Sunday, June 13, 2010
Many people have allergies to airborne dust, mold, and pollen. These tiny particles can accumulate in your home environment, potentially leading to health problems. At first glance, freestanding ionic air purifiers seem like a good deal: They're affordable, quiet, and are said to clean particles from the air. Studies by consumer groups have cast doubts on the performance and health benefits of these appliances.
Ionic air purifiers work by producing a high-voltage static electric charge inside the unit. The grid attracts dust and other allergens, which cling to it. Although units sold in the United States are designed to prevent a shock hazard, shocks still may result from metal objects inserted into the purifier, from water accumulating under it, or by not having it plugged into a grounded outlet.
Ozone, an unstable, chemically reactive form of oxygen, is formed when normal airborne oxygen molecules (O2) pass near a source of high voltage. According to the Environmental Protection Agency (EPA), ozone is known to cause health problems in people exposed to it for long periods. Known short-term effects include coughing, lung pain, and shortness of breath. Ozone may combine with lemon and pine-scented agents in cleaners to form formaldehyde, a carcinogen. A 2005 Consumer Reports investigation of air purifiers found several models emit unacceptably high amounts of ozone. These models failed an Underwriters Laboratories sealed-room ozone test. Although your rooms probably have adequate ventilation, you should avoid excessive ozone in your home. Even a well-designed unit may emit ozone if it becomes dirty. The high voltage will arc inside the device, causing a hissing noise. The high-voltage arc produces ozone.
The 2005 Consumer Reports article reported test results of several home air purifiers and found the air-cleaning ability of some of them poor. The consumer group rated five of seven units "poor" for removing dust, smoke, and pollen when switched to their highest setting. Many customers would consider this a serious purchase, intending to alleviate their allergies or protect their families from smoke and pollutants, and may believe that they are protected when in fact they are not. The assumption that the unit works may lead the customer to delay other efforts to improve air quality in the home.