Every year, some journalist pretending to be
writing a responsible article about air cleaning ambushes
us. Inevitably, it turns out to be some simplistic attention
getting tactic, trashing air cleaners uniformly.
What IS true is there are number of air purifiers
out there in the marketplace; some of which are best sellers
to consumers, which have very questionable effectiveness.
Yet there is a reason why the government reimbursed people
for hepa air filters if they lived near Ground Zero; or why
they recommend them for homeland security or why hospitals
use them in infectious disease units. Yes, they do work, but
some of them not as well as you would want all the time, and
you need to know what you are buying.
The problem is one of discrimination and education.
How does a consumer make an educated choice? This is a subject
about which our staff could give chapter and verse[and frequently
do when people who telephone us!].I cannot even begin to tell
you how many air cleaners we get in here to test and which
do not pass the cut. During the last six months we have had
machines to test which smell either of plastic and ozone[which
is toxic],efficiency levels which are disgraceful, replacement
filter costs which are a rip off, untruthful or misleading
specifications, shoddy materials; the list goes on and on.
There is a reason why AllergyBuyersClub.com
has garnered the reputation of being incredibly knowledgeable
about air cleaning, and David Barnaby, the coauthor of this
article, puts prospective products through their paces.
We have attempted to reproduce in this article,
the kind of questions and advice we would give you if you
phoned us. If you can absorb it all, this article tells you
everything you need to know, and if you are confused, you
can still phone us up and we will keep our advice as short
and sweet as you like.
Do
You Need an Air Purifier for Allergen, Virus or also Odor
and Gas Control?
There are many choices for the consumer in the
marketplace. Your choice of air purifier will be completely
different according to what you are trying to achieve. For
instance, if your main goal is to clear the air of allergens,
you should choose an air purifier which would remove the large
particulates such as pollen with a pre-filter, but also smaller
allergens, which would be particulates from 0.3 to 5 microns
in size. These smaller allergens include mold, bacteria, animal
dander, fumes, and house dust mite allergens. A Hepa filter
would trap particulates of this size and remove them from
the air in your room. However, it is important to note that
more than 90% of all particulates are 0.3 of a micron and
smaller in size. These are known as “lung penetrating
particles” and are the ones most dangerous to your health.
Particulates of this smaller size, include viruses, some bacteria
and germs, some house dust mite allergens, cat allergens,
smoke, soot, fumes, and smog.
Since
most standard Hepa filters [and there do exist some Hepa filters
with enhanced filtration capabilities such as IQAir]
would not be able to trap most of these smaller particles,
there are also some machines that utilize ultraviolet light
in combination or as a standard alone machine, where the rays
will breakdown the DNA and RNA of the microorganism, and while
not “killing”, they will sterilize those microorganisms,
thus preventing them from being able to reproduce and grow.
An Excellent example of the this would be the CARE
Air Defense System air purifiers. A word of caution; all
ultra violet machines are not equal and their quality and
effectiveness varies enormously. The most important factor
determining the effectiveness of ultra violet light is whether
the rays are strong enough in the first place, which is referred
to as its dosage. Also, the rays need to expose the microorganism
to the light for a long enough time in order for the DNA and
the RNA to be altered. Even if the ultra violet light is not
completely effective, having one is better than nothing, because
some of the micro organisms will be sterilized by the rays
when they collide with the light or “bump around”
with a side to side movement, so as not to move through the
UV chamber too fast.
If you need an air purifier primarily for odor
and gas control, you would want an air purifier that will
first remove the majority of the particulates in a pre-filter
and then have the gases and odors removed by the gas filter.
Gas molecules are very small so they cannot be removed by
even the finest Hepa filter. They are 0.001 and smaller. Therefore,
they need to be physically removed by a substance that will
trap them in their many micro pores. A good substance commonly
used is activated carbon where it is super heated and steamed
resulting in millions of tiny pores. Each one of these pores
will be able to adsorb the gas molecules. Once the pore cannot
hold anymore of the gas molecules, it is said to be saturated,
which means it will not be able to adsorb anymore gases and
odors. Another method of gas and odor removal is through chemical
absorption where the gas molecule will be exposed to a chemical
agent where in combination with water molecule a chemical
reaction will occur whereby this gas molecule will be broken
down into a harmless byproduct such as carbon dioxide. A common
substance used is alumina silicate, alumina oxide, and potassium
permanganate. These are particularly effective at removing
your lighter molecular weight gases such as formaldehyde.
