AIR QUALITY RATINGS

What is the Merv Rating? 

MERV is the Minimum Efficiency Reporting Value, a scale designed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) to rate the effectiveness of air filters. Basically, a higher MERV rating indicates better filtering performance.

The most commonly recommended MERV ratings for residential filters range between MERV 5 and MERV 13. In fact, filters within this range can perform nearly as efficiently as true HEPA filters. They all essentially trap the same range of particulates — such as dust particles, mold spores, dust mite debris, tobacco smoke, pet dander, and pollen — but each filter has a higher capturing capacity as the MERV rating increases.

There are really two different components to a MERV rating. One is the ability to remove large airborne particles, or particles between 1 and 10 microns. These "large" particles include pet dander, pollen grains, dust mite debris, etc. However, the bulk of indoor air pollutants are in a smaller size range. MERV also rates the filter's ability to remove submicron particles — those smaller than 1 micron.