The Science of Masks 8: Risks of Masks
Claim there are no downsides to masks by not looking for any downsides
It’s Part 8! Why are you still here? Unlike me, you seem like the sort of person who would have friends, and things to do.
If you’re new to this mental trash heap, we are currently looking at the scientific research on using face masks to prevent the spread of infection, while simultaneously spending too much time watching Dharma & Greg, a TV show from back before I lost all hope for humanity. I have been assured by many well-educated and well-meaning people that there is, indeed, something very wrong with me.
With all the overly optimistic discussion about the potential benefits of masks, not many people have been talking about the potential risks. In fact, most folks seem to think there are no downsides.
Well known author and comic strip writer Scott Adams might be one of those people. He has written that masks are a reasonable precaution and his logic, summarized, is as follows: either masks work (even if only a tiny bit) or they don’t. And he can choose to wear one, or not. This gives four possibilities: if he doesn’t wear a mask, nothing happens (whether they work or not). If he wears a mask, either nothing happens or there is some benefit (even if it’s small).
Appropriately we are also up to Episode 19: “Dharma’s Tangled Web” in which Dharma is trying to keep a secret from Greg. Science, like relationships, shouldn’t contain secrets.
Warning: almost completely irrelevant, and definitely uninteresting, but at least brief, explanation of Pascal’s Wager.
I seriously recommend you skip this part.
Some folks may notice that Scott Adams’ argument is similar to Pascal’s Wager, a very famous philosophical argument sometimes taken as proof of the existence of God (although it’s not clear whether Pascal really thought this, to him it may have been mostly a mental exercise).
Pascal posited: either God exists, or He doesn't, and either you believe, or you don't. This creates a 2 x 2 matrix of possibilities.
If a person believes: either nothing happens or he goes to heaven.
If a person does not believe: either nothing happens or he goes to hell.
Pascal concludes the logical person minimizes his risk by choosing to live as though God exists. Various objections to this reasoning have been raised but the one of interest here is this: there are many religions with many gods, and some have stiff penalties for believing in the wrong one. So arbitrarily stating that one choice comes with no risk is setting up a false comparison.
(Note that I have just summarized in a couple of paragraphs a philosophical argument about which entire volumes have been written. But I’m lazy and your time is valuable so let’s move on.)
Restart here if you skipped the part about Pascal.
Mr. Adams is ignoring a possibility: what if masks cause harm (even if just a little bit)? Then choosing to wear a mask might help (even if just a little bit) or it might cause harm (even if just a little bit).
My question for Mr. Adams, and anyone else who insists there are no downsides to masks, is this - did you look?
I did.
Studies that actually looked for negative outcomes from wearing masks
Way back in Part Something or Other we learned that in some of the randomized controlled trials the groups wearing masks had worse outcomes than the control groups. So anyone who actually read those studies would be lying if they said there was no evidence of potential risks.
This time around we’re looking at studies specifically about negative impacts of masks, which are unfortunately not common.
Topics mentioned in the literature include infection, excess carbon dioxide and/or reduced oxygen, and headaches. As described in detail previously, MacIntyre et al. (2015) noted increased infections among participants wearing cloth masks and as a result recommended against their use by health care workers and cautioned against community use of masks.
Moisture retention, reuse of cloth masks and poor filtration may result in increased risk of infection.
The idea that masks can also be a source of infection is stressed by another study by Chugtai et al. (2019) measuring the amount of virus found on surgical masks of health care workers after being worn for hours.
1. Contamination by respiratory viruses on outer surface of medical masks used by hospital healthcare workers (Chughtai et al. 20191)
To emphasize the small amount of research on this subject, this study was published in 2019 in BMC Infectious Diseases and the authors believe it is the first such study.
To our knowledge this is the first study examining the presence of respiratory viruses on the outer surface of used medical masks.
C’mon guys, that’s what I just said.
If wearing a mask does reduce the amount of virus inhaled, then one would expect that virus to be on the mask. The authors warn that extended use of medical masks for more than 6 hours without replacing the mask can increase the risk of infection.
