The device that you or your HVAC contractor changes once or twice a year is designed, primarily, to keep the cooling coils clean. It has very little effect on the removal of airborne particles that maybe harmful to your health.
These general duty air filters are comprised of very open mesh or pleats that allow air to pass through easily but capture larger dust and dirt particles to minimize any deposit of dirt on the cooling coils which could, over time, significantly reduce the efficiency of the coils and also put dirt on the blower wheel.
Dust particles you can see are about 20 microns in size or lager. As a comparison, your hair is about 100 microns in diameter. However, airborne particles that may harm you body when inhaled are usually smaller than 1 or 2 microns in size. The efficiency of the general duty air filter on these sized particles is about 25% at best. Meaning your health is not protected in any way from indoor airborne contaminants with these general duty filters.
Perhaps the best way to get some real basic information on how filtration actually works is to go to the Pure Air Systems website. ..https://www.pureairsystems.com There you will find a section entitled “Pure Air University.” This is broken down into simple sections detailing how filtration actually works and the reasons why you may want to look beyond the general duty filters if you really want to clean up your environment.
PAS produces high end HEPA based, fan powered, air filtration systems and has since 1985. 32 years of experience in working with all types of airborne contaminant applications allows them to share their experience and knowledge of this process with anyone who cares to go to their website.
If you have any other questions you can always call the technicians at Pure Air Systems. You can reach them on their toll-free number at: 800-869-8025.