The American Lung Association is frequently asked by the medical community and the lay public alike about the usefulness of the various available air cleaning devices and technologies. With the prevalence of asthma increasing in the last decade, particularly in children, to an estimated 14.6 million Americans affected and the mortality rate due to asthma almost doubling, we must carefully consider the value of simultaneously applied source control, ventilation, and air cleaning in relieving symptoms and improving health. This report is generated in part because many Americans are using air cleaners to achieve beneficial health effects. Although these effects are not yet known, it is hoped that the gathered data will provide guidance for choices made in anticipation of health effects. Indoor Air Pollutants of Concern Air cleaners are generally marketed to reduce indoor air pollutants ranging from dusts to chemicals to gases.
Particulates are solid or liquid materials small enough to suspend in air.
Particulates can include inorganic and organic compounds as well as small living organisms such as bacteria and viruses. While dust mites themselves are too large, dust mite feces and body parts can become airborne and the principle allergen of the dust mite is derived from its feces. Exposure to intact dust mites usually results from contact with bedding, upholstered furniture, carpets, and other reservoirs. Figure 2 lists the sizes of various types of particles and the time to settle one meter. Particulates are of principal concern from a health perspective because they can carry foreign proteins and because the smaller particles penetrate deeply into the respiratory tract.