Well, once you go indoors you have a lot more control over this. Think quarantine scenario since this is basically what we're talking about. Nothing gets in that hasn't been cleared.
When you're talking about what you put into your body, which is directly related to the quality of life you're going to have (you may not see the effects of this right away but you will see it), then I don't think cheap should be our first concern.
Having said that, it wouldn't have to be insanely expensive either. It depends on the scale, right?
