| The
spectrum of air filters and cleaners is differentiated in
a number of ways. Here's a closer look at the main types:
HEPA air filters, which stands for High Efficiency
Particulate Accumulation, is a highly effective filter originally
designed for removing radioactive particles from air. Today
HEPA filters are used in military, industrial and scientific
applications and in certain portable and room-size residential
home air filters.
Made from finely woven glass particles formed
into a pleated filter that has a very large surface area,
a HEPA filter--by definition--removes 99.97% of all .3 micron
particles from the air.
Unfortunately, high replacement cost is a
real disadvantage to HEPA filters--they generally must be
replaced once every year to 18 months, depending upon use,
and they typically cost from $70 to $125.
And because the filters are so dense, they
require a strong blower to move air through, racking up higher
energy costs. The larger the surface area of a HEPA, the better--so
find out its square footage before buying one.
ULPA air filters, which stands for Ultra Low
Penetrating Air, is a filter developed for use in hospitals
and manufacturing "clean rooms" such as those employed
in the semiconductor industry. Now available in self-contained
home air cleaners, the filter is an intercut web of micro-fibers
that traps 99.99% of .1 micron particles from the air.
"HEPA-type" filters, made for both
self-contained units and forced-air systems, have not met
the rigorous standards of a genuine HEPA, but some, like the
pleated types, are almost as effective.
Most range from 25 percent to 95 percent effective
at microscopic particle removal. Before buying one, be sure
you know how good it is at blocking respirable-size particles.
With continuous use, HEPA-type filters must be replaced every
year at a cost of from $30 to $45.
Though ordinary 99-cent furnace filters catch
about 75 percent of bulk dirt, they capture very little--often
less than 3 percent--of the minute pollutants. Slightly more
effective for a forced-air system are treated filters. These
disposable products, which typically sell for under $10, have
been coated with dirt-trapping glycol or mineral oil. Though
they stop about the same percentage of bulk dirt, they block
up to about 10 percent of the smaller, microscopic particles.
An electret or electrostatic air filter uses
synthetic fibers that create a static charge to attract particles.
Costing from $15 to $100, electrostatic filters come plain
or pleated, disposable or reusable. Though you just hose out
reusable models to clean them, they still have to be replaced
periodically.
Disposable models should be replaced quarterly.
Depending on the make, an electrostatic filter blocks between
10 percent and 35 percent of microscopic particles. Some are
sold as kits; the frame is permanent, the filter pad is replaced
every couple of years.
An electrostatic precipitating ("electronic")
air cleaner draws particles in by fan and charges them with
a series of high-voltage wires. A precipitating cell (a series
of plates) that carries the opposite electrical charge attracts
the particles as they pass by. You can buy portable versions
or whole-house models that connect to the cold-air return
plenum on the furnace.
They are quite effective, removing about 95
percent of bulk dirt and 85% percent of microscopic particles.
Whole-house electronic air cleaners, sold through heating
contractors, cost $300 to $900 installed, depending on the
complexity of the installation.
A negative-ion generator uses tiny, charged
wires or needles to create ions (gas molecules with a negative
charge) that latch onto airborne particles. A fan in the unit
distributes the ions back into the room, but they tend to
stick to walls, floors, tables and other surfaces, and may
stain them.
Air
Purifiers | Basic
Types Of Air Purifiers | Your
Whole House Air Purifier |
A
Quick Guide to Air Purifiers |
Quiet
Air Purifier
| Hidden
Dangers: Reduce Toxins in Your Home
|
How
an Air Cleaner Works
| How
Effective Are Home Air Cleaners and Air Purifiers?
|
About
Air Purifiers And Dusting Your Home
| Air
Purifier Ratings |
Using
Car Air Purifiers To Prevent Allergy Symptoms |
