Air Purifiers

Im doing a report on air filtration devices and Im trying to find the market share for HAPA filters, Ozone Filters, Ionic Filter (Ionic Breeze Sharper Image) and overall how large the market is.

My wife and I just got back from SanFransisco and we're both sick. We read all the articles on how not to, we didn't use blanket, hand sanitizer, wipes. But, we both used the over head air at full blast. There were several sick people on the plane and we were in the back, I heard the back is worse due to poor air filtration.