Why Are MERV Ratings for Air Filters Important for Clean Air?


Air filters are essential to ensure that your HVAC produces safe, quality air. According to recent data, the global HVAC filter market is projected to reach $4.5 billion by 2026.

When it comes to changing your home’s air conditioner filters, they’re not all the same.

Read on to learn more about MERV ratings for air filters, so you can decide which rating will provide your home with the healthiest air possible.

What are MERV Ratings for Air Filters?

Every air filter has a MERV, or Minimum Efficiency Reporting Value assigned to it. This “rating” measures how well the air filter captures air particles such as pet dander, dust, and other airborne particulates.

Each MERV rating is based on specific sizes of the particles, which pass through the filter when your HVAC unit is running. These MERV ratings for air filters go from as low as the number one to as high as 16.

The particles are measured in microns and can range in size based on what they are. For example, carpet and textile fibers are larger than 10 microns, while tiny microscopic bacteria measure less than 0.3 microns.

How MERV Value is Determined

Air conditioner filters are put through two basic tests to determine their MERV rating. The first test is called the Dust Spot Efficiency Test. This test measures the ability of the filter to remove dust particles from the air.

The second test is called the Arrestance Test, which determines how well the filter removes synthetic particles in the air. These particles are injected into the air for testing purposes, and most quality filters can remove around 90% or more of them.

A low MERV rating of number one could work fine for a basic window unit that’s cooling off a smaller room. However, air conditioning filters with higher MERV ratings do a much better job of improving air quality by removing smaller particles and allergens.

Residential MERV Ratings

The air filters in most residential HVAC systems have a MERV rating of between one and four. The higher number filters out pollen, fibers, and dust mites fairly effectively.

You’ll find that most of the affordable, disposable filters at your local home improvement store have MERV ratings in this range. While they can help to provide your home with clean air, they don’t remove smaller particles like mold spores, pet dander, and other irritants. 

These filters are usually made of fiberglass and aluminum mesh. Check the information on your air filters to determine how often they should be changed. In most cases, all air conditioner filters should be replaced every 30, 60, or 90 days at most.

Real World Examples

Let’s dive into some of the common particles that different MERV ratings can filter. Anything with a rating of between two and four can filter pollen, dust mites, sawdust, and textile or carpet fibers.

Air filters with MERV ratings of between 5 and 8 can filter everything mentioned above, as well as mold spores and cement dust. Filters rating between 9 and 12 can handle everything we’ve mentioned as well as coal and lead dust, legionella, and humidifier dust. They’re best used in construction settings, large residential and commercial buildings, and hospital laboratories.

The highest MERV ratings between 13 and 16 are ideal for surgery rooms and clinics/hospitals, smoking lounges, and commercial buildings. Not only can they remove the particles already listed, but they can also filter out bacteria, auto fumes, tobacco smoke, face powder, insecticide dust, and even small particles like copier toner. 

Special Considerations

If you or someone in your household has asthma, allergies, or another respiratory condition, you may need air filters with a higher MERV rating. Consider the home environment, like whether you have pets or carpet.

These factors will play a role in the MERV rating that’s best for you and the indoor air quality of your home. Higher MERV ratings mean that the filter can remove not just higher numbers of airborne particles but also smaller ones.

If you have a health condition, consider a filter with a MERV rating between 11 and 13. If air quality isn’t as much of a concern for your family, you should be fine with air filters showing MERV ratings of around 8.


You may notice the term HEPA listed on your air conditioning filter. This term is short for High Efficiency Particulate Air, as defined by the U.S. Department of Energy.

These pleated mechanical air filters can remove close to 99.97% of particulates like dust, mold, bacteria, and any airborne particle the size of 0.3 microns. While these filters are the most effective, they’re also the most expensive available.

You may see HEPA filters used in appliances like vacuum cleaners. However, they’re not quite as common in residential HVAC systems.

Filters with High MERV Ratings

If you want your system to produce clean air and have the best possible air quality in your home, choose a filter with a higher MERV rating. Typically, a rating of 13 is ideal for this scenario.

Filters with a MERV 13 rating can trap at least 85 percent of air particles 1 micron in size and larger. They also trap at least 50 percent of particles between 0.3 and 1 micron in size.

You’ll usually find this type of air filter in an industrial or commercial setting, but it’s also possible to use them for your home. HEPA filters and air filters with a MERV rating of 16 are more commonly found in hospitals and clinical settings. MERV 16 filters have the highest rating before you’d need to switch to HEPA.

Whatever type of filter you use, it’s important to change them regularly. Doing so will keep your system running smoothly and help to prevent unexpected repairs

Keep Your Air Clean

As you can see, MERV ratings for air filters are crucial to ensure you have clean air in your home. Remember to consider the health of yourself and your family when you choose the right MERV filter rating for your system.

Advanced Mechanical, Inc. has won numerous awards thanks to our outstanding service. If you need help with your HVAC system, get in touch with us today.

Scroll to Top