Most urban centres in sub-Saharan Africa and many in Asia and Latin America are dangerous places to live and work. This can be seen in aggregate statistics for nations' urban populations that show (for instance) high infant, child and maternal mortality rates.
The dangers particularly affect low-income populations living in informal settlements. These areas often lack most risk-reducing infrastructure (such as safe, sufficient, accessible and affordable water; good-quality sanitation and electricity; all-weather roads; and street lighting) and risk-reducing services (including healthcare, waste collection, emergency services and policing).
But when basic provisions for these are in place, urban centres can be among the world's least dangerous places to live – shown by very high life expectancies.
Local government responsibility
The Sustainable Development Goals (SDGs) mention addressing these risks and 'leaving no one behind'. But they don't acknowledge that the responsibility largely falls to local governments, and that most risk in urban areas cannot be reduced when local governments fail their responsibilities.
These failures, and their causes, including inadequate support from higher levels of government and international agencies, are the most important reasons so many urban centres are so dangerous.
In high-income and some upper-middle income countries, urban governments have dramatically reduced most of the life- and health-threatening risks by providing infrastructure and services, but also by managing land-use. This is important for making serviced land for housing available and affordable, for protecting watersheds, and for avoiding settlements on dangerous sites.
In most cases, this has required well-functioning city governments and strong civil society pressure, including demands from organisations representing the urban poor.
There is little comparable progress in low- and many middle-income countries. Indeed, many have gone backwards: the proportion of their urban population lacking sanitation and piped water at home is lower today than it was in 1990 (PDF).
Data and local action
Cities in high-income countries also have information on risk: through censuses, vital registration systems, surveys, hospital records and data on air pollution. Reporting on road accidents, for example, has often led to concerted action. Similarly, understanding the health impacts of small particles has led to more stringent air pollution controls.
Reducing risk depends on local knowledge to identify and understand risk, and then local capacity to respond. Where conventional responses are too expensive or beyond local government capacities, communities are important.
There are many examples of household and community-level action on risks. For instance, communities have led on installing sewers and drains (PDF) in many informal settlements in Karachi and other urban centres in Pakistan, and Mumbai's informal settlements have hundreds of community-designed and managed toilets and washing facilities (PDF).
But community organisations cannot build the city-wide systems – the water mains, trunk sewers and drains, waste disposal, public transport, and so on. What was important in both these examples was community organisations working with government agencies and within local resource constraints.
When there is no local risk data
Where formal information systems don't exist, or where good information cannot be obtained from them, then new locally-rooted data collection is needed.
Applying the DesInventar methodology to cities shows up many local risks that usually go unrecorded. This draws on local sources, such as newspaper reports, and includes events where people died or lost property but where too few were affected for a disaster to be recorded.
But it also faces limitations – for instance there are no records on most premature deaths from infectious and parasitic diseases on which it can draw.
What too often gets forgotten is local people's knowledge and capacities. These can be accessed through household surveys, site visits, discussions with community organisations (PDF), and focus groups and interviews with key individuals (including local government staff and community leaders).
This is the third of three blogs drawn from the editorial in the April 2017 issue of the international journal, Environment & Urbanization. This issue is on 'Understanding the full spectrum of risk in urban areas' and it was prepared in partnership with Urban Africa Risk Knowledge (Urban ARK). The first blog was on 'Urban risks: where are the top five biggest blinds spots?' and the second was on 'Addressing the needs of vulnerable groups in urban areas'.
Police, emergency services and hospitals also hold records on some risks. Then there are the detailed surveys and maps undertaken in hundreds of cities by slum/shack dweller federations. These provide much of the data needed to inform risk reduction and engage local populations in setting priorities.
Functioning local democracies are another route to local knowledge on risks as they make local governments respond to demands by those who lack risk-reducing infrastructure and services, and this serves as a substitute for spatial data on risk.
Research programmes can help too. Urban ARK is a three-year programme of research and capacity building led by 12 policy and academic organisations from across sub-Saharan Africa, with partnerships in the United Kingdom. It aims to identify the most serious risks and break cycles that make risks accumulate.
The work is concentrated in four core cities – each presenting different development and hazard contexts: Ibadan (Nigeria), Karonga (Malawi), Nairobi (Kenya), and Niamey (Niger). Additional research is under way in Freetown (Sierra Leone), Dar es Salaam (Tanzania), Mombasa (Kenya), Dakar (Senegal), and Addis Ababa (Ethiopia).
International support for local action
International agencies must recognise they need to support local action by local governments, local universities and local civil society organisations. There is much they can do.
These agencies can help local groups access data from government agencies at all levels. They can pressurise national statistical offices and census bureaus to serve and support local governments and other local groups by providing useful data.
International agencies can also learn to support 'co-production' between local governments and groups at risk. But perhaps most important of all, international agencies must develop a capacity to help fund and support a range of initiatives in each locality, including civil society initiatives.
In short, the focus needs to be unrelentingly 'local, local, local', as agencies assess the most serious everyday risks, as well as the small and large disaster risks facing each settlement, and act on these.
Urban centres can be among the world's most healthy places to live and work – but many are among the least. How healthy they are is powerfully influenced by local government competence, local information, and support for local action.