If you hate masks and are a passionate anti-masker, spare yourself the misery of reading this post only to find there is no way to do anything other than yell at your screen. Just remind yourself the world works your way at the moment and so you have nothing to fear and nothing to worry about if a few folks here and there are interested in finding out about masks for preventing airborne illness. Just move along.

I have compiled this information on request from people in my own life and I think it may have some value for others out there who are interested. Here goes…

The Current Airborne Illness Leader in our World Today

This past December, on a Friday afternoon, STATSCAN dropped data that currently 1 in 9 in Canada have Long Covid. What is Long Covid? First of all, the virus that causes Covid is a new coronavirus named SARS-CoV-2. You catch SARS-CoV-2 and you get a Covid infection from it. And about 40% of us will show no sign we are infected (asymptomatic). 1

SARS-CoV-2 is not a respiratory virus despite it having been given the name: Severe Acute Respiratory Syndrome Coronavirus 2. While it usually first enters the body through the respiratory system (breathing it in), its actual mode of invasion into our cells is through Angiotensin-converting enzyme 2 receptors (ACE2) on the surface of our cells throughout our body. ACE2 receptors are everywhere.

“The ACE2 receptors are ubiquitous within the human body, particularly overexpressed on intestinal epithelial cells of the gut, endothelial and smooth cells of the blood vessels, heart (epicardia, adipocytes, fibroblasts, myocytes, coronary arteries), lung (macrophages, bronchial and tracheal epithelial cells, type 2 pneumocytes), brain, testis, and on tubular epithelial cells of kidney.” 2

SARS-CoV-2 is a syncytial (sin-sih-shull) virus meaning it has the ability to cause fusion of neighboring infected cells to create giant cells called syncytia (sin-sih-shi-ya). Syncytia wreaks havoc throughout the body. [Good thread on this topic: Dr. Sean Mullen on Twitter/X]

Science has not arrived at a consensus yet, but some percentage (perhaps all) infections, both asymptomatic and symptomatic, lead to the virus taking up permanent residence in the body. 3 Viral persistence is not new to us. To name just a few viruses that take up residence in the body after the initial infection: the Epstein-Barr virus (EBV or human herpesvirus (HSV)-4 present in about 90% of our population), chicken pox/shingles (varicella zoster, in 95% of the population), Ebola (EBOV) and acquired immune deficiency syndrome (HIV/AIDS). The HSV, EBV, HIV and likely EBOV viruses can all create syncytia. Many bacteria also have the same ability to persist in some people too: Streptococci and Staphylococci species, Mycobacterium tuberculosis (TB), Borrelia burgdorferi (Lyme’s Disease). The immune system interacts with all these viruses and bacteria over the long term. Some immune systems can override some viruses or bacteria some of the time to force them to go dormant in the tissues and organs throughout the body. When that happens, you have latent EBV, or TB, or Lyme’s…etc. Approximately 25% of the population has latent TB. You may have noticed an uptick in the prevalence of shingles and active TB in recent years and I will get to that in a moment.

The establishment is still squabbling over the definition and diagnosis of Long Covid, but I find the evidence leads to it being the disabling impact of viral persistence in the body where the virus is not latent or in remission. Long Covid is not limited to symptoms of cognitive decline/damage, energy deficits that are far more sinister than fatigue, dysautonomia (malfunction of the autonomic nervous system controlling basic things like blood pressure, heart rate, digestion, etc.) and mast cell activation syndrome. As SARS-CoV-2 loves ACE2 and is syncytial, Long Covid will include the sudden post-infection appearance of heart disease and failure, circulatory diseases and cardiac arrest, as well as disparate conditions such as cancers, connective tissue disease, eyesight, smell and hearing loss, dementia, parkinsonism, diabetes, chronic pancreatitis, ulcerative colitis, liver and kidney failure and Crohn’s.

