>"sub micron particles are considered aeresol. They arent really produced in any detectable quantity with normal breathing, though they arent non existant. However unless its humid out they are going to evaporate super fast as well."
Actually sub-micron particles are created in infectious levels with every breath.
@freemo @torresjrjr @NEETzsche @mkljczk @ducheng
Even when all the H2O has evaporated from a particle, there can remain lipids and the protein shell of the virus itself can help keep it viable. This is one of the reasons why variants can become more transmissible, because outer proteins can allow them to survive even when all the water has evaporated. UV light also plays a factor.
>"The point here is that airborne isnt airborne in the same sense as smoke."
The particles are roughly the same size, and can stay in the air the same amount of time, its survivability that makes the difference, not the time it's airborne.
🇳🇱
> Actually sub-micron particles are created in infectious levels with every breath.
Incorrect, studies have shown normal breathing creates virtually no aerosol.
> Even when all the H2O has evaporated from a particle, there can remain lipids and the protein shell of the virus itself can help keep it viable.
No viruses dont persist outside of droplets. That would be true airborne status and there is simply no evidence to suggest that is the case as shown by the following study:
"If SARS-CoV-2 could travel in the air, outside liquid droplets, it might be carried longer distances on air currents. There is currently no robust scientific evidence to support airborne transmission of SARS-CoV-2."
Morawska L, Cao J. Airborne transmission of SARS-CoV-2: The world should face the reality. Environment International. 2020 Apr;139:105730. DOI: 10.1016/j.envint.2020.105730.
> I remember reading that first study you cited (Jayaweera, et al., 2020 Jun 13), and I've used it in helping to form my understanding. It said, "In general, infected people spread viral particles whenever they talk, breathe, cough, or sneeze."
> Breathe.
Read the data not the commentary. Normal breathing was shown in their study to produce virtually no aerosol. Any commentary about it is moot against the data.
> I don't like to use the words "aerosol" and "droplet" because, as that study said, those terms mean different things to different people. When an infected person breathes they shed virus within sub-micron particles. Period.
False the study clearly shows in its data that normal breathing produces virtually no aeresol (<5um) or droplet (>5um), period!
> That second study (Morawska L, Cao J. 2020 Apr) which studied COVID transmisability and made a claim about viability in particles with little or no H2O, that was studying pre-delta variants.
There is no reason to think that all of a sudden post-delta variants can magically exist outside of a droplet. The only difference of consequence is the density of the virus is much much higher.
> As I said, the newer variants are better at surviving in the air, that's why the R0 is so high, why people who wear cloth masks still get sick and transmit. It's airborne.
The new variants only produce many more viron per droplet, they dont do anything to be more airborne other than through this mechanism. It does of course mean it takes far less exposure to catch the virus, but it doesnt mean the viruses are suddenly existing outside of droplets..
@freemo @torresjrjr @NEETzsche @mkljczk @ducheng
>"Read the data not the commentary. Normal breathing was shown in their study to produce virtually no aerosol. Any commentary about it is moot against the data."
Do you mean that chart from the 1945 study of >1um particles? Specifically which data -- it's a long article.
>"False the study clearly shows in its data that normal breathing produces virtually no aeresol (<5um) or droplet (>5um), period!"
Again, it's an overview article covering a lot of material. Exactly where in there is that data?
>"There is no reason to think that all of a sudden post-delta variants can magically exist outside of a droplet. The only difference of consequence is the density of the virus is much much higher."
I said post-alpha, not post-delta. There are a lot of differences, not just density (if you mean viral load per particle -- mass/volume density also plays into, too, with regard to settle time). The ability of the outer proteins to protect the RNA inside the virus and the ability the spike proteins to attach and get the RNA into the cells is also a big factor. It's not just viral load.
The point is that if a sick person breathes or talks, with or without a cloth mask, they'll put particles with virus into the air. That's how it's transmitted -- sick people breathe it out, and potential hosts breathe it in. It's airborne.
