Got the Conair Medium Room Air Purifier to test. 
We have animals and seasonal allergies. I set it up in my room above the litter box to see how well it worked since my cat sleeps in my room. I usually take my allergy meds before I sleep since my cat has alot of fur. It took about 2 days before I didn't have to take my allergy meds, specially at night. I was very surprised how good this air purifier worked. Its very quiet that my cat didn't even realize it was there like other brands I have tried. There has been less allergies and less particals from litter box which also would make me sneeze when my cat would kick up dust from the litter. I would definitely recommend this for anyone that suffers from allergies. Will be purchasing more for the rest of our home.