I recently had the opportunity to speak with a world class engineer who happens to run his own show. I am keeping his name private. We spoke on the topic of masks. He asked me a few questions based on his understanding of how they work. He knows i am a Medical and Aerospace Engineer. The questions in bold are from him to me. What follows is our conversation:
1. Using a volume chamber to test masks, we have found that they are useless. We put holes in the mask which would simulate gaps around the sides of a mask allowing fluid flow to pass out through the path of least resistance. (2)Your point on filtration levels for various sized particles is correct and well known, but once a mask has gaps, it almost doesn’t matter.
Though the idea of this seems to be logical, the methodology is not accurate. Reason being, when wearing a mask, the path of least resistance is not in front of the mouth, its around the eyes and nose as you have shown in your(The engineer im speaking with) photos. Poking holes in the mask at the mouth level completely forces the infected particles into the mouth area, completely changing the streamline functions of the flow of air. You are literally "telling" the air were to go, rather than letting it follow a natural streamline. Of curse, it will fail. The entire sole purpose of the machine is to test filtration THROUGH the medium at a given point. If you remove the material at that given point, then its a pointless test. Its like removing the bottom of a coffee filter in the coffee machine and hoping no grounds get in your coffee..
Even if you have a gap by the eyes and nose, you have to remember that human skin is extremely sticky for aerosolized particles. They will stick very well to human skin, this is
in-fact another method of how they spread and why we have been washing our hands since the 1870’s with soap, even though germ theory came out in the 1500’s and America didn’t incorporate hand washing as a hygiene practice until 1980…
The contour of the cheeks, the fine human hairs on the skin, the oils, other dust particles, facial hair, all play a role in capturing aerosolized particles and keeping them from entering your mouth and nose. This is why we cannot use the volume chambers used to test masks without doing other tests. It does not imitate natural particle flow at all, it literally forces the infected particles in the direction you want. The best way to test masks is to allow the natural flow of the infected particles. This is why I chose to use live, infected people, including myself haha. You must use petri dishes for the tests. Petri dishes are the gold standard for pathogen growth, culturing viruses and bacteria. Petri dishes are very sensitive and will grow pathogens at even the slightest amount of contamination. This is why they are the best; one minuet particle falls on it, and it spreads like wildfire, it’s a pandemic in a container. I even did tests in dirty homes as controls and even then, I had ONE colony of growth after 7 days of culturing. I had infected patients wearing a non-fitted mask cough, spit, sneeze and yell in the mask while we had petri dishes all around the gaps, the front of the mask, the sides, the bottom, and all at different distances as well. We used cheesecloth (sounds dumb) as one control and then no mask as the other control.
Using no mask, the petri dishes all grew mass amounts of infected colonies, same with the cheesecloth. This is exactly what I wanted. We then used a 600TPI cotton non-fitted mask first. We had the petri dishes all around the face starting at 6 inches, then 1 foot, then 2, then 4 then 6 then 8. ONE small colony (far below the ID number and PFU ratio) grew on the dishes 6 inches away IN A DIRTY environment, HOWEVER, when we swabbed their checks, sides of the nose, eyelids, and forehead, the petri dishes grew the infected particles. This is why it is important NOT to touch your face when sick and then touch other things. We did the exact same test using a basic surgical mask, the kind you showed in your video, however, I'm not sure where you got yours and why it didn't clasp against the nose, because for the last 15 years, all of the masks I have used have a metal band in the nose to make a tighter fit. You mask must have either been made terribly or altered. BUT then again, I didn’t tighten the band on the surgical mask to prove a point, I purposefully left it very very loose. Using the exact same approach, in a dirty environment, the petri dishes grew NOTHING on them using a basic surgical non-fitted mask. We then repeated the tests in a clean environment and using the 600tpi cotton mask, nothing grew on the dishes. This is why we have been using petri dishes in medical labs for years. It’s the only way to actually test the natural behavior of organic, living pathogens, even though a virus is NON living, it absolutely MUST WITHOUT A DOUBT use a LIVING host cell to replicate and infect humans. This is why using the boxed style chambers that you and I are seeing a lot of tests with are highly in-accurate when it comes to gap testing. The machine is meant to test filtration of the material and filtration only, with a specific pressure gradient and volumetric flow of 12L per minute. The best method of testing is of real infected people and real environments, not clean rooms, not sterile labs, but dirty stores, dirty homes, and hundreds of petri dishes haha. Inhalation of particles through a mask works the same as exhaling, it’s a 2 way street and the argument that people say “masks only work in one direction” need to remember that the material is the same on the front and the back, there is no magic happening on the inside vs the outside of a material. Its uniform and the same throughout.
