PIP: In developing countries, environmental hazards in urban areas mainly affect low-income people--especially women, children, and migrants--the people who are least able to avoid the hazards and/or least able to deal with the illness or injury they cause. Poor people are priced out of safe, well-located, well-serviced housing and land sites. Hazards include biological pathogens; chemical pollutants; scarce, over-priced, or poor quality natural resources; physical hazards; natural resource degradation; and national/global environmental degradation. These preventable health burdens cause disease, accidents, and premature death. Biological pathogens have the most serious impact on human health. Crowded conditions, poor sanitation, inadequate water supplies, poor facilities for preparing and storing food, and inadequate hygiene contribute to biological pathogen-induced ill health. Common chemical pollutants in urban areas are lead, indoor air pollutants from fuel combustion, toxic/hazardous wastes, and ambient air pollution. A shortage of fresh water is often why some urban households do not have a safe and adequate water supply. Limited land in cities prevents the urban poor from growing their own crops or maintaining livestock. Common physical hazards in cities are traffic accidents; burns, scalds, and accidental fires and poisonings; falls; and floods. Overcrowding, poor building material, and settlements on dangerous sites (e.g., flood plains, steep hillsides, and dumps) are example of physical hazards. Noise, overcrowding, inappropriate design, and stresses contribute to the growing psychosocial health problems of many urban dwellers in developing countries, especially of adolescents and young adults. Poorer urban residents who begin or are included in initiatives to improve their neighborhoods are more likely to develop integrated responses to nonenvironmental and environmental problems and to make sure that environmental action programs meet local needs and realities.