There are some very good air purifiers on the market by such
companies as Oreck®, Honeywell®, Austin®, Friedrich®, Hunter®,
Kenmore®, IQAir®, Blueair®, Electrolux®, Panasonic®, Airfree®,
Holmes®, Prozone®, FreshAir®, EcoQuest®, Biozone®, Bionaire®,
Whirlpool®, Sharper Image®, Sila®, Hamilton Beach®, GE®, Lumipure®,
Amcor®, Lifewise®, Bell & Howell®, Delonghi®, Aranizer® and Surround
Air®, but you must understand the technical differences among these
purifiers before you can find one that's right for you.
HEPA Filter air purifiers
HEPA filters employ a cloth type filter that can trap 99.9% of
particles 0.3 microns or larger in size, and a fan to move air
through the machine. HEPA filters can be very effective in clearing
out almost any harmful particles from the air in a room. These
devices usually have a replaceable filter that can last several
years depending on how filthy the air is in your home. Although some
don’t like the noise level of a HEPA machine, it can usually remove
more pollutants than a ionic machine.
Advantages: allergens are captured; not being released into the
air once trapped. Disadvantages: Does not eliminate chemical fumes,
gases, cigarette smoke, or odors
Ozone air purifiers
Ozone is a highly reactive oxidant that destroys certain
bacteria, chemicals, bacteria and chemicals. Although ozone is very
effective against strong odors, there is a caution you should
consider.
When ozone reacts with substances in the air, the substances are
broken down into other materials that are also pollutants. This is
where the controversy lies with ozone machines. You can run ozone
machines on low (if they are adjustable), which manufacturers often
advise. However, if you are clearing a room from smoke or odors you
can run it on high while keeping people out of the environment
altogether. Later, turn the machine off and open windows to clear
out the ozone.
Advantages: Extremely effective against odors. Disadvantages: Not
effective on allergens and most chemicals.
Carbon air purifiers
Activated carbon air filters consist of a system of pores that
are tiny in size. These pores are highly adsorbent, chemically
reacting to particles that pass through them and the particles and
odors actually bond with the carbon.
This is the most absorbent filter on the market today, so it is
extremely effective in capturing certain types of particles (see the
chart below for more information). Note that most carbon activated
devices also incorporate HEPA technology, thereby combining the
advantages of both types of technology.
Advantages: Highly effective with chemicals, gases, smoke, and
odors. Disadvantages: Not effective with allergens and
micro-organisms.
Ionic air purifiers
Ionic air purifiers do not have a cloth filter like the HEPA
machines. They work by "ionizing" the air, causing particulates to
gain a positive or negative charge. Why charge the particles?
The charge is necessary for two reasons. The air ionizer contains
collection plates that have an opposite charge from the particles in
the air, so the particles are drawn to the collection plates (these
are referred to as “capture” ionic purifiers). Also, the
particulates can be attracted to other particles that have an
opposite charge. When this happens the two particles with opposite
charges wind up sticking together and falling out of the air (these
machines simply release ions into the air without capturing them on
plates). By the way, many people like ionizers because they are very
quiet compared to most HEPA machines.
Advantages: can remove extremely fine particles anywhere in a
room; even several feet away from the machine. Disadvantages: Not
effective on odors; doesn't kill germs but removes them from
household air.
Ultraviolet light air purifiers
Ultraviolet (UV) lamps are known to sterilize micro-organisms
that pass through it, including germs, viruses, bacteria, and mold;
so microorganisms, after treated with this light, can no longer
reproduce and grow. At least we know this to be true when UV light
is used in sufficient dosage and a sufficiently long period of time
to do its job.
When used in an air purifier, does the UV light have enough time
to perform and sterilize correctly while air is moving through it,
possibly at a brisk rate of speed? There is an innovative approach
that uses UV lamp combined with a HEPA filter, so particles trapped
in the filter can be treated with UV light for an effective amount
of time.
Advantages: Helps destroy microorganisms that cause disease.
Disadvantages: Not effective on allergens, smoke, odors, or
chemicals.
Purifying hydroxyl radicals
Hydroxyl radicals are powerful cleansing agents that occur
naturally in the Earth’s atmosphere. They are created when oxygen
atoms pull a hydrogen atom from water vapor, which then form the
radical. Hydroxyl radicals are 1,000,000 times faster at destroying
pollutants in the air than ozone. They are the most powerful method
of neutralizing mold, bacteria, and viruses.
New proprietary technology has combined hydroxyl radical
technology with ultra violet light and negative ions resulting in an
air purifying system that neutralizes every category of pollutant in
your home, including odors, without the need for filters!
Advantages: removes every category of pollutants when combined
with negative ions and UV light technologies; no filters needed;
inexpensive. Disadvantages: only available from one manufacturer.