Thursday, January 31, 2013

The pros and cons of HEPA air purifiers

HEPA or High Efficiency Particulate Arresting air purifiers use a fibrous filter to trap ultrafine particles. HEPA filtration was actually born from an infamous and historically significant event; the development of the atomic bomb. It was created to prevent the spread of minute radioactive particles. Today, HEPA plays an equally important role in home air purifiers, filtering dangerous particles from air pollution and smoke that have been linked to heart disease, cancer and respiratory illnesses. While widely recommended, HEPA-only air purifiers have a significant disadvantage; they cannot filter out other worrisome modern-day pollutants like chemicals, gases and odors.

What exactly is HEPA?
HEPA filters are comprised from tightly arranged fibres that trap hazardous fine particles that could otherwise be inhaled and settle in the body. To be classified as HEPA, the filter must remove at least 99.97% of all particles greater than 0.3 micrometers. Air purifiers that claim to be "HEPA-type" or “HEPA-like” may not have been adequately tested and could provide inferior air filtration. 

Why can’t HEPA air purifiers filter all types of contaminants?
While the design of the HEPA filter is ideal for trapping ultrafine particles, other pollutants like gases, fumes, chemicals and odors pass right through.  Air purifiers that trap a wider range of contaminants combine HEPA filtration with another filtration media. 

Air purifiers with activated carbon
The most efficient filter material for trapping gaseous pollutants is activated carbon. Like HEPA, activated carbon was developed by the military, and then commercialized for residential use.  It’s so effective, that activated carbon is widely used by heavy industry to trap toxic chemicals and is also used in water filtration. As home air quality concerns shift to dangerous airborne chemicals, some manufacturers have unfortunately used carbon as marketing ploy. These types of inefficient air purifiers use only a thin carbon mesh and claim their units can remove odors and chemicals. The adsorption capacity of carbon-mesh is so limited that these types of filters may be full within only weeks or days of use, depending on the level of pollutants in the environment. Only air purifiers with pounds of deep-bed activated carbon can provide lasting adsorption of chemicals, gases and odors.

How does activated carbon work?
The carbon used in air purifiers has been specially treated to open up millions of microscopic pores that attract and trap chemicals, gases and odors. Only a handful of granular activated carbon has a surface area larger than most suburban shopping malls. 

Hybrid Air Purifiers
The most effective air purifiers for today’s air quality challenges combine both of these excellent filtration methods into one unit.  When used together, a HEPA and deep-bed activated carbon air cleaner can remove a wider range of airborne contaminants including allergens like dust, pollen and dander as well as smoke, cleaning chemicals, VOCs (volatile organic compounds) and strong odors.

Learn More
For more information on hybrid HEPA-carbon air purifiers speak with an AllerAir air quality expert at 1-888-852-8247 or connect via the live chat link at

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