General Information

An air purifier filters dust, smoke, pollen, pet dander, mold spores, and other airborne particulate as small as 0.3 microns.

Most air purifiers are tested for efficiency in terms of Clean Air Delivery Rate (CADR). These ratings indicate the volume of filtered air delivered by an air purifier, allowing you to compare one air purifier to another. The higher the CADR numbers, the faster the unit filters the air.

Today's homes often are built energy efficient to "hold" air inside - avoiding heat loss in the winter and heat gain in the summer. Of course, what's better for your energy bills isn't necessarily better for indoor air quality. This type of "tight" construction often doesn't allow the home to breathe.
HEPA stands for High Efficiency Particulate Air (filter). HEPA is a technology developed in the 1940's by the U.S. Atomic Energy Commission to full-fill a top-secret need for an efficient way to filter radioactive particulate contaminants. HEPA is a type of highly efficient filtration media that removes microscopic particles from air passing through the filter. There are different ranges of efficiencies depending on the particle size. The most efficient form of HEPA removes 99.97% of particles with a size of 0.3 microns that pass through the filter. A HEPA air purifier will not capture chemical gasses.

The air inside many homes often is many times more polluted than outside air. Here are some little known facts about the air inside many homes:

  • The Environmental Protection Agency (EPA) estimates that indoor air pollutant levels may be as many as two to five times higher than the pollutant levels outdoors.
  • Indoor air pollution is one of the top environmental concerns in the country.
  • Americans spend up to 90 percent of their time indoors.
  • Indoor air pollutants such as tobacco smoke, pollen, mold, dust and animal dander often are associated with asthmatic and allergic reactions in persons.
The size of airborne particles that an air purifier captures are measured in microns. A micron is approximately 1/25,400 of an inch or approximately 100 times smaller than a human hair. Particles of this size are not visible to the naked eye.
Dirty air is drawn into the air purifier through the inlet grill. Some of the units have a washable pre-filter that traps larger airborne particles. Air then passes through the carbon filter with help reduce odors and captures larger particles. After passing through the carbon filter, the air then passes through the HEPA filter made of tightly woven fibers. Some units have electronic ionizers which further assist in particle removal. The fan then redistributes the filtered air throughout the room.
Washable foam helps capture larger particles and can be easily cleaned. Simply remove the foam from your machine and wash it in warm, soapy water. Rinse and drip dry the foam thoroughly before replacing it.
AHAM is an acronym for the Association of Home Appliance Manufactures. It is an organization that certifies the testing results of home appliances such as refrigerators, room air conditioners, dehumidifiers and room air cleaners. They use outside labs to test products and rate a variety of appliances. Please see for more information.
The room size is generally recommended based on unit's performance ratings (CADR). Most air purifiers will have the appropriate room size reference on the front of the packaging. They can vary from 6ft x 9ft to 20ft x 24ft.