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Once
a topic relegated to obscure scientific research journals, indoor air
quality, or the lack thereof, is a subject that's finally getting some
well-deserved attention. As consumers have begun to appreciate the atmospheric
consequences of airtight homes built from and filled with chemicals
and other synthetic materials, they've been paying more attention to
reports that say indoor air often contains unhealthy levels of airborne
pollutants.
With the EPA ranking indoor air pollution as one of the top five environmental
risks to public health, and the National Academy of Sciences estimating
that it costs the U.S. between $15 and $100 billion in annual health
care expenses, the issue of air quality inside our homes is one whose
time has come. Only one question remains: What can we do to breathe
a little easier?
For
many, the best answer lies in air cleaning systems, a fast fix for many
indoor air problems. Unlike expensive retrofits or a wholesale banishment
of the modern conveniences that create indoor air pollution, air filters
and other similar devices provide a solution that's inexpensive, effective,
and sacrifice-free.
Practice Your Own Clean Air Act
When
shopping for an air cleaner, it's important to remember that not all
technologies remove all pollutants. Different air purifiers use different
methods, and each has its own limitations in terms of the kinds of air
pollution it can handle. Further complicating the picture is the fact
that many devices incorporate more than one technology.
To
help you keep it all straight and find the device that's best for you,
here's a look at the different technologies available, the types of
air pollution they remove, and some air cleaning machines in which they
are found:
- Activated
Carbon Filters
clean by trapping pollutants in microscopic pits present in the carbon
and by a physical process called adsorption in which gases adhere themselves
to a material's surface. Activated carbon is steam-treated to increase
the number of cavities. It provides moderate filtration and odor removal
and will remove many common gaseous pollutants and volatile organic
compounds (VOCs-chemical compounds that exist in a gaseous form at room
temperature), pesticides, combustion by-product gases, tobacco smoke
particulates, odors, ozone and many organic chemicals. Used in UV Air
Purifier, AAPS 10000 Series, AAPS 20000 Series, Healthmate, Healthmate
Jr., Roomaid, Desktop Air Filter.
- Corona
Discharge Devices are not filters, but they do destroy contaminants
using a process called electronic plasma incineration. Essentially a
miniature lightning factory, such devices destroy bacteria, viruses,
molds, odors, dust, and tobacco-smoke particulates and gases. The process
also creates purifying negative ions and small amounts of ozone. Used
in Personal Air Supply, Deluxe Personal Air Supply, Sani-Mate.
- Electrostatic
Filters use a plastic filter media that becomes negatively
charged via static electricity that's built up on its surface by passing
air currents. (Some electrostatic filters have a permanent charge.)
This negatively charged surface attracts and holds those pollutants
that are positively charged including molds, pollens, bacteria, and
particulates like asbestos, animal dander, and tobacco smoke particles.
Electrostatic filters are not very efficient on their own and are often
used as a pre-filter in a more comprehensive system. Used in Desktop
Air Filter.
- Electrostatic
Precipitators generate negative electric charges and impart
them to passing pollutants. Now negatively charged, these contaminants
are attracted to a series of positively charged collection plates. Like
electrostatic filters, precipitators will capture molds, pollens, bacteria
and particulates like asbestos, animal dander and tobacco smoke particles.
- HEPA
Filters were originally developed to remove radioactive particles
from the air in nuclear labs. HEPA stands for "High Efficiency Particulate
Air". These filters consist of a dense maze of fibers that trap at least
97% of all particles down to 0.3 microns in size. HEPA filters excel
at removing particulates like asbestos, dust, pollen, mold, animal dander,
and tobacco smoke particles. They will also remove bacteria and viruses.
Used in UV Air Filter, Blueair, Healthmate, Healthmate Jr., Roomaid.
- Ion
Generators work by releasing negatively charged ions into the
air, but do not actually filter the air. Instead, these ions attract
positively charged pollutants and transfer their charge to them. The
newly negatively charged pollutants are drawn to a positively charged
surface. Some ion generators include such a surface, others do not.
If there is no positively charged surface, the particles, made heavier
by the ions, simply fall to the floor where they should be regularly
vacuumed. Ion generators generally remove only smaller particulate pollution
types including tobacco and smog-related particulates, and bacteria.
Evidence suggests that negative ions can also create a feeling of well-being,
produce greater mental and physical energy, and bring relief from allergies
and asthma. Used in UV Air Filter, Blueair, Car Ionizer.
- Ozone
Generators work by creating ozone, a highly reactive form of
oxygen that can destroy many contaminants. However, ozone is also an
air pollutant itself, one that can harm skin, eyes, and mucous membranes,
and affect respiration. Exposure to concentrations of ozone as low as
80 parts per billion can cause such effects, and the FDA has set a limit
of 0.5 parts per billion for all indoor ozone devices. In spite of this
regulation, their use in the home continues to spark debate about the
potential risks and rewards of intentionally adding ozone to indoor
air. Many ozone generators come with a timer, allowing you to program
the unit to run only when the house is unoccupied. Ozone is very effective
at destroying bacteria, viruses, and odors and is a great choice for
moldy basements, garages, or other areas outside of your main living
space. It will also break down certain VOCs into less harmful compounds.
However, ozone is also capable of reacting with existing pollutants
to create new types that weren't previously present. Used in Ozone Generator.
- Ultraviolet
Light Purifiers use UV light to kill airborne disease germs,
bacteria and viruses but do not filter the air. Though this technology
effectively destroys pathogens, it is best used in conjunction with
a type of air filter. Used in UV Air Filter.
- Zeolites
are any of a group of natural aluminum silicate minerals that, like
activated carbon, excel at removing odors and many gaseous pollutants
via adsorption. Unlike carbon, however, zeolites can be easily recharged
by outdoor exposure to sunlight which frees the adsorbed pollutants
and restores the minerals for reuse. Used in Healthmate, Heathmate Jr.,
Air Refreshers.
Where
to get the Air Purifiers described here
Go to http://www.gaiam.com
About
the Author
Geoff Davis is a freelance writer and commercial inkslinger whose work
has been featured in an variety of local and national media. He lives
sustainably with his wife, daughter and faithful canine in the forested
wilds of Monkton, Vermont.
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