Air filters are categorized by their MERV ratings. It’s vital that you know the significance of MERV ratings before considering getting or replacing an air filter for your house or workspace.
We will start with what the MERV rating is and its significance before discussing the MERV rating you should use.
What is MERV Rating
MERV rating, which stands for Minimum Efficiency Reporting Value, is the standard system used to estimate the efficiency of an air filter in catching small air particles.
The MERV rating falls between 1 – 20, with a higher rating indicating that the air filter can trap smaller air particles. This statement is misinterpreted by many to mean the air-filters with the higher ratings are the best. In reality, this isn’t usually true, as the best air filter for you will be the one that suits your needs.
Why MERV Rating Is Important
The MERV rating’s primary function is to help assess the air quality control of an air filter. It helps offer a balance between air quality control and energy efficiency.
A proper understanding of the MERV rating helps answer the question, “what MERV rating should I use.” It helps determine which air filter will function well in residential areas, hospitals, and industrial workplaces. It allows you to compare the pros and cons of each air filter before picking one.
For example, the MERV 6 air filter can be used in a home where no occupant has breathing issues/allergies. In contrast, the MERV13 air filter is recommended for use in a house where an occupant has asthma/allergies as it can remove particles from mold spores to milled flour, from cooking dust to hair spray.
Levels of MERV Rating
The MERV rating measurement scale was designed in 1987 by the American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE).
The measurement scale represents the worst-case performance of an air filter when filtering air particles in the range of 0.3 – 10 microns. These particles include pollen, mold spores, dust mites, tobacco smoking, sprays, and pet dander.
The MERV rating levels range from 1 – 20. These levels are most times grouped into MERV 1-4, MERV 5-8, MERV 9 – 12, MERV 13 – 16, MERV 17 – 20 based on their minimum particle size, types of particle filtered, and the place of use.
To help determine the best MERV rating for you, let’s take a look at the general guideline for MERV rating:
MERV 1 – 4
- It filters down to particles with sizes greater than 10 microns.
- It controls pollen, dust mites, cockroach debris, sawdust, textile and carpet fibers
- It’s usually used in residential window A-C units and furnaces.
MERV 5 – 8
- It filters down to particles with sizes between 3 – 10 microns.
- It controls particles controlled by MERV 1 – 4, plus mold spores, household dust and lint, concrete dust, pudding mix, pet dander, and hair spray.
- It’s usually used in residential and commercial buildings.
MERV 9 – 12
- It filters down to particle sizes of 1 – 3 microns.
- It controls all particles controlled by MERV 1 – 8, plus legionella, milled flour, nebulizer droplets, auto-emission particulates, humidifier, and lead dust.
- It’s usually used in residential and commercial buildings (that require very high air quality) and hospital laboratories.
MERV 13 – 16
- It filters down to particle sizes of 0.3 – 1.0 microns.
- It controls all particles controlled by MERV 1 – 12, plus bacteria, sneeze droplets, smoke & fumes, insecticide dust, cosmetic dust, and paint pigments.
- It’s usually used in general surgery facilities and in-patient care hospitals.
MERV 17 – 20
- Filters down to particle size less than 0.3 microns.
- It controls all particles controlled by MERV 1 -16, plus virus carriers, sea salt, carbon dust, radon progeny, and microscopic allergens.
- It’s commonly used in pharmaceutical manufacturing, orthopedic surgery, and radiation buildings.
What MERV Rating Should I Use at Home
Selecting the best MERV rating for use at home depends on factors such as:
- Your Budget
- Your Local Environment
- An occupant with respiratory problems
- Smoking Occupants
- Keeping of Pet
These factors are to be kept in mind before selecting an air filter.
We recommend the MERV 8 – 13 for homes due to the particle sizes and types of particles it filters.
The MERV 8 is ideal in houses with no allergic or smoking occupants and who don’t live in areas where smoke pollution is rampant.
The MERV 11 is ideal for houses where pets are kept, as it helps control the dog and cat dander or has an occupant with mild allergies.
The MERV 13 is sometimes referred to as “the health shield MERV 13.” It filters almost all allergen forms such as pet dander, pollen, dust mites, bacteria, mold, smoke, and fog.
Other Air Filter Rating Scales
Asides from the MERV rating, two other scales are used for air filters: MPR and FPR.
- The MPR (Microparticle Performance Rating), also known as the 3M scale, assess the air filter’s ability to filter particle sizes of 0.3 – 1 microns. Its basic filter is rated at 100, and its best filter is placed at 2800. The MPR 2800 is the equivalent of MERV 14.
- The FPR (Filter Performance Rating) is also known as the Home Depot scale. It has a ranking of the numbers 4,7, 9, 10.
4: Good, equivalent of MERV 8
7: Better, equivalent of MERV 11
10: Premium, an equivalent of MERV 13
By now, you should have an answer to your question, “What MERV rating should I use?” and now know the factors to consider when selecting an air filter for home use.
The lower MERV rating (8 – 13) is recommended for homes, commercial buildings, and industrial workspaces. While higher MERV ratings are recommended for use in hospitals, laboratories, and sterile facilities.