3. The size of the covid particle is debated, but that is why in “I did calculations up to 5 microns” is not accurate becasue the key is that they are mostly aerosols and not droplets.
This is a HUGE misnomer in the engineering world and I don’t know how it started. Aerosols is NOT a particular particle size. Droplets ARE aerosols. The definition of aerosols in particle physics, fluid dynamics, microbiology, standard medical texts, and thermodynamics is this:
Aerosols by definition are a system of liquid or solid particles uniformly distributed in a finely divided state through a gas, usually air.
Visible dust particles, which are MASSIVE, are aerosols because they follow a uniform pattern known as a path-line. Particles in the 5 micron sized range are aerosols because they follow a uniform pattern. Sub-micron particles, such as 0.4 microns, are aerosols as well because of how they flow through the atmosphere in a uniform pattern.
This now leads into the virology area of my degree. the smallest host cell a virus, including coronaviruses, which there are over 250 types, as well as covid19, can successfully invade and adequately use to replicate itself and infect humans is 0.4 microns. Anything smaller than that, the host cells organs, food supply, fluids, and resources are too small for a virus to successfully replicate. This is NOT a calculated number either. This has been studied and tested over and over and over with growing viruses in host cells on petri dishes, again, why petri dishes are the gold standard. EVERYTHING we know about pathogens, biology, bacteria, viruses, all come from studying them on petri dishes, for over 40 years with the same conclusion, that for a virus to replicate successfully, the host cell has to be a specific spherical size with the proper and adequate resources needed for said virus. Same idea as a goldfish gets as big as the environment will let it. Aerosols that are even in the 0.2 micron sized range and smaller, only have fragments of a virus because the size of droplet was inadequate, and does not have enough respiratory fluids to allow the virus to replicate. Even if it did, this is not an issue since particles that small bounce off of the atmospheric gasses, this is known as Brownian motion. N95 means it captures 95% of particles in the 0.3 micron sized range, and viruses are smaller than 0.125 microns: Again!!! viruses do NOT work that way. We do NOT breath out viruses or virions, that is NOT how viruses work. We breathe out infected host cells or respiratory droplets in an aerosolized uniform pattern with a particle size of 0.4 microns, again, the smallest size sufficient enough to allow replication. Also, not EVERY breath has infected cells, the viral load is not very large compared to other sources of particle. Remember, viruses hitch rides on our respiratory fluids because they are FORCED through our respiratory system which mean they will be encapsulated in host cells or fluids. 0.3 microns was picked as the defacto because it is the HARDEST size of particle to capture, not the ONLY size it can capture. When they are this small, their density almost matches that of air, making them follow the same streamline path. This makes them difficult to capture. However, engineers and doctors are smart and came up with the idea to statically charge the material to act like a magnet. This is why it can filter out 95% of the HARDEST size to capture, because its a giant magnet. Never ever wash a N95 mask. The water will kill the static. Its when particles are different densities than air, that they follow a different path than the larger particles that match similar densities to the surrounding atmosphere. When they break the streamline, they will bounce off of other gasses or molecules in the air. Particles smaller than 0.3 microns have this behavior of bouncing off of the other gasses and molecules in the air. This is known as Brownian motion, and particles this size are far easier to capture. Therefore, IF WE DID BREATHE OUT VIRUSES, we would have no issue capturing them. BUT SINCE WE DONT BREATHE OUT VIRUSES BECAUSE THATS NOT HOW IT WORKS, AND WE KNOW THE SMALLEST HOST CELL THAT CAN HOLD A VIRUS IS 0.4 MICRONS, which is pretty large. Think of bouncing a baseball into 3 soccer nets, chances are, it will not pass through. But if you were to throw the ball, it could pass right between all 3 nets. This is why the mask material is statically charged, to make sure the "baseballs" get stuck to the net rather than pass through. I have had the opportunity to also have data published by the American Chemical Society on filtration of particles using various household items. They used a volume chamber as well, but did not poke holes in the cloth, they attached the material to a pipe and loosely fitted it. A 600TPI, single layer pillow case will filter out 98% of 0.4 micron sized particles and 80% of 0.1 micron sized particles. Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks | ACS Nano To further validate this data, i used petri dishes to really test the filtration level of masks, which you can read at the beginning of this blog:)
