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. Today, however, there are several types of permanent air filters available in various efficiencies that can help you filter the air in your home. If you suffer from allergies, asthma, hay fever or other breathing difficulties, there is an air filter that can help you.