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
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
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 Job?
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 efficiency.
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
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 will struggle.
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
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.