The air purifier was a gift in which I am so grateful. But when asked if i noticed if the quality of air had improved, my answer was I could not tell a difference in the air and when I went to wipe down the filter there was nothing to wipe off after 4 to five weeks since I have set it up in my house; I was surprised that there wasn't any dust or anything to wipe off.no dust or anything. At all to with Ed could tell a difference... Although, I can't tell a difference in air quality; I certainly don't want to claim there is no improvement. I just don't know how to put it to the test. Maybe I could get feedback if labcharge will read this review.