Concerns about indoor air quality and the rising incidence of asthma and allergies have made portable air cleaners a big business. US consumers spent about $275 million on these devices in 2003, and that number is expected to increase to $370 million by 2008. (1) But just how effective are these devices? Are they truly necessary? Can air cleaners remove enough dust, pollen, tobacco smoke, pet dander, microbes, and toxic gases, like formaldehyde, to make a difference? Well ... maybe. It depends on how the cleaner is made and maintained. It also depends on the amount of indoor pollution.
Neither the Environmental Protection Agency (EPA) nor the American Lung Association recommends depending upon air cleaners as a first-line defense against allergens. No machine is as effective as source control. That is, no machine will remove the particles, gases, and odors associated with cigarette smoking as effectively as having people smoke outside. One of the best ways to reduce house dust mites is to get rid of carpeting (one of their primary habitats) and using hard surface flooring instead. Vacuuming with a machine equipped with a HEPA filter every day or so and regular dusting with a Swiffer duster or electrostatic cloth can go a long way towards reducing allergy symptoms in those who are sensitive to dust.
Ventilation is the second tactic to use before turning to air cleaners. EPA has found that in many cases indoor air is more polluted than outdoor air. Unless you live in an area with poor air quality, opening windows may be one of the easiest ways to better indoor air quality. During cold weather, use bathroom fans to send hairspray and other odors outdoors. In warm weather, air conditioners can decrease the amount of pollen that enters a home. People with central heating and air conditioning may find it helpful to use pleated filters, such as 3M Filtrete Ultra Allergen Reduction and Precisionaire NaturalAire Micro-Particle, instead of the regular, loose-weave filter. The denser fabric in these pleated filters capture more particles. They do require the fan to work harder, however, and may affect energy costs.
Air cleaning devices are considered the third most effective strategy for reducing indoor pollutants and do not replace the need for the first two. Picking an effective air cleaner is daunting. Part of the problem is that no industry standard exists. The Association of Home Appliance Manufacturers (AHAM), Consumers' Union (Consumer Reports' publisher), and Air-Purifiers-America.com have different ways of evaluating the devices; and none of these groups test all machines on the market. AHAM provides voluntary certification of the clean air delivery rate (CADR) for tobacco smoke, dust, and pollen and the appropriate room size for each device it tests. CADR is the amount of clean air measured in cubic feet per minute (cfm) that an air cleaner delivers to a room. Consumers' Union injects measured amounts of dust and smoke into a sealed test room, then measures the result after a device has run at high speed...