> So you're saying that your test showed that above 2.5um the masks > you tested did do something? They blocked almost all of the particles larger than 2.5 mi

> So you're saying that your test showed that above 2.5um the masks > you tested did do something? They blocked almost all of the particles larger than 2.5 microns, which surprised me. The masks did nothing to block particles even a bit smaller than 2.5 microns. I checked the presence of particles at 1.0 microns or larger, and the after-the-mask number was only smaller by the number of particles 2.5 microns or larger that the mask had blocked. The ability of Chinese factories to make masks that filter that precisely surprised me even more. > So the masks were helpful (because respiratory droplets range from > <1um to >100um). They did something, but I do not have numbers on what quantity of virus particles we inhale from droplets in each size, so I can not do math or science on this. “When you can measure what you are speaking about, and express it in numbers, you know something about it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarely, in your thoughts advanced to the stage of science.” ― Lord Kelvin