In “Purchasing A Home Air Purifier—Part 1,” I went over some of the reasons why a home air cleaner is a good investment. In Part Two we tackle the question: “How can you tell if the air purifier you are buying is going to work or do the job it is intended to do?” To answer that question we need to review the different filtration methods each system uses.
Long ago the standard of effectiveness for eliminating dust particles was set by the HEPA system, which eliminates particles that average .3 micron in size. This is the particle size most likely to be inhaled and deposited in the lungs and the most difficult for mechanical filters to catch. But now, thanks to the advancements in technology, along with HEPA Air Purifiers, we have the option to buy Ultraviolet Air Purifiers, Ionic Air Purifiers, Ozone Air Purifiers and more.
HEPA Air Purifiers: You may be familiar with HEPA filters if you have a vacuum equipped with one. To be considered a true HEPA filter, it must be capable of removing 99.97% of particles as small as 0.3 microns, which is 1/75,000 of an inch, or 1/300 the diameter of the human hair. HEPA filters trap particles and contaminants and have a life span of about two years.
Ionic Air Purifiers: Ionic air purifiers contain negative ion generators that charge airborne particles so they become attracted to and settle on room surfaces. By doing so they effectively remove harmful particles from the air you breathe. However, if you have this type of purifier in a room that sees a lot of activity it may defeat the purpose. Excessive room activity stirs the particles and puts them back into the air. For this reason, many ionic air cleaners contain electrostatic precipitators, which trap particles on oppositely charged metal plates. The plates need to be cleaned regularly for optimal performance.
Ultraviolet Air Purifiers: Studies show that ultraviolet light is one of the more effective methods to reduce and control airborne particles. (Hospitals commonly use ultraviolet air purifiers.) This is how they work: As contaminated air passes through intense ultraviolet light, bacteria, viruses and some organic compounds are destroyed. Basically, the ultraviolet light damages the DNA of contaminants, consequently they are unable to reproduce. Because some viruses are too small to be trapped by HEPA filters, ultraviolet light is one of the only ways to eliminate airborne viruses.
Ozone Air Purifiers: Ozone in the lower atmosphere has proven to successfully reduce airborne contaminants. Ozone air purifiers release an ozone enriched gaseous plasma into the air that seeks out airborne contaminants. The ozone then alters their chemical makeup and often leaves only carbon-dioxide, oxygen and water behind. Since this purification method does not draw the surrounding air into a central filter it allows large areas to be cleaned effectively.
Activated Carbon Filters: Activated carbon is charcoal that has been treated with oxygen to open millions of small pores between the carbon atoms. These pores adsorb harmful gases and odors. Carbon filters are excellent at trapping gases that pass through traditional particle filters. However, once the pores become filled with trapped contaminants the filters loose effectiveness and need to be replaced.
Most home air filtration systems are a major investment. By reviewing filtration methods; along with the size, price and purpose of each unit you should be able to find the right model for your home.