Air Cleaners | Types of Air Cleaners

Many doctors recommend indoor air-cleaning devices for pa­tients with respiratory problems. Good models, designed to clean an entire room, are available for $90 and up. Some compa­nies will allow you to rent or lease one on a trial basis.

The efficiency of these machines has long been in dispute. Some say they're wonderful, others insist they're worthless. Part of the answer depends on the weight of the airborne particles and how long they stay in the air.

Animal dander, for instance, is tiny and light and floats for a long time. Larger specks such as pollens or dust mite particles drop quickly. Within ten minutes, 95 percent of pollens fall from the air spontaneously. Air cleaners are only effective on those particles still in the air.

There are two main types of air cleaners:

Mechanical Filters

These use layers of densely packed fibers to trap the particles as the air passes through. The most effective mechanical filter, the HEPA (high efficiency particulate arresting), collects 95 to 99.97 percent of the small particles.

Some HEPA air cleaners are available with ionizers, which supposedly filter the air and replace negative ions to give air a revitalized, outdoor feeling. The value of ionizers, however, is questionable.

Electronic Devices

These charge the particles, then draw them in by attraction to a plate carrying the opposite charge. The electrostatic precipitator can be useful, but requires frequent cleaning. Otherwise it can produce ozone, which may irritate the airways.

In short, air cleaners can remove pollens, dander, spores, smoke, and dust, but never completely eliminate gases, tobacco odors, viruses, bacteria, or pollutants that constantly enter the house from outside.

An air cleaner should be set in the middle of a closed room but not on a carpet, where it can stir up settled dust. Run it on high after vacuuming and after pets, smokers, or heavy per­fume wearers have been present. (If pets live in other parts of the house, keep their litter boxes meticulously clean.)

For more home protection, equip your heating outlets with a dust filter that you clean or change once a month. Use small electric heaters whenever possible, and avoid burning wood in the fireplace. The smoke adds mold, insect debris, pollen, and dust particles to the air.