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

Sun Jun 14 16:31:45 EDT 2020

Excellent question, but it doesn't appear to be addressed in this study, 
Richard.  I think they were simply trying to get some sense of the 
magnitude of the problem.  Some commercial masks have numbers associated 
with them (like the N95 masks), but the sheer variety of potential 
materials for home made masks would make that second step a time 
consuming task, so I suspect the next phase won't come as quickly.  At 
least the droplet size and density has some specificity that could be 
compared with typical mask materials and numbers of layers.

On 6/14/2020 3:04 PM, Richard Knoppow wrote:
> 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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>

-- 
Michael Hanz - KC4TOS