Why Are Air Filters Rated?
The quality of an air filter is assessed by its rating, which tells you how well the filter are at blocking particulates in the air.
The higher the rating (for MERV, FPR, and MPR), the smaller the air and dust particles your home ac air filter can capture.
Without a standardized air filter rating method, homeowners and other HVAC customers will never know how well their air filter is working to fight against a wide range of airborne particles, such as:
- Dust
- Pollen
- Smoke
- Pet dander
- Hair
- Odors
- Bacteria
- Airborne viruses
To asses air filter filtration capacity, we use a term “micron” which allows us to know how the smallest size of particle that an air filter can be blocked.
Micron sizing can range from visible to very small only a microscope can spot the particles.
Here’s a handy chart to give you an idea of the range of micron sizes:
It’s important to note that anything in the size range between .001 microns and 10 microns can reach deep into the lungs by being inhaled. Any particulates under around 100 microns can actually be inhaled into the nose.
The MERV, MPR, and FPR rating systems each consist of a range of numbers that represent the filtration effectiveness based on the micron size that it can filter out. Below, we’ll break down where the rating systems come from and how to use them when shopping for your next filter.
MERV Air Filter Ratings
MERV stands for “Minimum Efficiency Rating Value.”
Every air or furnace filter in the US carries a MERV rating, which is the only nationally regulated rating system for air filters. Established by the ASHRAE (American Society of Heating, Refrigerating, and Air Conditioning Engineers), the MERV rating system specifies a filter’s ability to capture air particles and pollutants.