It’s “viral load” theory, idea that how much virus you get can determine
* how likely you are to get it
* how severe a case you have when you get it.
“viral load” is the key term to search for more
So, in order to understand the “mask controversy” you need to be aware of the concepts. The use of masks in Medicine was part of the introduction of “Science” in Medicine 100 years ago. Surgeons wore mask in surgery for understandable reasons which were “new” at the time. It was discovered in the 40s or thereabouts that if you put a surgical mask on a TB patient it stopped or severely reduced the transmission of TB. I think this was the first use of masks for patients.
As growing awareness of asbestos occurred in the 70s people began there was a great need in Industry to protect workers from “Respirable Dust-5 microns or less), the reason we no longer make building from stone so much is Silicosis.
It was realized right away the “masks” that protect people from TB didn’t have to do what masks that were intended to protect the wearer. To protect the wearer the mask must be sealed so no air can be inhaled around it.
So why the controversy? When I was in training in the 80s Bone Marrow Transplants were a new thing. Destroy a Pearson’s immune system concurrently with EVERY SINGLE CANCER CELL could potentially save a cancer patient’s life and their immune system could be “recreated” by transplant afterwards. It worked for some cancers. The large urban hospitals where doctors are trained began putting up “Laminar Flow Rooms” for these patients to protect them during the phase when they had no immune system whatsoever. Even Pediatric Hospitals, big names you see everyday, had only one or two.
The Infectious Disease people realized the “Isolation” of old used largely for TB patients was no longer enough for “Isolating” in the hospital those patients who had VERY communicable diseases, such as measles, so they started engineering rooms that weren’t quite as aggressive as “Laminar FLow” but simple “negative pressure” was enough.
Here is the source of some of the controversy. In Medicine, the place where we have used “sealed masks” or “respirators” is in these negative pressure Isolation Rooms. AFAIK it is the only place in the hospital where these type of masks were worn. Which is why I posted and you are hearing, the place where these masks “do their job” is in these rooms and by staff who are trained in how to avoid their failures (touching the outside of the mask on exit, etc,)
This thread was talking about masks and viral loads, and what might be considered a large enough load to get infected. Found the following recent article today:
Excerpt:
In February, scientists in Wuhan, China—where the coronavirus outbreak originated—sampled the air in various public areas, and showed that the virus was either undetectable or found in extremely low concentrations. The only exceptions were two crowded sites, one in front of a department store and another next to a hospital. Even then, each cubic meter of air contained fewer than a dozen virus particles. (No one knows the infectious dose of SARS-CoV-2—that is, the number of particles needed to start an infection—but for the original SARS virus of 2003, one study estimated somewhere between 43 and 280.)
These particles might not even have been infectious. “I think we’ll find that like many other viruses, [SARS-CoV-2] isn’t especially stable under outdoor conditions like sunlight or warm temperatures,” Santarpia said. “Don’t congregate in groups outside, but going for a walk, or sitting on your porch on a sunny day, are still great
ideas.”
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The article is pretty good - goes into some of the arguments about how we don’t really know if the regular flu is “airborne”.