Clearing 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
  • 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 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

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 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

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.