What Is A MERV Rating

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When you think about air filtration and the air quality inside your home, it seems like a simple process. The HVAC system has a filter that removes the contaminants from the air. And your job is to replace that filter when it becomes covered with dust and dirt. It sounds simple enough. But then you go to buy new filters and find that they all have a different MERV rating, which complicated the process considerably. MERV is the acronym for Minimum Efficiency Reporting Values. And the rating lets consumers know the size of the particles the filter will capture.


The MERV system has a range of 1 to 16, and the higher the number, the better the filtration. But you need to know a little bit about the size of certain microscopic particles to appreciate the various levels of filtration on the MERV system. A rating of 1 to 4 is the most basic filter you can purchase, and it is expected to remove around 20% of the particles in the air inside your home. It is important to remember that they are the largest particles in the air. A level 6 will remove around half the particles contaminating your home’s air. If you increase to a level 8, you filter out just under 85% of all the foreign particles. Stepping up to 12 to 14 will provide about 90% filtration, including some of the smallest particles in the air.


A technical discussion of MERV ratings will get into microns and the actual measurements of things that the average person will never see or grasp. So to make the system more meaningful, let’s explore the particles that each filter will trap. A MERV of 4 or below will snag your typical contaminants like dust mites, pollen, and carpet fiber. Filters that range from 5 to 8 will trap hairspray, powdered food mixes, or hairspray. A rating of 9 to 12 gets you a filter that will capture dust from a humidifier, automotive emissions, and legionella, the bacteria that causes Legionnaires Disease. Any filter that is a 13 or above is considered high quality and would be used in commercial properties, hospitals, and clean rooms to capture bacteria, viruses, and other very tiny particles.


While air filters do not have specific materials or coatings to attract harmful particles in the air to improve health, they remove items that are well known to cause allergic reactions in many people. So for a person battling allergies from dust, pollen, or pet dander, the added air filtration is beneficial. The purified air reduces breathing challenges and increases the oxygen in the person’s blood to feel more energetic and healthy.

If you or a loved one is suffering from breathing complications, call 952-208-4570 to speak to Blue Ox Heating & Air about air filtration options. Increasing your Grant home’s air quality will benefit everyone in your home, from better breathing to more restful and restorative sleep.