Nordic Pure 20x25x6 MERV 15 Plus anti-allergen pleated AC / furnace air filters are made by adding a hand cut flat panel infiltrated with activated charcoal to our standard pleated filter to greatly reduce unwanted odors. Each time air passes through a Nordic Pure pleated furnace filter, airborne dust, pollen, mold spores, pet dander, smog, dust mite debris, and bacteria are captured and removed. Our filter media prevents the growth of bacteria or mold, resulting in a much healthier living space. Particles in indoor air are measured in microns; for scale, a human hair is about 70 microns wide. Each Nordic Pure 6” MERV 15 air filter will capture more than 90% of all airborne contaminants from 1.0-10.0 microns, and up to 95% of all contaminants from .30-1.0 microns. It is important to note that because of this high filtration and air flow restriction, HVAC systems should be rated to handle filters of MERV 15 and above, which are not typically used in residential settings. This high performance HVAC replacement filter will outperform non-electrostatic fiberglass filters, washable filters, poly disposable filters, and will help keep your air conditioning and heating systems running efficiently, saving you money on utilities and costly maintenance. Because of this high filtration and air flow restriction, heating and air conditioning systems should be rated to handle filters with a rating of MERV 15 and above. The effective life of your air filter depends on both the inside and outside conditions in which you work. We recommend that you change your air filter every 3 to 6 months to maintain maximum efficiency and indoor air quality.