☝🏻 Modern NBC Honeywell filters aren't cheap. I know, I looked into modifying a surplus skin tight Russian gas mask, first term Trump. If I survived a nuclear blast I'd still hope to be able to breathe was the point.

Either way, it gets costly because once you open that filter, you better be ready to use it, kind of thing, meaning they start to degrade once you open one. So, it's not the masks really that get ya, it's the price of the filters.