How SARS-CoV-2 spreads: new science

[Hoodsail]

Regarding pursuit of a Covid-19 "free" hospital if you require acute care, investigate the sophistication of the institution, if you are admitted. Some hospitals have negative-pressure rooms throughout, like Smilow Cancer Center - Yale New Haven Hospital here in CT. This center was converted over 100% to Covid-19 pts with cancer pts moved to other institutions. That was back early on in the pandemic, but would expect its an option around the world and maybe again with current infections/hospitalizations on the increase. Can be a difficult decision to pursue acute care while weighing risk of infection.

[TBear60]

One thing you're not discussing here is the difference between particle droplets and aerosolized particles. Huge difference in terms of transmission distance and filtering; whether with masks (what kinds of masks) and AC filtration. Droplets are large moist particles that are stopped from travelling by the simplest of masks on the wearer (eg. I sneeze and push out droplets, which are stopped from travelling beyond my mask.) Aerosolized particles however, will easily pass through most masks (not N95) and can then travel a greater distance in moving air. "Unmasked" droplets cannot travel as far whether or not the air is moving; too heavy. Look at the science behind Gortex to see these differences! The next question is how infectious that droplet or aerosolized particle is and how long the virus contained therein can survive outside a host!
Many questions still unanswered from the scientific community!
Simple protections: distance and masking!

[ikanode]

The article isn't necessarily about aerosolized transmission. Even droplets (which are understood to be the main means of transmission) can be carried on interior air flows.

" Traditionally, droplets are defined as large (>5 microns) aqueous bodies. However, airborne (or aerosolized) transmission of the virus has been proposed as a source of infection almost since the inception of the COVID pandemic. By comparison to droplets, aerosolized particles are infinitesimal." Read the full article!
https://www.pennmedicine.org/updates...debate-article


Good air conditioner filters will stop droplets but if you're downwind of someone with covid, the filtration hasn't happened yet.

" MERV 13 AIR FILTERS
Traps and blocks 98% of airborne particles as small as 0.3 microns. Recommended for superior residential and commercial use and smoke lounges."
--from a product page but there are many brands

[jmschmidt]

Roger that. If there is a 30K wind blowing and you are six feet, or 600ft, down wind of an infected person it maybe possible to catch the virus, but if you are up wind, two feet might be enough to insolate you.

[malcolmlj]

From "The Spectator" magazine last week.
So far Covid 19 has killed 0.015% of 1% of the worlds population.

Helps with perspective.

[darylat8750]

Originally Posted by Gaia

Correct, AC units do not filter virus sized pathogens or virus sized anything. Nor do masks. Nor do almost anything else. What they both do filter to some helpful extent is droplets of water from the very small to visible size, that might contain the incredibly tiny virions.

They might do a better job of it if the filter fibres were coated with a surfactant, like soap. The surfactant would immediately kill the virus as well as trapping it but that is off the topic.

Jim sv Gaia

Does soap kill virus ?

[Franziska]

Perspective is in the eye of the beholder. If you or your next are part of those 0.015% it's terrible.
If one is responsible for one of the folks belonging to those 0.015% it's almost as bad.

Originally Posted by malcolmlj

From "The Spectator" magazine last week.
So far Covid 19 has killed 0.015% of 1% of the worlds population.

Helps with perspective.

[Wotname]

Originally Posted by darylat8750

Does soap kill virus ?

Short answer - yes.

Long answer - it's more complicated than that but I'll leave it to the experts give the longer answer.

[canyonbat]

Originally Posted by NedX

Anyway, my point in posting it was to show the picture. You can give the thread 0 stars.

Oh cool! I can’t wait to start rating threads!

[Cadence]

I'd guess is someone expelling it directly close to you. If the air circulation is true? Don't fly.

