Population change and economic development are closely linked, and the growth and expansion of cities occur mainly due to the transition from rural to urban societies. The promises of increased economic opportunities and accessible health care, education, and transportation are among the most important reasons encouraging people to move. This fundamental demographic process makes significant changes in the population of urban places, making the rural-to-urban transitions often chaotic.
The rapidly developing urban centers, defined as megacities with a population of 10 million or more, present a unique opportunity to study the future of our planet and how to make it more resilient and sustainable. Today, the world population is concentrated in cities, and this trend will continue in the future. The predictions are that by 2030, two-thirds of the world’s population will reside in urban areas, and there will be 41 megacities, of which more than 80% will be in low and middle-income countries. On the one side, megacities are culturally, socioeconomically, and racially diverse, while environmental heterogeneity exists in those areas. Future comprehensive studies of megacities should focus on common issues and consider the complex health outcomes of the natural and built environmental landscapes (Patel & Burke, 2009).
If megacities can successfully provide safety and security, there might be several benefits of living in megacities. The declining population in rural areas will reduce the stress on natural environments, while the increasing population in cities will provide effective aggregation of the limited resources. However, the high-density population of megacities makes the citizens exposed to various threats of disasters. Traditionally, the disasters are either natural (hurricanes, floods, earthquakes, etc.) or technological disasters (radiation leaks, oil spills, infrastructure collapses, derailments, etc.). It is undeniable that great opportunities and significant challenges accompany the rise of cities around the globe. Many world regions have increased the number of city dwellers, which makes the questions about the safety and health of the dense environments paramount.
Today, 55% of the world’s population lives in urban areas, and considering the UN predicts that by 2050, this number is expected to increase to 68%. The gradual shift from rural to urban areas, combined with the overall population growth, could add 2.5 billion people to urban areas by 2050. Approximately 90% of this increase will take place in Asia and Africa (UN, 2018).
Food security is one of the most common issues in urban-build environments. Namely, megacities are often poorly equipped and cannot provide stable food sources for sustaining massive populations. Low and middle-income megacities face severe food shortages and poverty due to increased food prices and malnutrition. Moreover, megacities face increased BMIs (body-mass index) due to sedentary lifestyles and shift toward a western diet (Saquib et al., 2016).
The extremely rapid growth of population in megacities causes significant challenges in the accommodation of the citizens, which often leads to unplanned and underserved areas. Homelessness, squatting, and slum areas are described as areas of overcrowded, poor, informal forms of substandard housing. Slums lack access to clean drinking water and sanitary facilities, and residents often don’t have the power over the land they occupy. A report by the UN shows that over 1 billion people live in slums or informal settlements, with 80% attributed to three regions: Eastern and South-Eastern Asia (370 million), sub-Saharan Africa (238 million), and Central and Southern Asia (227 million). It is estimated that by 2030, over 3 billion people will require adequate and affordable housing (UN, 2019).
Air pollution is another serious problem that affects the well-being of all people globally. Statistics show that over 92% of the global population is exposed to higher than recommended concentrations of PM2·5, which is the cause of 3 million premature deaths annually. Megacities are the areas with an extremely high concentration of these substances, and exposure can cause fatal health conditions, including stroke, chronic obstructive pulmonary disease, and lung cancer (WHO, 2016).
Urban-heat-island effect is another negative consequence of living in megacities. This atmospheric phenomenon is characterized by temperatures increasing by 40-50 °F in the city compared to surrounding areas. This vast difference in temperatures leads to higher incidents of dehydration, heatstroke, and cardiovascular and respiratory diseases. The high temperatures encourage increased use of cooling systems that release greenhouse gases into the atmosphere, further aggravating the heat-island effect (Campbell-Lendrum & Corvalán, 2007).
Megacities face a significant challenge in providing clean, running water and sewage removal, essential for disease control and decent living. Additionally, the old colonial infrastructure of some megacities makes dealing with the volume of new materials in sewer systems more complex. The lack of freshwater to meet the standard water demand occurs due to drought, leaking infrastructure, and unsustainable groundwater extraction. It is projected that from one-third of the global urban population in 2016 (933 million), by 2050, approximately one third to nearly half of the global urban population (1.693–2.373 billion people) will be affected by water-scarce urban population, with India projected to be the most severely affected (increase of 153–422 million people) (He et al., 2021).
Traffic in megacities is heavy and odious. With over 10 million residents, traffic in megacities has two problematic features. First, vehicle variation inhibits the movement. It is not uncommon for some megacities with different types of transportation to share the same roads all of which move at different speeds and have different maneuverability. As a result, the flow is blocked, and all traffic participants cannot move effectively. Moreover, as part of unsustainable urban development, traffic increases air pollution and causes health risks associated with harmful pollutants. This ultimately has severe economic and social costs. Despite the fact that many well-developed megacities have made significant progress in reducing air pollution, there are still many challenges in achieving clean and breathable air, among other issues.
Other challenges associated with urban-built environments include overcrowding, a scarcity of open space, inadequate electricity supply due to high demand, high levels of inequality, unemployment, urban violence, etc.
To answer the initial question: are megacities safe for a living?
If they are adequately managed, megacities have fantastic potential to reduce poverty and improve living conditions for millions of people. Still, considering all of the facts listed above, it is safe to conclude that megacities may not always be the best choice. Each individual can make most of the advantages that megacities offer and try to make the planet a better living place. Starting with small choices, we all can make megacities healthier and more tolerable.
Sources:
Campbell-Lendrum, D., Corvalán C (2007) Climate change and developing-country cities: implications for environmental health and equity. Journal of Urban Health, 84, 109-117.
He, C., Liu, Z., Wu, J. et al. (2021). Future global urban water scarcity and potential solutions. Nature Communications 12(4667) . https://doi.org/10.1038/s41467-021-25026-3
Patel, R.B. & Burke, T.F. (2009). Urbanization—An emerging humanitarian disaster. The New England Journal of Medicine, 361, 741-743.
Saquib, J., Saquib, N., Stefanick, M. L., Khanam, M. A., Anand, S., Rahman, M., Chertow, G. M., Barry, M., Ahmed, T., & Cullen, M. R. (2016). Sex differences in obesity, dietary habits, and physical activity among urban middle-class Bangladeshis. International journal of health sciences, 10(3), 363–372.
United Nations. (2019). Sustainable development goals- 2019 report. UN Department of Economic and Social Affairs, Statistics Department. Retrieved from: https://unstats.un.org/sdgs/report/2019/goal-11/.
United Nations. (2018). World urbanization prospects: The 2018 revisions. UN Department of Economic and Social Affairs, Population Department. Retrieved from: https://population.un.org/wup/publications/Files/WUP2018-Report.pdf.
World Health Organization. (2016). Ambient air pollution: a global assessment of exposure and burden of disease. World Health Organization. Retrieved from: https://apps.who.int/iris/handle/10665/250141.