Is HEPA Filtration What Your Home Needs for Improved Indoor Air Quality?

Published on: December 15, 2014
Air filter closeup | AC Southeast

High efficiency particulate air (HEPA) filters come installed in household items ranging from vacuums to air conditioners. If air goes through it, it could have a HEPA filter. Commercials refer to these filtration systems, and the filter cartridges themselves command prices that are significantly higher than similar but lower-rated filters. Are they worth it? Why is HEPA filtration such a big deal? Put simply, these filters remove virtually any type of pollutant from indoor air, potentially reducing respiratory irritation and illness from airborne pathogens.

What Exactly Is HEPA Filtration?

Typically, HEPA filters provide both mechanical and electrostatic filtration to remove even the tiniest particles in the air. Industry standards use the filtration rate with particles that are 0.3 microns in size, because that’s the size that other types of filters typically miss. Larger particles are generally caught in the filter media itself, while smaller particles are more likely to be trapped by the electrostatic charge.

Standards for HEPA filters require that the filter capture at least 99.97 percent of all 0.3-micron particles. While requirements for labeling may change in various countries, this is the efficiency rating that’s required for use in aircraft and that has been adopted as the standard for home filters. Some capture as much as 99.999 percent, and most will capture virtually all particles in smaller and larger sizes. This means that the resulting air is, for all practical purposes, completely purified.

How Are HEPA Filters Different From Others?

Filters are typically labeled with the industry standard minimum efficiency reporting value (MERV) rating, which ranges from 1 to 16. The most efficient filters have higher MERV ratings, and HEPA filters receive the highest rating. Most disposable household filters have a MERV rating of 1 to 4, but some range as high as 8 or 9.

The vast majority of filters will capture dust, dirt, pet hair and other common household contaminants. Taking it one step further, the HEPA filter captures pollutants that sail right through most other filters, including:

  • Bacteria. Many types of bacteria circulate through the typical house, potentially infecting respiratory tracts and broken skin. While most types of bacteria are harmless, some can cause illness multiple times before they die out.
  • Fungus. Mold and various fungi release minuscule spores that come in through doors, windows and air vents, and they can grow anywhere there’s a little moisture.
  • Viruses. Most viral particles measure right around 0.3 microns, so they’re the most difficult to remove from your home’s indoor air. HEPA filters are able to remove such things as cold and flu viruses, among other common viral pathogens.
  • Pollen and spores. Released by all manner of plants and trees, spores and pollen fill the air and wreak havoc on allergy sufferers. These are the primary culprits behind most seasonal allergies, and many escape standard furnace filtration.

Filters that have been tested on viruses and bacteria may be labeled as “microbially tested,” but HEPA filters without the label are usually also effective against these particle types. The ability to filter out common allergens and pathogens often makes HEPA filters a top choice for commercial applications (including hospitals), allergy sufferers, and immune compromised individuals.

Is HEPA Filtration Compatible With Your HVAC System?

HEPA filters have to be thick and dense to achieve the appropriate level of filtration, which unfortunately limits their application in home furnace systems. In order to work, the HEPA filter needs more air pressure than most standard HVAC systems can provide.

Most furnaces are built with an open slot where the filter slides in. When the fan runs, the air passes over the filter before entering the enclosed furnace. There is no significant air pressure in these standard systems. Putting a HEPA filter in a furnace that’s not properly equipped will result in little or no airflow through the ducts.

An auxiliary air cleaner can be added to your HVAC system. This is essentially an enclosed HEPA filter with a blower to provide air pressure. This unit forces air through a HEPA filter, and then blows it back into the normal airflow. In most cases the air cleaner won’t handle all of the air that moves through the furnace, but it still results in significant overall filtration.

For more information on what HEPA filtration can do for your Southeast U.S. home, or to find a contractor to install HEPA filtration equipment in your existing HVAC system, contact us at AirConditioningSouthEast.com.