Masks, COVID-19 and Pro Rep

From 2023/9/16

photo of two N95 face masks

UPDATED: September 16, 2023

Hospital admissions and wastewater testing indicates COVID-19 is currently at low levels, but starting to increase again with the autumn weather and resumption of school.

Canada’s Chief Public Health Officer Dr. Theresa Tam said she hoped “people have developed the habit to be able to use masks as needed during the respiratory virus season, not just for COVID, but for all the other respiratory pathogens” and that “now is the time to get your masks ready if you don’t already have them.” September 12, 2023

The World Health Organization recommends universal masking in crowded spaces January 15 2023

The Public Health Agency of Canada recommends wearing a mask in public indoor settings (last updated April 22, 2022).

Masks continue to be advised, particularly for health care settings, public transit, and other crowded settings. The newest dominant variants are even more contagious than earlier ones.


In a comprehensive review of research up to Sep 7 2020:

“masking, both in health care settings and in the community, decreases transmission”. There is no firm evidence that COVID-19 spreads other than by being breathed in; in the few cases where direct contact or surface transmission is alleged, airborne transmission has not been completely excluded. Infected people can spread it for up to two days before they have symptoms, and up to six days after symptom onset. The risk of spread is far higher where people are close together and there is poor air ventilation.

Wearing mask reduces severity of COVID-19. Oct 29 2020:

“where all workers were issued masks each day and were required to wear them, the proportion of asymptomatic infections among the more than 500 people who became infected was 95%, with only 5% in each outbreak experiencing mild-to-moderate symptoms.” (5% compared to about 60% getting symptoms ordinarily, if not wearing a mask. See also.)

Tight mask fit is critical and difficult to achieve Jan 22 2021:

Only N95 masks may provide adequate filter protection, but more than half of users fail to get an adequate seal at the edges. Moderate facial stubble on a male did not prevent a good fit. May 18 2021 update.

Many scientists are recommending that the public wear face masks to fight coronavirus. Here’s the evidence, info on using and making masks, and the not-so-surprising connection to proportional representation of voters.


  • Canada’s performance
  • Science calling
  • Disinfecting and re-using N95 masks
  • Homemade masks
  • Learn more
  • Public policy

Canada’s performance:

Recently Canada is doing extremely well in the provision of vaccinations.

In the bigger picture, arguably the most reliable measure for international comparisons of success or failure in controlling COVID-19 after it gets started, is the number of days it takes for total COVID-19 deaths to double. By that measure, Canada did poorly compared to the world as a whole for many months before getting to par July 6 2020. By November 22nd of that year, Canada was doing much better than the world – coronavirus deaths had taken 189 days to double, while in the world as a whole it was taking only 113 days for deaths to double.

As of January 4, 2023, Canada’s coronavirus death rate among known cases was 1.1% and the world average was 1.0% but these figures are very approximate, because many countries, including Canada, are no longer attempting to test and count many cases.

Most cases go undiagnosed. Data from a study of Canadian blood donations released September 8 2020 shows that at least 2 out of 3 cases, possibly many more, never receive a positive test result for COVID-19 in spite of being infected.

Approximately one half of new infections are transmitted from persons who have no symptoms.

Science calling:

Scientists have been calling for face mask wearing to beat coronavirus:

January 2023:

“Previous studies have proven that wearing an ordinary
surgical mask can ensure a relatively low risk of infection
in most scenarios for the ancestral strain; however, it is less
effective for the SARS-CoV-2 variants, making it necessary
to replace ordinary surgical masks with N95 masks to
reduce the infection probability to approximately 1% in most

Prof. David Fisman, one of Ontario’s top COVID-19 experts December 19 2021:

Against omicron everyone needs “N95 masks, KN95 masks, CN95 masks”

Twenty-three scientists December 2 2021:

Ordinary pleated medical masks costing 13 cents each were found to slow COVID-19 spread under field conditions in Bangladesh.

U.S. Centers for Disease Control (CDC) July 30 2021:

“universal masking is essential to reduce transmission of the delta variant”

Professor Linsey Marr May 13 2021:

“…the evidence…is overwhelming now, that COVID-19 is being transmitted by aerosols.”

