MERV is an acronym that stands for Minimum Efficiency Reporting Value, and it is a  shorthand way of letting someone know the efficiency of an air filter when it comes to removing particles from the air. The MERV was created by the American Society of Heating, Refrigerating, and Air Conditioning Engineers as a guideline when choosing air filters.

Air filters, regardless of the manufacturer or the price, will have a MERV value assigned to it. It is a universal standard, and the higher the rating the higher the performance of the filter. Most of the time, you will find that residential filters will be rated from 1-12. However, there are some homes that may utilize filters with a higher MERV rating if a resident has severe allergies, for example. Now, let’s get a better look at the ratings, the particle sizes the filters can handle, and their typical application.

MERV 9 – 12:  These are very high-quality filters that tend to be the highest range you can use for a residential setting. They can keep out very small particles (3.0 μm to 1.0 μm). The type of particulates that would fall into this category and that the air filters will protect from include lead dust, milled flour, dust from humidifiers, and particulates stemming from auto emissions. They are often used in high-quality residential setups, as well as high-quality commercial setups. You will often find these air filters used in hospital laboratories, as well.

Having quality, clean air filters is important to the cleanliness of the air. If there are too many particles in the air, it can cause respiratory problems, and it can make life very difficult for those who suffer from allergies, asthma, and COPD, for example.

The air filter serves another purpose, as well. It is also meant to provide a layer of protection for the HVAC equipment that is being used. Without a filter, it would cause dirt and particulates to build up on the equipment. Over time, this could cause a substantial amount of damage to the equipment, which would necessitate a replacement.

MERV Rating 5 – 8: These filters are used to keep out particles that are sized 10.0 μm to 3.0 μm. Examples of particles that can be kept out with filters of this MERV rating include spores, mold, dust mite debris, hair spray, and cat and dog dander. These can be used for applications including higher quality residential units, general commercial units, and industrial locations.

MERV 13: These are some of the highest quality filters you will find, and they can keep out particles between 1.0 μm and 0.3 μm. They can keep out bacteria, smoke, dust from insecticides, paint pigments, face powder and even droplets from sneezing. These are typically only used in hospital and surgical settings.