Masks – Pandemics in British Columbia

Masks seem like they couldn’t possibly work. How could wearing a little piece of cloth possibly be effective?

Evidence: Masks Work

However, there have been a lot of real world studies that masks do actually work at reducing infections. They are not perfect, but they do significantly lower the risk of the wearer and the people around the wearer. Here are some studies:

This study from Norway (2024-05-29) did it, and found that people who were asked to wear a surgical face mask in public places for 14 days were 29% less likely to report symptoms consistent with a respiratory infection than those who were asked to not wear a mask in public.
This HUGE study in Bangladesh (2021-09-09) sent people out to villages to stand around and remind people to wear masks. The reminder-people had zero enforcement authority, all they did was remind people to mask up. The compliance, even with reminders, still wasn’t great (42% in those villages, vs. 13% in non-reminder villages), but there was a statistically significant difference in how many cases and deaths villages had depending on whether they had reminder-people or not.
This study from Arizona (2021-10-01) found that schools without mask mandates were 3.5 times more likely to have outbreaks than schools that had mask mandates.
This study from USA (2021-10-01) found that children’s case rates were 2.1x higher in counties without mask mandates than with.
The US CDC used to have a page (found in their archive dated 2023-06-28) that listed a ton of studies, but now their web site says almost nothing about masking. @@@ go through and make sure I’ve got all of the studies @@@
This review article (2021-01-11) cites a lot of studies and concludes that masking works.
This paper (2020-10-15) reports that 66% of hamsters in a cage adjacent to a cage with COVID-infected hamsters got infected themselves. (There was one infected hamsters in one cage and three uninfected hamsters in the other cage. Two exposed hamsters were examined after five days, and the other at seven days.) When a barrier of surgical mask-material was placed in between the pair of cages, only 12.5% of the exposed hamsters got sick when the fabric was placed to simulate the sick hamster “wearing a mask”, and 37.5% of the exposed hamsters got sick when the fabric placement simulated the exposed hamsters “wearing a mask”; the “masked” hamsters also got less sick than the “unmasked” hamsters in the first part of the study.
This paper from South Korea (2024-10-14) reports that COVID-19 levels was much much lower in speaking trials when the speakers wore N95 masks than if they did not. However, they still found significant amounts of COVID-19 in the air (although they admit it might have been in the room air before they started testing), and urge people (as much as one can in an academic article) to do two-way masking.
This article from Missouri (2021-12-01) reports on a study looked at the difference between counties in Missouri which had mask mandates and those which did not, and found that the risk of COVID-19 was 37% higher in counties which did not have mask mandates.. (See graph below.)

From the CDC archive masks page:

This study from the US (2020-06-12) of an outbreak aboard the USS Theodore Roosevelt, an environment notable for congregate living quarters and close working environments, found that use of face coverings on-board was associated with a 70% reduced risk of infection.
This study from China (2020-05) reported that in 124 Beijing households with more than one 1 laboratory-confirmed case of SARS-CoV-2 infection, mask use by the index patient and family contacts before the index patient developed symptoms reduced secondary transmission within the households by 79%.
This study from Massachusetts (2023-08-04) examining SARS-CoV-2 secondary attack rates among eight public K-12 school districts in Massachusetts (70 schools with >33,000 enrolled students) during the 2020–21 school year found an unadjusted secondary attack rate of 11.7% for unmasked versus 1.7% for masked interactions.40
This paper from Thailand (2020-11) reports that, among more than 1,000 persons interviewed as part of contact tracing investigations, those who reported having always worn a mask during high-risk exposures experienced a greater than 70% reduced risk of acquiring infection compared with persons who did not wear masks under these circumstances.
This case study from USA (2020-07-17) found that when 67 clients got haircuts from two symptomatic hairdressers where everybody wore a mask, nobody got sick.

How Masks Work

But how can masks possibly work? Breath goes in and out!

