If you want to be completely sure that the air in your home is totally free of fungi, pollen, dust and other micro-particles too small to see, you should install a High-Efficiency Particulate Air (HEPA) air filter. HEPA filters provide a much higher filtration level compared to normal furnace or air conditioning filters. A HEPA filter can remove up to 94 percent of the particles normally present in the air in your house. If these air pollutants are not removed, they can build up and create a film on your furniture and walls. When you start using a HEPA rated filter, you will not only improve your health, but also you will be able to see and feel the difference.