About MERV Ratings

The higher the MERV value of an air filter, the more efficient it is at removing particles.

At the lower end of the efficiency spectrum, a fiberglass cardboard frame filter might achieve MERV 4 or 5. Store bought pleated filters range from MERV 6–12. Higher-end filters, such as those used in hospitals and clean rooms, range from MERV 13–17.

MERV 17 is a true HEPA filter, and MERV 18–20 are ULPA filters and have the highest efficacy.

High-MERV filters can remove more particles, including extremely small contaminants. However, these filters tend to be associated with increased airflow resistance, referred to as static pressure. When filter media becomes denser, the filter’s efficiency increases – but so does the static pressure. The system fan motor has to work harder to push air through the filter, increasing energy consumption.

For optimum performance, select the highest efficiency filter with the lowest static pressure.

A Polarized-Media Air cleaner achieves an equivalent to a MERV 14 – 15 performance with the static pressure of a MERV 8 filters. It doesn’t rely on smaller pores to collect particles, rather its magnetic polarized field attracts the particles and sticks them to the replaceable media.

Particle size is usually measured in microns, a metric unit of measure. A micron is 1/25,000 of an inch. There are over 20 million particles in the average cubic foot of indoor air.

Approximately 98% of all particles (by count) are below 1 micron in size. Visible particles represent only a small fraction of particles found in indoor air.