The Size
and Quality of the Hepa filter in your Air Purifier.
The more square feet of Hepa filter media there
is in an air purifier, the more particulates it will be able
to remove from the air before it becomes clogged. Also the
air purifier will be able to remove more particulates with
each pass. The quality of the Hepa filter is very important
both in the material used and the design. The pleats of a
Hepa filter need to be uniform so each one has the same efficiency
of filtration. If the pleats are too close together they can
restrict the air movement too much resulting in a loss of
airflow. Some Hepa filters out there use synthetic materials
and not paper. Thin paper is the best material because it
will be both effective at removing the highest percentage
of the microscopic particulates while not restricting airflow
too much. However, the better grades of Hepa filters are extremely
delicate and can be easily damaged. This is why the better
air purifier companies will house the filter in such a way
as to protect the actual Hepa filter material.
Lung Damaging
Particles
Lung damaging particles are of most concern
because of the fact they are small enough to get through your
sinus cavities and into your respiratory system while at the
same time large enough not to be exhaled out. Therefore, it
is very important when considering which air cleaner to purchase
to make sure it will be able to filter all of these particulates.
The size range will vary from 9 microns to 0.3 of a micron
in size. This is why the Hepa filters have become so important
to the air cleaning industry.
Particulates
in this lung damaging size range are some bacteria, most molds,
fumes, smoke, smog, diesel exhaust, cat allergens, pollen
fragments, house dust mite allergens, settling dust, and suspended
atmospheric dust. All of these particulates can cause an allergic
reaction. Keep in mind, it is still necessary to filter out
particulates smaller than these, but particulates smaller
than 0.3 of a micron have a better chance of being exhaled
out of your respiratory system. However, some of them will
still remain in your lungs to do damage. In addition, the
American Lung Association believes particulates that have
been ionized have a better chance of sticking to your respiratory
system so their likelihood of being exhaled is low. Therefore,
an air cleaner’s ability to filter out particulates
in the 0.01 to 0.3 of a micron in size is important, since
this would include some bacteria, viruses, some pet dander,
some house dust mite allergens, and some of your smokes and
smog. An excellent example here would be the IQAir
HealthPro Plus.
Is Ultraviolet
Effective in Air Purifiers?
Ultraviolet [UV] light is a known proven effective
way to sterilize germs, bacteria, mold, viruses, and other
microorganisms. However, these results are achieved in a correct
controlled environment. For example, if a surface with germs
on it, is directly exposed to UV light with enough intensity
(dosage) for a long enough period of time (exposure), the
surface will be sterilized. However, it becomes more difficult
to attain this control when you try to sterilize microorganisms
in an air purifier. The biggest question in regard to UV light
in an air purifier, when the micro organisms are moving through
the air purifier at a fairly high rate of speed because of
the fan, but are they exposed to the rays of the UV light
long enough to alter the DNA and the RNA of the micro organisms?
There will be a higher efficiency of sterilization of micro
organisms the lower the fan speed. However, if someone is
also trying to clean the air of other particulates at the
same time, there will be a decrease in air changes by lowering
the fan speed, and thus a decrease in the air cleaning capacity
of the machine. Another hybrid approach is to have a UV light
that bathes the Hepa filter with continuous light which will
kill all of the micro organisms that have been trapped by
the Hepa filter. This means there will be no need to worry
about what is happening to all of these bacteria and germs
that are sitting on the Hepa filter for such a long period
of time. However, there is also concern as to what the rays
from the UV light will do over time to the material of the
Hepa filter. The Hepa material can become brittle and start
to break up over time when exposed to UV light so the life
of the Hepa filter may become shortened.
The CARE
ADS air purifier is a great example of an air cleaner
where the company has tested its effectiveness in medical
systems and are confident that their product will work in
all sorts of situations where virus control is needed.
Carbon
or Other Types of Fill for Specialized Gas Control for Air Purifiers There
are many different types of carbon available to be used in
gas filters ranging from coal based to coconut shell. The
main purpose of carbon filters is to physically adsorb the
gas molecules into their pores. Activated carbon filters will
be best at removing the VOCs and SVOCs, which are of a higher
molecular weight. However, carbon filters will not be very
effective in humid conditions where the air contains a large
amount of water molecules. Carbon is also not effective in
removing the lower molecular weight gases from the air such
as formaldehyde and sulfur and nitrogen dioxide. These require
specialized gas control ingredients made up of Chemisorbers
which will chemically remove these gases. What Chemisorbers
do is react with a water molecule in the air and the gas molecule
to chemically break it down into a harmless form such as carbon
dioxide. This is chemical absorption. Common Chemisorbers
are alumina oxide, alumina silicate, and potassium permanganate.
