LOLWUT?
Duke's data shows cotton masks are VERY effective, particularly multi-layer ones.
Three-layer surgical masks and cotton masks, which many people have been making at home, also performed well.
This is what I'd posted for you in other threads.
Do you read what you post, or just "headlines"?
For the control trial (green curve), the five distinct peaks correspond to the five repetitions of the operator speaking. In the case of speaking through a mask, there is a physical barrier, which results in a reduction of transmitted droplets and a significant delay between speaking and detecting particles. In effect, the mask acts as a temporal low pass filter, smoothens the droplet rate over time, and reduces the overall transmission. For the bandana (red curve), the droplet rate is merely reduced by a factor of two and the repetitions of the speech are still noticeable. The effect of the cotton mask (orange curve) is much stronger. The speech pattern is no longer recognizable and most of the droplets, compared to the control trial, are suppressed.
Mask, Name,Description
1, ‘Surgical’ *Surgical mask, 3-layer
2, ‘Valved N95’N95 mask with exhalation valve
3, ‘Knitted’Knitted mask
4, ‘PolyProp’2-layer polypropylene apron mask
5, ‘Poly/Cotton’Cotton-polypropylene-cotton mask
6, ‘MaxAT’ 1-layer Maxima AT mask
7, ‘Cotton2’ 2-layer cotton, pleated style mask
8, ‘Cotton4’ 2-layer cotton, Olson style mask
9, ‘Cotton3′ 2-layer cotton, pleated style mask
10, ‘Cotton1’ 1-layer cotton, pleated style mask
11, ‘Fleece’Gaiter type neck fleece
12, ‘Bandana’ *Double-layer bandana
13, ‘Cotton5′ *2-layer cotton, pleated style mask
14, ‘Fitted N95’N95 mask, no exhalation valve, fitted
‘Swath’ Swath of mask material, polypropylene
‘None’ *Control experiment, no mask
Literally, if 2 people are wearing masks, the relative protection - EVEN in close contact, is about 0.1 x 0.1 = 0.01 the droplet amounts vs No Masks.
https://advances.sciencemag.org/content/early/2020/08/07/sciadv.abd3083
