non-medical grade masks don't stop it either.


The goto mask for the medical folks is N95. That passes 5% at 300nm. If perfect stopping was required, the cases among medical folks would be much worse.

Another note about the N95 masks is that some have an exhale valve. This makes the mask more comfortable but it only filters incoming air. The masks designed for medical use don't appear to have these valves?


I think it's about attenuating the transmission odds so that the number of virus particles you get does not overwhelm your immune system.

If we are talking about odds, then the available tools are limiting trips, social distancing, at least some mask for sender and receiver, building ventilation, and situational awareness.

There is a fitted cloth mask design floating around that uses two layers of cloth. With my beard, it seems to seal better than the pressed fiber masks and I can put a layer of proper filter media in between the cloth layers.

Interesting times. Get to research and make technical things with a sewing machine.