The amount of gas filter media is important in measuring the
effectiveness of a gas filter but this is not the entire story.
Obviously, the more micro pores of carbon, the more gas and
odor can removed and the longer the gas filter will perform
before all of its pores are saturated and need to be changed.
What are just as important are the particulate
filters included with the gas filter in the air purifier.
If there is an inefficient pre-filter before the air encounters
the gas filter, a great deal of the micro pores in the carbon
will be used to collect the particulates not removed by the
pre-filter. Therefore, a gas filter containing many pounds
of activated carbon could prematurely become saturated. The
design of the gas filter is also important as to airflow.
A gas filter with fine activated carbon will cause a lot of
resistance to airflow. However, if the gas filter consists
of larger pellets the air will flow through the filter easier.
Also, a pleated design can result in a larger surface area
of carbon, which would increase the efficiency of the rate
of gas removed since the gas molecules will have a better
chance of being adsorbed with this larger surface area.
Technologies
Other than Hepa Filters for Air Purifiers Worth Consideration
Hepa filters are an example of mechanical filtration.
The advantage to this filtration method is there is no reduction
in its efficiency at removing the particulates from the air
over time. In fact, a Hepa filter will become more efficient
as it collects more particulates, because it is so fine. The
only reason you need to eventually change it is because it
will start to effect the airflow through the air purifier,
which will result in a loss of air cleaning capacity and also
may damage the motor because of the heat that may buildup.
The disadvantage to this kind of filtration is that these
air purifiers tend to be noisy, especially on the higher speeds.
Their filters are replaceable and can be rather expensive,
especially on the more efficient air purifiers which remove
more from the air over a shorter period of time.
The other types of air purifiers are called
electronic air purifiers and they utilize a single or combination
of technologies to clean the air in a room. An electronic
air purifier works by charging the particulates upon entering
the machine by an ionizer. This is a wiring mechanism that
creates an electrical charge; with the outcome being the particulates
are negatively charged.
There are four different forms of electronic
air cleaning:
1.
The first is called an electrostatic precipitator, which consists
of a series of metal collection plates that are oppositely
charged to the ionized particles. Therefore, the particles
will be attracted to these metal plates like a magnet with
the net result being the ability to collect particles as small
as 0.1 of a micron. There is a drawback to this type of air
purifier, which is as the collection plates collect the particles,
and their surface area becomes covered by the particulates,
their ability to attract the particles will decrease until
the plates are taken out and cleaned. In a good unit you may
start out at an efficiency of 80% and degrade down to as little
as 20%. Thus, it is imperative you clean the metal collection
plates on a regular basis as frequently as daily to weekly.
These types of air purifiers will generate a fair amount of
ozone definitely enough for you to smell and may be annoying
to some people. Most of these machines generate safe levels
of ozone.
2. The second type
of electronic air purifier uses a media charged filter. This
means it has a electrostatic filter that will collect the
particles by being oppositely charged to the ionized particles
and therefore able to collect particles again as small as
0.1 of a micron. This filter will start out at a high efficiency
as much as 80 to 90 percent but will decrease as the surface
area of the filter becomes clogged with particulates. The
biggest decrease will be in the smaller particles, because
remember this is not a Hepa filter and it is not able to mechanically
remove the microscopic particles, because it is not as fine
and thick a filter. It will however maintain its ability to
filter out the larger particulates better than the electrostatic
precipitator because its filter media is small enough to collect
the larger particles without having to rely on the opposite
charging attraction needed for the smaller particulates. However,
you will still have a decrease in the efficiency to as low
as 50% if the filter needs replacing and it is not changed.
3. The third type
of electronic air purifier is the negative ionizer. This machine
attempts to clean the room by basically eliminating the particulates
from the air. The particles are not removed from the room
just from the air. The way it works is the particles are drawn
into the machine where they are ionized and negatively charged.
