I know of filterless technology the goes out to the source of the problem.. It eliminates particultes (anything floating) in the air and drops them...so your not breathing it.. NO FILTERS TO REPLACE...!

I have wondered about the filterless approach. What type of mechanism is involved? I read up on Ionic and other methods. I got a Ionic one a couple of years ago. Was horribly disappointed in it although I think it was supposedly a very good brand. What have you found that you like really well?