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An air purifier without an activated carbon air filter is only half an air purifier
Just as in the case of other air purification technologies, the activated
carbon air filter is misunderstood, misleadingly advertised, and
mistakenly dismissed as unimportant.
Ionic type air purifiers do
not use one at all. Air purifiers promoting their HEPA or HEPA-type
media may include a thin fibrous pad with a few token ounces of
activated carbon.
How should you, as a consumer, evaluate these
products? Will they do for you all that you expect from an air cleaner?
Or should you insist on something more?
The very companies that
should help make your decision an easier one often do just the
opposite. Unfortunately, one of the most frustrating things about
searching for air purifiers is the prevalence of hype and the absence
of real information.
Rather than follow suit and toss dozens of
alarming "quotes from experts" at you, I hope to answer some of the
most basic questions you may have.
What can an activated carbon air filter really do for you?
Will activated carbon filters prove to be your only real defense against chemicals and odors?
How
does activated carbon work in air purifiers? How much do you need? How
can you evaluate which air purifiers are best for your needs?
No
other air purifier technology comes close to removing the volume of
chemicals that activated carbon does. If you're serious about making
the best possible choice in air purification, why not take the time to
review the information in this article?
What can an activated carbon air filter do for you?
Air purification with activated carbon air filters is the single best way to remove chemical pollutants from the air.
An
activated carbon filter will adsorb some of almost any vapor,
especially organic molecules and solvents. Activated carbon can adsorb
and retain a wide variety of chemicals at the same time.
Activated
carbon air filters work well under a wide range of temperatures and
humidity levels; are inert and safe to handle and use; and are readily
available and affordable.
Activated carbon filtration can remove
organic acids, alcohols, aldehydes, chlorinated hydrocarbons, esters,
ethers, ketones, mercaptans, amines, halogens, halogen acids, sulfuric
acid, sulfur dioxide, phosgene, as well as odors from human and animal
sources, urine and other waste, perfumes and household cleaning
chemicals.
While activated carbon does remove many volatile
organic compounds (VOCs), some compounds like formaldehyde and
inorganic gases respond best to chemisorbers that break down the
pollutants by chemical reaction.
You should look for air
purifiers containing activated carbon impregnated with appropriate
chemisorbers and catalysts to control the particular pollutants that
concern you.
How does activated carbon work in air purifiers?
 Carbon that is 'activated' undergoes a process which opens up millions of tiny
pores and fissures to enhance the material's adsorbent properties.
The
process creates a very large internal surface area, which is key to the
power of activated carbon - the more surface area - the more the carbon
can adsorb. Only one pound of activated carbon typically has a surface
area of 125 acres.
When gases, chemicals and odors pass slowly
through a thick filter packed with activated carbon they become trapped
in the million of pores opened by the activation process. Due to the
large internal surface area of activated carbons it can adsorb up to
60% of its weight. Good carbon filters, depending on the environment in
which they are used, can last up to 5 years before all of the pores are
full. What should you look for when choosing your activated carbon air cleaner?
Is protecting your family from airborne chemical toxins important to
you? Would you like to control unpleasant odors from cooking, cleaning
or smoking? Do you have sensitivities to volatile organic compounds?
An
activated carbon air filter is the best way to accomplish these tasks,
but will just any old purifier claiming to have activated carbon be
good enough?
Many air purifiers claim to use activated carbon
for gas and odor removal, but will not mention how much is in their
filter. This is because they have simply coated a mat with a few ounces
of activated carbon. In an average home, that small amount of carbon
could get saturated in days, even hours. After this, the filter would
need to be replaced or it would be doing nothing.
For an
activated carbon filter to be effective, there needs to be a sufficient
amount of activated carbon so the air passing through is able to
deposit its pollutants.
When choosing an activated carbon filter
it is important to find one that provides a large activated carbon bed
weighing many pounds. Additionally the activated carbon media needs to
be protected from premature clogging by being placed behind a
pre-filter.
An optimal flow of air needs to be available to pass
through it. A cylindrical shaped design is an ideal solution for
allowing maximum contact with the air.
It is best if the air
filter's activated carbon bed and HEPA filter can be replaced
separately as the activated carbon filter will typically have a shorter
life than the HEPA filter. They both should be relatively easy to
access and replace, preferably without tools.
Another point to
look for is whether you can replace the activated carbon media itself
without replacing the entire containing cartridge. Bulk media is much
less expensive than a complete cartridge unit.
Among the best
air purifiers offering activated carbon air filters are Allerair,
IQAir, Blueair, and Austin Air. The best place to buy any of these air
purifiers online is achooAllergy.com.
Return to Home Air Purifier Guide home page.
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