Uploaded June 2020 | Updated September 2026, 2 weeks ago
A clean air filter can make a big difference for the indoor air quality (IAQ) of a home. The filter in an HVAC system plays an important job, trapping particulates, including allergens, asthma triggers, respiratory irritants and other contaminants, as air circulates through the home. They help to keep the HVAC system clean, while removing airborne matter that could otherwise cause health and comfort issues.
Unfortunately, because air filters are out of sight, many people forget to change them on a routine basis. If not regularly replaced, they can become overloaded with dust and particulate matter which can make the HVAC system run less efficiently, increasing energy costs and perhaps decreasing the life of the system. A dirty filter may also negatively impact indoor air quality if it is no longer properly removing airborne matter. In a high humidity environment, a dirty filter could even support the growth of mold, releasing spores and odors into the air.
While following the manufacturer’s recommendation for the type of air filter to use and how frequently to change it, there are other factors that can come into play. For example, how frequently is the HVAC system used; how large is the home; do family members or building occupants suffer from allergies, asthma, COPD or other respiratory conditions; are there pets in the home; and is the home in an area prone to outside air pollution, high pollen counts or dusty conditions?
As a general rule, subject to the conditions previously mentioned, a home’s air filter should be changed at least every 90 days. In some homes, air filters may need to be changed much more frequently, even monthly.
The type of air filter can also play a role in how frequently it needs to be changed. Filters are given a minimum efficiency reporting value (MERV). These are rated from 1 to 16. MERV ratings above 12 are typically used in special circumstances outside of a residential setting. The higher the MERV rating, the more effective it is at filtering airborne particles, but these denser filters may need to be changed more frequently. Also, if higher MERV filters cause too much resistance, a pressure drop in the HVAC system could lead to problems.
Fortunately, changing air filters is usually a simple process with the filters either being housed near the furnace or air handler, or in return air vents in ceilings or walls.
These are just a few things to know about changing air filters and residential indoor air quality. To learn more about this or other building science, environmental, health or safety issues, please visit the websites shown below.
Clark Seif Clark csceng.com
EMSL Analytical, Inc. emsl.com
LA Testing latesting.com
Zimmetry Environmental zimmetry.com
Healthy Indoors Magazine healthyindoors.com
A clean air filter can make a big difference for the indoor air quality (IAQ) of a home. The filter in an HVAC system plays an important job, trapping particulates, including allergens, asthma triggers, respiratory irritants and other contaminants, as air circulates through the home. They help to keep the HVAC system clean, while removing airborne matter that could otherwise cause health and comfort issues.
Unfortunately, because air filters are out of sight, many people forget to change them on a routine basis. If not regularly replaced, they can become overloaded with dust and particulate matter which can make the HVAC system run less efficiently, increasing energy costs and perhaps decreasing the life of the system. A dirty filter may also negatively impact indoor air quality if it is no longer properly removing airborne matter. In a high humidity environment, a dirty filter could even support the growth of mold, releasing spores and odors into the air.
While following the manufacturer’s recommendation for the type of air filter to use and how frequently to change it, there are other factors that can come into play. For example, how frequently is the HVAC system used; how large is the home; do family members or building occupants suffer from allergies, asthma, COPD or other respiratory conditions; are there pets in the home; and is the home in an area prone to outside air pollution, high pollen counts or dusty conditions?
As a general rule, subject to the conditions previously mentioned, a home’s air filter should be changed at least every 90 days. In some homes, air filters may need to be changed much more frequently, even monthly.
The type of air filter can also play a role in how frequently it needs to be changed. Filters are given a minimum efficiency reporting value (MERV). These are rated from 1 to 16. MERV ratings above 12 are typically used in special circumstances outside of a residential setting. The higher the MERV rating, the more effective it is at filtering airborne particles, but these denser filters may need to be changed more frequently. Also, if higher MERV filters cause too much resistance, a pressure drop in the HVAC system could lead to problems.
Fortunately, changing air filters is usually a simple process with the filters either being housed near the furnace or air handler, or in return air vents in ceilings or walls.
These are just a few things to know about changing air filters and residential indoor air quality. To learn more about this or other building science, environmental, health or safety issues, please visit the websites shown below.
Clark Seif Clark csceng.com
EMSL Analytical, Inc. emsl.com
LA Testing latesting.com
Zimmetry Environmental zimmetry.com
Healthy Indoors Magazine healthyindoors.com