A Covid infection also dysregulates our immune systems. 4 Not only will that mean we will be unable to fight off common colds and flus (sick all the time much?) but latent viruses and bacteria already in the body receive a get-out-of-jail-free card. That is why many people after a Covid infection get shingles, or show signs of reactivated EBV, or suddenly develop symptoms of TB because they were a former latent carrier.

We also never develop permanent immunity to any coronavirus including SARS-CoV-2 and all of our current vaccines cannot prevent infection (but do lower the risk of immediate death and hospitalization during the acute phase of the infection). Each infection we get increases the chance we will get Long Covid. 5

[Edited: I have edited the next section a bit to make the information a bit clearer as I have had some feedback that spit particles just smears it all into the droplet/fomite dogma of our times]

The virus that causes Covid is airborne. What does this mean? It means that it hitches a ride on the vapour of exhaled air and when we talk and breathe on each other (never mind singing or coughing at each other). The Covid virus does not do so well on surfaces– or what is called fomite transmission. While lab created versions of the virus did show that fomite transmission was a concern, in real life, SARS-CoV-2 does not survive on surfaces at all well. 6

What this means is that larger spit particles (droplets) that fall immediately on surfaces are not how you get Covid. It is the tiny vapour particles that hold viable SARS-CoV-2 virions that can float about in the air for hours that will ultimately infect you. Think of it as very tiny floating dust particles that you can see when the sunlight catches them in a living room. 7, 8

And without anthropomorphizing a virus (trying to make it seem like it thinks and plans its next move), cycling this virus through our populations over and over has allowed for selection pressures to make the current variants more transmissible and more immune evasive.

In Canada, those who have already had at least one Covid infection is somewhere in the range of 75-83% of the total population. The goal now for the vast majority of us should be to not keep getting repeat infections so we can avoid the disabling impacts of active Long Covid if we have been lucky enough to avoid it so far.

As I want to get to the topic of masks, I will not address all the common nonsense about hybrid immunity, immunity debt, vaxed and relaxed, it’s the spike, and other unscientific concepts coined to suggest that we can ignore the pandemic (yes, it is still a pandemic). We will save that for another time.

Masks

Rule Number One

The best mask is one you will wear and not take off while either in the presence of others, or in indoor spaces.

Rule Number Two

There are two kinds of risk: proximity and air quality.

Rule Number Three

Both proximity and air quality risks rise with Time.

That means that if you are outdoors on a humid, still air day chatting with a friend on a bench in the park, that could add up to a higher risk of infection than silently sitting in the Vancouver Orpheum [due to excellent air quality, 9] listening to the orchestra. It could.

The point of those examples is to let you know that you cannot actually assess these risks to make an informed decision– information is always missing. You will not know infection status (rapid tests are not dependable and 40% show no symptoms and yet can infect you); you will not know how well the indoor air is cycled and cleaned; you will definitely not know how the air flows in an indoor space (meaning you could be infected from someone in a cubicle on the other side of the entire floor or even floors below you); you will not know how many infectious people have been in a space maybe hours ahead of you; you will not be able to exhaustively cross-examine friends and family to determine whether their “isolated before our gathering” means the same thing to them as it does to you; you will never know whether the infectious dose for you is five seconds or five hours, and on and on it goes.

Anyone who says they assessed the risk and it was minimal to nonexistent is practicing hubris and magical thinking, not risk assessment.

Which is why you depend on Rule Number One. Yes but,

Why Wear a Mask at All?

If you believe that science has shown that masks do not work to prevent catching airborne illnesses the most benevolent interpretation of that opinion would be that you are likely not aware that the wrong scientific field has been looking at mask use in mostly medical settings.

A randomized controlled trial (RCT) is considered the “gold standard” of scientific experiments. When an RCT is well designed and all the possible confounders have been considered to get results that are solid and not in need of nudging to make them statistically relevant, it is extremely useful in the field of medicine. The pinnacle of an RCT is a double-blinded randomized controlled trial where neither the experimenters nor the subjects know whether the subjects are receiving the treatment under investigation or a placebo.