From there they are sent back into the room where they are
attracted to the positively charged walls, furniture, positive
and neutrally charged particulates where they collide with
them until they are heavy enough to fall to the floor. The
result is that the air becomes free of particulates and the
particle count is reduced. The drawback to this type of air
purifier is that all of your particles land up on the floor,
walls, and furniture. As the particles lose their charge they
will release themselves from the walls falling back into the
air. Also, unless you are regularly vacuuming and dusting,
the particles will be kicked back into the air when any air
movement occurs by a door being opened or someone walking
in the room. A major concern is that if an ionized particle
is inhaled, it is more likely to stick to the walls of your
respiratory system thus increasing the chance of an allergic
reaction. The advantage of these kinds of air purifiers is
that they will be quiet because there is no resistance to
air flow and there are no filters .Also the tendency will
be to use them for treating a large amount of air, because
if a smaller, quieter fan is used, it will still result in
a large amount of air being circulated through the machine.
Also, there are no expensive filters to replace such as with
Hepa filters and no pre-filters that need to be cleaned. Still,
we tend not to recommend negative ionizers except if they
are used in conjunction with other air cleaner technology.
4. The fourth and
definitely the most controversial air purifier is an ozone
machine. Its whole premise is based on the use of ozone to
clean the air but its claims are very suspect. The ozone machine
manufacturers claim the air is cleaned and the gases, chemicals,
and odors are removed from the air. However, the ozone reacts
with the chemical and it breaks it down into another form
of pollutant. The question is whether this new form of pollutant
is even worse than the original chemicals. Also, to be effective,
it must emit high levels of ozone which have been determined
to be detrimental to the respiratory system. Therefore, you
have a dilemma with this machine, which is to run it at safe
low levels and have little effect, or on high levels, where
the concentrations could be dangerous to humans. In addition,
the question of particulates in the air is not even addressed,
since there are no filters to trap the particles. You may
be familiar with their use in the hotels where to prepare
a room for a customer, the machine is put in place and the
machine turned on high. The windows and doors are closed and
the room is left unoccupied while the machine is in operation,
which is usually to remove the smoke odors. Once the room
is cleaned hotel staff will go into the room, turn off the
machine, and open the windows to air the room out and rid
the room of the ozone. Ozone is a concern to human health
and this has been well documented by the EPA.
There are also air purifiers that use a combination
of a pre-filter to collect the large particulates, and a UV
light. These air purifiers will emit ozone into the room,
which reacts with the gases and odors in the room and chemically
breaks them down into another form.
In conclusion, the main advantages to electrostatic
precipitators are there are no expensive filters to replace
and they are quieter than Hepa filters. The disadvantages
are, ozone is emitted and there is a steady reduction in efficiency
as the metal plates become dirty, so regular cleaning is imperative.
The main benefit of media charged filter electronic
air purifiers are that they will be quiet and clean a large
amount of air. The disadvantages are the cost of the replacement
filters and there will be a gradual efficiency drop as the
filter becomes dirty.
The main advantage to negative ionizers are
that there are no filters to clean or change, and they will
be quiet. The disadvantage is that the particles are not actually
removed from the room, and can work themselves back into the,
thus re-polluting the room caused by movement such as a door
opening and closing or people moving about. Also, negative
ionizers create a good amount of ozone, so the odor and human
reaction either to the odor or toxicity needs to be addressed.
The advantages to the fourth type of electronic air purifier,
the ozone machine, is debatable. They can be dangerous and
their air cleaning ability is suspect. However, for smoke
odor removal after smoking or a fire they are the air purifier
of choice because of the low cost.
With all these types of technologies out there
the only ones we would consider would be the media charged
filter type such as the Blueair,
which uses the ionizer to charge the incoming particulates
so the particulates will be attracted to the electrostatic
filters. There is no ozone emitted by this air purifier.
An
AirFree
Sterilizer works by incinerating the particulates at high
heat at 400 to 600 degrees. It is effective at removing airborne
particulates of size 1 micron and smaller. This would include
germs, bacteria, mold, viruses, pet dander, smoke, and house
dust mite allergens. Keep in mind, this is not something you
would want to use to remove dusts, pollens, and other larger
particulates. Also, since it does not use a fan it is not
able to circulate the air in a room and attain the proper
number of air changes to clean the air quickly of everything
in a room. The Airfree sterilizer works by slowly over a 1-
3 week period removing the airborne bacteria, viruses, molds,
etc. as stated above and it continued operation will maintain
the sterilized environment. It is therefore an ideal machine
for virus and spore elimination.
Its most effective use is to prevent mold from
reoccurring in the future. Each unit will sterilize an area
of 250 square feet with an average ceiling height of 8 feet
so it will control an area of 2000 cubic feet. One of the
three things necessary for mold to grow is the presence of
air born mold spores. Normally, there will always be an abundance
of these because they are in great supply in the outdoors
and some of them will always circulate into the inside of
your house. However, the use of the Air free Sterilizer will
eliminate them so mold formation will become very difficult.
