I started out using in my craft room, which is located in our basement. I turned on just as instructions stated.  I waited for the Air Purifier auto sensor to change color; but the light stayed the same.  I'm thinking something must be wrong.  I then decided to take to my garage for testing.  Boy oh Boy did that light turn bright red.  

I currently have it in our bedroom and set on Auto.

I can't say that I have noticed a change in air quality on a physical level.