A systemic failure exists in and between urban settings worldwide that is expressed in social exclusion, polarization, degradation of the environment, increase of informal livelihoods, and health inequities11. The scale and pace of urbanization over the past 50 years is unprecedented in history. The nature of urban change differs within and among regions. In some countries of Africa and Asia the growth of slums and informal settlements equals or surpasses urban growth.
The social dynamics and economic forces responsible for the “invisible” walls that separate the inhabitants of the informal settlements Kibera and Mathare in Nairobi from the wealthy business centre on the other side of Moi Avenue or the people living in “asentamientos” such as Quiňonez or La Fosa in San Salvador from the gated communities such as San Benito may be similar or differ from those producing the divide between the inhabitants of cités such as Sarcelles, Saint Denis and the city centre of Paris (Caldeira, 2000; Marcuse and Van Kempen, 2002; Rodgers, 2007; Marcuse, 2005). In Sub-Saharan African cities, children living in informal settlements are more likely to die from entirely preventable respiratory and waterborne illnesses than children in rural areas (UN-Habitat, 2006). Child mortality in Nairobi’s slums is 2.5 times higher than in other cities in Kenya and three to four times the Nairobi average (APHRC 2002). Non-communicable diseases, the leading cause of death in both low and middle-income countries, are increasing, particularly, in the urban centres of low-income countries12.
Access to the social determinants of health and of health equity is widening between as well as within cities (CSDH, 2008), while urban change is taking place in a context of other global challenges - due to economic globalization, climate change, a financial crisis, the informalisation of the economy, energy - and food insecurity, old and emerging armed conflicts as well as the changing patterns of the spread of infectious diseases. The capacity of urban and/or multi-scalar governance to anticipate, to address or to mitigate the differential health impacts of these and other challenges has been limited so far. Policy - and decision-making processes aimed at reducing the inequities and improving population health are
11 Equity in health is the absence of systematic disparities in health (or in the major social determinants of health) between groups with different levels of underlying social advantage/ disadvantage – that is wealth, power or prestige. (Braveman, 2003).
12 In low and middle income countries, the prevalence of hypertension is increasing with rates being higher in urban than in rural settings (Addo et al, 2007). Stroke mortality in urban East Africa is more than 5 times higher than in England (Walker et al, 2000).