HEPA Filters

HEPA stands for "high efficiency particulate air" (according to Wikipedia) or for "High-Efficiency Particle Arresting" (according to Honeywell, a leading manufacturer of HEPA filters). It is a standard that is intended to achieve 99.97% air filtration.

HEPA filters, were originally developed during World War II as part of the atomic bomb Manhattan Project. Later developments were for hospitals, scientific laboratories and for companies manufacturing products such as pharmaceuticals and computer chips.

More recently, as technology advances and prices fall, HEPA filters have entered the home, and hundreds of models are now available from dozens of manufacturers.

They work by drawing in air and trapping all particles down to a size of 0.3 microns, including allergens. Sometimes a carbon filter is incorporated, to trap gases and smells. A fan sends the air back into the room.

A typical model is one of Amazon.com's top sellers), the Hamilton Beach 04161 TrueAir HEPA Air Purifier with UV Germicidal Light (pictured above).

According to a product description:

Recommended for rooms up to 200 square feet, this portable air purifier is equipped with a UV germicidal light to help kill airborne micro-organisms and a three-speed fan to continuously circulate air through two filters that remove smoke, pollen, dust, animal dander, dust mites, molds, bacteria, viruses, and odors. Helpful for asthmatics, allergy sufferers, and in a cold or flu patient's room, the purifier contains a true HEPA filter that is at least 99.97 percent effective at trapping airborne particles as small as 0.3 microns. There's also a carbon pre-filter to reduce odors.

The Achoo! Allergy website puts the case for HEPA filters:

An air purifier will improve your health. Americans spend about 90% of their lives indoors, and the Environmental Protection Agency (EPA) estimates that, on average, indoor air is two to five times more polluted than outdoor air.

Modern homes are sealed tightly for energy efficiency. Energy efficient homes are good for your electric bill, but bad for your allergies. Those tight seals trap all kinds of contaminants in your home: pollen that blows in when a door or window is opened, cat dander that hitches a ride on clothing, or chemicals and irritants released by cleaners and perfumes.

Pollutants like tobacco smoke, pollen, mold, dust, and animal dander can cause asthmatic and allergic reactions, making homes unpleasant and unhealthy for allergy and asthma sufferers. Other contaminants, like chemically reactive gases and volatile organic compounds (VOCs), can cause allergic reactions and more serious health problems.

Even if your symptoms are not noticeable now, that doesn't mean the air inside your home is clean. According to the EPA, health affects may show up only after long or repeated exposure; therefore, it's a good idea to clean the air in your home now, especially if you have kids. Prolonged exposure to airborne allergens and pollutants can cause allergies (and more serious health problems) to develop later in life.

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February 21st, 2007
Updated: November 9th, 2007