the Air on What to Look for in an Air Purifier
If you are dedicated to improving the indoor air quality of your home,
you’re aware that there are certain steps you need to take to reduce
the amount of allergens and airborne particles. Two of these, source control
and ventilation, you may have already addressed. But the third, finding
a good air purifier, can be confusing if you aren’t
sure what to look for in this type of home appliance.
Fortunately, once you understand the basic types of air cleaners and
how they work it becomes easier to select the right style of air purifier
for you and your family. There are also organizations like the Association
of Home Appliance Manufacturers (AHAM) who review and certify air purifiers
annually using a standardized testing and ratings system to make it easy
for you to compare different models to one another.
What Kinds of Air Purifiers Are There?
- Ozone Air Purifiers These release small amounts of ozone (positively
charged oxygen molecules) into the air to reduce airborne pollutants.
They also are very effective at reducing odors, and will sometimes give
off a fresh, sharp scent rather like the odor after a thunderstorm.
- Electrostatic Air Purifiers These use static electricity to
draw airborne particles to the filters contained in the unit. The particles
stick to the filter. (Who knew something so annoying could be so handy?)
When the filters are full, you throw them out and replace them. These
are usually used as a furnace filter or as a pre-filter component on
some other type of air purifier (such as an ozone or ionizer system).
- Electro-Static Precipitators Similar to an electrostatic purifier,
these also use a static charge, but there are no filters to throw away.
Instead, two metal plates create two opposite electrostatic charges.
These attract airborne particles, including dust, smoke and pollen,
to one of the plates. When the plate is coated, you can remove it, rinse
clean and use it again.
- Ionizers These release a magnetic charge into the air that
will cause airborne particles to stick to the filter.
- HEPA Filters HEPA stands for High Efficiency Particulate Air
Filters, and are designed to remove 99.97% of airborne pollutants as
they pass through the filter. Trapped germs die from lack of moisture,
making them ideal for operating rooms and electronic labs. HEPA filters
are sometimes added to an existing system such as your heating and/or
air conditioning unit.
Each of these types is good for different situations, and you can also
find many air purifiers that combine two or more methods for greater efficiency.
More important than the particular method you choose is how effective
it actually is. No matter which kind you have or how much you paid for
it, if it isn’t doing the job, you’ve wasted you money.
How Do I Know if the Air Purifier I’m Considering Will Do the
There are two things to look for any time you shop for an air cleaner:
the MERV and the CADR. These are ratings developed to help you compare
one brand and style of air purifier to another, regardless of whether
they are ionizers, electrostatic, or ozone, and get an idea of their relative
What’s a MERV?
MERV means Minimum Efficiency Reporting Value. The American Society of
Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) developed
a range of numbers to help consumers compare filters. The higher a MERV
number, the better a filter performs.
A filter generally has two features that will be important to you: how
quickly the air can flow through it and how well it filters out pollutants.
The higher a MERV number, the more dense the filter and the more particulates
it will capture.
Okay, what’s a CADR?
We mentioned CADR earlier, and it is the most important rating to look
for overall. It stands for Clean Air Delivery Rate, and is exactly what
it sounds like – it tells you how quickly it will circulate clean
air throughout the room, filtering all of the air through the filtering
system once. Currently, twenty-nine manufacturers of air purifiers list
their CADR rating on their packaging so that you can easily compare them
to each other.
You should look for an air purifier with a CADR number that is equal
to about two-thirds the size of the room you will be using it in. For
instance, if you have a 10’ X 15’ room (150 square feet),
then you should get a purifier with a CADR number no less than 100.
If you get a rating higher than you need, you will simply have your air
cleaned even more quickly and efficiently, but if you get a rating lower
than recommended, the efficiency won’t be there and the air purifier
There will actually be three CADR numbers: one for pollen, one for tobacco
smoke, and one for dust. For the best results, use the number for tobacco
smoke, which is the smallest particulate in the ratings system.
But What About Cost?
Obviously cost is an issue to most of us – if we were made of money,
we’d simply hire someone to come in and sterilize our homes and
install whole-house air purification systems, hire daily cleaning teams,
have someone follow the dogs around sucking up the pet dander....where
were we? Oh! Cost!
The cost of air purifiers can vary widely, and it’s a bit surprising
to note that you can’t always judge the value of an air cleaner
by its cost. There are several things to consider when you buy one that
will impact your decision. While you may pay less for one over another
initially, operating costs and accessories can add up over time, making
some systems much more expensive in the long run.
Filters If you choose an air purifier that uses paper or fiber
filters that are disposable, be sure that they are HEPA filters. These
are 99.97% efficient for dust and mold spores and well worth the cost.
Anything less is throwing money away. Also check to see if you can order
replacement filters in bulk for a discounted price.
Plates An air purifier with cleanable plates may cost more initially,
but figure out the cost of filters over a few years’ time and compare.
Will you save money by paying more up front and cleaning the metal plates
rather than worrying about the filters?
Operating Costs Always try to find out what the estimated operating
costs will be. What does the manufacturer estimate the monthly electrical
usage will be? Will the air purifier run constantly or will it cycle?
Extras If you have someone in your family who is particularly
sensitive to environmental changes, such as a migraine sufferer, you may
consider some extras such as a programmable ozone monitor, worth the extra
money in order to prevent sensitivities being triggered.
With so many excellent air purifiers on the market and the Internet available
as an excellent information resource, there’s no excuse not to invest
in improving the quality of your home’s air. It’s a relatively
inexpensive way to cut down on colds, respiratory infections, asthma attacks
and a host of other health problems by allowing everyone in your house
to breathe easier.
About the Author
Lori Wilkerson is a full-time freelance writer. Right now she knows a
little bit about almost everything and a lot about electrical air purifiers, ozone air purifiers, and whole house air purifiers. She is a reformed ex-smoker and regularly
offends people by sending them outside to smoke.