Parking lots are filthy places. They accumulate pollutants such as oil, grease and toxic chemicals, pesticides from adjacent landscaping, road salts, heavy metals, and bacteria from trash. Run-off from these pollutants ends up in local water systems, and add to overall pollution. A recent report by the National Water Quality Inventory shows that runoff from urbanized areas is the leading cause of water quality impairments to surveyed estuaries.
Other studies show that each parking space in the United States costs $6-$23 annually, in health and environmental damages to society caused by air pollution alone. Added up, this comes to between $4 billion and $20 billion annually. In some suburban areas, parking spaces outnumber drivers, and parking lots as big as small neighborhoods dot the countryside. One