DEAR DOCTOR K:

I keep a tidy house, but no matter how much I clean, there's more dust than I'd like. Is dust dangerous to my family's health?

DEAR READER:

Yes, depending on its contents, dust can be harmful to your health.

What is dust? It's a little like sausage: You don't want to know what's in it. But I'll tell you anyway.

More than half of household dust comes from soil either tracked into the home or wafting in as airborne particles through doors and windows. The remainder of dust is a hodgepodge that includes skin cells from family members, skin cells and fur from household pets, carpet fibers, kitchen grease -- and more.

Household dust often contains remnants of household chemicals and possibly even heavy metals. It also contains bacteria, fungi and dust mite (insect) particles that can trigger allergies. In particular, the debris dust mites leave behind can provoke powerful allergic reactions.

The most vulnerable family members are the youngest: Infants are up to 100 times more susceptible to the health hazards of dust-borne pollutants than adults.

Perhaps the most effective way to control dust levels is with regular housekeeping. Frequent vacuuming, preferably using a vacuum cleaner with a high-efficiency particulate air (HEPA) filter, is a good place to start. It may be necessary to vacuum several times a week.

Cleaning can temporarily launch into the air dust that has settled on floors, carpets and furniture. People with respiratory allergies should consider wearing a mask that filters out dust when they clean. One way to capture the dust that gets stirred up is 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 like Grab-it or Swiffer that are treated with chemicals to attract dust.

You should consider putting heavy-duty doormats in front of doorways to stem the amount of soil coming into your house. Even better: Remove your shoes upon coming inside.

Install weatherproofing around doors and windows to help keep out airborne particles. Filters on heating and air conditioning systems should reduce dust. Portable air cleaners with HEPA filters are another option. Air purifiers are a less effective option than HEPA filtration, and they may emit small amounts of ozone, a gas that can worsen asthma symptoms.

I've talked about how dust in the home can trigger allergies, so you'd think that dust is just plain bad. But it may not be that simple. New research indicates that newborns and very young children who grow up in relatively "dirty" surroundings, such as farms, may actually be protected against developing allergies and allergic diseases (such as asthma) later in life. I'm not urging you to keep a dusty home for the first few years of a child's life, but someday you may hear that advice!

(Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.)

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