The heated sterilization process used by the
Airfree Sterilizer is intriguing, and backed up by an unusual
number or laboratory studies as to its effectiveness. Particularly
interesting about this technology is the measurement of the
residual level of contaminants in a room after the testing
period which can be as low as 85% reduction from its original
levels which has exceeded our results in testing of hepa filters.
What is difficult in all the study results we have seen from
any manufacturer is the rate of recontamination which is a
factor in real life. If you live in a major city, your environment
is constantly being recontaminated at a pretty fast clip so
it is difficult to ever get completely “pure air”
even with large filters going at full speed.
How Serious
is the Problem You are Trying to Remedy?
It is very important to determine how serious
is the air quality problem you are trying to solve. If you
are dealing with allergies, the more serious they are, the
purer the air needs to be around you. One person with light
allergies may feel fine with a cheaper quality air purifier,
while somebody else with more severe allergies may find that
same machine to be completely in ineffective and still be
symptomatic Also, the exact nature of allergies or sensitivities
is an important factor when choosing an air purifier. Different
air purifiers are needed for those suffering from multiple
chemical sensitivities or asthma. If a person has asthma,
it is recommended they purchase an air purifier with a gas
filter to control gases and odors, which can trigger an asthma
attack. People with multiple chemical sensitivities can react
to almost anything, so the correct choice of air purifier
is extremely important, since this person could react to the
material that makes up the air purifier such as glue on the
Hepa filter or out gassing from plastic parts. When dealing
with gas, odor, and chemical situations, the more concentrated
the amount of gas contamination with perhaps a high rate of
recontamination, the stronger the gas filter needed. If you
wanted to control general cooking odors, you would need a
basic gas filter, while cigarette and cigar smoke requires
a very large and powerful gas filter.
Sizing Your
Room and the Right Size Air Purifier
The size of the room is a significant factor
when choosing an air purifier because in order to properly
clean the air in a room, you will need to exchange the air
in the room several times each hour. The reason for this is
that initially the air will have a certain pollution level
depending on your external environment and activity inside
the area you are planning to clean and maintain. In the beginning
the air changes will be necessary to reduce the pollution
level until it is reduced by around 80%. After this the continuation
of the air purifier will be to maintain the cleanliness of
the air. The more efficient an air purifier is with each pass
the less air changes that will be needed to clean and maintain
the air quality. Factors affecting how much you will need
to clean the room would be the construction of the room as
far as how much infiltration of pollution would be allowed
to enter the room each hour. Also, how much activity is there
in the room as far as doors opening and closing, people walking
around, etc. This activity will stir up all the dust and particulates
that has settled on the floors, furniture, and walls. Normally,
you will look for a range of 2 to 8 air exchanges an hour
with 2 air exchanges only being acceptable with the most efficient
of the Hepa air purifiers. When cleaning the air for gases,
odors, and chemicals it will be better to run the air purifier
at a lower speed so the gas molecules will have more contact
time with the activated carbon. This would also be true for
units utilizing UV light to sterilize the particulates.
Where are
you Going to Put the Air Purifier in your Room? The
placement in the room is important when you consider your
air purifier choices. We recommend for bedrooms a quieter
air purifier with less air exchanges during the night, than
a family or living room where there will be more traffic and
faster re-polluting of the air. Placement of the air purifier
in the room will always be best if it is in the middle of
the room. However, since particulates and gases will through
diffusion maintain an equal distance between one another,
as the particle count is reduced as the air purifier cleans,
the room, the remaining particulates will spread out to maintain
this equal distance. As they move across the room, they will
eventually be drawn into the vacuum that is created by the
air purifier’s fan. Therefore, placement of an air purifier
on the sides or ends of a room will be able to filter the
particles on the opposite side of the room.
Noise Level
in Air Purifiers
Noise level is a personal choice because some
people do not mind, or even welcome a background white noise,
while some people cannot stand any fan noise whatsoever. Also,
when someone is purchasing an air purifier for a bedroom,
they are usually looking not only for a quiet air purifier
but also a smooth running machine that will not have an inconsistent
pitch and noise level. What is helpful is not to make a purchasing
decision solely based on the area size a specific air purifier
can clean. The reason being a unit that can clean 800 square
feet will still do an excellent job in a 200 square foot room
with one important additional benefit. Because of the larger
capacity air purifier, you will be able to properly clean
the smaller room on the low or medium speeds, which are almost
always significantly quieter on the larger Hepa air purifiers.
