Most air purifiers use either HEPA filter or washable stainless
steel/Aluminum collection cell as their filtration media. Some air
purifiers also use pre-filter to increase the overall filtration
HEPA is an acronym of High Efficient Particulate Air. Any true HEPA
filter guarantees that the filter will capture airborne particles down
to 0.3 microns in size, 99.97% of the time. (Particles smaller than 0.3
microns are still trapped by HEPA filters but effectiveness is reduced
to less than 99.97%.)
To clean an entire room, all of the air in the room needs to pass
through the air cleaner's filter. Air cleaners are rated by the amount
of air moving through the filter. This rate is called CADR or Clean Air
Delivery Rate. CADR measures the amount of particle-free air being
delivered into the room. The higher the CADR, the larger the room size
that an air cleaner can be cleaned.
Negative Ions are very healthy to our
body & believed to produce biochemical reactions that increase
levels of the mood chemical serotonin, helping to alleviate depression,
relieve stress, and boost our daytime energy.
Ozone and ionic air purifiers have recently received a lot of attention
in the media recently due to reports showing that they may be
detrimental to one's health. Ozone has been used to purify municipal
water supplies for years, and for highly contaminated areas such as bars
or salons, ozone can be very effective in cleaning the air.
Even through most ozone air purifiers release ozone that is well below
the allowed amount as established by the government, caution should be
taken if you suffer from respiratory problems, as event minute amounts
ozone gas may worsen symptoms. With that in mind, if you are an allergy
sufferer or asthma sufferer, look for air purifiers with HEPA filters
Yes, but only when occurring in extremely high concentrations - much
higher than what an ozonating air purifier is capable of producing.Ozone
is much like any other element in that it has its range of effects. It
is harmless and useful at moderate concentrations, but harmful at
extremely high levels. Take table salt for example, which provides
essential fortification for nerve cells and the kidneys, and prevents
heat stress disorders at lower concentrations. At higher levels, though,
salt can result in hypertension and cardiac failure. Electronic air
purifiers will not produce ozone at a level higher than what is
considered healthy in outdoor settings.
Negative ions are negatively-charged electrical particles that are
magnetically attracted to allergens and other airbone contaminates,
which are positively-charged. The newly-formed larger particles are then
able to fall harmlessly to the ground, and out of the air we breathe.
Ozone oxidizes (burns) pollutants, destroying them altogether. The ozone
molecule (O3) is highly reactive, so whenever it encounters a floating
particulate, one of the oxygen atoms breaks away to oxidize the
pollutant. This leaves behind O2 (pure oxygen), refreshing the air event
more. Ozone has the 2nd highest oxidation potential out of all the
The most important thing to remember is that these microscopic
pollutants are out of the air you breathe, which renders them harmless.
If they are not in the air, they cannot find their way into your lungs
where they do their damage. It should be pointed out that these are
microscopic particles and not specks of dirt, so your floors, furniture,
and other surfaces will not suddenly become "dirty" once these
pollutants begin falling out the air. Fortunately, Ionic Air Purifiers
produce a continual supply of negative ions and low levels of ozone,
which means "kicked up" particulates will find themselves grounded again
There are no official standards to measure an air purifier's performance
at this time, and the FDA has repeatedly asked groups of experts to
recommend such standards. Nonetheless, the Association of Home Appliance
Manufacturers (AHAM), does conduct independent tests which measure an
air purifier's Clean Air Delivery Rate, or CADR.
CADR determines how much clean air an air purifier delivers to a room,
and this is measured in cubic feet per minute. Air purifiers are usually
tested on their ability to remove three types of common pollutants:
smoke, dust, and pollen. If an air purifier has a CADR rating, this
measurement is usually found on the packaging.
PCO is one of the newest and most advanced air purification technologies
on the market today. PCO air purifiers work by using broad spectrum UV
light and a titanium dioxide-based chemical catalyst to oxidize
pollutants such as chemicals, gases, bacteria, and VOCs and turn these
contaminants into harmless water and carbon dioxide.
