Air Purifier Criticism

Image courtesy Amazon An ionizing air "washer."

Ionizing and ozone air purifiers have come under fire from consumer groups, consumer review magazines and even the Environmental Protection Agency (EPA). Two claims are at the heart of the controversy: that these types of air purifiers are not effective at removing contaminants from the air and that ozone generators could harm people.

In 2002 and 2003, Consumer Reports tested several different air purifiers, including Sharper Image's Ionic Breeze. Independent researchers checked and verified the tests. Consumer Reports found that ionizing air purifiers like the Ionic Breeze created "almost no measurable reduction in airborne particles" [ref]. Sharper Image sued Consumer Reports. The magazine later conducted further tests in response to Sharper Image's complaints and still found the Ionic Breeze to be ineffective. Sharper Image's lawsuit against Consumer Reports was thrown out, and the company was forced to pay more than half a million dollars to cover Consumer Reports' legal fees.

The EPA has also released information warning the public about air purifiers that generate ozone. Because the manufacturers are not making specific medical claims about these devices, they do not need Food and Drug Administration (FDA) approval. In fact, there really is no government oversight over consumer air purifiers other than the HEPA standard, so any manufacturer claiming that such a device is "government approved" or "government certified" is misleading consumers. However, concerns about the generation of ozone in people's homes have led the EPA to conduct studies on the subject.

All ionizing purifiers generate some ozone, but ozone generators are specifically designed to release the gas, and in much larger quantities than ionizing purifiers. The EPA states, "Relatively low amounts [of ozone] can cause chest pain, coughing, shortness of breath, and, throat irritation. Ozone may also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections" [ref]. Their studies indicated that even when used according to manufacturer instructions, many ozone-generating purifiers created ozone concentrations in a house in excess of public health limits. They also found that ozone as used in a household air purifier "has little potential to remove indoor air contaminants." They also noted that ozone has a tendency to react with chemicals and form by-products that are potentially even more dangerous.

The EPA's final recommendation on the matter: "The public is advised to use proven methods of controlling indoor air pollution." Ozone generators are not among the proven methods listed on its site.

Clearing the Air
If ozone generators and ionizing purifiers have questionable efficacy at cleaning air, what can be done to remove contaminants from our homes? There are three basic steps, in order of usefulness:

1. Get rid of the source of the contaminants. If the problem is cigarette smoke, smoke outside. If mold is causing problems, identify the moldy areas and clean them up. Severe cases may require extensive work to get at mold within walls, but if the mold is left in place, the problem will only get worse. When pet dander is a problem, the pet could be limited to certain areas of the house and kept off furniture. Good hygiene along with regular cleaning and vacuuming will remove a great deal of dust and limit opportunities for mold growth. Using special plastic bags on mattresses and box springs can also keep down allergy-causing contaminants.

   Image courtesy Andrea Booher/FEMA Mold growing on household walls should be cleaned thoroughly and as soon as possible to avoid illness.

2. Dilute the air in your house. In other words, open the windows. The air outside probably contains fewer contaminants than what is inside (unless you live downwind from a coal plant). Allowing fresh air inside will sweep away some contaminants.
3. Clean the air with an effective filter system.

The next logical question, of course, is "how do you know which air cleaners are effective?" Fortunately, there is an industry standard that makes it easy to compare air cleaners. The Association of Home Appliance Manufacturers (AHAM) assigns a Clean Air Delivery Rate (CADR) to air cleaners. AHAM runs a standard test to see how well an air cleaner removes certain contaminants from a volume of air. An air cleaner bearing the AHAM seal will have three CADR numbers listed: one for tobacco smoke, one for pollen and one for dust. A higher number indicates a greater ability to clean air, with maximums of 450 for pollen and smoke and 400 for dust [ref]. AHAM recommends using an air cleaner with a CADR number at least two-thirds the area of the room.

From the CADR Web site: "For example, a 10-foot by 12-foot room -- 120 square feet -- would require an air cleaner with a tobacco smoke CADR of at least 80. If your room size is smaller, the unit will simply clean the air more often or faster. If you have ceilings higher than 8 feet, you'll want an air cleaner rated for a larger room."

For lots more information on air cleaners and related topics, check out the links on the next page.