[ARC5] AB5S Kung Flu Update, 13 June - source?

Sun Jun 14 15:04:54 EDT 2020

    Were there any tests of speakers using conventional masks? 
The difference made by the masks would be important.

On 6/14/2020 11:54 AM, Michael Hanz wrote:
> That pretty much aligns with my view, Scott, with the addition 
> of information from an interesting study about aerosols 
> produced by simply "normal" talking, reported at 
> https://www.nytimes.com/2020/05/14/health/coronavirus-infections.html 
> (The National Academy of Sciences detailed report is at 
> https://www.pnas.org/content/117/22/11875 ).
>
> The gist of the article was:
> "To see how many droplets are produced during normal 
> conversation, researchers at the National Institute of Diabetes 
> and Digestive and Kidney Diseases and the University of 
> Pennsylvania, who study the kinetics of biological molecules 
> inside the human body, asked volunteers to repeat the words 
> “stay healthy” several times. While the participants spoke into 
> the open end of a cardboard box, the researchers illuminated 
> its inside with green lasers, and tracked bursts of droplets 
> produced by the speaker.
>
> The laser scans showed that about 2,600 small droplets were 
> produced _per second_ while talking. When researchers projected 
> the amount and size of droplets produced at different volumes 
> based on previous studies, they found that speaking louder 
> could generate larger droplets, as well as greater quantities 
> of them.
>
> Although the scientists did not record speech droplets produced 
> by people who were sick, previous studies have calculated 
> exactly how much coronavirus genetic material can be found in 
> oral fluids in the average patient.  Based on this knowledge, 
> the researchers estimated that a single minute of loud speaking 
> could generate at least 1,000 virus-containing droplets."
>
> Here's a picture of the test setup:
>
>
> That makes it even more than a courtesy to wear a mask, 
> especially since most coronavirus spreaders aren't even aware 
> when they are in the early stages of their infection.  The 
> cloth masks are indeed not perfect, but they are only intended 
> to reduce the frequency of the much larger droplets, not the 
> much smaller virus which is attached to them.
>
> - Mike  KC4TOS
>
>
> On 6/14/2020 2:00 PM, Scott Johnson wrote:
>> I consider the primary reason for masks, or bandanas, or whatever, not to
>> protect yourself, but to protect other from you.  It is a courtesy, if you
>> sneeze, cough, or slobber when you talk, it effectively prevents the aerosol
>> from going further than the fabric.  Not wearing anything in proximity to
>> the public identifies one as  careless and reckless.  If you are in a high
>> risk group, and truly worried about your own safety, then you shouldn't be
>> exposing yourself needlessly.  I have heard so many opinions, some that are
>> diametrically opposed, and all from supposed experts.  Don't care to hear
>> any more. Common sense coupled with common decency should prevail.  BTW, one
>> of my engineers did a CFD model in Solidworks of a sneeze in a room with
>> closed loop HVAC.  It propogates and dissipates pretty much like a fart.
>>
>> Scott V. Johnson W7SVJ
>> 5111 E. Sharon Dr.
>> Scottsdale, AZ 85254-3636
>> H (602) 953-5779
>> C (480) 550-2358
>> scottjohnson1 at cox.net
>> scott.johnson at ieee.org
>>
>> -----Original Message-----
>> From:arc5-bounces at mailman.qth.net  <arc5-bounces at mailman.qth.net>  On Behalf
>> Of Hubert Miller
>> Sent: Saturday, June 13, 2020 11:21 PM
>> To:arc5 at mailman.qth.net
>> Subject: Re: [ARC5] AB5S Kung Flu Update, 13 June - source?
>>
>> Generally good advice, but I question the non-cough non-sneeze 26 foot
>> business, no matter what your doctor said.
>> I have read several articles in the New York Times precisely on this
>> question, and those articles are well informed, very well informed,
>> frequently updated. Ask your doctor his source for his information. I recall
>> now they also had an article comparing actual effectiveness of different
>> kinds of masks, both homemade and commercial, and gave actual numbers
>> compared to N95, and what thickness required even with homemade.
>> Also, masks are dry material, so what is your informed reckoning of how long
>> virus lives on them ?
>> As for health professionals dying despite masks, well, you would have to
>> know the extent of their exposure and their full suiting equipment to assign
>> this to mask inefficiency.
>> Don't forget UV exposure either, to kill virus. These parameters apply
>> outside also.
>> I found Elderberry anything to be pretty much sold out locally last time I
>> shopped, but I'll take another look in the next days.
>> -Hue Miller
>>
>>
>>
>>
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>
> -- 
> Michael Hanz - KC4TOS
>
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