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It seems the reasoning by officials is, "Yes, it's airborne, but there's not enough N95 masks for everyone so we don't want to cause panic or an N95 mask shortage for doctors and nurses by admitting it's airborne."
> they constructed an air-tight closed ventilation system that connected a six-room tuberculosis ward to an exposure chamber with 150 guinea pigs. (Among rodent animal models, only guinea pigs could cough and sneeze, making them ideal for studying how respiratory diseases spread.) The guinea pigs were exposed to the infected air over a four-year period. A second group of 150 guinea pigs acted as controls: their air ducts were irradiated with UV-C lamps to kill TB bacilli.
Results:
> an average of three guinea pigs per month contracted TB, while no controls were infected. The experiment [also] quantified how many TB infections could be expected to result from exposure to a given number of patients over a defined interval.
Relevance to COVID-19:
> Riley’s research points to wearing masks and disinfecting air in enclosed spaces as two of the most effective tools for fighting COVID-19
TL;DR: the actual experiment: > they constructed an air-tight closed ventilation system that connected a six-room tuberculosis ward to an exposure chamber with 150 guinea pigs. (Among rodent animal models, only guinea pigs could cough and sneeze, making them ideal for studying how respiratory diseases spread.) The guinea pigs were exposed to the infected air over a four-year period. A second group of 150 guinea pigs…
> The animals were used so frequently as model organisms in the 19th and 20th centuries that the epithet guinea pig came into use to describe a human test subject.
It seems the reasoning by officials is, "Yes, it's airborne, but there's not enough N95 masks for everyone so we don't want to cause panic or an N95 mask shortage for doctors and nurses by admitting it's airborne."
Also supposedly if a disease is declared airborne then hospitals have to adopt various isolation measures beyond just N95 that are very costly. This may be the reason the powers that be won't announce airborne transmission until after the pandemic is over.
Who says that saying its airborne "has" to mean that certain procedures have to be adopted? That's not a rule of the universe, it's a rule that humans came up with and agreed upon and humans have the power to fix. We distilled down a set of physical principles into a set of guidelines, forgot the underlying physical principles and now operate purely in the world of the manmade guidelines, totally oblivious to when the guidelines are no longer reflecting the physical reality.
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I was thinking HEPA filtration may already cater for virus's, but with HEPA certification being .3 microns and the COVID-19 virus 0.12 microns, then it gets down to individual air conditioning systems. Some may use ionising in combination or UV. So I foresee a whole raft of legislation and requirements for office spaces ahead. Which will only help drive the work from home long-term as cheaper office space. But also h…
The human species already has a significant level of herd immunity against four other endemic coronaviruses. The same thing will eventually happen with SARS-CoV-2 one way or another, but hopefully we will have an effective vaccine soon enough to accelerate that process while minimizing the death toll.
TL;DR: the actual experiment: > they constructed an air-tight closed ventilation system that connected a six-room tuberculosis ward to an exposure chamber with 150 guinea pigs. (Among rodent animal models, only guinea pigs could cough and sneeze, making them ideal for studying how respiratory diseases spread.) The guinea pigs were exposed to the infected air over a four-year period. A second group of 150 guinea pigs…
- It contains no experimental data, it's a review of possible methods.
- It's not about Covid-19, although that's to be expected.
- The masks it talks about are N95 and N100 respirators (which it notes aren't in adequate supply).
Some interesting quotes:
> If one assumes that influenza is transmitted by respiratory droplets [..] rather than by aerosols [..], the supposition may be that keeping a safe distance may obviate the need for a mask. It is stated that the range of such droplets is generally no more than 3 ft. We are unable to locate the basic science behind that assertion.
> Whether contagious as a respiratory droplet, aerosol, or both, there have been no controlled studies to investigate the efficacy of respirators in preventing the transmission of influenza A
> there is a theoretical problem in the logic underlying N–95 respirators. Assume an N–95 mask functions better than its rating and at a sedentary inhalation rate blocks 98% of the bioaerosols that it is confronted with. We are still left with the 2% that penetrate through the filter, to be inhaled by the wearer. Whether discussing tuberculosis, influenza, measles, or smallpox, we do not know the concentration of pathogenic bioaerosols in the environment, nor do we know the minimum infectious dose for these pathogens.
Anyway I don't think anyone disagrees with their conclusion that having everyone wear N100 masks is a good idea, but I'm not sure if any of their proposed methods are feasible. And the most important conclusion of their research is perhaps that we know way too little about possible countermeasures.
Can ultra-high resolution, ultra-high framerate and ultra-high zoom camera's measure exhalation of virii particles out of a humans mouth?
Edit: some sizes here, including SARS-CoV-2
https://www.news-medical.net/health/The-Size-of-SARS-CoV-2-C...
Russian FSB has just arrested (on secret state security charges) on his short trip back home from China a top high voltage systems specialist who has been working for the last two decades on UV water and air cleaning system in South Korea and China. Seems it is becoming a sought after hot tech in the current situation.
Earlier quoted context omitted.
I was thinking HEPA filtration may already cater for virus's, but with HEPA certification being .3 microns and the COVID-19 virus 0.12 microns, then it gets down to individual air conditioning systems. Some may use ionising in combination or UV. So I foresee a whole raft of legislation and requirements for office spaces ahead. Which will only help drive the work from home long-term as cheaper office space. But also h…
All viruses mutate, but so far SARS-CoV-2 has been mutating relatively slowly. It has an error correction mechanism which blocks the majority of mutations. By contrast influenza lacks that error correction and mutates much faster, which is why we need a reformulated vaccine every year. The human species already has a significant level of herd immunity against four other endemic coronaviruses. The same thing will even…
That's true, but that might change soon (the "every year", not the mutation speed): Results of [0] are supposed to be published this quarter. I am hopeful for them to be positive.
[0] https://www.biondvax.com/2020/07/last-of-12400-participants-...