However, using RCTs for the worlds of physics and engineering yield very strange study designs and largely nonsensical conclusions. The parachute you might wear when jumping out of a plane is not certified for safe use because they ran an RCT where half of all the subjects leapt out of the plane with a placebo-chute and the other half had the real parachute.

All the safety equipment that surrounds you from medians and barriers on the road, to seatbelts, to drinking water, to safety glasses, to carbon monoxide and smoke detectors, to high-visibility vests, to faller’s pants for chainsaw kickback...it is the laws of physics that shape and design those items for safety. It turns out if you do not wear or use safety equipment then that safety equipment does not work.

One of the biggest failures of the pandemic has been the leaders of public health, populated almost exclusively by medical doctors, catastrophically overstepping their field of expertise. Air quality, air exchange, air flow, the physics of particles in the air and all personal protective equipment necessary to lower the risk of infection, are solidly in the fields of physics and engineering and not medicine.

If you are actually working with the SARS-CoV-2 virus in a lab, this (below) is one of several variations of personal protective equipment (PPE) you must wear. Those helmets they are wearing are battery powered air purifying respirators (PAPR).

Photo Credit: UCI Office of Research BSL-3/ABSL-3 Laboratories

All respirators can filter out airborne contaminants and some respirators with cartridges and cannisters will also filter out chemicals and gases. Some respirators provide a completely separate clean air source (think scuba diving). From surgical/medical masks up to PAPR, how well masks filter out airborne contaminants is the first and best physical barrier you have between you and an airborne infection.

If Masks Are So Great, Why Weren’t We Always Wearing Them?

Many cultures have been wearing masks to prevent the spread of airborne illnesses for much longer than the West’s recent adoption of them during the current pandemic. It is just one more example of the fact that we can always make progress in our understanding of how we can protect ourselves and others. In the West, we used to be quite comfortable drinking sewage-laden water. Yet, at some point we recognized that water-borne illness went away if we stopped drinking sewage-laden water. Sometimes humans are able to improve their lot.

Does the Mask Work and Fit?

Let us talk types of masks:

Surgical: blue baggies, procedural/medical masks.
Earloops respirators*
Headstrap respirators
Elastomeric respirators
Elastomeric P100 respirators
PAPR

*This confuses everyone, but respirators are masks (or have a mask component) but not all masks are respirators.

The above list is a simplification and I will work through a bit more of the nuance now. There are several awesome citizen scientists who have been performing comprehensive fit tests on all the mask types out there these days. The examples below are far from exhaustive and meant to give an idea of the types within the category.

Surgical: Procedural/Medical Masks

Procedural/medical masks were designed to avoid droplets from the practitioner falling in the sterile field of a surgery or dental procedure. You can find several videos on YouTube showing how the aerosol simply flows up past the eyes and also to either side of the cheeks to the back of the person as well. It means that someone wearing this mask who is Covid+ will share the infection with others. It also means someone who is Covid- with this mask will breathe in any virus in the air through the gaps as well.

KN94/FFP2 earloops, KN95 earloops and even N95/99 earloops.

The 94 (FFP2 are 94 equivalent), 95 and 99 indicates the percentage of airborne particles that the mask will successfully filter out of the air. These earloops come in all kinds of colours and designs and are easy to slip on and off around the ears.

If you like these, you need to know a couple of things for getting a good seal: you have to completely flatten the metal nose piece first (it is usually a folded sharp point when you pull it out of the package). Then you have to curve it around your nose with your fingers to ensure there is no gap right on bridge of your nose. Ideally get the clasps on the earloops you see with the Kaze mask image so you can slide them to create as snug a fit as possible for the mask around your face without hurting your ears.

As attractive and easy to take on and off as all of these earloop options are, it is very difficult to pass a fit test with any of them because our ears cannot create enough pull to create a perfect seal around the face. While KN94/5/9 are vastly superior to medical/surgical masks for protecting you and others, this brings us to headstraps.

