SEARCH
SARS-CoV-2 aka COVID-19: Studies of Transmission via Coughing and Sneezing offer Compelling Evidence to Require Facial Coverings
Related: cognitive commitment, confirmation bias, health, particulate respirators and masks, SARS-CoV-2 aka COVID-19 aka Coronavirus
SARS-CoV-2 is the virus; COVID-19 is the disease.
COVID-19: Public Policy MUST be Changed: Facial Coverings should ALWAYS be Worn To Protect Others
COVID-19 (SARS-CoV-2): the Tide is Turning for Facial Covering / Mask Official Recommendations
Reader Bob Z writes with two links which makes it head-scratcher as to why some kind of facial covering or mask is not mandatory in any place frequented by the public during this pandemic.
JAMA: Turbulent Gas Clouds and Respiratory Pathogen Emissions Potential Implications for Reducing Transmission of COVID-19
Recent work has demonstrated that exhalations, sneezes, and coughs not only consist of mucosalivary droplets following short-range semiballistic emission trajectories but, importantly, are primarily made of a multiphase turbulent gas (a puff) cloud that entrains ambient air and traps and carries within it clusters of droplets with a continuum of droplet sizes (Figure; Video).
The locally moist and warm atmosphere within the turbulent gas cloud allows the contained droplets to evade evaporation for much longer than occurs with isolated droplets. Under these conditions, the lifetime of a droplet could be considerably extended by a factor of up to 1000, from a fraction of a second to minutes.
... Owing to the forward momentum of the cloud, pathogen-bearing droplets are propelled much farther than if they were emitted in isolation without a turbulent puff cloud trapping and carrying them forward. Given various combinations of an individual patient’s physiology and environmental conditions, such as humidity and temperature, the gas cloud and its payload of pathogen-bearing droplets of all sizes can travel 23 to 27 feet (7-8 m).
DIGLLOYD: those distance figures make MUCH more sense to me. I could not have said how far but it’s obvious that 6 feet 2m was never realistic.
In the cloud: How coughs and sneezes float farther than you think
: A novel study by MIT researchers shows that coughs and sneezes have associated gas clouds that keep their potentially infectious droplets aloft over much greater distances than previously realized.
“When you cough or sneeze, you see the droplets, or feel them if someone sneezes on you,” says John Bush, a professor of applied mathematics at MIT, and co-author of a new paper on the subject. “But you don’t see the cloud, the invisible gas phase. The influence of this gas cloud is to extend the range of the individual droplets, particularly the small ones.”
Indeed, the study finds, the smaller droplets that emerge in a cough or sneeze may travel five to 200 times further than they would if those droplets simply moved as groups of unconnected particles — which is what previous estimates had assumed. The tendency of these droplets to stay airborne, resuspended by gas clouds, means that ventilation systems may be more prone to transmitting potentially infectious particles than had been suspected.
...Their conclusions upend some prior thinking on the subject. For instance: Researchers had previously assumed that larger mucus droplets fly farther than smaller ones, because they have more momentum, classically defined as mass times velocity.
DIGLLOYD: in science, assumptions are a Very Bad Idea.
I am glad to see real science confirm what I assumed all along, that droplets have a far broader range than believed. That the droplet lifespan is much longer than believed by a factor of up to 1000 compounds the significance geometricaly: longer lifespan multiplied by much broader distribution might mean 10000 times more risk than assumed.
Remember all those people returning home a month ago, packed in like sardines at customs? Think of the awesomely high risk of infection by airborne means under those conditions.
Fndings like these suggest that the main driver of COVID-19 infection is airborne transmission*. There never has been any credible alternative explanation, and that should have been obvious from the start, hence my January29 recommendation for masks.
The failure of public health officials to mandate the use of facial coverings in public places during this pandemic was and is in my view medical malpractice.
Obviously when a mask blocks the yuck, spread is massively reduced. In that post, I had written “I’d guess 100 times higher than if that cough had been blocked by a facial covering”). It should be obvious to anyone with a few neurons still firing that blocking a violent spewing of respiratory yuck with any covering is vastly superior to an unrestricted blast. Hence the “cough into your elbow” advice. I can’t see how it takes much mental effort to make the connection between “cough into your elbow” and wearing a facial coverings. The WHO, CDC, Surgeon General are not as abjectly stupid as they appear to be, but something far more diseased.
Would COVID-19 could have been hugely reduced in spread and many lives saved if only the so-called experts in the WHO and CDC had not been so pedantically dogmatic and presumptuous about their knowledge?
* By “airborne transmission” I mean both spread directly through the air as well as the contamination of surfaces (deposition of virions through the air). Though the key tranmission vectors as yet remain unproven, no other explanation makes sense, and 'airborne' dovetails perfectly with the high infection rates seen for passengers isolated on cruise ships yet infected anyway—ventilation system!