The study shows that the prolonged use of medical masks (> 6 h) and frequent clinical contact in healthcare setting increase the risk to health workers through contaminated PPE. Protocols on duration of mask use should specify a maximum time of continuous use.
[Irrelevant show update: To cover for something else, Dharma has just lied to Greg about having lunch plans with Jane Seymour (at that time Jane Seymour was starring in her own show, Prairie Doctor with English Accent).
Having lied to her husband is intolerable for Dharma, so she has come up with a way to make the lie not a lie. She has driven 5 hours to Los Angeles and sneaked into the studio of Jane Seymour’s show with a turkey sandwich - if she convinces Jane to take a bite of the sandwich, then she didn’t lie.
Jane Seymour manages to say with a straight face “this turkey sandwich… it’s not going to undo the lie you told your husband.”
Imagine how much better off we would all be if the CDC had the same moral compass as a moderately successful 90s sitcom. Or if they had any moral compass. Hell, even a moral night-light.]
2. Carbon dioxide rebreathing in respiratory protective devices: influence of speech and work rate in full-face masks (Smith, Whitelaw, & Davies 20132)
Another area of concern, but with limited research, is the possibility of increased carbon dioxide levels inside a mask. This study was published in the journal Ergonomics, and in it the authors warn that breathing in the CO2 trapped in a respiratory protective device (RPD) is a potential health concern.
Increased levels of CO2 rebreathing in RPDs can have a profound effect on the respiratory system and is a concern regarding respirator use.
The study measured the CO2 level inside the RPDs and noted that it exceeded the standards set by OSHA (the Occupational Safety and Health Administration) for ambient CO2 in the workplace. It is unknown whether this resulted in a higher than normal level of CO2 in the participants since this was not also being measured.
Data collected showed that dead-space CO2 ranged from 2.5% to 3.5% CO2 which is significantly above OSHA’s ambient workplace standards. Roberge et al. (2010) concluded that even though the RPD did not impose any significant physiological burden on participants, CO2 retention was a possibility due to elevated transcutaneous CO2 (equivalent to arterial CO2 ) levels. On a similar note, although no symptoms of CO2 retention were recorded in this study, the increases in CO2 during speech were sufficient enough to impact the participant.
Note the authors were testing a mask that covers the whole face, not surgical or N95 masks. I originally thought this study was less than useful, then life turned up the insanity dial to 11 and people started marketing full face masks for use in ordinary life.
The “ordinary life” in that sentence is an example of something that back in the 1990s we used to call sarcasm.
Another study, Roberge et al. (2010) is mentioned and it used N95 masks. That study also measured CO2 levels above standards for ambient air in the workplace, and O2 levels below the standards.
3. Physiological impact of the N95 filtering facepiece respirator on healthcare workers (Roberge et al. 20103)
The authors of this study, published in the journal Respiratory Care, are all affiliated with the CDC through the National Institute for Occupational Safety and Health. The study used N95 respirators that are representative of supplies in the National Strategic Stockpile.
The authors note that the respirator, which they refer to as a filtering facepiece respirator (FFR), was not taxing for the healthcare workers in the study, but they did measure CO2 levels inside the masks that were higher than workplace standards. They conclude that elevated levels of carbon dioxide in people wearing FFRs (pCO2, the amount of carbon dioxide dissolved in the blood) is possible.
In healthy healthcare workers, FFR did not impose any important physiological burden during 1 hour of use, at realistic clinical work rates, but the FFR dead-space carbon dioxide and oxygen levels were significantly above and below, respectively, the ambient workplace standards, and elevated pCO2 is a possibility. Exhalation valve did not significantly ameliorate the FFR’s pCO2 impact.
The mixed inhalation/exhalation O2 and CO2 levels in the FFR VD microenvironment did not meet the Occupational Safety and Health Administration’s standards for workplace ambient O2 and CO2 concentrations.
