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 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 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.

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.

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