CDC recommends “mask fitters” February 13 2021:

A mask fitter is a small device worn over your mask to help prevent air leakage at the edges, described here. The CDC says snug fit can also be encouraged by wearing a cloth mask over a disposable mask and choosing a mask with a nose wire.

363 Canadian experts January 4 2021:

“…physical distancing and effective face-fitted masks, are key to reducing short-range aerosol transmission risk… ventilation and air filtration are critical additional measures…”

European scientists December 3 2020:

Making face masks mandatory reduced the number of new infections by around 45% some twenty days later.

Nine American researchers November 20 2020:

In Kansas “after July 3 [2020], COVID-19 incidence decreased in 24 counties with mask mandates but continued to increase in 81 counties without mask mandates.”

14 Denmark researchers November 18 2020:

In the first randomized, controlled experiment in the world, three thousand people were assigned with disposable ear-loop masks, and three thousand without. Five people in the mask group got sick compared to fifteen in the control group, based on standard PCR and clinical diagnosis of COVID-19, which is a statistically significant difference (P=0.04) but too small a sample for an accurate comparison. (Their additional work, involving antibody tests, incurred massive false positives and time lag effects, preventing meaningful interpretation.)

Two U.S. professors November 4 2020:

Introduction of mandatory mask policies in regions of the U.S. reduced COVID-19 fatality growth rates compared to areas without mandated masks.

Three U.S. professors, July 31 2020:

Masks may lead to less severe symptoms by reducing the infection dose – “universal public masking during the COVID-19 pandemic should be one of the most important pillars of disease control”

Three scientists, June 16 2020:

COVID-19: “Aerosols can accumulate, remain infectious in indoor air for hours, and be easily inhaled deep into the lungs. For society to resume, measures designed to reduce aerosol transmission must be implemented, including universal masking…”

Four European scientists, June 2020:

The first experimental-like evidence confirms that laws requiring face masks in public cripple the virus. Researchers compared regions of Germany with early law adoption, such as Jena, with regions of Germany adopting the law later:Graph showing adoption of law requiring face masks in public in Jena, Germany, resulted in stoppage of growth in COVID-19 cases.

June 16:

Doctors and scientists call for Alberta to make wearing a mask mandatory in public.

Five scientists, June 11:

A peer-reviewed study finds wearing of face masks in public is the most effective of all means to prevent COVID-19, and “The current mitigation measures, such as social distancing, quarantine, and isolation implemented in the United States, are insufficient by themselves in protecting the public.”

Lancet medical journal, June 1:

A review of 172 studies finds face masks, physical distancing, and eye protection reduce the risk of coronavirus infection. Though with low certainty, they estimated mask wearing reduced the chance of infection 85%.

British Medical Journal, BMJ Global Health, May 28:

Within households surgical facemasks were 79% effective  in preventing transmission of COVID-19.

Ten scientists from 8 countries (3 Canadians), May 22:

“there is high-quality, consistent evidence that many (but not all) cloth masks reduce droplet and aerosol transmission”

Seven scientists, May 1:

“our study shows that even face-masks of low efficacy (home-made cloths masks) will lead to a dramatic reduction of disease burden” “This study shows that the use of face-masks in public is always useful”

CBC, Apr. 25:

“wearing a mask appears to be astonishingly powerful, and the cost is nearly zero…And when we compare the level of evidence we have to something like washing hands, it’s vastly, vastly, vastly, vastly higher.”

Study of 169 countries, Apr. 23:

Weekly increase in deaths, without masks: 40%;  with masks: 3%

“These results support the universal wearing of masks by the public to suppress the spread of the coronavirus.”

Arizona State Univ. researchers, Apr. 21

“..face mask use should be as nearly universal (i.e., nation-wide) as possible and implemented without delay, even if most masks are homemade and of relatively low quality.”

Macleans magazine, Apr. 20:

The Czech Republic implemented mandatory mask measures and their fatality rates dropped sharply.

World Economic Forum, Apr. 7:

“Areas that have not effectively managed risk, such as New York and Milan, do not have mandated widespread wearing of masks…When masks are worn, they are extremely efficacious.”

