They did not work. The aerosol went in different directions and hung in the air. The point being is that masks do not work in containing aerosol which is the medium that Wuhan uses to get around. The slightest of breezes from an air conditioner, fan or even a door closing or someone just walking by is enough to spread it. Masks will prevent droplets from shooting at someone but so will someone sneezing into their elbow or turning their head.
It’s not about individual particles. It’s about quantity.
Every human on earth by now has probably inhaled a single Chinese flu virus. It got exhaled or failed to attach or whatever.
There is way too much talk of age and comorbidities. Truth is lots of old people who are very sick have tested positive, had some symptoms and walked away. How? Their initial dosage was not high. A high enough initial dose will kill a 22 year old (did you know 20% of total deaths from Covid have been < 65 yrs old, 20% is a lot).
Masks will reduce the initial dose. That’s what saves life. Even if it were naked virus, filters are defined by 95% stoppage. 5% would get thru, and that’s a lower dose than otherwise. A totally encapsulating PPE would let some individual 90 micron virus particulate get in. 1 won’t kill you.