Nature Outlook |
Urban health and well-being
With more than half of the world's population already living in cities and further growth expected, the health of urban dwellers is crucial to global well-being. This Nature Outlook explores some of the obstacles to a healthy, happy urban life – and the development of strategies to overcome them.
For more on urban health and well-being from nature.com, see: nature.com/subjects/environmental-social-sciences
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From their earliest beginnings, cities have brought both benefits and risks to the health of their inhabitants. Although some of the hazards have been banished, others remain — and new ones have emerged. By Stephanie Pain
Transporting people around the cities of the future is a public-policy challenge, but it's also an opportunity to improve the health of urban populations.
Water is a necessity for any city, but too much of it can threaten lives and infrastructure. As climate change looms, new approaches can help to turn a threat into a resource.
Exposure to nature makes people happy and could cut mental-health inequalities between the rich and poor.
Deprivation leads to stress, and stress to bad health. A park, and the science behind it, aims to break that chain.
Pollution poses a significant challenge to food production in urban environments, says Andrew A. Meharg.
The growth of slums in the developing world's rapidly expanding cities is creating new opportunities for infectious disease to flourish and spread.
Cities are complex environments. Planning interventions that borrow principles from theoretical physics could help to improve peoples' lives.
Flood losses in coastal cities will rise due to increasing populations and assets. Research now quantifies average losses in the 136 largest coastal cities. Estimated at approximately US$6 billion in 2005, average annual losses could increase to US$52 billion by 2050 on the basis of projected socio-economic change alone. If climate change and subsidence are also considered, current protection will need to be upgraded to avoid unacceptable losses.
Primary and secondary organic aerosols emitted by road vehicles are hazardous to health and climate, with diesel trucks and cars considered the main offenders. Platt et al.show that, despite constituting a small fraction of the fleet, two-stroke scooters can dominate vehicular pollution in some cities.
An enduring paradox of urban economics is why cities support levels of enterprise, such as patents and inventions, higher than the countryside. Here Pentland et al. suggest that the density of social ties provides a greater flow of ideas, resulting in increased productivity and innovation.
It is often warmer in a city than in the surrounding rural areas, sometimes by up to a few degrees. This urban heat island effect is commonly explained as a consequence of a lower rate of evaporative cooling in urban areas. But here Xuhui Lee and colleagues use climate modelling to show that for cities across North America, the daytime urban heat island effect varies with the efficiency of heat convection between the land surface and the lower atmosphere. The convection effect varies with climate regime, causing significant urban warming in wet climates but cooling in dry climates. Aerodynamics also play a part, and if urban areas are aerodynamically smoother than surrounding rural areas, urban heat dissipation is less efficient and warming occurs. The health impact of heatwaves means that mitigation of the heat island effect may be beneficial. The authors suggest that aerodynamic spoilers — a city-wide increase in building height for instance — may be impractical. But efforts to increase urban albedo, by installing reflective roofs for instance, might be worth pursuing.