A 21st Century Priority Demands a Public Health Perspective

The converging trends of globalization, urbanization, and population aging present unprecedented challenges and opportunities to advance global health. We propose a new conceptual framework for urban design and policy that integrates a public health perspective in order to optimize three linked goals: population health, environmental sustainability, and successful population aging.

Urban shapes health

For the first time in history, a majority of the world’s population live in urban areas, occupying two percent or less of the earth’s surface; by 2050, almost two-thirds of the population will be concentrated in urban areas. Urbanization is an increasingly global phenomenon: most large cities are in low- and middle-income countries, and Africa and Asia are expected to experience the most urban growth over the next several decades.

With a majority of people living in urban environs, global health now depends on the creation and maintenance of healthy cities. Today’s cities shape the health of the majority of the world’s population through multiple pathways: the quality and availability of drinking water; clean air; affordable housing; nutritionally adequate and affordable food supply; walkable and safe streets; ease of obtaining exercise; nonpolluting public transit; investments in children’s education; and access to health and social services.

A large and growing body of urban health science provides important insights into the ways and degree to which both infectious and non-communicable diseases, as well as mental health, injury, disability and violence are all modified by urban context. For example, the geographic marginalization and relocation of the poor into toxic, physically vulnerable (e.g. flood zones) and/or under-resourced urban ‘slum’ areas increases health inequities through physical and social determinants. Cities consume most (60-70%) of the world’s energy and produce the vast majority (75-80%) of carbon dioxide emissions, threatening our environmental sustainability as well as creating disease burden that falls disproportionately on the disadvantaged, whether by socio economic status or by age, as the very young and old. For example, recent data indicates that exposure to various particulate matters (e.g. coal dust and polycyclic aromatic hydrocarbons) impairs lung development in utero, disrupts neurocognitive development, of young children and increases risk for obesity in children exposed in utero. That same air pollution increases death rates in those with heart and lung diseases, and exacerbates climate change. Many of the MDG 2015 goals (e.g., improving maternal and child health) cannot be achieved without the advancement of healthy urban environments. Moreover, the epidemic of lifestyle-sensitive non-communicable diseases—which, not coincidentally, emerged in tandem with the growth and globalization of cities—cannot be successfully addressed unless we recognize the complex and myriad ways in which urban shapes health.

Designing for urban health:

a tri-benefits approach

Given their major role in shaping population health, urban environments should be considered as a formal unit of the health system. Applying a public health lens to urban planning and design will enable global leaders to identify and invest in interventions that promote population health. In addition, as noted in the examples above, the health burden created by urbanization is often caused by the same factors that are threats to environmental sustainability. Consequently, the World Health Organization, recognizing that many of the same aspects of urban design can benefit both health and sustainability, now advocates an approach that designs for co-benefits, i.e., interventions that meet both goals.

It is now time to add a third set of goals to these co-benefits, namely designing to optimize cities for old and young. Population aging, like urbanization, is an increasingly global trend as well, in fact, a major success of global health interventions. The babies born into today’s ‘young’ societies will grow old in aging societies. Urban design that promotes accessibility for people of all ages and capabilities will ensure that, as they become older adults, they can stay active and independent longer, participate actively in their communities, and remain in the workforce as desired. (The importance of this issue has been noted by a growing number of global business leaders who are actively supporting innovations to promote and maintain a healthy workforce.) Integrating a third WHO goal, the creation of age friendly cities, into our urban public health perspective enables us to proactively address population aging and embed the concept of health promotion across the life span.

Designing for tri-benefits offers the most effective as well as cost-efficient approach to address the trifecta of population health, environmental sustainability and population aging. Achieving three goals with any one intervention not only magnifies the return on investment but also provides a platform through which to meet goals of a broad range of stakeholders. Applying a public health perspective to urban design and policy enables us to shape health through multiple domains: physical and build environment, socioeconomic environment and community norms and practices. Developing policies and interventions that meet the triple goals of health promotion, sustainability, and optimizing cities for the very young and old can yield positive change across multiple domains, as evidenced by the following three examples:

Urban bike-share programs promote biking as transportation by providing low-cost access to bikes for short trips within cities. These programs, now adopted in cities all over the world, are cost-effective means to reduce urban driving, increase physical activity among citizens, and normalize biking as a means of transportation while improving our quality and decreasing energy consumptions and carbon footprint. The programs have also generated economic growth through the creation of new jobs and businesses. The impact on population health via reduced exposure to air pollution and increased physical activity has yet to be measured (and should be). However, experiences to date point to the need for bike lane and traffic design that also protect pedestrian safety, especially for slow walkers and parents with strollers.

Decreasing the urban ‘heat island’ effect through covering urban rooftops with reflective white paint. This simple change in the physical environment achieves many benefits, including: reduced cooling demands and energy consumption within buildings; reduced energy expenditures; reduced emissions of air pollutants and greenhouse gases; and improved health and comfort, particularly for the most vulnerable citizens (e.g., frail older adults and people with cardiac and lung disease). In New York City, where this has already been implemented, the initiative also galvanized volunteers and served as an effective educational and awareness building campaign among city residents, helping to change community norms.

Transforming human into social capital: harnessing the opportunities of longer lives. Making the most of the success of longevity will require effective disease prevention across the lifecourse and investing in keeping people healthy as they are. There are models for doing that in a win-win investment through public health programs like Experience Corps. This program is designed to create new roles for older adults meeting profound unmet needs in society, like helping ensure children’s success in school-while also designed to enhance healthy aging. These programs work, and have high impact in cities that offer safe walking and urban transport as well as the new social institutions that are designed to deploy the capabilities of older adults for societal needs.

Global health leaders as well as leaders of cities have an impressive history of developing innovative interventions that co-benefit sustainability and population health. The addition of population aging as a lens through which to analyze issues and measure the success of interventions provides a new and invaluable perspective. As indicated by the examples above (as well as many others not named here), designing cities to optimize the health and well-being of the very young and old will create cities that work well for everyone. Implementing solutions with multiple benefits maximizes return on investment from effective approaches while providing visionary leadership for 21st century global health. This principle, while the newest addition in this conceptual framework, may prove to be the most practical and impactful over the long-term. GHD