The Basics: Air Purifiers

Whether you want a way to clear the air of allergens or just need some relief from your cat's dander, an air purifier is a welcome addition for those seeking a cleaner environment. Before you hit the checkout line, it can be helpful to understand the different types of air purifiers, because each specializes in removing certain types of pollutants.

There are five main types of air purifiers, including HEPA, ozone, carbon, ionic and ultraviolet light; air purifiers are primarily categorized by filter type. Some air purifiers combine more than one type of filter for greater efficiency.

HEPA filter air purifiers are very effective at trapping allergens. In fact, a HEPA filter can capture particles as small as 0.3 microns. This type of air purifier is often used in hospitals and other clinical settings. The filter can -- and should -- be replaced about twice a year, although some can last several years. HEPA filter-type purifiers tend to be noisier than others, but the trade-off is that they remove more pollutants than some other types. HEPA filters are not effective at removing cigarette or cigar smoke, odors or fumes, which is why they are often combined with other filters, such as carbon filters.

Ozone air purifiers tackle odors, but do not clear allergens or chemical pollutants from the air. There is some controversy surrounding ozone air purifiers. According to the Environmental Protection Agency, ozone gas can potentially cause harmful health consequences. At the worst, ozone can damage the lungs when it is inhaled; at the least, it can worsen respiratory conditions such as asthma.

Carbonair purifiers are effective at clearing smoke, odors, chemicals and even gases from air. Using activated carbon, these filters have small absorbent pores that chemically react to pollutants as they pass through the filter. This reaction causes the pollutants to bond with the carbon and become trapped. Carbon air purifiers do not trap allergens and bacteria, so they are often paired with HEPA filters.

Ionic air purifiers don't work on odors, but they can remove very small pollutants from large spaces. Ionic air purifiers, also known as electrostatic air purifiers, work by giving particles in the air a negative or positive electrical charge, and then draw the particles to plates within the air purifier. Ionic air purifiers run very quietly. There is some controversy surrounding this type of air purifier because a byproduct of the electrical charge is ozone gas, which can exacerbate respiratory conditions like asthma. The American Lung Association does not advise using ionic devices.

Ultraviolet light air purifiers target and destroy bacterial microorganisms, but are not effective against allergens, odors, smoke or chemical fumes. Ultraviolet purifiers treat air with UV light as it passes through the purifier. This means that germs, viruses and bacteria are killed when they come in contact with UV light. Many UV purifiers also include HEPA filters that trap pollutants so they are more efficient.

How To Shop

As you learn more about air purifiers, it can be useful to narrow the choices in the marketplace by answering a few questions. First, determine what you want to accomplish by purchasing an air purifier. Do you want to remove germs and bacteria from the air? Pet odors? Cigarette smoke? Or, are you simply seeking an effective, all-purpose air purifier?

Because different air purifiers are made for different tasks, uncovering the answers to these questions will help you decide which type of air purifier will work best for you.

Look for an air purifier that is powerful enough for the space in which you need to use it. If you need an air purifier to exclusively clear the air in a child's bedroom, it's likely a small unit will do the trick. If, on the other hand, you want cleaner air in a large living room, be sure the air purifier can handle the job. Each air purifier should list the volume of clean air emitted, measured in square feet. The clean air volume and the size of the room will need to be a good match in order for it to be effective.

Some types of air purifiers are noisier than others. You'll probably want to select a quiet model for a bedroom, while a somewhat noisier model may work in a less-frequently occupied room.

It is also important to keep in mind the operating costs of the air purifier that you select. Often, better-constructed air purifiers are designed to run 24 hours a day, and most manufacturers will list the amount of electricity used by each unit. Most will also report how often the machine's filters will need to be replaced. Some air purifiers require changing the filters at regular intervals. You may want to select a portable unit that can be used in a bedroom at night and in your home's main living area during the day.

Make sure you understand the warranty and its limitations. Long-term warranties are best, but even long-term warranties are typically limited in scope. Many air purifiers come with 5 or 10 year warranties. Read the warranty requirements carefully. Some manufacturers require you to replace filters at regular intervals, such as every six months, or the manufacturer will void the warranty. Always return the product registration card enclosed in the product packaging. This card lets the manufacturer know where to notify you in case there is a recall.