If someone purchases an air purifier that is tight in its
sizing capacity they will find they need to run the unit on
high most of the time, and even the smaller air purifiers
are noisy on the high speed. The only reason someone should
not consider a larger air purifier is because of the physical
size being too large for the room.
A perfect choice for a quiet air purifier for
bedroom use is the Blueair
501 and BlueAir 402. For a small bedroom and for portability consider
the Hamilton
Beach series.
Automatic
Monitoring of Pollution Levels in a Room
There are some air purifiers which have an infrared
detector that will monitor the amount of particulates in its
vision. Initially, when turning on the air purifier, it will
automatically run itself on the high speed, because the particle
count will usually be high. As the particles in the detector’s
vision are reduced, it will turn itself down to the medium
speed and eventually to the lower speed. The idea in theory
is excellent but since the area being measured is so small,
the accuracy of this automatic monitoring device is in reality
pretty minimal. A separate particulate monitor is recommended.
Efficiency
Level of your Air Purifier
Two critical things to consider when measuring
how effective an air purifier is at performing, is the amount
of air that it can clean each hour and what percentage of
the pollution does it remove from the air that is circulating
through it. This second factor is called the efficiency. For
example, if the particle count per cubic foot of air going
into the air purifier is 1,000,000 particles and the particle
count of the air coming out after it has passed through the
filters is 300, than the efficiency of the air purifier would
be 99.97%. Therefore, you can see how the efficiency of the
machine is important since a machine that is only 60% efficient
would allow 400,000 particles to go back into the room. The
efficiency is important because there are many air purifiers
on the market that have a Hepa filter but their relative efficiency
is undocumented. This only means that the filter has been
tested to remove 99.97% of all of the particulates that are
0.3 of a micron in size or larger. However, this is when all
of the particles in the air contact the Hepa filter and none
of the air is able to bypass the filter itself. Once you take
the Hepa filter and install it in the air purifier other variable
are involved. As the air is drawn into the air purifier, some
of the air can bypass the filter media depending on the way
the filter is housed inside of the air purifier. As much as
40 or 50 percent of the air can pass by the filter media in
some Hepa filter based air purifiers resulting in poor performance.
Our most efficient machines in our testing were
the IQAir
series and the Clarifier series.
The Importance
of a Prefilter for your Air Purifier The
pre-filter is one of the most significant parts of an air
purifier. Most pre-filters are designed to remove particulates
5 to 10 microns and larger. This is useful because the very
large particles will be removed from the air[such as pet hair
or large dust particles], which will protect the gas filter
media or the Hepa filter media from becoming used up prematurely.
However, you must realize that the percentage of particulates
in the air that are 5 microns and larger is very small. For
example, if there are 1,000,000 in the air per cubic feet,
there is normally only around 400 to 800 particles that are
5 microns and larger. Therefore, much of the particulate removal
is still left for the pores of the activated carbon of the
gas filter, if it is the next filter in line after the pre-filter
or the Hepa filter. A large gas filter with 15 pounds of activated
carbon can become quickly saturated if it has no pre-filter
or the pre-filter is not very efficient. Also, the Hepa filter
is too expensive a filter if it is used to remove particles
larger than 1 micron. The best example of a pre-filter is
the one on the IQAir
Healthpro which is 100% efficient at removing particulates
1 micron and larger. In addition, it is 55% efficient at removing
particulates 0.3 of a micron and larger. So as you can see
this filter will remove 90% of all of the particulates in
the air and prolongs the life of the Hepa and gas filters.
Filter Change
Indicator Lights
We find a filter change indicator light to be
extremely helpful, because someone’s ability to actually
see particulates in a room to judge whether a hepa filter
needs replacing, or relying on smelling odors to judge the
life of the gas filter, is not an accurate or scientific way
to track the life of the filters. In addition, you would need
to remember to check the filters periodically to examine them.
The best air purifiers will have individual filters for each
of these purposes. A well-constructed air purifier will have
a separate pre-filter, gas filter, Hepa filter, and post filter.
It will indicate when each of these filters needs to be replaced.
All of the guesswork is eliminated, and you will not be running
the air purifier with filters are clogged which should be
changed, or be prematurely changing filters, which is unnecessarily
expensive.
Ease Of Changing Filters
This is something that is often overlooked and
can prove very frustrating to the owner of an air purifier.
