Anyone who has a dog knows that it's easy to become noseblind to the dog smell. We also have allergies and sinus issues and since getting our Sans, we've been sleeping much better and waking up with far less congestion and other issues. The other evening, something was on the stove too long and the Sans color immediately changed to let us know that the air quality had gotten worse. It works just as it should and I'm very happy with the purchase.