The ABCs of Indoor Air Quality – MERV Ratings

When shopping for air filters for your home you may have seen something called a MERV rating. MERV is a rating system created by The American Society of Heating, Refrigerating and Air-Conditioning Engineers that stands for “Minimum Efficiency Reporting Value”. MERV is simply a measurement of how effective a filter is at removing contaminants from the air on a scale from 1 to 16. The greater the MERV rating of a filter, the more effective it will be at removing fine particles from the air passing through it.

You might be thinking, if I want the cleanest air possible I need to purchase a filter rated near the maximum of the MERV scale. The reality is, most home air filters with a MERV range of 7-12 will effectively remove the vast majority of even the small contaminants. Filters with a MERV rating higher than 12 are most often used by hospitals and in manufacturing facilities with “clean rooms”. They are not the best choice for most furnaces.

In fact, using a filter with a higher MERV rating can create excessive airflow resistance in your home’s HVAC system, making it work harder and less efficiently than it was designed to operate. If you’re looking for cleaner indoor air, an integrated indoor air filtration system will offer more effective filtration than a furnace filter when it comes to removing finer indoor air pollutants.

Have questions about filtration and indoor air quality? Give ABC Southwest Plumbing & Air Conditioning a call. We’re here to help.