Masks don’t have to stop all the virus to help. The more virus particles you are exposed to, the sicker you get. Thus, if a mask keeps a lot of the particles from going out / coming in, even if it is not all, that’s a win.
Masks catch a lot of the particles in your breath. How many? I don’t know, and it will vary depending on the mask. However, catching some is better than none, because the more virus particles you inhale, the sicker you get.
Humidity helps. There are a number of papers I have read that say that respiratory viruses are sensitive to humidity. One thing I’ve read is that when the air is drier, the droplets you expel evaporate faster, making them smaller, making it easier for them to surf on air currents and stay in the air. Another is that the respiratory tract doesn’t do as good a job of conveyor-ing out junk when it’s dry. Well, when you wear a mask, the humidity of what you inhale and exhale goes up. Maybe this makes your respiratory tract work better and you produce more droplets and fewer aerosols. (Note: this is my theory, I’ve never heard anyone else float this theory. I could be all wrong.)
Masks change the breath direction. When you talk to a friend without wearing a mask, your breath goes forwards, right towards whoever you are talking to. When you are wearing a mask, even if the air leaks out the sides, it is no longer going forwards: it’s going up or backwards, not towards your friend. (Watch this video of a woman exhaling smoke through various masks.)
Masks slow breath down. When your breath is redirected through the top or sides of a mask, it slows down. The slower breath particles go, the more they will fall to the ground.
Masks are more effective when the contagious people wear them. Masks work best when the droplets are big, and the droplets are biggest right when they come out of your mouth/nose.

I don’t know if ether is a good proxy for COVID-19 or not, but this video of someone shooting ether through a mask / no mask to how far it travels is entertaining, at least!

Scientific Modelling

Here are some papers which talk about measurements of aerosols or which do mathematically modelling of virus dispersion with and without masks:

This paper says that if two people are speaking, one infected and one not, at a distance of 1.5m:
- If neither is wearing a mask, the susceptible person is 90% likely to get infected after just a few minutes.
- If the infected person is wearing a surgical mask and the susceptible person is not wearing a mask, the susceptible person won’t hit the 90% likely threshold until 30 minutes.
- If the infected person is wearing a FFP2 mask and the susceptible person is not wearing a mask, the susceptible person will only be 20% likely to be infected after until 60 minutes.
- If both people are wearing surgical masks, the susceptible person will be under 30% likely to be infected after 60 minutes.
- If both people are wearing FFP2 masks, the susceptible person will be under 0.4% likely to be infected after 60 minutes.
This paper says that not every exhaled particle has a virus in it, and that in most environments, there are few enough that a surgical mask can deflect enough that a surgical mask is usually good enough. (For hospitals, or arguing nose to nose with an anti-vaxxer, you ought to have an FFP2.)

Reusing Masks

This web page (not peer-reviewed, but probably still good) (2024-07-30) reports that you can reuse your mask many times with minimal degradation.

Why don’t People Wear Masks?

This thread (2024-10-13) about this blog post (2024-10-03) brings up a number of hypotheses about why health care workers do not mask, including:

This response to the thread says that masks make it more difficult to make an emotional connection, which is professionally important to doctors. Like, if their “customer satisfaction” scores aren’t high enough, ~~they can get fired~~ their contract might not be renewed.
In this article (2024-10-01), the new head of the NIH suggests that health care workers (including herself) don’t mask because it is traumatic — a reminder of a highly traumatic time.
- This blog post finds this attitude offensive and ableist.
  - The author posits that health care workers don’t want to accept that disability — Long COVID — could happen to them, so resist accepting a marker — wearing a mask — which is associated with the disabled.
  - The author points out that people don’t stop wearing seatbelts because they were in a traumatic car accident. (I suggest that imagined people would have been wearing seatbelts as a matter of course before the imagined car crash, so the seatbelt wouldn’t be as strongly associated with the imagined car crash as masks are with the pandemic.)
This response reports that some health care workers worry about CO2 buildup and/or inhaling hazardous microfibres from the mask. However, this paper (2021-06-05) from China says that — in general — you get less crap from your mask than it filters out from the ambient air.
This response suggests that masks make communication more difficult, especially when working with the hearing impaired. The author also points out that some patients get hostile upon seeing a mask, and take it out on the health care worker.

Do Masks Cause Problems?

Okay, but what are the actual downsides of masks? Are the people who say they “can’t breathe” in masks just faking it? Maybe not.

This paper from Germany (2020-12-21) reports that wearing a mask affected physical exertion.

The airway resistance was twice as high with a surgical mask as without;
Heart rate was elevated heart rate somewhat (160.1 beats per minute vs. 154.5 bpm);
Constant-load tests “resulted in a significantly different ventilation” (77.1/minute vs. 82.4/minute). (I do not know what that measures.)

A number of people have voiced concerns that children need to be able to see mouths in order to learn how to speak. I would like to point out that blind children learn to talk just fine.