World Health Organization (WHO) adviser Prof. David Heymann, Apr. 4:

“wearing a mask is equally effective or more effective than distancing.”

Canadian Medical Association Journal News, Apr. 3:

“..25% to 50% of people with COVID-19 do not have symptoms but may still spread the virus…masking of the public may be beneficial..”

University of Ottawa epidemiologist, Mar. 27:

“masking up Canadians is rational and promising to try.”

Lancet medical journal, Mar. 20:

“health authorities should optimise face mask distribution to..frontline health-care workers and..older adults..and people with underlying health conditions.”

Cochrane Library review of 67 scientific studies, 2011:

Comparing hand washing, social distancing, and face mask wearing, “Surgical masks or N95 respirators were the most consistent and comprehensive” to reduce the spread of respiratory viruses. (And the advisability of the public wearing ordinary cloth face masks was confirmed in a separate review by 19 scientists April 10, 2020.)

Disinfecting and re-using N95 masks:

Re-using the best (“N95”) masks:

N95 masks retained their filtering ability used daily for a month. (Some medical staff in the USA are reusing them for more than 2 weeks.) Do not wash N95 or commercially made surgical masks because this reduces their filtering efficiency. Note that a tight fit around the face is critical; N95 masks are designed to be disposable and if mishandled can easily lose their ability to form a tight fit, so it is recommended to do a User Seal Check each time a mask is donned. (Medical staff require a professional Fit Test, but medium size N95 masks of different brands fit 80 to 95% of users.)

For the average person wearing an N95 mask or better, in an environment with low to moderate levels of virus, the risk of infection is about proportional to the amount of leakage around the edges. This tends to be worse with ear loops compared to head bands, and can vary a lot with the model of mask.

If a person is exposed to a high level of virus then an infectious dose is going to get by almost any mask. (As YouTube mask expert Aaron Collins says, the typical leakage at the edges of face masks is around 5% of your breath and can be much higher – various sources such as

In the unusual case that a person receives professional training and fit testing and achieves a near perfect fit, then the risk of infection at low to moderate levels of virus will be about proportional to 100 minus the mask’s percentage filtration efficiency.

Governments around the world still failing:
As of October 17, 2022 there have been NO randomized controlled trials comparing N95 vs surgical masks for covid protection in healthcare settings. ( published online February 3, 2023 and in print April 2023).

FOR WEARERS OF EYEGLASSES: A poor fit over the bridge of the nose will not only reduce the filtration effectiveness of your mask, but also make annoying fogging of your glasses occur more often. Sometimes even with a perfect seal, glasses will fog up – because hot air rises. Normally air expelled from our nose or mouth is projected far enough in another direction that glasses don’t get condensation except in the coldest dampest weather, but wearing a mask means the air gets expelled equally in all directions, after which the warm lighter air can rise to the glasses if there isn’t enough wind in the area.
Assuming you’ve already ensured you have a tight fit but you’re still getting condensation, three solutions that should help are:
1) block the air at the top of the mask, e.g. applying tape or tissue to the inside of the mask around the bridge of your nose, or applying surgical tape or a Band-Aid on the outside of the mask at the bridge (if you overlap the tape onto your skin you will also ensure a tight fit)
2) arrange to have more wind – such as from a fan and open windows
3) antifog lens spray (or any surfactant that puts water into a thin even film instead of microscopic droplets; washing with bar soap, rinsing and patting dry is said to leave enough soap residue to work).

Note there is still a great deal of excessive caution or ignorance in the advice given by some experts. For example, the Danish Health Authority says “Never reuse disposable face masks.” (October 5 2020, Such advice is based on fear that handling a mask might transfer virus from the outside of a mask, but there is no evidence this occurs in practice and “Never reuse disposable face masks” is highly impractical until manufacturing capacity is far greater. The science is clear that an undamaged disposable mask will be effective worn for more than a month. (Though note, a mask that becomes damp from breath needs to be rotated with a dry mask.) Any trace virus on the mask will be inactivated at room temperature within days, and can be avoided by not touching eyes, nose or mouth without carefully washing one’s hands first, which is general advice.