We inhale roughly 10,000 quarts of air every day, and this brings not
only oxygen into our lungs, but also harmful pollutants. This, coupled
with the fact that we spend up to 90 percent of our time indoors, makes
us highly susceptible to harmful indoor particulates such as dust,
dander, mold, chemicals, and even carcinogens. Exposure to these
pollutants has been shown to cause a range of health problems such as
allergies, asthma attacks, and damage to the respiratory system. With
this in mind, investing in an air purifier can improve the health and
well-being of you and your family.
Whether you're looking for an air purifier for general air purifying or
have specific air purifying concerns, in general, here are two things
to consider when purchasing an air purifier
For complete and thorough control of particulates such as dust, dander,
and pollen, look for air purifiers utilizing HEPA filtration, as they
have the ability to remove 99.97% of particulates from the air you
breathe. Odor control will require the use of Activated Carbon air
purifiers, and if mold is a problem, look for air purifiers featuring UV
Air purifiers are usually rated based on area size. Proper filtration of
a specific area will require an air purifier that can handle the area's
square footage. For example, if your living room is 400 Square feet, an
air purifier designed for personal spaces up to 100 square feet will
not be sufficient.
Also, be sure to look at the size of the particle the machine is capable
of removing, cost per square foot purified, the cost replacement parts
and how often they need to be replaced, electricity cost, the noise
generated, warranty, physical size
The Environmental Protection Agency (EPA) themselves have declared
indoor air quality as the nation's worst environmental health problem,
and have also warned that indoor air is generally 2 to 10 times worse
than outdoor air pollution. In addition, allergies, asthma, and hay
fever are becoming much more prevalent and severe in recent years as a
direct result of rapidly worsening indoor air quality.
Virtually every home is affected, so yours is also most affected to one
degree or another. This is especially true if your home or building was
built in the last 20 years, or if it has several sources of indoor air
pollution (many will probably surprise you). If you have asthma or some
other respiratory condition (such as hay fever), then you are probably
more sensitive to the indoor air quality problem. Also, if your home has
excessive moisture or if you have a chronic leak, then you are more
likely to have mold or dust mite problems.
Asthma and sinus allergy problems took a sharp turn for the worse about
20 years ago. Not coincidently, houses and buildings began to be
constructed in an air-tight fashion at about this time in an effort to
gain more energy-efficiency, as a result of the energy crisis of the
1970s. However, more and more studies are showing that this tight
construction is creating an extremely unhealthy environment for
breathing, by trapping pollutants indoors, while keeping natural
air-cleansing agents out. We are also finding out that asthma problems
are much more a results of environmental triggers than anything else,
and most people spend more than 90% of their time inside, which means
that indoor air pollutants affect our health far more than outdoor air
Dust, people, carpet, plywood and other construction materials,
mattresses, furnishings, pillows, blankets, HVAC systems, household
cleaning products, aerosols, insecticides, humidity, anything moist,
pets, insects and other bugs, food, and cigarette smoke are all common
sources for indoor air pollutants.
No, but air purifiers can definitely help reduce the amount of
medication needed by you or a family member. Many asthma medications
that asthmatics take are reactive, meaning they are taken to relieve
asthma attacks which are generally caused by environmental triggers.
Removing environmental triggers such as airborne allergens and
contaminates from the air will decrease asthma problems, therefore
enabling a reduction in medication. Considering all of the side effects
and financial costs imposed by asthma medications, investing in an air
purifier is a good decision.
|Most air purifiers utilize common air purification technologies such as
HEPA, Activated Carbon, Ionizers, and UV bulbs, and these methods are
usually categorized by filter type:
Recent developments in air purification have also seen more air cleaners
employing the use of Photocatalytic Oxidation, or PCO. By using broad
spectrum UV light and titanium dioxide, PCO is an extremely powerful
purification method, and PCO air purifiers can even eliminate particles
as small as 0.001 microns (HEPA filters are only able to filter out
pollutants as small as 0.3 microns).
