Q. A friend of mine talks a lot about her allergy to dust mites. What are dust mites and where do they come from?

A. These tiny critters cannot be seen by the naked eye. Almost every house and apartment in the country harbors dust mites—they are not a sign of poor housekeeping! As small as they are, dust mites are probably the biggest cause of year-round allergies and asthma. Actually, the problem is not the mites themselves but rather their waste products. Dust mites thrive in warm, humid environments, but even when the temperature drops and they die, their waste remains.

Dust mites live largely in our carpeting and furniture—sofas, chairs, pillows, and mattresses. Bedrooms appear to be their favored hangout. Vacuuming using special filters helps a bit, as does dusting your surroundings. But the vast majority of dust mites stay put because they’re so deeply buried.

People who are sensitive to dust mites should minimize their exposure to the organisms and their waste by enclosing mattresses and pillows in dust-proof covers and washing the bedding every week in water that’s at least 130º F. They should also not have carpeting, upholstered furniture, or curtains in their bedroom.

So, that’s a big part of the dust mite story.

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