House dust

Dust mites are microscopic creatures co-habitating with humans in virtually every type of housing and linked to asthma attacks and allergies. They live off human skin flakes, which are constantly sloughed off. They rapidly reproduce in moist environments and thrive in centrally-heated carpeted homes. It itself is not a serious threat to health, but it sets up sensitivities very early in life (in the form of antibody production) which are compounded by exposure to other pollutants later on. Typically, an allergy to the mite or to cigarette smoke can develop into asthma later in childhood and to hay fever in the teens.

On the Isle of Wight more than one-tenth of children studies from birth were found to have developed by the age of two an allergy to the house dust mite.

A 2001 study sampled bedding in 831 homes where about 2,500 people lived from 75 different locations across the USA. In addition to vacuuming up dust samples, the researchers collected environmental data and information about the study participants' race, income level, and health status. The results were that some 86% of American homes have detectable levels of dust mite allergen, but more importantly, around 23% of homes have enough of the irritant to trigger respiratory problems. Since mites are drawn to humidity, the incidence in the more humid North-East was was four times that of the drier West. In addition, low-income families' homes have a higher level of dust mites. Other risk factors for dust mites are living in single-family homes, high bedroom humidity, mildew odor in the bathroom, and living in a home built before 1978.

"In environmental science, we're very interested in environmental justice, the lower socioeconomic class families are disproportionately affected," says Zeldin.