Also I notice he doesn't have references for droplet size?
https://www.thelancet.com/action/showPdf?pii=S2213-2600%2820%2930323-4"Although surgical masks offer little protection from
inhaled agents, they have a role in protecting healthcare workers when worn by patients. Placing surgical
masks on patients with multidrug-resistant tuberculosis
decreased transmission to guinea pigs by 56%,138 and
masking of patients with cystic fibrosis reduced
P aeruginosa air contamination by 8%.139 Surgical masks
reduced the quantity of influenza viral RNA by 2·8 times
Viewpoint
www.thelancet.com/respiratory Vol 8 September 2020 921
in small particles and by 25 times in large ones.45 More
recently, surgical masks effectively reduced large droplets
(>5 µm) of seasonal coronaviruses from three of ten
patients to 0 of 11 (p=0·09) and small aerosols (<5 µm)
from four of ten patients to 0 of 11 (p=0·04).47 Similarly,
surgical masks reduced droplets of influenza from six of
23 to one of 27 (p=0·04). However, the reduction in
influenza small aerosols (<5 µm) was not significant.
There is mounting evidence suggesting that the wearing
of masks can reduce transmission of SARS-CoV-2 in community and health-care settings.
Thats by Kevin P Fennelly Pulmonary Branch, Division of
Intramural Research, National
Heart, Lung, and Blood
Institute, National Institutes of
Health, Bethesda, MD, USA