Headstrap Respirators

Headstrap respirators come as N95/FFP3 and the occasional N99 as well. These are usually 3-panel design and there are three brands that seem to do very well for many different kinds of faces for passing fit tests (I will explain fit tests in a moment): 3M Aura N95, Draeger/Dräger 1950 N95 (small) and Trident N99. 3M Auras are US made, Draeger is European and Trident is Australian. The 3-panel design allows for the seal to be maintained when you talk or laugh.

@FitTestMyPlanet is active on Twitter/X and posts the QNFT histograms on all the masks fit tested at Test the Planet.

Headstrap N95 and N99 create the pull of the mask to the face to create a solid seal. They come predominantly in white usually with the company logo slapped on the front. They do not lend themselves to whipping on and off because the process of getting them on the face means you put it on with every intention of keeping it on for hours.

The mask has to be unfolded; the metal nose piece (usually with foam insert on the inside of the mask) has to be molded into the shape of the nose a bit; and the straps have to be folded to the other side of the mask making sure the lower and upper straps do not get crossed. You bring the mask up to your face then pull over first the lower strap around your neck and then place the upper strap at the back of the head (many videos show putting the upper strap over first). You check a mirror to make sure the mask is straight and then you adjust things until you feel you have a good seal all the way around the mask. There are many YouTube videos you can find on how to put on a headstrap N95/99, here is one example.

The good news is that people who wear 3M, Draeger (small), or Tridents all tend to like how comfortable these are to wear once they are in place. Women with long hair often do a hack where they pull up the hair away from the crown, place the upper strap and then drop the hair back down so that the headstrap is no longer visible. The quality of the strap is very important and you want them not to slip down from the back of your head or fray at the cheek.

All the above masks are considered single use as they have an electrostatic charge that will dissipate eventually. However, it is fine to reuse these masks with a bit of care if they are not dirty, got wet, or were compromised with sweat.

If you have ever walked into a healthcare setting and they insist you remove these headstrap N95/99 mask to put on a “clean” surgical/medical mask, there is no science to support doing so. They often argue that your mask could be contaminated as a reason to insist on this absolutely ridiculous risk to you. The electrostatic charge means all the possible contaminants are not going anywhere. And fundamentally this is a frank refusal by the medical establishment to push that SARS-CoV-2 is an airborne and not a fomite transmissible virus.

Alright let’s talk Fit Tests.

What is a Fit Test?

Many healthcare providers tell the public that headstrap N95/99 masks are useless if they are not fit tested, as though you need special medical training to wear one in a way that will not harm you or others.

A fit test is performed each year for most healthcare providers using N95 headstrap masks. The provider puts on the mask and a giant hood is placed over their heads. A small aerosol spray of bitters is sprayed under the hood that the provider will be able to taste it if there is any gap in the mask. That is it. You taste the bitters; your fail your fit test.

The fit testing kits used in hospitals are available to all, but are pricey: 3M Qualitative Fit Test Kit Apparatus FT-30, however here are the member-of-the-public options that are equivalent: Fit testing at home methods.

Fit testing is not performed each time a healthcare professional dons a mask. What this means is that while they have a good understanding of what brand and size potentially gives them a good seal, they still have to fit each new mask and adjust it to their face well each and every time, in the absence of confirming with the fit test that they have got it right. That is no different than any member of the public.

Frequently Asked Questions

Can I get infected with Covid when I am wearing a fit-tested headstrap N95/99?

The answer is yes. And that answer is often used to bolster Ye-Old-Masks-Don’t-Work argument.

But the issue is not the mask. The issue is the disgusting dirty air thick with infectious virions that you may breathe in and for how long you might have to do that.

