What is MERV?: A Homeowner’s Guide to Choosing an Air Filter

March 19, 2014

So, you’re looking for a new home air filter, eh? You have several choices, but you keep seeing MERV and wonder if it’s important.

Well, it’s as important to air filters as MPG is to cars.

MERV stands for Minimum Efficiency Reporting Value. Clear as mud, right? This rating tells you what size of particles (dust, allergens, etc) an air filter can catch. The higher the MERV rating, the smaller the particles the air filter can catch.

So the higher the MERV rating, the cleaner your family’s air will be.

The harmful particles each MERV-rated filter can catch

MERV ratings range from 1 (least effective) to 16 (most effective). 

There are 4 different tiers of MERV ratings that catch a certain size of particles. 

Note: The particle size is measured in microns (one-millionth of a meter or .00004 of an inch).

Here are the 4 tiers of MERV ratings according to ASHRAE tests:

  • MERV 1-4 (OK): Mostly catches particles that are 10 microns and larger—like dust, pollen and carpet fibers. Can catch some particles between 3-10 microns. This is your typical disposable fiberglass filter.
  • MERV 5-8 (Good): Better at catching particles as small as 3-10 microns—like mold spores, dust mites and animal dander.
  • MERV 9-12 (Better): Catches particles as small as 1-3 microns—like legionella and lead dust.
  • MERV 13-16 (Best): Better at catching all of the above, plus it catches particles as small as 1-.3 microns—like tobacco smoke and bacteria.

How to pick the right MERV rated air filter for you

When choosing a home filter, find the one that meets your:

  • Family’s health needs (does anyone have asthma or allergies?)
  • Environment (do you have pets?) 
  • Budget (higher MERV rated filters are more expensive)

Keep in mind that a 13-16 MERV rated filter is usually for commercial purposes (like hospitals) because they’re that powerful.

But if you have awful allergies or asthma and need that level of air filtration, we recommend getting a whole house air cleaner. This is installed in your cooling system’s air handler (inside air conditioner unit) and filters out particulates such as, mold, pollen, pet dander, and smoke from the air.

Ask one of our experts if you have a question about whole-house filtration.

Advanced Air has been serving Fort Myers, Naples and the surrounding areas for over 25 years.