This air filter helps make the air in my home feel and smell fresh. We have a new puppy and it helps to remove the smell of having a pet in my kitchenliving room. It does require that you refill it each day, as I use it on the max setting all the time. I keep it in on my kitchen counter so it is very easy to refill. It has a safety mechanisms in place that will cause it to shut off if you add too much salt. I am not sure how long the filter lasts or how much it costs to replace. I am also not sure the science behind how it filters the air.