- Mechanical Filters such as HEPA and Activated Carbon force air through a mesh that traps particles.
- Electronic Filters such as ionizers use electrical charged to
attract and deposit allergens and irritants onto electrostatically
- Hybrid Filters contain elements of both mechanical and
electrostatic filters, and many air purifiers use this type of
- Ozone Generators release ozone-rich gaseous plasma into the
air, and this plasma alerts the chemical makeup of pollutants into
harmless carbon dioxide, oxygen, and water.
- Gas Phase Filters remove odors and gases, but do not filter out particulates.
- UV Sterilization involves the use of UV light, which damages the DNA of microorganisms and bacteria.
HEPA filters were originally developed by the Atomic Energy
Commission to capture radioactive dust pollen, and by definition, a True
HEPA filter must be capable of removing at least 99.97% of particulates
as small as 0.3 microns such as dander, dust, and pollen. Therefore,
because of their superior filtration abilities.
||Indoor Air Quality
||Environmental Protection Agency
||Photo Catalyst Oxidation
||Association of Home Appliance Manufacturers
||Clean Air Delivery Rate
||Multiple Chemical Sensitivity
||Minimum Efficiency Rating Value
||Cold Catalyst Filter
||Activated Carbon Filter
||Ultra Large Particulate Air Filter|
"reverse osmosis," it is probably best to start with normal osmosis.
According to Merriam-Webster's Collegiate Dictionary, osmosis is the "movement of a solvent through a semipermeable
membrane into a solution of higher solute concentration that tends to
equalize the concentrations of solute on the two sides of the membrane."
That's a mouthful. To understand what it means, this picture is helpful:
On the top is a
beaker filled with water, and a tube has been half-submerged in the water. As you would expect, the water level in the
tube is the same as the water level in the beaker. In the middle figure, the
the tube has been sealed with a "semipermeable membrane" and
the tube has been half-filled with a salty solution and submerged.
Initially, the level of the salt solution and the water are equal, but over
something unexpected happens -- the water in the tube actually rises. The
rise is attributed to "osmotic pressure."
A semipermeable membrane is a membrane that will pass some atoms or molecules but not others. Saran
wrap is a membrane, but it is impermeable to almost everything we commonly
throw at it. The best common example of a semipermeable membrane would be the
lining of your intestines, or a cell wall. Gore-tex is another common
semipermeable membrane. Gore-tex fabric contains an extremely thin plastic film
into which billions of small pores have been cut. The pores are big
enough to let water vapor through, but small enough to prevent liquid water
In the figure above, the membrane allows passage of water
molecules but not salt molecules. One way to understand osmotic
pressure would be
to think of the water molecules on both sides of the membrane. They are in
constant Brownian Motion. On the salty
side, some of the pores get plugged with salt atoms, but on the pure-water side
that does not happen. Therefore, more water passes from the pure-water side to
the salty side, as there are more pores on the pure-water side for the water
molecules to pass through. The water on the salty side rises until one of two
· The salt concentration
becomes the same on both sides of the membrane (which isn't going to happen in
this case since there is pure water on one side and salty water on the other).
· The water pressure rises
as the height of the column of salty water rises, until it is equal to the
osmotic pressure. At that point, osmosis will stop.
Osmosis, by the way, is
why drinking salty water (like ocean water) will kill you. When you put salty
water in your stomach, osmotic pressure begins drawing water out of your body
to try to dilute the salt inyour stomach. Eventually, you dehydrate and die.
In reverse osmosis, the
idea is to use the membrane to act like an extremely fine filter to create drinkable water from salty (or
otherwise contaminated) water. The salty water is put on one side of the
membrane and pressure is applied to stop, and then reverse, the osmotic
process. It generally takes a lot of pressure and is fairly slow, but it works.
R.O. Membrane Pores 0.0001 microns
Virus 0.2 to 0.4 microns
Bacteria 0.4 to 1 microns
Metals & Chemicals are usually larger
So, what you get is pure drinking water.
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