Nordic Pure 12x24x1 MERV 13 Plus Carbon 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 tobacco and fireplace smoke are captured and removed. Our treated synthetic filter media prevents the growth of bacteria or mold, resulting in a much healthier living space. MERV 13 air filters are comparable to air filters with the MPR rating of 1900-2200, FPR rating of Blue, and APR rating of Diamond. Particles in indoor air are measured in microns; for scale, a human hair is about 70 microns wide. Each Nordic Pure 1” MERV 13 air filter will capture more than 90% of 1.0-10.0 micron contaminants and up to 75% of .30-1.0 micron contaminants. 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. The effective life of your air filter depends on both the inside and outside conditions in which you live. We recommend that you change your air filter every 30-90 days to maintain maximum efficiency and indoor air quality.