- The Washington Times - Monday, December 18, 2006

An air purifier just may be the perfect gift this holiday season for someone suffering from allergies, says Dr. Ross Myerson, medical director of occupational and environmental health at Washington Hospital Center in Northwest.

People who have significant allergies to common indoor air contaminants, such as dust, mold spores and animal dander, may benefit from any number of devices that help clean the air, he says.

The devices “definitely remove particulates from the air,” Dr. Myerson says. “They have varying efficiencies.”

With so many air purifiers on the market, sometimes it’s hard to tell what they do and whether they actually work. Many doctors agree, however, that most air purifiers can improve the quality of a home environment.

Sneezing, itchy eyes, runny nose and postnasal drip are symptoms suggesting someone might benefit from an air purifier, says Dr. Sonya Malekzadeh, associate professor of otolaryngology at Georgetown University Hospital in Northwest.

“If you see your doctor and they determine you have allergies, you should do environmental control,” Dr. Malekzadeh says. “Avoid the things that you are allergic to. Get rid of carpeting. Put plastic covering on the bed. Change filters on the ducts every three months. Avoid sleeping with pets. At the same time, you can get filters that clear the air of the little particles.”

High-efficiency particulate air (HEPA) filters are the most efficient air purifiers, she says. The filters were developed to capture 99.97 percent of particles 0.3 micrometers in diameter, such as pollen, dust mites, mold spores and animal dander, she says.

Many HEPA filters use carbon filters that remove larger particles, including odors and tobacco smoke. The machines come in different sizes to accommodate rooms of various sizes. The filter in the air purifier must be changed routinely, or the device won’t work properly.

Electronic precipitators, another type of air cleaner, move air over electronically charged plates, she says. The plates change the charge of the particles and capture them. These machines do not use replaceable filters; instead, they must be cleaned regularly.

Most people don’t need to run their air purifiers when they are away from their houses, she says. It’s usually enough to run the machines when someone is home. It’s best to put the devices in the bedroom, where people spend most of their time, she says. Because some air purifiers can be noisy, users should make sure the fan they are considering purchasing won’t keep them awake at night.

Allergy sufferers should be realistic about how much an air purifier can help improve their allergies, especially if it is the only environmental control measure taken, says Dr. Claus Helbing, an allergist and attending physician at Inova Fairfax Hospital and Inova Alexandria Hospital. He has offices in Annandale and Springfield.

“Air purifiers don’t always do what the patient hopes,” Dr. Helbing says. “It only takes particles suspended in the air. Often, heavy dust particles aren’t taken out of the air.”

For instance, animal dander, mold and pollen are smaller than heavy dust particles, he says. Also, air purifiers won’t remove elements trapped in carpets; the particles must be moving in the air for the devices to eliminate them.

Further, patients who choose an electronic precipitator should look for one that produces as little ozone as possible, Dr. Helbing says. Ozone can make the air smell good, but it also can hurt the lungs in high concentrations.

“Companies don’t always provide impartial information about their air purifiers,” Dr. Helbing says. “They seem to work better for animal dander than dust particles.”

People with severe dust-mite allergies should cover their mattresses, box springs and pillows with special casing, he says. Fine-woven sheets can prevent dust mites from penetrating them. Keeping windows closed and running central air conditioning can limit the effects of pollen in the spring.

If there are moisture problems in a house, it often smells musty because of mold. Homes should be kept dry, and a dehumidifier should be run in the coolest place of the house. Apartments on ground floors usually are damper than those on the second or third floor.

Professional duct cleaning often helps heating, ventilating and air-conditioning systems, Dr. Helbing says. In a few instances, companies spray chemicals when cleaning ducts, and people might react adversely to them, he says.

In addition to portable air purifiers, most HVAC systems can be equipped with the cleaners, says Victor D’Amato, director of Atrium Environmental Health and Safety Services in Reston. He is a certified industrial hygienist and certified safety professional.

Similar to the room devices, HEPA filters connected to an HVAC system must have the filter changed periodically, he says.

“The longer you leave it in place, the more dust accumulates, and the harder it is for the air to pass through it,” Mr. D’Amato says. “If it becomes clogged, you don’t get proper air distribution through the home. You starve the fan. If it can’t get enough air to move, the motor burns out.”

There is a chance that the cost to run an HVAC system could increase when using a HEPA filter, he says, as it takes more energy to pull the air through the system with the filter.

When cleaning the plates in an electrostatic precipitator, people should be careful not to shock themselves with the charged plates, he says. Before it is cleaned, the device should be disconnected from its power source.

Also, even if the system has a filter, it only works if the filter is installed properly.

“The filter is only as good as it fits into the airstream,” Mr. D’Amato says. “If you put a HEPA filter in a duct, the seal around the filter has to be airtight. Particulates will follow the path of least resistance. If it can go around the filter, it will.”

Installing a filter on a home system may not solve everyone’s allergy problems, but it will improve the environment, says Mark Schneider, certified industrial hygienist at MasiMax Resources in Reston, which offers environmental health and safety services.

“I am one for filtration as being the real way to rid the air of potential contaminants that cause allergic reactions,” Mr. Schneider says.

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