The true bluish Allergen air filter is specifically for families with allergies and pets. It is 53 times more than fiberglass filters and will past up to 4 months. During the manufacturing process, we the filter media with an electrical current . This process the filter to attract very small particles much the same way magnets attract metal. The end result is a far more effective . The electrostatically charged filter media sub-micron mobile allergens like dust, dirt, pollen, pet dander, dust touch debris, microscopical allergens, smoke and smog. 100 % man-made filter media will not the growth of bacteria, mold, or fungi in normal use.