I just brought this a week ago. I been running it on low most of the time. the second day I had it I notice the air seem to smell fresh and clear. its so quiet that I sometimes check to see if it is on. I have a small place with a cat and I have it in my living room and seems to take care of all rooms. I smoke and now I don't see smoke floating around. Before I got this unit every three days I see dust and cat hair on my tv and tables, but its been a week now and no dust or cat hairs on everything. I am glad I brought this unit and everyone should check this one out before buying some other one.