ATLANTA - Concerned about poor indoor air quality? No problem. Just install an air cleaner/purifier and everything will be fine, right? Well no, not necessarily. According to a new report from Air Quality Sciences (AQS), no matter the type or size of the building, air cleaning alone won't do the trick. Also, not all air cleaners/purifiers are alike.

"Indoor air contains a mixture of visible and invisible contaminants, some of which can lead to health problems, lower worker productivity, and result in building occupant complaints. Creating and maintaining a healthy indoor environment requires three key strategies that work hand-in-hand: source control, ventilation, and air cleaning," said Marilyn S. Black, Ph.D., chairman and chief scientist of AQS.

According to the AQS report, "Clearing the Air on Indoor Air Cleaners/Purifiers," first and foremost, you need to control the sources of indoor pollutants. Experts agree, however, that although source control is the only completely effective way to remove pollutants from indoor environments, getting rid of all contaminants often is not feasible or practical, which is why you also need good ventilation and air cleaning. Using products that emit low levels of indoor pollutants, such as volatile organic compounds (VOCs), is a great start as it strengthens the ability of ventilation and air cleaning to dilute and remove indoor air pollutants, the report said.

Determining what type of air cleaner/purifier to use can be complicated as it depends on what types of indoor air pollutants are to be removed, the size(s) of the indoor space(s), the type of building, and what activities are going on in the building. Budgetary (first cost and maintenance) and energy costs and conservation considerations also must be taken into account. Further, when it comes to some types of air cleaners, marketing claims can be very confusing, the report noted.

For instance, some air cleaners are especially designed to remove particulates only, while others also are fitted to remove gases, vapors, and odors. Some rely on physical mechanisms to capture contaminants and others electrically charge particles to attract them into filters. The filters themselves come in a variety of styles, sizes, and materials, the report said. This past spring, a veritable thunderstorm of controversy erupted in response to a Consumers Report article (May 2006) on another class of air cleaners that produces ozone at high levels for the purpose of air cleaning.

"The idea is ozone reacts with odor-causing VOCs and removes the odor while leaving a fresh, clean smell. Research has shown, however, that ozone as an air cleaner or purifier is not particularly effective and in fact can be hazardous to health. These air cleaners are not to be confused with other electronic air cleaners that produce ozone at very low levels as a byproduct, which are not considered dangerous," Dr. Black said.

One guide to choosing an air cleaner/purifier to is review the results of independent product testing for performance. AQS, for example, offers a comprehensive test method that assesses the effectiveness of air cleaners/purifiers in four distinct areas:

  • Particle removal efficiency, which measures the percentage of dust removed from the air, which differs from other test methods that measure how much dust a filter collects;

  • Chemical removal efficiency, which measures the percentage of VOCs and formaldehyde removed from the air;

  • Odor removal efficiency, which measures the reduction in malodor perception; and

  • Ozone emissions, which measures the amount of ozone released during operation.

    During this test, a dynamic environmental chamber is contaminated with a known concentration of particles and specific chemicals and malodors. The air cleaner/purifier is turned on and airborne levels of VOCs, dust, and ozone are measured before, during, and after operation. A human odor panel also evaluates the quality, intensity, and characteristic rating on a scale of 1 to 5. The odor analysis follows ASTM guidelines for sensory evaluations and DS-61, Atlas of Odor Characteristic Profiles.

    "Independent testing allows manufacturers to demonstrate their product's effectiveness and safety, especially for air cleaners that remove VOCs and odors or that may generate ozone. Independent testing also gives consumers peace of mind that the air cleaning products are operating as intended and are not contributing to indoor air pollution," Dr. Black said.

    For more information on this test method, contact AQS at 770-933.0638 and ask for Product -Evaluations. The AQS report, "Clearing the Air on Indoor Air Cleaners/Purifiers," is available at no charge under the White Paper section of the Premium Content Page of the AQS - Aerias IAQ Resource Center Website at

    Publication date: 07/24/2006