Tuesday, March 28, 2006

Breathing Easy: Cood central air filter helps control dust in home

MARK R. SHELLER

Tucson Citizen

Editor's note: This is Mark R. Sneller's last column for the Citizen.

Last of two parts

As part of our annual summary, last week we talked about two classes of respiratory irritants: gases and particles. And we discussed the various types of indoor gas irritants such as polishes, cleaners, waxes and fragrance products.

This week we'll discuss particles.

There are probably 50 types of particles that we inhale on a daily basis, among them: pollen, mold, carbon (six different types), plant parts, cornstarch particles (talcum powder), drywall dust, spider webs, natural and artificial fibers including fiberglass, food particles, and so forth.

Notice I didn't mention dust. This is because all of the above make up dust and the dustier the indoor environment, the more of each the dust will contain.

The dust is circulated throughout the home, although almost all the dust in a home comes from tracking dirt in and grinding it underfoot to finer and finer particles. These are driven by air currents to pile up against walls.

Good central air filtration works to remove these particles. The 3M Company make a good pleated filter that is available at reasonable cost from most local hardware dealers.

People may breath in particles smaller than 10 microns, called PM10s by the government. The more dust we have, the more particles are inhaled. Many particles, such as pollen grains and mold spores, are larger than this, but still allergenic and asthma-triggering.

New discoveries about allergens are being made all the time. One example is diesel exhaust carbon that is constantly in our air, outdoors and indoors. This carbon is not only allergenic unto itself, but can combine with other allergens. For example, rainfall will cause grass pollen to release its inner starch granules, which then attach to the carbon, which in turn, is inhaled. Thus, we have an explanation for "thunderstorm asthma."

Another discovery is that the cornstarch particle used as body talc is allergenic to people with a corn allergy and can pick up the latex antigen when used in latex gloves. Cornstarch particles are very prevalent in hospitals and specialty health-care settings. Public and scientific pressure is causing hospitals to use gloves that do not have cornstarch as a lubricant.

A third discovery is that when one member of the household is allergic to a food product such as wheat, it is not enough to keep wheat out of that person's diet. If other members of the family use wheat products, bread, for an example, the particles will become part of the indoor dust and be inhaled by the wheat-sensitive person, causing allergenic or asthmatic reactions.

Reducing particle counts in the home can be accomplished in several ways: simplicity of the home, frequent dusting with special static clothes and good air filtration. Remember that the fan on the central system must operate for eight hours a day to do any good.

Mark R. Sneller, Ph.D., is an indoor air consultant and director of Aero-Allergen Research. He can be reached at P.O. Box 12023, Tucson, AZ 85732-2023.

Good central air filter helps control dust in home