I love the 411, we purchased due to our allergies. We made this purchase from consumer reports and reviews of customers. It is quiet, works great. Tested by our kitchen when cooking dinner and it made a huge difference. We are sold. We do not experience the smell that others have stated at all. I am very sensitive to orders. To us it is quiet, on high a bit noisier, we don't mind it at all. My son loves this unit, we are placing in his bedroom. Ready to purchase more Blue products for our home.