Housing and health
Improving the lives of at least 100 million slum dwellers was a Millennium Development Goal target relevant to sustainable cities. Slums are defined as residential neighbourhoods that "lack one or more of the following: improved sanitation, safe drinking-water, security of tenure, durable housing, and sufficient living area (no more than 3 people sharing the same room)". 18
However, a revised target for reporting on slum improvement is now widely acknowledged as necessary to facilitate country-level measurement of progress indicators against a better defined baseline.19 It is now apparent that the number of slum dwellers is far higher than originally estimated in 2000 and that number has grown in the intervening decade – although slum dwellers as a proportion of the urban population have indeed declined since 2000.20
The indicator suggested here, in the context of Rio+20 Sustainable Cities theme, defines urban slum improvements in terms of simple, concrete physical features that capture synergistic aspects of health, equity and sustainability. For instance, in developing countries one quarter of the urban population uses coal, wood, or biomass for household cooking and heating – a large contribution to not only indoor but also outdoor air pollution.21 Thus improving aspects of a slum home's energy system helps health and environment.
More structurally sound, safe, and energy-efficient housing design, including good use of natural ventilation, can also help reduce domestic injuries and vulnerability to extreme weather/disasters. In addition, improving housing quality can reduce exposures to conditions of excessive heat, cold, and dampness, which are risk factors for a range of cardiopulmonary diseases (both infectious and noncommunicable).
Commercial and public buildings – if beset by poor ventilation/daylighting – and indoor air pollution can contribute to infectious disease transmission and chronic diseases as well as reduced morale and productivity. In some settings, commercial and public building energy use may not only be a large proportion of a city's total pollution and climate footprint, but also more rapidly amenable to policy interventions due to built-in market incentives for efficiencies.