Also, viruses are not just protected by small water molecules which quickly evaporate, there are also larger molecules -- proteins, peptides, lipids, and glycoconjugates of those and other large molecules in those particles that can help or hinder the virus. It's not just water.
I dont have the study nearby, on my phone
Yes i do agree that it transmits aggressively through aerosol. Normal breathing through the nose is likely not a danger, but even talking softly at close distance is.
The point is the virus does not have anything new in later variants allowing it to survive outside droplets nor is it truly airborne. The viral load is just so high that even small droplets can infect.
It is not like smoke though which is truly airborne, the half life on droplets are about an hour, smoke would last much longer.
@freemo @torresjrjr @NEETzsche @mkljczk @ducheng
Yes, talking likely produces more particles because of the vocal cords shaking off a bunch stuff (using scientific terms - #humor).
Smoke does last longer -- so if you use that as an analogy, and tell people to act like they are avoiding smoke -- then they will also be protected against the virus, which is less pervasive.
Yes, you have to dig into the articles to understand what they offer. Many times the studies don't offer much additional to the body of knowledge because of how they designed, etc.
One thing I know for sure, most reporters who cover this area are certainly not up to the task. The same could probably be said about those who are in policy-making positions as well.
@freemo @torresjrjr @NEETzsche @mkljczk @ducheng
Pre-covid research (mostly influenza) focused on transmisiblity due to particle size, i.e., that stopping "droplets" would stop the virus because they thought smaller particles would not be viable, but since the start of the pandemic they've completely changed that paradigm...
-------
quote:
"Recent studies indicates that aerosol transmission of the severe acute respiratory
42 syndrome coronavirus 2 (SARS-CoV-2) is plausible since the virus can remain viable and
43 infectious in aerosol form for hours.
"Is the Current N95 Respirator Filtration Efficiency Test Sufficient for Evaluating
Protection Against Submicrometer Particles Containing SARS-CoV-2?
3
4 Changjie Cai 1,* , Evan L. Floyd 1 , Kathleen A. Aithinne 1 , Toluwanimi Oni 1
5 1
6
7
Department of Occupational and Environmental Health, University of Oklahoma
Health Sciences Center, University of Oklahoma, Oklahoma City, Oklahoma 73104,
USA
8
9
10
To be submitted to:
Revised on June 8, 2020
citing:
1. van Doremalen N, Bushmaker T, Morris DH, Holbrook MG, Gamble A, Williamson
179 BN, et al. Aerosol and surface stability of SARS-CoV-2 as compared with SARS-
180 CoV-1. New England Journal of Medicine. 2020; DOI: 10.1056/NEJMc2004973
181
2. Asadi S, Bouvier N, Wexler AS, & Ristenpart WD. The coronavirus pandemic and
182 aerosols: Does COVID-19 transmit via expiratory particles? Aerosol Science and
183 Technology, 2020; 54(6), 635-638.
@freemo @torresjrjr @NEETzsche @mkljczk @ducheng
This was an interesting discussion, I'm tagging with some tags to make it more discoverable.
#COVID19 #virus #airborne #science
#vax #vaccine #masks #respirator
#respirators #coronavirus
@freemo @torresjrjr @NEETzsche @mkljczk @ducheng
I remember reading that first study you cited (Jayaweera, et al., 2020 Jun 13), and I've used it in helping to form my understanding. It said, "In general, infected people spread viral particles whenever they talk, breathe, cough, or sneeze."
Breathe.
I don't like to use the words "aerosol" and "droplet" because, as that study said, those terms mean different things to different people. When an infected person breathes they shed virus within sub-micron particles. Period.
That second study (Morawska L, Cao J. 2020 Apr) which studied COVID transmisability and made a claim about viability in particles with little or no H2O, that was studying pre-delta variants.
As I said, the newer variants are better at surviving in the air, that's why the R0 is so high, why people who wear cloth masks still get sick and transmit. It's airborne.