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

Scott Robinson spr at earthlink.net
Sun Jun 14 16:48:13 EDT 2020 

Atmy local supermarket for sure, and, I think, at most other other 
stores as well, the rule is: no mask, no entry. This may be local (Marin 
County, California) regulation, but seems like a good idea to me.

/scott robinson

On 6/14/20 1:42 PM, Bill Cromwell wrote:
> Hi,
> 
> The differences between N95 and my bandanna are irrelevant since I 
> cannot get even one N95 mask. It won't work with my beard anyway and the 
> bandanna covers most of my beard. All due respect to Ken, I will do the 
> best I can with what I actually have available. At the local store we 
> call maskless people "nudists". We stay as far from them as we can.
> 
> 73,
> 
> Bill  KU8H
> 
> bark less - wag more
> 
> On 6/14/20 4:31 PM, Michael Hanz wrote:
>> 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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>>>
>>
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