I’m a jiu-jitsu black belt with a strong background in biology (BSc and MSc) who has been working in emergency response and hazmat for over 20 years (currently a captain in the fire department) and have been a strong advocate of taking COVID-19 seriously.
Back in March I went on record saying that COVID was a huge concern for jiu-jitsu practioners.
Since then I’ve published tips for training during coronavirus, advocated for training pods, have interviewed historians about the resistance to mask wearing, and worked with Doctor Chris Moriarty on a protocol for opening up jiu-jitsu academies during a pandemic.
Today’s article has nothing to do with BJJ. It focusses on whether masks and face coverings work to prevent coronavirus transmission.
What Do I Mean By “Masks”?
For this article I’m primarily talking about masks and face coverings, which means everything from surgical facemasks to homemade cotton masks to bandannas.
This is a surgical mask style of face covering. It primarily protects other people.
I’m NOT talking much about N95 masks. N95s (and N99s) absolutely work and I used them all the time when I’m working at the firehall.
They provide quite a high standard of protection; he reason they’re called N95s is because they filter 95% of small particles. But they’re less comfortable to wear and there are significant shortages of them currently in many countries.
This is an N95 mask. It protects the wearer AND protects other people too.
Do Masks Protect the Wearer?
I keep on running into this narrative saying that “Masks don’t work”. When people say this they usually mean that wearing face coverings like surgical masks don’t protect the person actually wearing the mask.
Now it’s true that the issue of whether face coverings and surgical masks protect the wearer is complicated.
You can find studies in different settings showing both that they do and that they don’t (click here to see a bit of a summary of the conflicting results).
That being said, there’s some recent data suggesting that face coverings like surgical masks don’t give total protection but DO reduce the total amount of virus particles people receive.
The severity of a viral illness depends, in part, on how many virus particles someone gets exposed to.
If you just get a small amount of the virus then there’s a better chance that you’re not actually going to get sick (i.e. remain asymptomatic) but still have a good immune response to the virus and become at least temporarily immune to coronavirus.
Click here to read the article from July 31, 2020, breaking down the evidence for surgical masks and face coverings reducing the dose of virus (the ‘innoculum’) and triggering asymptomatic infections.
Do Masks Protect Other People?
At this point it’s really not debateable that masks protect OTHER people?
This is the whole “I wear my mask to protect you, you wear your mask to protect me” line of argument.
Has any study show that they are 100% effective in preventing transmission? No, but there’s a TON of evidence showing that it really cuts down on the infection rate and lowers your total dose of the virus (coronavirus is a dose-dependent illness, meaning the more virus you get dosed with then the sicker you’re going to get).
Basically masks DO protect other people from virally and bacterially transmitted respiratory infections, especially when those illnesses are transmitted primarily by repiratory droplets and aerosols (the tiny drops of water that turn into a white fog when you exhale outside in the cold).
If you’re only going to read one paper about the science proving that masks protect other people then read this one: Face Masks Against COVID-19: An Evidence Review. If you download the PDF from that location you’ll find it’s a very extensive and well written article.
Here are some epidemiological studies conducted in the USA since the pandemic began proving that mask wearing DOES significantly limit the spread of Covid from person to person…
“Tennessee Areas Without Mask Requirements Have Higher Death Toll Per Capita” https://www.vumc.org/health-policy/news-events/tennessee-areas-without-mask-requirements-have-higher-death-toll-capita
“Trends in County-Level COVID-19 Incidence in Counties With and Without a Mask Mandate — Kansas, June 1–August 23, 2020” https://www.cdc.gov/mmwr/volumes/69/wr/mm6947e2.htm
Association of country-wide coronavirus mortality with demographics, testing, lockdowns, and public wearing of masks (Update August 4, 2020): https://www.healthaffairs.org/doi/10.1377/hlthaff.2020.00818
Community Use Of Face Masks And COVID-19: Evidence From A Natural Experiment Of State Mandates In The US https://www.healthaffairs.org/doi/10.1377/hlthaff.2020.00818
Infections and Serologic Responses from a Sample of U.S. Navy Service Members: https://pubmed.ncbi.nlm.nih.gov/32525850/
Ah, you might object that these studies were all done in the USA where Fauci and the CDC are all in league to spread chaos and fear….
Well how about studies done in OTHER countries.
Like in China: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7264640/
Or Thailand… https://pubmed.ncbi.nlm.nih.gov/32931726/
Or Germany… https://www.pnas.org/content/117/51/32293
Or Canada… https://www.nber.org/papers/w27891
This is just SOME of the epidemiological evidence that masks work to prevent the spread of Covid 19 and reduce mortality.
The evidence for masks (especially N95 and KN95 masks) greatly reducing transmission at this point is overwhelming. To argue against these (and other) studies you would have to suggest that tens of thousands of scientists and public health officials in tons of different countries are working together to promote a lie.
Masks work. The end.
Are Masks Safe?
A few months ago there was a sudden rash of memes suggesting that mask wearing would inevitably lead to carbon dioxide poisoning, viruses recirculating within the mask, the collapse of the immune system, and a bunch of other dire outcomes.
If you think about this for 10 seconds you know that this has to be false.