We do not know the viral load needed to succumb to infection and it likely varies from person to person and maybe within a single person depending on their immune status in that moment too. An N95 is certified to never let more than 5% of the aerosol particles through the mask, and the N99 only 1%. Most masks perform better than their ratings certification status, but it does mean that between 1-5% of what is out there could get in through the well-fitted mask.

If I am in an emergency room where one in 10 patients has infectious Covid and I am a nurse wearing an N95 for my 12-hour shift I am probably not going to get Covid. The reason for this is air exchange systems in most hospitals are so good that the only risk I face is the time I am in close proximity to an unmasked Covid+ patient or colleague. That is why the rare doctor or nurse who still wears N95s throughout their shifts (and not just when they see patients) has likely never had Covid despite the fact that they see a tremendous number of Covid+ patients and colleagues while on shift. They will take their breaks alone outside (or in their cars) to unmask and have water and food. They are very unlikely to get an infectious dose through that N95 during the close exposure time they have even if 5% of aerosol particles reach their lungs.

Remember it is both air quality and proximity over time.

If I am at a wedding reception held at a restaurant where everyone is eating, drinking, dancing and yelling over music, my N95 for six hours might not help me avoid a viral load. I am exposed to both the proximity of those yelling over the music to chat with me as well as all the virions piling up in the air and not adequately filtered out and replaced with fresh air.

But by far the biggest risk of catching Covid while in a headstrap N95 or N99 is user error. Trying to sip or eat by lifting up the mask up just for a moment? Bad idea. Just taking the mask off in the bathroom stall while you are alone in there? Bad idea. Going outside the restaurant and taking off the mask there while chatting with a few folk outside? Bad idea. Also, you could just be very unlucky and somehow not have gotten a good seal on that particular day with that particular donning of the N95 and it let just a bit more in than when you get a great fit that would pass a fit test.

All this is a very strong argument for having everyone in KN95 and N95 earloop or headstraps because a hundred people dancing in not absolutely perfectly fitted masks still means that there will not be enough virions getting past all those masks to infect anyone even if a dozen or so in the room are masked and asymptomatically Covid+.

Can I get CO2 poisoning from wearing a mask too long?

No. 10, 11

You will find a plethora of papers on the CO2 concentration build up in masks all performed on healthcare workers.

If you walked masked on a treadmill for six hours you still are not likely to match the CO2 found on many commercial flights (yes, not just when they are idle on the ground – in the range of 1000-3000 ppm). Many classrooms have higher concentrations of CO2 than what you would have behind your N95 after 14 hours. And that CO2 level may cause reversable headaches and temporary cognitive impairment in healthy individuals both unmasked in a classroom or masked for 14 hours without any breaks at all.

However, wearing these masks is particularly problematic for those with serious lung disease and some other chronic conditions. And the formaldehyde means many develop contact dermatitis with prolonged mask wearing as well. The biggest disservice we did to our community was to suggest that mask wearing is an individual choice. If those of us who can wear masks do so, we make it possible for those who cannot to remain a part of our community.

But there is no reasoning to be had on these topics, so I am simply assuming you are reading all of this because you are interested in wearing masks again to protect yourself and perhaps the people in your life as well.

But I can smell perfume/smoke/fish so obviously masks do not work.

Smells are a different size than aerosol particles. Remember that an aerosol particle, when it comes to Covid, is a floating vapour particle with a SARS-CoV-2 virion attached along for the ride.

A SARS-CoV-2 virion all by its lonesome is a tiny 0.1µm (microns). An aerosol/vapour particle is 4.5-5 µm. Most smells are absolutely miniscule at 0.01µm.

To filter out gases and smells you need P100 rated for particle, chemical and gas filtration. See below.

What about when I cannot mask?

For many medical procedures, including an MRI, a mask is going to be prohibited. Most masks have some metal which is decidedly not a good idea for an MRI. Here is a suitable option for many of those situations:

The ReadiMask has adhesive to stick to your face so there is a) no metal and b) no straps. Also useful for seeing a hairdresser.

