My Wife and I have allergies and as winter is here, they normally get worse. Early on while the unit just sits there and does its thing, I still wondered how it really works. It has now been 4 weeks and my Wife, and I realized no more sneezing and stuffiness. In fact, our sinuses have never been this clear for years and like I said it is winter. I did ask for clarity on what the numbers indicate on top of the unit and the response was quick and in a way I could understand. I think it would be wise if they put that on their website and/or in the box with the unit. We are very happy with our Sans whole house unit. We did sign up for the new filter sent every 3 months and I'm glad we did so we won't forget.