We have horrible allergies and the allergens have been strong this year. I put the purifier in my daughter's room because she is just miserable with all the mold spores out right now. It makes a noticeable difference. Before bed she gets her allergy pill and then sleeps with the purifier on. In the morning she wakes up without that huge stuffy allergy nose and headache. But if we don't have the purifier on she goes right back to being stuffy and not able to breathe. It has made a huge difference in the quality of air in our home.