Dental work and surgery/general anesthesia require access to your mouth. Next to no medical or dental professional in 2024 will be willing to wear an N95 to keep you safe while you are unable to wear one. Their receptionists will advise you that as these professionals are not mandated to do so, they cannot be asked to do so. It becomes a negotiation and all I can say is that maybe at some point in the future dentistry and medicine licensing bodies might reintroduce their members to the concepts of airborne illnesses and professional obligations to care for their patient’s safety in the absence of public health orders that legally mandate them to do so.

What about getting an infection through the mucus membranes of the eyes or even ears?

The ear does not appear to be the case unless you are receiving surgery with drilling in/around the ear itself. As for the eyes, there is no consensus at this point. 12, 13

We do have some evidence that folks who wear glasses were less likely to contract Covid than those who do not. 14

Maybe at the moment it leans in favour of putting on glasses or safety glasses/goggles if you are in an enclosed space with lots of people for an extended period of time.

What if I have to be on a plane for 14 hours– I will get too dehydrated.

Here is yet another gadget to consider and it is also well reviewed: SIPMask. You can install this on KN94/5, N95, N99 respirators and safely have fluids throughout your flight without removing your mask. I have also seen this installed on a FLOMask elastomeric (see photo below in Elastomeric Section).

What about masks that have valves so I can breathe out more easily?

While the CDC indicates the valve in no way compromises the efficiency of the filtered air you as the wearer are receiving, I find the CDC, as a public health entity, lacks the physics expertise necessary to make these determinations and this study suggests there can indeed be leakage on the inhalation: Particle leakage through the exhalation valve on a face mask under flow conditions mimicking human breathing: A critical assessment. When you push the air out, there is a small filter that is fitted in the valve that moves away from the mask to the edge of the valve lowering the resistance of your exhalation. When you inhale, the filter is pulled back towards the mask to create a tight filtered seal for you when you breathe in. But there is a tiny moment where air is coming in unfiltered before your inhalation pulls the filter back in place and sometimes it does not come back flush in its space either.

Of course, if you are Covid+ you are spreading the virus out unimpeded through the valve as well. I would suggest the masks with valves are a reasonable solution for someone who has lung disease or other conditions that make wearing a mask without a valve impossible. Any mask you wear is always going to lower your exposure to the virus.

Corollary To Rule Number One

Lowering Viral Load is Always a Good Thing

What about nasal sprays and mouthwashes instead of masks?

Some types of nasal sprays and mouthwashes can lower the viral load if you have been exposed and can keep the viral load suppressed if you actually get sick with the virus as well.

CPC Mouthwashes

Efficacy of Cetylpyridinium Chloride mouthwash against SARS-CoV-2: A systematic review of randomized controlled trials

A caveat on CPC mouthwashes: if you use them aggressively you may nudge yourself towards a Candida infection (thrush/yeast infection). Remember that SARS-CoV-2 takes the boots to your immune system and any Candida species that have happily co-existed in various mucus membranes in your body now get out of hand when your immune system is compromised.

Iota-Carrageenan Nasal Spray

Betadine

I am personally most familiar with this type of nasal spray as it is available in Canada as Betadine. It can also be found in the UK, but it does not seem to be available in the US. 15, 16.

Iota-carrageenan nasal spray is a algae-based spray that essentially coats the nasal passages and it pre-dates Covid as an over-the-counter treatment for reducing the severity and length of symptoms of the common cold. The safety profile is attractive and if you are in a country where this is available, you can easily use it if you a) suspect you have been exposed, and b) throughout the course of having a Covid infection to lower the severity and length of symptoms during the acute phase of the infection.