This study used healthy subjects who wore the mask for only one hour, so the authors point out the results may differ for people susceptible to excess CO2 or who wear the masks during activity for a much longer duration. Since they were not measuring pCO2 during this study that question remains open.
Future studies will also need to address the possibility of CO2 retention in susceptible individuals and the physiological impact of FFR (with and without exhalation valve) worn for longer periods.
[Dharma and Jane Seymour (who, I must admit, makes prairie dresses look kinda hot) are now mainlining pixie sticks and making up the latest Covid numbers for CNN.
I could be wrong about that, but let’s be honest - a lot of CNN shows look and sound like they were written by teenagers on a sugar high.]
4. Headaches and the N95 face-mask amongst healthcare providers (Lim et al. 20064)
The authors of this study surveyed healthcare workers in China during the original SARS outbreak to determine risk factors associated with the use of masks, publishing their results in Acta Neurologica Scandanavica.
About a third of healthcare providers surveyed in this study reported headaches with the N95 face-mask wear and we identified pre-existing headaches and prolonged duration of N95 face-mask wear as important risk factors for the development of these headaches.
The headaches could be caused by hypoxia (not enough oxygen), hypercapnia (too much carbon dioxide), mechanical pressure, or stress.
The etiopathogenesis of N95 face-mask-associated headaches could possibly be related to hypoxemia, hypercapnia, mechanical factors or the stress associated with its use.
This study highlights the relatively high prevalence of headaches with the use of the N95 face-mask amongst healthcare workers working in high-risk areas.
Although the actual cause is not known, the authors point out that these headaches can be caused by too much carbon dioxide or too little oxygen.
Summary: Do you have a headache now? Maybe you should take off that mask. Or maybe it’s just my writing style.
First, masks are not like flypaper. The little viruses don’t die the instant they touch the mask, and bacteria and fungi and stuff will actually grow there so please wash the darn thing before you give yourself aspergillosis.
Second, some people will experience elevated levels of carbon dioxide and lowered levels of oxygen in their masks. These levels will sometimes fall outside the ranges recommended by OSHA for workplace safety.
OSHA is another GAA (Government Acronym Agency) so maybe we think they’re full of you-know-what but maybe they had a reason for those recommendations.
And finally, remember that in some of the studies reviewed previously the mask wearing groups had more sick people than the control groups. Anybody see a connection here? Stuff grows on masks, people who wear masks for no reason seem to get sick more…
We’re getting near the end of all this silliness, and the next post is short (really, really short). We will be looking at a paper about a mathematical model on viral spread so we can better understand why models are not a form of proof. Hint: GIGO is an old software acronym that stands for Garbage In Garbage Out.
And we learn why there’s a small statue of a duck next to Dharma & Greg’s front door.
Chughtai AA, Stelzer-Braid S, Rawlinson W, et al. Contamination by respiratory viruses on outer surface of medical masks used by hospital healthcare workers. BMC Infect Dis. 2019;19(1):491. Published 2019 Jun 3. doi:10.1186/s12879-019-4109-x
https://pubmed.ncbi.nlm.nih.gov/31159777/
Smith CL, Whitelaw JL, Davies B. Carbon dioxide rebreathing in respiratory protective devices: influence of speech and work rate in full-face masks. Ergonomics. 2013;56(5):781-790. doi:10.1080/00140139.2013.777128
https://pubmed.ncbi.nlm.nih.gov/23514282/
Roberge RJ, Coca A, Williams WJ, Powell JB, Palmiero AJ. Physiological impact of the N95 filtering facepiece respirator on healthcare workers. Respir Care. 2010;55(5):569-577
https://pubmed.ncbi.nlm.nih.gov/20420727/
Lim EC, Seet RC, Lee KH, Wilder-Smith EP, Chuah BY, Ong BK. Headaches and the N95 face-mask amongst healthcare providers. Acta Neurol Scand. 2006;113(3):199-202. doi:10.1111/j.1600-0404.2005.00560.x
https://pubmed.ncbi.nlm.nih.gov/16441251/