Absolutely the best air purifier around! I used to use nasal sprays 3-4 times a day. Thought I was just "addicted" to them so that I needed them more often. I also coughed and constantly cleared my throat. I've always had allergies to dust, mold, and mildew...and cats. Bought 2 of the 1100 sqft units and, after two days, I have never need nasal sprays again! Not kidding! And the coughing that I had for 10 years or more just stopped! Guess my issues were all allergy related. We bought our first two Alen units after adopting two kittens over Christmas. Today, I'm purchasing two more of the 1100 sqft units, this time with the HEPAOdor filters to help with the litter box odors. Best purchases I've ever made for my health's sake!