Despite numerous planning challenges, cities offer more efficient economies of scale on many levels, including the provision of goods, services and transportation. With sound, risk-informed planning and management, cities can become incubators for innovation and growth and drivers of sustainable development.
An estimated 60 percent of the world’s population will live in urban areas by 2030, and most of the expected 1 billion increase in urban dwellers between 2015 and 2030 will occur in Africa and Asia.
Improving the quality of housing
In Sub- Saharan Africa more than half the urban population lives in slum conditions. Countries that have faced civil war report the highest rates: In the Central African Republic, South Sudan, and Sudan more than 90 percent of the urban population lives in slums. Moreover, both the Central African Republic and Mozambique have seen the number of slum dwellers rise since 1990 (figure 11b). In those countries poor people move from rural areas to cities in search of greater opportunity but often end up even more entrenched in poverty. Other Sub- Saharan countries have made extraordinary progress in reducing their urban slums. Rwanda lowered the proportion of its urban population living in slums from 96 percent in 1990 to 53 percent in 2014. Mali also saw a large decline, from 94 percent of its urban population to 56 percent.
Reducing the environmental impact of cities
According to the 2013 Global Burden of Disease study, exposure to outdoor air pollution (as measured by levels of particles less than 2.5 microns in aerodynamic diameter [PM2.5]) is responsible for 2.9 million deaths per year, about one every 10 seconds.1 Outdoor PM2.5 levels are highest in East Asia and Pacific (40 micrograms per cubic meter in 2013) and South Asia (45 micrograms per cubic meter, more than four times the guideline value recommended by the World Health Organization; figure 11c). In both regions the levels of outdoor PM2.5 have increased from their 1990 levels.