Disinfecting masks from COVID-19 virus:

This is a controversial and rapidly evolving subject. An N95 mask may be oven heated at 70° C (158° F) for 60 minutes (keeping it at least six inches from metal) to decontaminate it from the COVID-19 virus (and many other but not all microbes).

NOTE: One alternative method — leaving masks for 3 days in a warm (22 °C) room — worked in one test but gave only partial decontamination in an experiment with a high viral load. On surfaces, higher temperatures (and possibly high humidity of 80+% RH) are expected to shorten the life of the infectious virus.

Homemade masks:

Commercially made disposable masks are widely available in Canadian stores at low cost and the rationale for homemade masks is  reduced. Tests show that woven fabric masks usually do not combine breathability and filtration as effectively as the meltblown and spunbonded material used commercially.

As explained in the “Science calling” section above, homemade masks can make a significant difference in stopping COVID-19, because “my mask protects you” if I am infected but still asymptomatic. Research published October 2020 revealed two layers of t-shirt material is surprisingly effective for this purpose. Unlike N95, surgical, and disposable dust masks, homemade masks can be washed for re-use.

Click to read: How to make homemade masks.  Alternatively, in a pinch a somewhat less effective mask can be made in less than a minute with just a sock and a pair of scissors.

What material to use? Various teams have experimented but there is still no standard advice. It has been suggested to use two or three layers, or cotton-based material woven densely enough that you cannot see bright light through it, but not so thick that you can’t still breathe through it with acceptable effort if you hold it tightly around your face.

Getting a tight fit is critical; pulling a section cut from pantyhose (nylons) over your head to stretch over your mask can improve the filtration by 15% to 50% by making a tighter fit at the edges of the mask.

Please note, there is a serious risk of doing more harm than good if a person fails to maintain social distancing and hand washing because they think they’re protected by a partially effective mask which they don’t even wear properly. Homemade masks usually filter out less than medical masks.

Children 2 and older, Apr. 8:

“According to the U.S. Centers for Disease Control and Prevention, children 2 years and older should wear ‘cloth face coverings’ when they are ‘in the community setting’ to help stop the spread of the coronavirus.”

“Dr. Deborah Gilboa said kids should wear masks whenever they leave the house.”

Learn more:

Filtration physics.

Where is COVID-19 caught?
Close contacts from overcrowding in workplaces and long term care homes are an obvious risk. A study in China found almost all infection spread occurred in a home or public transportation. Just a few outbreaks were associated with restaurants (3%), entertainment venues (2%), or shopping (2%). As the epidemic slows in Canada, wearing a face mask when riding public transport or in retail shopping areas is still a wise choice.

Public policy:

Countries with Proportional Representation of voters have been more effective in controlling the novel coronavirus (Joel Selway, Washington Post, May 19, 2020); “health systems in proportional representation countries have a wider geographic distribution of hospitals and medical personnel, less waste and better coordination of the health system across the country.” That’s not a coincidence. Pro Rep attracts better candidates to a more civilized political system, including more women. Pro Rep has been shown to result in better governance generally, including health care, as documented elsewhere here at . (Admittedly the specific connection of Pro Rep to controlling COVID-19 is controversial since a different unrefereed study model failed to find an effect of Pro Rep or women leaders on COVID-19.)

Government Mismanagement:

As of June 27, 2022, it is still not known what the infectious dose of COVID-19 is, or whether it is transmitted on surfaces. In a recent survey, about one third of Canadians indicated that they approved of the Government of Canada’s handling of the pandemic so far.

The Trump and Trudeau governments brushed aside the lack of face mask availability to the public by asking Americans and Canadians to save them for healthcare professionals. However, as the late Justice Archie Campbell wrote: “there is no longer any excuse for governments and hospitals to be caught off-guard and no longer any excuse for health workers not to have available the maximum level of protection through appropriate equipment and training.”

