Instead of having to replace your disposable air filter several times a year, consider buying a permanent one that can be washed and reused indefinitely. Most of these filters have lifetime warranties, so you'll save money in the long run as well as reduce tha amount of waste you send to the landfill. If half of the US households replaced their disposable air filters with a single reusable one, the number of air filters saved from landfills each year could blanket the entire land area of Washington DC.