Deteriorating paint in older homes is the primary source of lead exposure for children, who ingest paint chips and inhale lead-contaminated dust. Between 1998 and 2000, a quarter of the nation’s housing — 24 million homes — was estimated to have significant lead-based paint hazards.

Substandard housing conditions such as water leaks, poor ventilation, dirty carpets and pest infestation can lead to an increase in mold, mites and other allergens associated with poor health. Indoor allergens and damp housing conditions play an important role in the development and exacerbation of respiratory conditions including asthma, which currently affects over 20 million Americans and is the most common chronic disease among children. Approximately forty percent of diagnosed asthma among children is believed to be attributable to residential exposures. In 2004, the cost of preventable hospitalizations for asthma was $1.4 billion, a 30 percent increase from 2000.