MERV (minimum efficiency reporting value) is a rating system developed to help consumers easily identify the particulate-capturing properties of air filters. To be more specific, the numbers indicate a filter’s ability of capturing particulates ranging in size from 10 microns down to 0.3 microns. For comparison, face powder can be as small as 0.1 microns, pollen is about 10 microns, and the period at the end of this sentence is about 600 microns.
A filter’s MERV is indicated on a scale of 1 to 16, with 16 being the best quality air filter. The following list describes common particulates and pollutants that MERV-rated air filters will remove from your living space.
- Filters rated 1-4 capture particulates larger than 3 microns. This includes pollen and large dust particles. These are basic disposable filters that protect HVAC equipment from debris, but not mold spores. Skip these and choose a better filter.
- Filters rated 5-8 catch particulates 3 microns and larger, including most mold spores (but not all), pet dander, pollen, dust mite by-products and debris, and aerosols (starch, hair spray, etc.). For many people, air filters in this range are more than sufficient.
- Filters rated 9-12 capture particulates as small as 1 micron, which includes Legionella, auto emissions (nice for homes with attached garages), humidifier dust and fiberglass insulation.
- Filters rated 13-16 capture particulates down to 0.3 microns. This includes bacteria, some viruses, most insecticide dust, sneezes, asbestos and much more. Keep in mind that air filters in this range may impede airflow to the point of straining the HVAC system. You may want to consult an HVAC pro to see if your system is compatible.