The best air purifiers are those requiring no tools to replace
the filters. Those units where you simply pop out a door,
pull the filter to be replaced out and replace it with the
new filter are by far the easiest. Some air purifiers require
some considerable disassembly, requiring tools; some are manifestly
more difficult than others. If it is tedious and difficult
to change the filters, the average person will put off changing
them way beyond their optimal change dates. Also, just because
some manufacturers say their pre-filters do not have to be
replaced but can be periodically vacuumed or washed is a bit
deceptive as the process of accessing the pre-filter is very
tedious and ignored my most people.
The easiest filters on an air purifier to change
are the Blueair
and Hamilton
Beach Air Purifiers. The IQAir
is quite easy too when you have done it once and the same
comment applies to the Clarifier or Allerair
series
Weight and Mobility of Your Air Purifier
Most air purifiers are on casters, so you will
be able to move them from room to room without having to physically
lift them. However, this is not helpful if you need to carry
it downstairs or upstairs. In this case, it is easier if the
air purifier is lightweight. The Hamilton Beach Series are
the easiest just to pick up and carry to the next room.
Upkeep Costs for an Air Purifier This
is another factor which is often overlooked by the potential
purchaser of an air purifier. An air purifier that costs $400
to $500 can end up costing from as little as $50 a year to
maintain or as much as $200 a year. You need figure out how
often the filters need to be changed and how much they cost.
Some air purifiers may have expensive filters, but you may
be able to go a longer period of time before they will require
changing. You should be aware that the quoted filter change
intervals because can vary significantly depending on how
often the unit is run and the pollution level of its environment.
For example, the Austin
Air manufacturer states you can go five years between
filter changes. However, we have found the norm is more like
three years for all machines, given the real life conditions
under which it is used. It is also helpful if the unit has
individual filters to change as opposed to one big expensive
combined filter to change. The reason why a combination filter[hepa
plus carbon] is a disadvantage is because when the Hepa filter
and the carbon gas filter are combined, both filters rarely
will require changing at the same time. Most of the time,
the gas filter will need changing before the Hepa filter.
However, if either side of a combo filter needs to be changed,
you are forced into replacing the entire filter, which is
an unnecessary expense.
Air Purifiers, Ozone Emissions and Outgassing
Any ozone emission, which is a toxic substance,
is not desirable regardless of whether the person has allergies,
asthma, or multiple chemical sensitivities. However, the effects
are usually worse for these people. In general, ozone is an
irritant to the respiratory system. It becomes progressively
irritating as concentration levels increase. The problem is
that most manufacturers do not monitor the ozone levels. Outgassing,
which can occur from the silicone used for the gaskets and
glues used to attach the filter media to the housing, can
outgas and cause a reaction, especially for people with multiple
chemical sensitivities. If you belong in this category you
should look for an air purifier where the pre-filter and Hepa
filter come before the gas filter, so any out gassing that
could otherwise occur will be removed by the activated carbon.
Keep in mind, it is recommended anyway that there be some
type of filter after the carbon gas filter, to remove any
carbon particles that may fall off as the air passes through
it.
A good air cleaner for those with multiple chemical
sensitivities is the Allerair
series.
Central Air
Cleaners
Central air cleaners will allow a person to
clean all of the air in their house with one unit. You should
only consider this type of air cleaner if you have a central
heating, cooling, or both that circulate air throughout the
house. The way a central air cleaner works is that it is tied
in with the existing central air system in the home. The central
air system will circulate the air back into the rooms of the
house through the ductwork and out the supply registers and
the air will return back to the system through the return
ductwork. A central air cleaner is installed by having the
return air drawn into the intake of the air cleaner and the
cleaned air then is circulated back into the central air main
return. It is recommended to intercept the air at the end
of the main return just before it goes into the furnace or
air conditioner. The installation consists of two openings
in the main return at least 6 feet apart to prevent shortcutting.
Ducting is run from the first opening to the intake of the
air cleaner and then from the outflow of the air cleaner back
to the second opening. The airflow of the air cleaner is only
to draw the air from the main system to clean it and not to
circulate the air throughout the house. It is for this reason
the central air system needs to be running while the air cleaner
is running. A central air cleaner is not strong enough by
itself to push the air through the HVAC system and out to
the rooms of the house and then back into the system. We recommend
setting the HVAC system with the fan on, so the air will circulate
regardless of the temperature setting.
