Some 52 percent of the world’s population lives in cities, a proportion that will only grow throughout the next few decades. Understanding the health challenges facing urban residents is crucial for those who seek to improve human health, especially since many of these challenges differ from those facing inhabitants of rural areas, where global health resources have traditionally been concentrated. At a private meeting on March 4 at the Wilson Center, experts described how factors ranging from climate change and greenhouse gas emissions to reproductive health and rights impact urban health.

Demographic Trends

Richard Cincotta, demographer in residence at the Stimson Center and a consultant to ECSP, opened the discussion with a description of the National Intelligence Council’s Global Trends 2030 report which emphasized demography as one of four “megatrends.” Urbanization falls into this category, he said, especially for developing countries with growing populations.

“Urbanization seems to all of us, as a process of individual choice,” he said, but it is in fact “a function of country growth.” Cities in rapidly growing countries grow at a faster rate than rural populations, he said, and as overall country growth rates slow so does urbanization.

For some countries, urban areas have similar age structures to rural populations. This is especially true for developed countries, like those in Europe, and for developing countries where health services are equally difficult to access for both rural and urban populations. For these developing countries, like many in sub-Saharan Africa, “the challenges of youthful populations, and all their health needs, political issues, and service requirements are still a big deal in urban areas,” Cincotta noted.

In other countries, like India, however, urban residents have significantly better access to family planning and other health services than their rural counterparts, which results in significantly smaller urban family sizes. As migrants move to cities, they tend to adopt these smaller family sizes. Still, India’s cities are growing more than three times as fast as the rural areas, thanks to migration, and more than half of India’s population will live in urban areas by 2050. These complex dynamics will play an important role in shaping India and other similar countries’ future age structures.

Growing Health Services Demand

Victor Barbiero, adjunct professor of global health at George Washington University, noted that cities can significantly stress developing countries. With large numbers of people living close together, cities can be “crucibles” in which “powerful intellectual, social, economic, or political forces” combine to exacerbate problems like poverty, violence, and extremism.

Another sector where this can be seen is in health. Barbiero said he expects continued urbanization to allow certain infectious diseases to persist and spread, including tuberculosis, HIV, polio, and diarrheal diseases. Chronic and non-communicable diseases like diabetes and cancer are also on the rise.

Why? Barbiero noted that for many cities, a lack of infrastructure and government engagement prevents effective action on health issues and the density of people allows diseases to fester. Ilene Speizer, research associate professor in the Department of Maternal and Child Health at the University of North Carolina at Chapel Hill, said that this is a common problem for growing cities, especially in developing countries – migration to cities happens before proper infrastructure can be constructed.

Looking at aggregated national-level health data can mask challenges and opportunities for urban inhabitants, said Speizer.

While people in cities are more likely to use contraception, for example, they are also more likely to engage in premarital sex, potentially with multiple partners, putting them at greater risk for infections like HIV. And while some data suggests that those in cities have greater access to healthcare, Speizer pointed out that this access varies greatly depending on socioeconomic class. A “thriving” industry of private healthcare has provided better access to many developing country urbanites, but is still too expensive for the poorest, which account for many new city-dwellers in developing countries. In sub-Saharan Africa, 62 percent of the urban population lives in slums, 35 percent in South Asia, and 25 percent in Western Asia, according to the UN.

Vulnerability to Climate Change

Janet Gamble, economist at the U.S. Environmental Protection Agency’s Global Change Research Program, agreed that the poor are disproportionately at risk, particularly as it relates to climate change. She noted that “both rich and poor are exposed to climate change,” but said the rich frequently have access to resources like insurance which can ease the impact of its effects.

Greenhouse gas emissions, the drivers of climate change, cause more respiratory problems on hot days, meaning that as climate change worsens, so will respiratory disease. And extreme weather events caused by climate change can seriously threaten cities.

For instance, heat waves significantly increase mortality in cities, especially among the old, infirm, and very young. Many cities are also located in coastal areas, making them more prone to floods and storms, which can destroy infrastructure and displace millions. In turn, these cities create ripple effects, like out-migration, which puts greater pressure on nearby areas as new migrants stress services and infrastructure.

Cities also house great opportunities to address climate change, said Jonathan Patz, professor and director of the Global Health Institute at the University of Wisconsin in Madison. Changes to how cities are structured can simultaneously address two major health threats: greenhouse gas emissions and inactivity.

In a case study of 11 Midwestern U.S. cities, Patz found if 20 percent of car trips were replaced by public transportation use every year, 500 deaths could be avoided, hundreds of thousands of hospital trips could be averted, and $7 billion could be saved in avoided healthcare and mortality costs because of the reduction in greenhouse gas emissions and related respiratory ailments.

Using bicycles for trips under five miles in good weather could save a further 700 lives because of the decreased morbidity brought on by more physical activity, he said.

These types of opportunities for large-scale change are a great advantage of new urban areas.

A Securitized Future for Urban Issues?

Urban areas will undergo “extraordinary changes” over the coming decades, said Cincotta. He predicted that the United States will continue to devote attention and resources to urban issues, in part, because “urban issues have become a security issue.”

Barbiero agreed, but in addition to more research, he said more action is needed. Development and global health interventions, many of which have traditionally focused on rural areas, need to begin being specifically tailored to urban areas. “Action takes commitment and resources, and we need champions and perseverance…and political support,” he said.