--this was my part of a post i did on these things in November of 2000--
I got an Ionizer (a living air breeze) it works great for getting rid of Odors, Smoke, and other crap, but you'd better get that dustbrush, or HEPA Vacuum Cleaner, beacuse all the particles drop like crazy. I bought an Air Filter after i got this thing, just to help minimize dust and dirt!! Mine does a 2500 Sq foot room, on high. I've never had it past 10% because the Ozone Smell makes me sick. The one I have an an RF Emitter which is supposed to ward off dust mites, and other microscopic insects, but i'm not too sure about that. My Buddy is a dealer for these things, and I just know it works wonders for a house with 3 chain smokers, and Mold!!
---and here's what i've experienced since---
Prolonged Exposure to Ozone is not recomended, i've read a lot of conflicting reports on this, and i'm not trying to start a war here, but i rarely use mine anymore. I only found out because shortly after getting it, my girlfriend would complain of burning eyes, nausea, and really bad throat irritation. I never got a manual with it, so i finally got one, and Come to find out, these are symptoms of ozone poisoning, listed right in the manual. Occasionally I would feel some severe nausea, and never thought it was Ionizer Related.
I think this is working out to be the best scenario for me, and quite a few other people....
the Ionizer, placed low in the room, (floor or such) in combination with a HEPA filter seems to be the best, but still, HEPA Filters still don't get all the Particles, they tend to just recirculate most stuff right back into the air, because most Airborne Irritants are smaller than 0.3 Microns, and HEPA Filters can't filter all of these particles. Ionizers can discharge particles as small or smaller than 0.001 microns, but they wind up on the floor, or stick to the wall.
I only turn mine on in extreme situations (multiple smokers, or old musty odors), or when i'm not home. I really think lots of fresh air is the best!! The Ionizer is great if you got a room that smells really bad, smokey, and/or really moldy.
Link to an old Ionizer Post
BTW if you get one, and you smell a strong bleachy smell in the air= that's Ozone (O3)!! Turn it down!!