CITIES AND HEALTH: FOR BETTER OR WORSE

by Emily Flies, 27th April at 15:52

*All posts are personal reflections of the blog-post author and do not necessarily reflect the views of all other DEEP members.

Historically, cities were considered centres for filth, disease, violence and amoral behaviour. Even today, urbanization has been linked to disease emergence and some diseases are more prevalent or spread faster in cities. However, many public health professionals argue that the city dwellers of today experience health benefits from improved access to healthcare, economic opportunities and vibrant social settings. So who’s right and what’s really happening with health in cities?

The relationship between urbanization and health is messy and constantly changing. But with a rapidly urbanizing world, its important for us to anticipate the health challenges of future city dwellers so we can do our best to ensure they are as healthy as possible. So here we take a look at the good, the bad and the unknown of urban health.

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The streets of Stuyvesant Heights, Brooklyn, New York, 1891. Available at: http://www.brownstonedetectives.com/the-filthy-streets-of-stuy-heights/

Sanitation, slums, and disease

Rapid urbanization is associated with poor infrastructure, overcrowding, and unsanitary conditions. Slum health is one component of urban health, and the United Nations estimates that over 1 billion people currently living in slums and there will be 2 billion slum-dwellers by the year 2030.

Unsanitary conditions can lead to high rates of intestinal parasites, particularly in children. In the slums of Karachi, Pakistan, over 52% of children are infected with parasites. Unsanitary conditions also facilitate the transmission of rodent-borne diseases like plague and leptospirosis.

One of the main unifying characteristics of all cities, regardless of their GDP per capita, is the high density of the population. Unsurprisingly, diseases that are transmitted from human to human can thrive in densely populated cities. For example, cities have higher rates of tuberculosis, with the highest rates being in the poorest areas of the city. Cities can also contribute to the transmission of emerging diseases like HIV, Zika, influenza and ebola.

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13th Compound, Dharavi, Mumbai. Photo: Akshay Mahajan. Licensed under Creative Commons 2.0. available at: http://www.who.int/kobe_centre/publications/cities_for_health_final.pdf

The economic and employment opportunities in cities also attract migrants from rural areas or from neighbouring cities. These influxing people bring with them whatever infections they carry (like schistosomiasis or African trypanosomiasis). Rural-urban migrants are often naïve to the diseases of the city and are often forced to live in sub-optimal, non-hygienic environments, thus facilitating the continued transmission of diseases like cutaneous leishmaniasis.

Health benefits of city living

On the other hand, cities of more developed countries are havens of culture, art, social interaction and good food. They are the economic engines of the world; 600 of the world’s cities hold 1/5 of the global population but generate 60% of the global GDP. People living in these metropoles have greater access to medical facilities, pharmacies, gyms, grocery stores and other “salutatory” (health promoting) features. Indeed, many of these amenities are accessible on foot, which is why urbanites are more likely to walk as transportation than their suburban or rural counter parts.

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A bird eye view of Rio de Janiero

Public health and infrastructure advances in cities in rich nations and affluent areas of cities in developing nations have led to a generally healthier urban population, compared to rural populations. Urban residents in developed countries are protected by regulations that limit the amount of air and water pollution, indoor smoking, CO2 emissions from cars, etc that can negatively impact the health of urbanites in developing nations. Public health advances in many cities have reduced the scourges of infectious diseases (especially tuberculosis, influenza and HIV) that devastated their populations throughout the 20th century. However, replacing this infectious disease burden is the rise of chronic diseases like diabetes, obesity, cardiovascular disease that seem to fill the void left by “cured” infectious diseases. It is currently unclear, however, why these chronic “lifestyle” diseases are rising in developed nations and urban areas.

Hope for the future

The economic and public health advances of cities, have led to an “urban advantage” on measurements of health. But significant disparities exist and the health of the urban poor is the worst of any demographic.

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Low-tech public health solutions can have a big impact on the wellness of residents in slums and low-income urban areas. For example, replacing dirt floors with cement led to a 78% reduction in parasitic infestations, 49% reduction in diarrhea, 81% reduction in anaemia, a 36 – 96% improvement in cognitive development in young children, and made adult residents happier (lower rates of depression and stress and higher self reported levels of satisfaction). An examination of the mortality rates in major cities over the last few decades revealed that the provision of clean water was responsible for nearly half of the total mortality reduction in major cities, three-quarters of the infant mortality reduction, and nearly two-thirds of the child mortality reduction. This same study found that the rate of return to these technologies was greater than 23 to 1 with a cost per life-year saved by clean water of about $500 in 2003 dollars. Similarly, the addition of biodiverse urban green spaces (BUGS) have been connected to myriad health benefits from improved cognitive function to reduced obesity and improved birth weights.

Thankfully, several initiatives are in place to help cities implement these solutions and5 improve the health of urbanites. The United Nation’s Healthy Cities initiative has over 1000 cities committed to ensuring that human well-being is at the centre of local development efforts. The New Urban Agenda, adopted by the UN in 2016 explicitly encourages the reduction of disparity in cities and the reinforcing health. With these initiatives and continued research to explain the recent rise of allergic and autoimmune diseases and the characteristics of cities that impact human health, city dwellers of the future can enjoy long and healthy lives.

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