Nitrous Oxide Nasal Spray

There is only one option on the market today created by Canadian company SaNOtize and its product is only authorized for use in the following countries at present: Thailand, Singapore, Hong Kong, South Africa, Malaysia, Cambodia, Germany (branded as VirXTM), Israel, Indonesia and Bahrain (branded as EnovidTM). It is far more expensive than iota-carrageenan nasal sprays, or xylitol sprays (xylitol sprays are available in the US but so far there is only in vitro (petri dish) studies and one 3-patient post exposure study showing xylitol inhibits Covid infections). 17, 18

Saline Nasal Irrigation and Gargling

Regular use (after possible exposure to Covid) of sterile saline nasal irrigation and gargling with salt water will lower viral load as well. 19, 20

There are individuals who have chosen to forego masks in favour of using nasal sprays and mouthwashes after being indoors with others. I do not know enough either way to say whether it is sufficient. But iota-carrageenan lowers the chance of getting Covid by 40-70%, so I would go for the additive protection for the win: N95 headstrap mask (only 5% possible exposure) and the addition of a nasal spray and/or mouthwash both pre and post exposure.

What if I and everyone around me tests negative on a rapid test/lateral flow test – I can safely unmask right?

No. These at home rapid testing kits have a problem that is increasing with newer variants. Everything comes down to sensitivity and specificity. The best way to frame sensitivity is that it measures the chance that you see a neagtive result on your RAT/LFT but you are actually positive for Covid. And specificity measures the chance that you get a positive result on the test but are actually negative for Covid. Of all the tests performed out there, only about 50% that have Covid are correctly identified with a positive rapid test result. That means 50% of those with a Covid infection are seeing a false negative result on their test. However, less than 2% get a positive test result when they actually do not have Covid at all. These tests have poor sensitivity and very good specificity.

One study found that the rate of false negatives was 67% within the first 4-5 days of the onset of Covid. 21

And now we are at Elastomerics and Elastomeric P100s.

Elastomerics

@nickelpin Twitter/X, FLOMask with installed SIPMask port.

The most commonly used N99 elastomeric that I have seen is the FLOMask. Those who wear it swear by it. An elastomeric mask has a rubber-like polymer seal around the edge. The advantages are that it keeps its shape and it is therefore easier to pull away from the face for a moment (holding your breath for say an ID check) in a way that N95/N99 3-panel with headstraps is not; it provides a good seal without a lot of adjustment; and it is reusable with replacement filters. It is an N99 so you get that bump of performance rating down from 5% of aerosol particles possibly passing through, to 1%.

Additionally, the FLOMask is known to be a bit easier to be heard from when you are speaking to others than the P100 elastomerics (see next section). Just a reminder, a fit test is relevant for these elastomerics and they fit some faces much better than others.

Another for which I have no direct or hearsay experience, but it appears to meet filtration ratings of 99.99% is the OmniMask. It has the added benefit of allowing for full visibility of your face.

Whether an elastomeric P100 filters out just aerosol particles, or also covers off chemicals and gases is all about the cartridges and filters you use in them.

Here is an example of a full-face P100 that has cartridges that protect against aerosol particles, gases and chemicals: CGSGDK Full Face Respirator Mask and it looks like this:

Elastomeric masks are all going to give you a far better immoveable seal than headstrap N95/99. They are expensive but cleanable and reusable. One hospital in San Antonio Texas became a darling for a moment in 2020 with the focus on protecting healthcare professionals at the time. They used valved elastomeric P100s instead of N95s as the one remaining hospital treating TB patients. They had never had a healthcare worker infected by a patient with TB in all that time. Obviously in that case, the healthcare workers could not infect their patients with TB and so the valve was a reasonable thing to have.

One challenge with these masks is it is difficult to be heard, as mentioned. One physician just uses a speech to text phone app with the phone up by his face which also works for wearing any face mask when speaking to anyone with hearing loss as well.

I saw one truly awful human being post on Twitter/X that she purposefully tells any cashier who might be wearing a mask that she cannot hear them until they are forced to take off their mask simply because she hates masks. The phone app, or a notepad and pen, solve dealing with both those just wanting to abuse their power over service providers to feel important, and those who genuinely struggle without the benefit of seeing someone’s lips move while speaking.

