I absolutely love this air purifier!  I keep it on auto and this past weekend we had someone come to the house to help put dry wall on and the purifier picked up on the dry wall dust/dirt, and it turned red and within five minutes it went back to blue (excellent air) and it kept doing it until the guy was done!  I also love there's an app you can control it from and it was super easy putting it together.  The noise is not loud, I could have it on the highest speed setting and could fall asleep to it.  10/10.