Situation and trends
Today, an estimated 828 million people live in slum conditions, representing around one third of the world's urban population. The vast majority of these slums – more than 90% – are located in cities of developing countries. Often, the fastest growing cities have the highest concentrations of these informal settlements. Slums are no longer just marginalized neighborhoods housing a relatively small proportion of the urban population. In fact, in many cities, slums are the dominant type of human settlement, carving their way into the fabric of modern-day cities, and making their mark as a distinct category of human settlement that characterizes many cities in the developing world. Slum dwellers experience difficult social and economic conditions that manifest in different forms of deprivation – material, physical, social, and political. They live in overcrowded, poorly constructed housing, often with insecure land possession. Housing in these settings ranges from high-rise tenements to shacks to plastic sheet tents on sidewalks, often located in undesirable parts of the city such as steep hillsides, riverbanks subject to flooding, or industrial areas. Slum dwellers' health is further affected by reduced access to safe food and water, poor sanitation, a breakdown of traditional family structures, high crime, and high unemployment rates. Due to the high population density, overcrowding, and lack of safe water and sanitation systems, slums are productive breeding grounds for tuberculosis, hepatitis, dengue, pneumonia, cholera, and diarrheal disease. Despite the tremendous need, healthcare services are generally difficult to access in these areas.