It’s also true that the ultimate way to protect our healthcare workers is to decrease the spread of COVID-19, and that would be assisted if the public were issued medical-grade masks. Ontario alone had 55 million medical masks that were “expired” and therefore unsuitable for medical personnel, but could have been used to provide every Canadian with one instead of being sent to a landfill.

On May 9, 2020, the Canadian government announced 8 million masks they received proved slightly substandard to the N95 medical requirement, but instead of purchasing them for the public, PM Trudeau announced “we will not be burdened with masks that do not fit our stringent requirements…we will not be paying…

Japan and S. Korea distributed face masks to every household early in the pandemic. Taiwan, Hong Kong and Singapore provided masks for their health care workers as well as their citizens en masse.


Since masks are important but do not give 100% reliable protection, what about other steps? Physical distancing is important because it reduces the chance of being exposed (the same as it reduces the chance you will smell someone else’s perfume). From hospital case studies there is absolute proof that the virus spreads through droplets in the air. The most common action taken by Canadians to protect themselves was hand washing. It is still not known whether this is misguided effort, that is, whether the virus has ever spread through touching surfaces, one’s face, or eating food. There have been two cases where fomite (surface) transmission was suspected, but transmission through the air was also possible. Some viruses do spread via surfaces and food, so to be cautious it is best to wash hands before touching the nose, mouth, eyes or food until more is known about COVID-19, and in any event this practice will reduce the risk of catching other illnesses such as flu. As of February 2022 there have been 5 million known deaths from COVID-19 but no cases proven to result from surface transmission, while the best modelling published in December 2021 indicates the risk of catching COVID-19 from touching surfaces, while theoretically possible, is near zero.

Obviously, everyone should try to get vaccinated unless you have medical advice otherwise. Do be careful in respect of fainting when you go; if it’s your first vaccination they will likely ask you to sit a while before leaving. Health authorities are turning a blind eye to the fact that it’s not uncommon for people to faint after being vaccinated. One small NS clinic reported two people fainted one day, and three the day before. One BC clinic reported only 3 cases of fainting (syncope) out of 8,500 vaccine doses administered. There has been very little research on this. A U.S. study decided to record all fainting events, and reported 17 fainting out of 8624 vaccinated, or 1 in 500 people. The BC CDC doesn’t list fainting among the side effects of going for a vaccination. One newspaper report says fainting after vaccination is “common” and “most of the people who have fainted…reported that they had not had anything to eat or drink before.” That’s why many vaccination stations had juice and cookies on hand for those who hadn’t eaten. Surprisingly, according to this report fainting from getting a needle wasn’t usually instant; about half of fainting occurred within 5 minutes of vaccination and half longer than that, with 7 out of 23 cases occurring more than 15 minutes after vaccination. In Ontario there were 33 cases of syncope (fainting) with the person being injured as a result, out of 6.4 million Pfizer doses, or 1 person in every 200,000. Out of 9 million COVID-19 vaccine doses there were 167 reports of anaphylaxis, which is more serious than most allergic reactions and means they received epinephrine and were sent to an Emergency Department, or 1 in 54,000. There were non-serious adverse side effects recorded in about 1 person in every 1200. Pfizer had a lower percentage of people with serious side effects reported than AstraZeneca, and four-fifths of these people were female. The cause and frequency of fainting is generally unstudied and unknown. The risks from COVID-19 are far, far worse of course.

Will a face mask keep you safe? If you are exposed to a very small amount of the SARS-CoV-2 virus then there is an excellent chance that an N95 mask will prevent you catching COVID-19. A surgical (pleated, disposable medical) mask will improve your chances somewhat less, and a non-medical cloth mask much less. However, if you are exposed to a very large quantity of virus particles, then the odds are high that some of it will get past any of these masks. (Equipment that has 100% filtration effectiveness exists, but is generally not available.)

Stopping the virus is the best way to protect our frontline workers in healthcare and essential services.

Until COVID-19 is beat, there’s no doubt we should be increasingly dedicated to our hand washing, social distancing and vaccinations.

The experience of other countries shows we also need people to use a fourth weapon, wearing a face mask when out in public.

Let’s do it together! Help spread the word!

#Masks4ALL #FlattenTheCurve #Covid-19