View source for Masks as Protection from Infection


[https://aapsonline.org/mask-facts/ Mask Facts], AAPS,  extracts without indication here: 
{{Quotation|
A COVID-19 (SARS-CoV-2) particle is 0.125 micrometers/microns (µm); influenza virus size is 0.08 – 0.12 µm; a human hair is about 150 µm.<br>
Larger respiratory droplets (>5 µm) remain in the air for only a short time and travel only short distances, generally <1 meter. They fall to the ground quickly.  Small (<5 µm) aerosolized droplets can remain in the air for at least 3 hours and travel long distances (up to 27 ft.).  Since 1961, experiments showed that viral-pathogen-carrying droplets were inactivated within shorter and shorter times as ambient humidity was increased. Dryness drives the small aerosol particles. 

HEPA (high efficiency particulate air) filters are 99.97 to 100% efficient. HEPA filters are tested with particles that are 0.125 µm (the size of SARS-CoV-2). Surgical masks are loose-fitting devices that were designed to be worn by medical personnel to protect accidental contamination of patient wounds, and to protect the wearer against splashes or sprays of bodily fluids. They aren’t effective at blocking particles smaller than 100 µm.

N95 filtering facepiece respirators (FFRs) are constructed from electret (a dielectric material that has a quasi-permanent electric charge.) An electret generates internal and external electric fields so the filter material has electrostatic attraction for additional collection of all particle sizes. As flow increases, particles will be collected less efficiently.

All the cloth masks and materials had near zero efficiency at 0.3 µm, a particle size that easily penetrates into the lung (SARS-CoV-2 is 0.125 µm)
Efficiency for the entire range of particles
T-shirts — 10%
Scarves — 10% to 20%
Cloth masks — 10% to 30%
Sweatshirts — 20% to 40%
Towels — 40%

Study measuring filter efficiency (2014, Korea)
https://aaqr.org/articles/aaqr-13-06-oa-0201
Evaluated 44 masks, respirators, and other materials with similar methods and small aerosols (0.08 and 0.22 µm)
N95 FFR filter — >95% efficiency
Medical masks — 55% efficiency
General (cloth) masks — 38% efficiency
Handkerchiefs — 2% (one layer) to 13% (four layers) efficiency.

The cloth that serves as the filtration for the mask is meant to trap particles being breathed in and out. But it also serves as a barrier to air movement because it forces the air to take the path of least resistance, resulting in the aerosols going in and out at the sides of the mask.

Randomized clinical trial of standard medical/surgical masks in health care workers (2010, Australia).
[https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1750-2659.2011.00198.x?fbclid=IwAR3kRYVYDKb0aR-su9_me9_vY6a8KVR4HZ17J2A_80f_fXUABRQdhQlc8Wo.
Study] was spurred by the H1N1 flu. While N95 masks offered protection against respiratory illness, medical mask wearers and control group numbers were similar.

[https://www.acpjournals.org/doi/10.7326/M20-1342 A study of 4 patients (July 2020, South Korea).]
Known patients infected with SARS-CoV-2 wore masks and coughed into a Petrie dish. “Both surgical and cotton masks seem to be ineffective in preventing the dissemination of SARS–CoV-2 from the coughs of patients with COVID-19 to the environment and external mask surface.”
}}
Studied different types of face coverings in non-clinical setting (August 2020).
[https://advances.sciencemag.org/content/early/2020/08/07/sciadv.abd3083
They used] a black box, a laser, and a camera. A person wears a face mask and speaks into the direction of an expanded laser beam inside a dark enclosure. Droplets that propagate through the laser beam scatter light, which is recorded with a camera. A simple computer algorithm then counts the droplets seen in the video.
The N95 led to a droplet transmission of below 0.1%.
Cotton and polypropylene masks, some of which were made from apron material showed a droplet transmission ranging from 10% to 40%.
Knitted mask had up to 60% droplet transmission.
Neck fleece had 110% droplet transmission (10% higher than not wearing a mask).
Speaking through some masks (particularly the neck fleece, bandanas) seemed to disperse the largest droplets into a multitude of smaller droplets … which explains the apparent increase in droplet count relative to no mask in that case.

[https://sentinelksmo.org/more-deception-kdhe-hid-data-to-justify-mask-mandate/
In Kansas, ] the 90 counties without mask mandates had lower coronavirus infection rates than the 15 counties with mask mandates. To hide this fact, the Kansas health department tried to manipulate the official statistics and data presentation.

Stanford engineers estimated that N95 masks cause a 5% to 20% reduction in O2 intake. This can cause dizziness and lightheadedness. 

----
If lockdowns and masks had an effect on covid, they should also have an effect on the incidence of colds and other infectious diseases. Eventually,  if the CDC collects that data, maybe we'll be able to see.
----