[nucleardog]

If you’re looking for a weekend project and are even slightly handy… a fan and a decent furnace filter is a good cheap solution.

I’ve got two 3M filtrete filters, some activated charcoal sitting in front of them, and a small duct fan to pull air through it all. (Build information is in this comment and the one reply: https://news.ycombinator.com/item?id=37223106). For what a filter rated for 600sqft would have cost me, I instead got one that can do 3,000sqft. Or more usefully less space with more air changes per hour (like ten per hour instead of two).

I’ve got a $600-ish German air quality monitor that says it does what it should, which makes sense because as long as you’re pulling air through the filters… they’re gonna filter.

If you’re looking smaller scale, you can buy sheets of activated charcoal and sheets of MERV13 filter material. A little 120mm fan and a tiny filter box could run pretty quietly in an office and do the trick.

However I think the most important advice I’d give (and also the cheapest!) is to, unless you’re in a _heavily_ polluted area, open your windows. No air filter you’re going to get will remove CO2 and once you start measuring it you’d be amazed/horrified how quickly it builds up indoors to “brain fog” levels.