Does anyone have an authoritative answer whether the standard NATO NBC filter protects against extremely small particles like a virus?
I have verified that some common commercial filters that protect you against some crazy chemical shit will NOT block extremely small particulates. In general, if it is not N95, P100, or HEPA rated, assume that it's no good against the current virus.
Fortunately, I had a full box of P100 cartridges left over from an asbestos abatement project and I still have a bunch of sealed NBC filters.