Trying to find a respirator is tough. I haven't found any that aren't restricted for sale to hospitals, frontline personnel, etc. From what I understand, the N95 masks do offer some protection as a ppm against the virus when transported on particles .3 micron or larger. While the virus itself is something like .175 micron, it matters how it is delivered...how big it's, "ride to your nostrils" is.
One study I read indicted coughs produce the vast majority of airborne particulars in the area of .35 to 1.7 microns. A Merv 8 filter won't stop even 20% max of those size particles. But an N95 would stop 95% of them. If 80% gets through to your lungs, you're gonna get infected. If just 5% do, that may not be enough virus to take hold. A Merv 8 would be pretty good at stopping a large % of large droplets above 3 microns, so it could catch and stop some, but it's not going to stop droplets smaller than 3 microns enough to protect you much.
Interestingly the particles emitted just from talking tend to be smaller on average than with coughing or sneezing, but they don't travel as far...thus the "6' rule. Within 6' of an infected person will almost for sure result in you inhaling some virus unless you are wearing an N95 mask. But inhaling just a little won't necessarily make you sick. Inhaling a lot most likely will make you really sick.
Here's another important thing to know RE: the 6' rule. The virus-carrying particulars remain in the air for a while. They don't immediately fall to the ground. And if you are in a place where the air is not completely still, the particles can be pushed up, down & around for hours. While they are slowly dissipating, this becomes a bigger problem when you're someplace with a lot of people...even if they are all observing the 6' rule because now you've got those particles gathering up, floating around in the air, combining with the particles of all the other people. So now if you're going someplace where there are a bunch of people in a contained space, even if everyone is standing 6' apart, if you don't have an N95 mask on you'd better hope the vast majority of those around you are not carrying the virus, or at least that they are wearing a mask decent enough to limit the amount of particles they put in the air.
This also applies to staying in one place with even one infected person...even if you stay 6' away because the stuff accumulates and can make it's way to you. If it's only for a few minutes, you're not likely to get enough exposure to get you infected...but if you stay too long, you might.
Bottom line as I understand it is, 6' rule is to protect you from the fine particles exuded from talking and even breathing if someone is carrying. Coughs & sneezes can extend the range much farther, so if you are within as much as 27 feet of one, get the hell away ASAP. 6' rule isn't nearly as effective if there are a large group of people in the space with you...even if they are all staying 6' apart. Never forget you should assume the surfaces you touch have been contaminated with virus unless you know for a fact they were properly cleaned just before you touched them. And when your fingers go to your nose or eyes, if there was Covid-19 on them from something you touched (including your own mask), you are really flirting with disaster because you're now giving those much smaller micron virus particles an express ride to your sinuses and lungs.
Long, but I hope it helps.
