I needed something for my family's severe allergies and asthma. We have many cats and the smell and dander permeated throughout the house. The kids and spouse didn't want to remove the cats, so I saw this unit and with the 60 day trial, tried one. 
It worked so well, I bought one for each floor of the house (3). Now we can't smell any cats, and the dander has been significantly reduced. I really believe this product does the job. I highly recommend!