Little John wrote:So, back to those pesky facts....
Really ?
Little John wrote:
Assuming Covid19 may be transmitted asymptomatically (for which there is no evidence as yet presented as far as I know
https://jamanetwork.com/journals/jamain ... le/2769235 Little John wrote:but which I more than happy to be pointed to if such evidence if exists - more on that later), then the virus particles would be transmitted in something called "aerosols". Such aerosols are as small as 0.004mm. That is 4,000th of a single millimeter. Just let that sink in for a second.
Actually that's 4 x 1000th of a mm, but that's not relevant, experts who have studied respiratory protection for decades explain: "The N95 filter indeed is physically around the 0.3 micron size. But that doesn’t mean it can only stop particles larger than that. The masks are actually best for particles either larger or smaller than that 0.3 micron threshold.
“N95 have the worst filtration efficiency for particles around 0.3,� Marr said. “If you’re smaller than that those are actually collected even better. It’s counterintuitive because masks do not work like sieving out larger particles. It’s not like pasta in a colander, and small ones don’t get through.�
N95 masks actually have that name because they are 95% efficient at stopping particles in their least efficient particle size range — in this case those around 0.3 microns.
Why do they work better for smaller ones? There are a number of factors at play, but here are two main ones noted by experts:
The first is something called “Brownian motion,� the name given to a physical phenomenon in which particles smaller than 0.3 microns move in an erratic, zig-zagging kind of motion. This motion greatly increases the chance they will be snared by the mask fibers.
Secondly, the N95 mask itself uses electrostatic absorption, meaning particles are drawn to the fiber and trapped, instead of just passing through.
“Although these particles are smaller than the pores, they can be pulled over by the charged fibers and get stuck,� said Professor Jiaxing Huang, a materials scientist at Northwestern University working to develop a new type of medical face mask. “When the charges are dissipated during usage or storage, the capability of stopping virus-sized particles diminishes. This is the main reason of not recommending the reuse of N95 masks.�
https://eu.usatoday.com/story/news/fact ... 343537002/
Little John wrote:
Thus, a virus particle in an aerosol could conceivably pass through a cheap paper or cloth mask in a manner akin to a bee flying through a chicken wire fence.
Unlikely, see above.
Little John wrote:
But, all of that is moot anyway since, given the above issue with aerosols, any mask must be fully airtight because such aerosols, being lighter than air, can float about for long periods and will drift wherever air flow pulls them. You know... round corners, into other rooms, round the edges of non airtight face-masks..... that kind of thing. Getting the picture yet?
To be precise, the kind of face-covering required to properly protect from virus aerosols is:
N99.5 A2P3 air-tight, face-fitted (clean shaven required) respirator including round the eye sockets and ideally with positive air pressure.
Minimum requirement.
Anything else is bollocks. It's as simple as that.
Your guidelines offer the highest possible protection, but less than perfect protection is still a benefit.
Little John wrote:As for larger saliva droplets, which are large enough to be subject to gravity and so will typically only travel around 2 meters (social distancing....remember that?), they will only be in evidence if someone is symptomatic (you know.... coughing and sneezing in your direction) But, if someone is symptomatic, they should not even be out and about. Instead, they should be self isolating for 7 to 10 days.
So people without symptoms never sneeze, cough, shout, sing ? Asymptomatic or, more accurately, pre-symptomatic transmission is real:
https://jamanetwork.com/journals/jamain ... le/2769235 "Many individuals with SARS-CoV-2 infection remained asymptomatic for a prolonged period, and viral load was similar to that in symptomatic patients; therefore, isolation of infected persons should be performed regardless of symptoms."
Little John wrote:This virus, in its current strain, is dangerous to the very old and frail or just the very frail. But that's it.
Nope. Once again you confuse "dangerous" with "fatal", it's dangerous to many demographics :
https://www.healthcentral.com/article/l ... oronavirus .
Little John wrote:The entire edifice of rationale on which the legally coerced muzzling of people in public spaces who are not elderly or frail and are in all ways either non-symptomatic or asymptomatic is bollocks from top to bottom.
This is not about safety. It is about compliance.
Hmmmm.