And the most glaring challenge with P100s is that human beings are social primates who follow the crowd. It is difficult enough wearing a white headstrap N95/99 while out and about running errands let alone going all “I live in an apocalypse” gas mask. The true rebels and independent thinkers in our society are not those running around “living their lives” without masks; it is the folks in elastomeric P100s.

PAPR: Powered Air Purifying Respirators

The only thing that says more apocalypse than elastomeric P100s is PAPR. These are entire systems that cost $1300-$2000+ USD. The only way an aerosol with a SARS-CoV-2 virion meets up with your lungs is if you take this off.

Another marked advantage to these systems is that your entire face is usually visible and it is why some who take commercial flights choose this option for identification and security clearances. They are not having to risk breathing SARS-CoV-2 laden air when removing the mask when told to do so at various checkpoints. One flyer decided to invest in one of these systems and she was able to pass the automated facial scan to confirm identification with her passport with the mask on. She was using this CleanSpace Halo system at the time:

She has since deleted her post on her experience because the trolls were unrelenting.

In an airplane you are getting around 1.5-7% of the air you breathe in as coming directly from someone else’s exhaled breath. That range has been captured in both published studies as well as citizen scientists armed with portable CO2 monitors in the past few years.

During a long flight with no one else masking on a plane and a current prevalence of people with active Covid at around 1 in 13 [22], if you have a Covid+ person who is “at the early stage of infection (1–5 days) able to exhale up to billions of viral particles per hour (2.01×108 copies/hour),” even 1.5% rebreathed air is a significant risk of infection. That risk is of course compounded with the time you spend in airports with industrial-grade air systems that cannot keep up with crowded boarding and security areas where it is much more common today to kettle passengers in corridors and long narrow queues with no seating, than to be in spacious pre-boarding areas filled with seats and great air exchange.

Wrap Up

This post is not an exhaustive list of all the mask options out there in each category. The ones I have highlighted involve no corporate sponsorship; they are just the ones I am most familiar with at this time.

I make no recommendations one way or the other for particular brands as the brand that fits your face is the one you need.

Are single use disposable masks an environmental concern? Yes. If you can afford a reusable elastomeric you can offset this impact.

Remember all safety equipment fails if you do not use it. Be mindful of the fact that the number one reason for getting Covid despite wearing an N95/99 headstrap respirator or better is user error. By the same token, also recognize that because we are currently pretending there is no pandemic, everything that protects you is just down to your lone respirator. Therefore, you could have done absolutely everything right and the viral dose in the air and near you for the amount of time you were forced to be there was too much even at only 1-5% of the aerosol particles getting to you.

The goal is to get Covid as few times as possible and not to give up when, despite your best efforts, you have ended up with the infection.

1 Prevalence of Asymptomatic SARS-CoV-2 Infection

2 Understanding the role of ACE-2 receptor in pathogenesis of COVID-19 disease: a potential approach for therapeutic intervention

3 Persistent SARS-CoV-2 infection in patients seemingly recovered from COVID-19

4 Immune dysregulation and immunopathology induced by SARS-CoV-2 and related coronaviruses — are we our own worst enemy?

5 Every COVID Infection Increases Your Risk of Long COVID, Study Warns

6 Low risk of SARS-CoV-2 transmission by fomites in real-life conditions

7 Detection and isolation of infectious SARS-CoV-2 omicron subvariants collected from residential settings

8 Building parameters linked with indoor transmission of SARS-CoV-2

9 ‘Pandemic Proof’ Architecture: Vancouver Symphony Orchestra Orpheum

10 Impact of long duration wearing of N95 masks on cardiorespiratory system and subjective sensations of health-care workers during COVID-19 era

11 Effect of N95 Respirator on Oxygen and Carbon Dioxide Physiologic Response: A Systematic Review and Meta-Analysis