I’ve been focused on dust recently. My husband’s grandson, Patrick, 26, and his inamorata, Becky, spent a few days with us last month. When they arrived, they left their shoes outside the door. Patrick is an environmentalist and Becky, a forest ranger. They live and work in the mountains of northern Maine and New Hampshire. As outdoors people, they habitually remove their shoes in order to avoid traipsing dust and dirt into the house from outside. That got me wondering.
I discovered that household dust often contains toxic chemicals and all sorts of allergens. About 60% of it comes from soil tracked inside on the bottoms of shoes or the paws of pets or as airborne particles that have wafted through doors, windows, and other openings, such as heating/air-conditioning ducts. etc. The remaining 40% is a potpourri of substances inside, like skin cells, pet fur, insect residue, carpet fibers, and kitchen grease.
One study that examined samples of dust from homes in California and the Midwest found arsenic and lead from auto emissions and defunct coal-fired power stations. Other research has shown the concentration of pollutants in households to be much higher than in the surrounding soil. And the source doesn’t have to be nearby. Particles can be carried on the wind for miles.
Another study of dust from 70 homes across the country found over three dozen chemicals that have been linked to immune system disorders and birth defects in laboratory animals. The chemicals come from flame retardants, pesticides, plastics, and other compounds found in furnishings, electronics, cosmetics, adhesives, textiles, and other consumer products. The chemicals rub or flake off in amounts that are too tiny to see or smell at the items are used, sat upon, or walked on.
Dust can also be home to a thriving community of bacteria, fungi, and dust mites. As many as 500 mites can live in a single gram of dust, each of them producing allergy-inducing droppings.
Endotoxins, a toxic substance bound to bacterial cell walls found in dust, are still another problem. A study by the National Institute of Environmental Health Sciences some years ago showed that adults who live in residences with increased concentrations of endotoxins reported higher rates of wheezing and other asthma symptoms. The symptoms were more pronounced in cases where endotoxin levels were elevated in bedrooms.
Best line of defense: Regular housekeeping
One simple way to stem the amount of soil coming into a house is to put heavy-duty doormats in front of the doorways. Even better, like Patrick and Becky, remove your shoes before coming inside, and ask visitors to do the same. Installing weatherproofing around doors and windows will help keep air-borne particles out—and lower your electric bill, too.
Filters on heating and air-conditioning systems will cut down on dust. Portable air cleaners with high-efficiency particulate air filters (HEPA) are another option. Some air purifiers apply an electrostatic charge to dust particles that draws them to metal plates within the unit. In addition to being less effective than HEPA filtration, they may emit small amounts of ozone that can worsen asthma symptoms and may have other bad health effects
But the single most effective way of controlling dust levels involves nothing more complicated than routine housekeeping. Regular vacuuming is a good place to start. The University of Arizona researchers found that vacuuming removed over 80 percent of the arsenic-containing floor dust in the houses they tested. In less dusty environments, you may be able to get away with vacuuming once a week. With a large family or multiple pets, several sessions a week may be in order.
But be careful. Cleaning tends to re-launch settled dust, and the longer the interval between cleanings, the thicker the dust layer. Therefore, it’s best to clean higher surfaces first and then work your way down. Wiping floors and hard surfaces with a damp cloth or sponge will eliminate a lot of dust. You can also use products chemically treated to attract dust, but many of them haven’t been tested for toxicity, so use them in moderation. Besides, water and a little bit of soap may be just as effective.