Thursday, December 27, 2012

How Does an Air Purifier Work?

Depending on the type of technology used, an air purifier can remove airborne dust, allergens, chemicals, gases, and odors. Owning an air purifier has become increasingly popular as indoor pollution levels have climbed. Here’s a brief overview of how various air purifier technologies work.
Furnace Filters
The most basic of air purifier filters can be used in your home’s heating and cooling system. It’s usually placed between the air return duct and the furnace. This box-like filter slides into a slot so that all air flowing to the furnace passes through a mesh of fibers. It traps large dust and other particles that could otherwise build up and damage the components inside the HVAC system.  This type of filter cannot remove chemicals, gases or odors.

A Room Air Purifier with a HEPA Filter
To be accepted as HEPA (high efficiency particulate air) filter, this type of cleaning technology must remove 99.97% of airborne particles 0.3 micrometers in size or larger. It’s generally made up of a densely fibrous type material that works by trapping passing dust and allergens. It is highly recommended and very effective on particles, but cannot trap chemicals, gases and odors. 

An Air Purifier with Ionizing Technology
This type of air purifier creates a small but intense electrical field. It works by charging air particles and pulling them to metal plates that have an opposite charge. This technology has come under fire for generating ozone, a potentially dangerous pollutant even in small quantities. Some experts, including doctors with the American College of Allergy, Asthma & Immunology don’t recommend this type of air purifier. They say that without fans, these units cannot collect airborne particles from more than a few feet away and as a result do not significantly improve indoor air quality.

Ozone Generators
An ozone generator works like an ionizing purifier, but purposely produces ozone. Ozone is made up of three oxygen molecules one of which can detach and apply itself to other substances altering their make-up. Manufacturers of these units claim that their air purifier technology cleans the air, however most world health agencies believe there is strong evidence that ozone is not only inefficient, but dangerous to human health. These types of devices have actually been banned in the State of California. There is also concern that ozone may react with chemicals in the air and form new pollutants with unknown health effects.

The most complete and effective air purifier contains a HEPA filter and an adsorbent material like activated carbon to remove chemicals, gases and odors. Activated carbon is extremely porous and has millions of tiny nooks and crannies that trap passing pollutants. Only an air purifier with this type of “adsorbent” (not absorbent) can remove the airborne pollutants left behind by HEPA dust filters.

Learn More
For more information on how an air purifier works or for a personalized recommendation, chat live with an AllerAir Air Quality Expert at

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