Most heating and cooling systems still use a basic air filter. These filters were originally designed to protect the equipment and not the people served by the equipment. The average air filter is only capable of removing 3–5% of the particles that pass through it. Due to this, we recommend you use pleated filters on any 1" air filters because they are not to thick. Today, however, there are several types of permanent air filters available in various efficiencies that can help you filter the air in your home. We always recommend the 213 and 413 aprilaire filters that go along with the 2210 and 2410 air cleaners. If you suffer from allergies, asthma, hay fever or other breathing difficulties, there is an air filter that can help you.