Keep in mind, a central air cleaner will be
able to filter out most of the particulates and remove most
of your gases and odors but it will never be as efficient
as a free standing air cleaner in a specific room exchanging
the air several times an hour. While the central air cleaner
will exchange the air in the house 2 to 4 times an hour because
of all the registers and duct work in the home 90% and better
efficiency is difficult. The big advantage is if you have
a 2000 to 4000 square foot home, you will be able to clean
the air with one air cleaner as oppose to several units and
it will be quiet.
Furnace Filters
An efficient filter in your heating or cooling
system can reduce your particulate levels and hence air pollution
by up to 50%. As long as your central air system is operating,
all of the air will circulate through this filter, so not
only will you be protecting your furnace and air conditioner,
but the incoming pollution will be reduced. These filters
are electrostatic so the flow of air creates a charge where
the particulates are drawn toward the filter. The particles
are not charged like an ionizer. Some of these filters are
not replaceable and require periodic cleaning every 1 to 4
months while some are replaced every 1 to 4 months. Keep in
mind, these filters will do nothing to remove gases and odors.
They are only for the removal of particulates. In addition,
they do not to replace an air cleaner, because even the best
filters will only remove particulates down to 1 to 1.5 microns
in size. In order to remove smaller particulates you would
need a Hepa filter and the resistance of such a filter would
restrict the movement of air in the HVAC system and cause
problems.
Your Air
Purifier Manual
Instruction and information from the manufacturer
is extremely helpful. In addition, you want to be sure you
can contact the dealer for after sales support after you have
purchased the air purifier. They should be able to work with
you, as a liaison between you and the manufacturer .A good
manual will explain the filters in the air purifier, how to
set the unit up if there is any assembly required, offers
troubleshooting advice, and gives you maintenance information.
A poorly written owner’s manual can be very frustrating
if you have any questions or basic troubleshooting situations.
Style and
Your Air Purifier
The choice of style of the air purifier is a
personal choice. Usually, if the air purifier is going to
be set up in a visible room such as the living room or the
family room the looks of the unit will be important. Color
will also be of importance. This will be less important if
the unit is being purchased for a less widely used room such
as a basement. For some, style will not be as important as
its level of effectiveness, but for others, the styling is
almost as important as choosing a sofa for their living room
or family room. Some people do not want it to stick out, but
blend in with the styling of the room. Keep in mind, the design
of the inside of the air purifier is more important. The looks
are strictly cosmetic. The exceptions would be the intake
and the outflow areas. You do not want the inflow and the
outflow areas near each other because you will have shortcutting,
which is where some of the air that has just been cleaned
may be drawn back into the inflow of the air purifier. Also,
you want the air to be sent back into the room in multi directions
and in a larger area. It is better for the air to be circulated
back into the room in more than one direction. Also, if the
air comes out of one small opening, it can be very uncomfortable
if a person is sitting close to it. The better designs are
where the air is drawn into the air purifier through the bottom
in all directions and outflows at the top in all directions
from the entire perimeter of the unit.
A good looking unit is the Blueair
and wins our beauty pageant award. Good multidirectional clean
air systems are the Blueair
and IQAir
air purifiers.
The Warranty
and Reliability of Air Purifiers
This is an area that most consumers concentrate
on and is very important. The old saying that you get what
you pay for is often true. If you buy a product that is inexpensive
with a short warranty, often you will find yourself replacing
the unit. You may realize later on you would have been better
purchasing a more expensive air purifier but one which was
better built, with the longer warranty. The best warranties
are those offering five years on the main fan and motor parts.
A reliable air purifier should have no problems with the motor,
fan, and electrical components and controls. The rest of the
air purifier consists of the filters, which need periodically
cleaning or replacement. Quality control is important and
any information you can glean about the reliability and breakdown
rates of air cleaners is recommended.
The Manufacturer’s
Reputation
Reputation of the manufacturer is important.
Chances are if previous customers are unhappy, and there is
published information of a product’s past performance,
you are also going to have problems. Of course, it is possible
a good manufacturer may go through a bad period on a particular
product, which is not reflective of the company in general,
or where the manufacturer has taken customer feedback to heart
and has acted upon to prevent repetitive problems in the future
Summary
In summary, the most complete air cleaning
system, assuming one has a central air system in their home,
would be an efficient furnace filter along with a central
air cleaner. In addition, a free standing portable air cleaner
in the bedroom and most frequently occupied rooms of the house
would complete the air cleaning system. If you do not have
a central air system in your home, you want enough air cleaning
to attain a minimum of 2 air exchanges with the most efficient
of Hepa air cleaners to as many as 4 to 8 air exchanges with
other types of air cleaners.
