What's the Difference in MERV Ratings FOR Air Filters?

MERV stands for Minimum Efficiency Reporting Value. The MERV system was designed by the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) as a scale to measure the effectiveness of air filters. Basically, this system allows you as the consumer to easily and effectively compare air filters to each other. It means that any MERV 8 rated filter, for example, will filter the same as another. Though there may be some slight differences in construction and quality between manufacturers, the MERV system provides clarity as to the level of filtration you can expect from an air filter with a certain MERV rating.

MERV ratings range from 1-16 and address the performance level of a filter as it relates to removing airborne particles from 0.3 to 10 microns. Airborne particulates are referred to in microns. How small is a micron? A micron is 1/1000 mm which is 1/25,000 of an inch. Although it may be possible to see particles as small as 10 microns under the right conditions, particles are typically visible beginning at about 20 microns. To put it into perspective, a dot (.) is about 600 microns.