Air filters remove airborne allergens and pollutants such as dust, mold, pollen, pet dander and bacteria from your indoor air. There is a vast array of air filters with different levels of measurement for determining the concentration of different particle sizes, usually by weight or count. This measurement of performance for air filters is called Minimum Efficiency Reporting Value (or a MERV rating). MERV ratings come from ANSI/ASHRAE Standard 52.2: Method of Testing General Ventilation Air Cleaning Devices for Removal Efficiency by Particle Size.
ANSI, the American National Standards Institute, accredits and ensures that the characteristics and performance of products are consistent with terms, definitions and testing of products. ASHRAE, the American Society of Heating, Refrigerating and Air-Conditioning Engineers, develops standards for its members and other professionals involved with refrigeration processes and the maintenance and design of indoor environments.
A MERV rating is based on three composite, average removal efficiency points for particles. Categories range from 1 (very low) to 16 (very high). The higher the rating, the more efficient your air filter will help to reduce indoor airborne allergens, pollutants and contaminants.
MERV 1 to 4 filters provides minimal filtration. These filters have to be replaced quite frequently and are typically disposable fiberglass or synthetic panel filters within a cardboard frame. These filters capture up to 80% of airborne particles as small as 10 microns. MERV 5 to 8 filters are good for capturing dust and mold spores. These filters have to be replaced, depending on usage, every 3 months. MERV 8 replacement air filters will reduce pollen, pet dander, dust and other contaminants as small as 3.0 microns.
MERV 9 to 12 furnace air filters capture up to 95% of airborne particles and contaminants like pollen, dust mites and mold spores, as small as 1.0 microns. These filters come in a deep pleated, boxed media or bag filters, which are some of the most efficient filters used in homes and commercial buildings.
MERV 13 to 16 air filters will trap up to 98% of airborne allergens and pollutants such as bacteria, tobacco smoke, cooking oil and droplet nuclei, as small as 0.3 microns. Filtration should be applied to process both return and outside air that is delivered as supply air. Finding the best-rated air filter for your particular need or application will help to keep your air clean and fresh. Don’t forget to change your air filter as recommended and especially when you change your clocks to Standard Time or Daylight Savings Time.