Where are the nurses, doctors, surgeons and anaesthesiologists passing out from oxygen restriction in operating rooms? Where are the welders and drywallers who often wear N95s (a more restrictive style of mask) with collapsed immune systems? Why am I not dead after wearing N95s for hours on calls?
The masks-will-kill-you narrative is patently false. I would go so far as to call it cynical disinformation.
Here’s one good rebuttal of many of the anti-mask talking points. Or if you’re more scientifically inclined take a look at this study in which they put health care workers (i.e. not the most fit people) wearing N95s (a much more restrictive mask than a surgical mask) onto treadmills for an hour and didn’t find ANY significant drop in blood oxygen levels: https://www.rcjournal.com/contents/05.10/05.10.0569.pdf
What About These Sites That ‘Prove’ Masks Don’t Work?
People keep on sending me links to official looking sites with many references. These sites then interpret these studies to conclude that masks don’t work.
Anyway, at the time of this writing I have spent many hours dissecting at least 5 of these anti-mask pages and sites.
These were sites across the left-right spectrum, ranging from sites promoting an anti-vaccine and 5G conspiracy agenda on the left, to conservative sites spreading anti-gun control and HIV-doesn’t-cause-AIDS messages on the right.
And I came away with a foul taste in my mouth.
They all followed the exact same pattern: lots of references to studies, along with short explanations telling you what those studies had supposedly found out. All of which looked very impressive and ‘sciency’ but as often as not those short ‘explanations’ were taken completely out of context, complete distortions, or straight up lies.
One example was an article summary saying something like “study shows masks don’t work” and the actual link was to a study that looked at the relative effectiveness of surgical masks and cloth masks in preventing influenza like illness transmission (surgical masks were more effective but nowhere in that study did they conclude that ‘masks don’t work’)
Or another article is linked to with an ‘explanation’ saying that this study shows there’s no asymptomatic transmission because one woman with covid was exposed to 455 people and none of them got sick. Well, turns out that study took place in China and everyone was wearing masks.
And to top things off there is absolutely no even handedness to the studies presented by these sites.
Legitimate reviews and meta-studies refer to both the studies where masks worked AND where they didn’t. Studies showing that masks didn’t work are much, much rarer, but they do exist.
But these masks-don’t-work sites just use a combination of cherry picking a very few studies and then grossly distorting the results of many other studies.
Why would they do this? I don’t know… political or ideological reasons I suppose, but they’re not following the science in good faith.
I guess they’re relying on people to read their headlines and be impressed by the fact that they cite articles. And then they hope that people don’t take the time to actually read and decipher the original articles 
Other Studies
I think that the Face Masks Against COVID-19: An Evidence Review article I linked to above is the single best article to to read and/or show people, but here are some other studies on the topic of masks protecting other people that I’ve been looking at…
Surgical masks significantly reduce the amount of RNA based virus in respiratory droplets being exhaled by both children and adults: https://www.nature.com/articles/s41591-020-0843-2
Medical masks significantly reduce the transmission of clinical respiratory illness between health care workers in a hospital setting: https://pubmed.ncbi.nlm.nih.gov/24472436/
Covid cases in different regions of Germany started dropping about 10 days after that specific region implemented mandatory mask wearing. Regions that implemented mask wearing later had their coronavirus cases drop later: https://www.iza.org/publications/dp/13319/face-masks-considerably-reduce-covid-19-cases-in-germany-a-synthetic-control-method-approach
In Kansas some counties opted out of mask wearing and others didn’t. The ones that mandated mask wearing ended up having a decrease in coronavirus cases and the ones that opted out of mandatory mask wearing had coronavirus cases increase: https://www.cdc.gov/mmwr/volumes/69/wr/pdfs/mm6947e2-H.pdf
This study shows that surgical masks reduce the distance travelled by exhaled air by more than 50%: https://pubmed.ncbi.nlm.nih.gov/23239991/
Making all individuals coming in contact with patients with lowered immune systems wear surgical masks reduced respiratory viral infections by about 60% https://pubmed.ncbi.nlm.nih.gov/27481873/
Surgical, cotton, poly-cotton, polypropylene, and knitted masks all hugely reduce the amount of droplets produced by human speech. Bandannas and fleece masks are least effective: https://www.sciencealert.com/simple-low-cost-experiment-reveals-which-face-masks-are-best-at-blocking-droplets
Performance of Fabrics for Home-Made Masks Against the Spread of Respiratory Infections Through Droplets: A Quantitative Mechanistic Study: https://www.medrxiv.org/content/10.1101/2020.04.19.20071779v2.full.pdf
A giant review of 216 different studies showed that face mask use had a large protective effect: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31142-9/fulltext?fbclid=IwAR3iBLcv6BRCrkx8r2UO8nT5T5Aw20ox3V9FcOqP4U_pChimEeqZOkTp_1g
And finally, an analysis of 200 countries showed that. “In countries with cultural norms or government policies supporting public mask-wearing, per-capita coronavirus mortality increased on average by just 16.2% each week, as compared with 61.9% each week in remaining countries. ” So countries where mask wearing was more common had MUCH less spread of covid. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7695060/)
Stay safe and take care of other people!
Stephan Kesting
