Interesting; I hadn't thought about air filters at all. Thanks for mentioning them! Five minutes of googling around leaves me highly skeptical the air filter mentioned in Louie's post, which you linked to, is the one anyone interested in life extension would want to buy, though; the air filter mentioned there is a "HEPA grade" filter, not a "HEPA" filter. The filter in question only claims that it can catch particles which are larger than 30 angstroms, while real HEPA filters catch at least 99.97 % of particles larger than 3 angstroms. As a quick check, this seems like it might matter since I'd expect HEPA filters to catch all of the six air contaminants the EPA mentions here, while a filter which only caught particles larger than 30 angstroms would only stand a chance of catching one of those six contaminants. Please pardon the back-of-the-envelope nature of this comment.