?
COVID-19 is a respiratory infection. It is therefore transmitted by droplets of infected liquid from the respiratory tract. The purpose of the mask is to put a barrier in place to prevent the droplets from spreading from one person to another when you talk, cough or sneeze.
It is now known that not everyone infected with COVID-19 has symptoms. In other words, some people may be unknowingly infected and infect others. For this reason, wearing a mask may help reduce the risk that an infected person will spread COVID-19 to others when physical and social distancing measures are not possible.
What is the scientific evidence for the effectiveness of widespread face mask use?
Beyond the logical implication of the mask, there is now increasing evidence that they are effective in reducing the transmission of the virus in the community. As a result, most public health authorities around the world now recommend the use of masks, including the World Health Organization, the CDC in the United States, and Health Canada.
Two particularly interesting studies are worth mentioning and sharing with you:
Published in the July issue of JAMA magazine, this study3 reports the results of a universal face mask policy that was quickly launched in the Mass General Brigham hospital system, involving 12 hospitals and over 75,000 employees in Massachusetts. This intervention required that all healthcare workers wear masks, but also required every patient to wear a mask equally, regardless of their COVID-19 status. The authors illustrated that when all members wore masks, infection rates decreased.
In a review of the scientific literature published in June in The Lancet,4 researchers found a series of studies suggesting that wearing a mask appears to prevent the spread of COVID-19. This scientific review assessed the effect of physical distance, wearing various types of face masks and goggles on the transmission of the respiratory coronaviruses responsible for COVID-19, MERS and SARS in public and health care facilities. It is precisely this study that has helped inform the most recent WHO guideline documents. It demonstrates that masks and eye protection reduce transmission, although this may vary depending on the type of equipment used (N95> surgical mask> single-layer fabric mask).
Unmasking the differences
There are different types of masks that are not all equivalent: N95, surgical and procedure masks, fabric masks (purchased or homemade).
The N95 mask blocks even the smallest droplets. Its efficiency for micro-droplets is about 95%, hence its name. To wear it properly, it is necessary to test the models on your face to ensure that no droplets will escape. The N95 mask is therefore used to protect oneself and others, which is different from the other two types of masks.
Surgical and procedural masks are looser, softer, and more flexible. They are effective at filtering large droplets, but are less leak-proof than N95 and do not require a test for proper fit. Smaller particles will therefore escape to the sides. Above all, they protect others.
A homemade mask is normally made of an absorbent fabric such as cotton. Homemade masks are not medical products and are not regulated like N95 and surgical masks. The fabric does not prevent even the smallest droplets from coming towards you and the small drops will escape through the sides. However, the larger droplets coming out of the mouth and nose will be trapped inside. Again, the goal is not to protect yourself, but to protect others.
What's the best mask?
N95 masks and surgical and procedural masks are available in limited quantities, so they should be reserved for health care workers.
The best homemade mask is one that you will wear properly and is comfortable. It should cover your nose and chin without slipping, and you should avoid touching your face continuously. If your hands are contaminated, you may inadvertently expose yourself to the virus. It should also be cleaned properly.
Tips if you are uncomfortable wearing your mask
Any change takes some time to adapt. If you feel uncomfortable wearing a mask or face shield, start by putting it on for a short period of time at home. This will help you get used to wearing it and see if it’s comfortable enough for your outings. You can also try different types of hand-made masks. Choose one that you are comfortable with.
Above all, don’t let up on physical and social distancing and proper hand washing.
For more information
Learn more for members of the Canadian Thoracic Society in the News:
July 17, 2020 – Dr. Kenneth Chapman: Just wear the mask and other truths from actual doctors
July 3, 2020 – Dr. Kim Lavoie: How to make COVID-19 mask-wearing a habit: Social scientists offer some suggestions
About the author
Dr. Josianne Hamel Bourbeau completed her medical studies and her specialization in family medicine at the University of Montreal. Her practice is versatile and diverse, as are her interests. She currently works at the GMF Ahunstic and at the Centre d’hébergement Notre-Dame-de-la-Merci in the CIUSSS du Nord-de-l’Île-de-Montréal, and at the Saint-Eustache Hospital in the CIUSSS des Laurentides. She is also involved in hospital teaching for undergraduate medical students for the University of Montreal. She firmly believes in the power of sharing medical knowledge to patients and between professionals in order to provide sustainable quality health care for all.