Air cleaner filters are made of a variety of materials, including fiberglass, cotton, carbon, paper and even metal.

Carbon (often found in HEPA air cleaner filters) is used because it is very safe and effective in eliminating harmful gases, molecules, chemicals, fumes and odors from the air. HEPA filters are made out of very fine glass threads with a diameter of less than 1 micron (a micron is 0.00004 in, 0.001 mm). By comparison, a human hair has a diameter of about 75 microns (0.003 in, 0.07 mm). The fine glass threads are tangled together and compressed to form a filter mat. HEPA filters will collect particles down to 0.3 microns (0.00001 in, 0.0003 mm) in diameter. While some HEPA air filtration systems combine HEPA filters with carbon-based materials, they stop mold spores, bacteria, viruses, pet dander and dust, and also help to eliminate stubborn gasses and odors from your home.