I have been using these for about 15 years now and love them. You would be amazed at how much stuff you can see trapped in one even after just a month. It will remove pollen, and even smoke and mold from the air. I would suggest getting a few for a season, especially if you dodn't have central air and are running the heat for the first time in the fall with a filter this fine. You will probably end up changing the first one after a month, then ever 3 after that unless there are constant pollutants in your house, like a lot of smoke or a mold problem.