[Djarraluda]

CIBSE and ASHRAE are the biggest most respected English language professional engineering organisations for a/c and vent. We have been studying this and publishing papers on it for many months. Yes, airflow direction affects droplet spread. Correct, ordinary filters don’t deal with the virus sized particles. We can and do use UV sterilisation in sensitive areas. COVID 19 has overwhelmed probably every hospital in the world in terms of negative pressure isolation rooms but... Research has been showing a major contributor to indoor contamination is a Lack of Fresh Air. Many countries have encouraged minimal fresh air for years as an energy conservation means. We have been fighting for better / higher minimum outside air flow rates and better consideration of intakes and exhausts. In Au’s. Outside air rates had dropped to 5l/s/person or less in bad designs non-compliant to standards. 10 is the recommended minimum. Sadly, proper research and peer reviewed papers take time to reach folk and even longer to reach legislation or Standards. The summary though is that fresh air is good, it dilutes concentrations and thus minimises risk.
Roger

[NedX]

Originally Posted by darylat8750

Does soap kill virus ?

Here's the scientific explanation of why washing with soap for 20 seconds works.

https://news.northeastern.edu/2020/0...from-covid-19/

Of course soap only helps clean your hands and prevents you from touching your eyes/nose/mouth with a contaminated hand (which is not the primary way SARS-CoV-2 is transmitted.)

[NedX]

Originally Posted by TBear60

One thing you're not discussing here is the difference between particle droplets and aerosolized particles. Huge difference in terms of transmission distance and filtering; whether with masks (what kinds of masks) and AC filtration. Droplets are large moist particles that are stopped from travelling by the simplest of masks on the wearer (eg. I sneeze and push out droplets, which are stopped from travelling beyond my mask.) Aerosolized particles however, will easily pass through most masks (not N95) and can then travel a greater distance in moving air. "Unmasked" droplets cannot travel as far whether or not the air is moving; too heavy. Look at the science behind Gortex to see these differences! The next question is how infectious that droplet or aerosolized particle is and how long the virus contained therein can survive outside a host!
Many questions still unanswered from the scientific community!
Simple protections: distance and masking!

Excellent points all. What's significant about the Korean study is that virus particles expelled by diners were able to infect diners sitting way farther way than six feet, and the explanation of how it happened.

Masks are irrelevant here, as are the size of particles, since whatever size they were, they got to the other diners; the whole "fall-to-the-ground" theory, which led to the six-foot-rule, is what's being indicted. The six-feet rule should go the way of disinfecting your mail; great idea, not enough and not helpful if you aren't taking the really important precautions that we know work.

[NedX]

Originally Posted by Djarraluda

CIBSE and ASHRAE are the biggest most respected English language professional engineering organisations for a/c and vent. We have been studying this and publishing papers on it for many months. Yes, airflow direction affects droplet spread. Correct, ordinary filters don’t deal with the virus sized particles. We can and do use UV sterilisation in sensitive areas. COVID 19 has overwhelmed probably every hospital in the world in terms of negative pressure isolation rooms but... Research has been showing a major contributor to indoor contamination is a Lack of Fresh Air. Many countries have encouraged minimal fresh air for years as an energy conservation means. We have been fighting for better / higher minimum outside air flow rates and better consideration of intakes and exhausts. In Au’s. Outside air rates had dropped to 5l/s/person or less in bad designs non-compliant to standards. 10 is the recommended minimum. Sadly, proper research and peer reviewed papers take time to reach folk and even longer to reach legislation or Standards. The summary though is that fresh air is good, it dilutes concentrations and thus minimises risk.
Roger

This is very helpful, Roger.
The good news is that scientists all over the world are going hell bent for leather to figure this thing out. Every thing we still don't know/can't get to is something thousands of experts are working on. (The epidemiologists I work with, optimists all, tell me this constantly.)

[bjp447]

I will bet Dr Fauci has a forum where you can discuss this till your hearts content
So can you go there so we can go back to boats. BTW if you just watch the news someone on some channel is pontificating about this study and a 100 others every day!