Knowledge????

On Wednesday, 30 December 2020 at 15:18:26 UTC, Eric Greenwell wrote:
2G wrote on 12/29/2020 11:34 PM:
On Tuesday, December 29, 2020 at 6:30:38 PM UTC-8, Guy Acheson wrote:
The politics of Covid is astounding.

For those of you who question the effectiveness of masks...oh my

I am a dentist. We have been wearing masks 100% of the time in our offices from the beginning.
We require all patients/delivery persons/anyone who enters our office to be wearing a mask that covers BOTH their mouth and nose.
No...we do not allow mouth shields or face shields in place of a mask. They are not the same thing at all.

From January 2020 through September 2020, less than 1% of all people who work in a dental office have tested positive for Covid.
A dental office is probably the most dangerous place you could be with regards to an airborne infectious particle.
Our handpieces blow air in the mouth which ejects the oral contents into the surrounding air in a mist.
Our instuments to clean teeth (ultrasonic scalers) create the finest of mists.
Yet, less than 1% have tested positive. Remember, all these people spend most of their time outside of the dental office so it speaks well of their behaviour outside of the office also.

I took a walk today in my town's park. Here in California we are having the most significant of all Covid surges. My local hospitals have ICUs that are 100+% full.
The dog park had more people than I have seen in many months. AND...there were less masks inside that dog park than inside my car.

That is why we are having this problem.

Now, let us talk about soaring.

The gold-standard mask, the N-95 (which you can't get), properly worn and fitted, filters particles down to 135 nm; coronavirus particles are 70-90 nm.. Let's go more extreme, the Stryker Flyte Helmet (https://www.stryker..com/us/en/ortho...on-system.html) used in high-risk areas for its filtered air supply; this helmet IS INEFFECTIVE in protecting wearers from COVID (https://link.springer.com/article/10...-020-04796-3):

"Sterile surgical helmet systems (SSHS) do not protect against aerosol particulate and therefore are not efficacious in protection against COVID-19. The fan system employed may even increase risk to the surgeon by drawing in particulates as well as delay recognition of intraoperative cues, such as exhaust from diathermy, that point to respirator mask leak."

Now, tell me again how effective those cheap, throw-away masks are.

Tom
Wearing effective masks, like N-95, might allow instruction to begin sooner than later, if both
instructor and student wore them. N-95 masks are generally still in short supply, but that may
change in the next few months, about the time our (northern hemisphere) flying season begins.
Some KN-95 masks, which are readily available now, might also be suitable, but the suitability
specific KN-95 masks is harder to determine; hopefully, that will change.
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

Do not use N95 or KN95 masks with expiratory valves. They are protective for the user but project out a jet of potentially viral loaded aerosol or droplet spray. That might be acceptable e.g. for medics treating already infected patients but not for community protection.

2G commented on the particle filtration parameter of N95 being slightly larger than the viral diameter. That is irrelevant - we don't expire individual dry viral particles. The object is to filter out the viral loaded aerosol or droplet particles. Aerosol droplets have around 30-50 times larger diameter than the virus - and droplets much larger than that. A well fitted cloth mask is a lot better than no mask for the same reason.

Kudos to Guy Acheson who clearly has the knowledge as well as skin (literally) in the game.

The value of the use of measures such as masks was understood a century ago during the 1918 influenza epidemic and there were the same issues of variable regulations and recommendations within and between countries - and the same variable compliance. Many articles attest to this. Try:

https://theconversation.com/face-mas...pulsory-137648

Next time round I hope that the lessons are learned: early and widespread adoption of even less than perfect measures e.g. masks, social distancing, hand washing, adequate fresh air ventilation (not just air-con), testing, tracking, tracing and quarantining, would make a huge difference. That's the other side of the exponential spread coin. Most of these are things that all individuals can enact themselves.