We placed this in a 600 sq ft open concept kitchen/living room. We leave the unit set on 4 to keep the air circulating. This purifier is quiet, and extremely effective. We have noticed the air quality lights change when windows are open, a lot of activity in the house, and even while cooking certain foods. We are extremely satisfied with the effectiveness and build quality of Alen products. We also purchased a T500 for a bedroom.The packaging has also been carefully thought out. We own a Dyson, and the build quality is sub par to the Alen. Dyson also has a sub par warranty. We have recommended (they have also purchased) Alen to several friends, we have also purchased one for an in law.