Dense urban metros have long been thought of as an ideal environment for the spread of disease. Is this view oversimplified? A recent article published in Qrius has pointed to research that would indicate that there is more to disease spread than population density.
They note that the construction of many urban metros have been designed with the spread of disease in mind. A prime example of this is the city of London, with its elaborate sewerage system designed to control the spread of water-borne diseases such as cholera that plagued the city for centuries.
Since the beginning of the year, the global media landscape has been dominated by coverage of the COVID-19 pandemic. Urban metros would, in theory, present an ideal opportunity for the disease to spread, with public transport systems and densely packed housing creating situations where it is all but unavoidable for people to come into close contact.
“In a train containing several hundred passengers, a single individual with the flu may sneeze. By sneezing, they may expose multiple individuals around themselves to the influenza virus. These individuals may be infected by the virus, or they may simply harbour it on their clothes and hands, spreading the virus further.
“Each person infected in this event will go about their day as usual, taking the virus and potentially spreading it to their place of work, as well as on any subsequent form of public transport. As these people return from work to suburban areas they take any infections with them. In this manner, any disease outbreak may spread across the entirety of an urban metro within hours.”
However, while many urban metros have seen cases of COVID-19 surge, many others have not. This indicates there may be more to the issue than simply population density.
Research from the writers of the article — Deepti Adlakha, Assistant Professor in Environmental Planning at Queen’s University in Belfast and James F Sallis, Professor of Family Medicine at the University of California, San Diego — has found almost no association between the density of a city and COVID-19 cases and deaths. They cite that “dense megacities such as Hong Kong, Tokyo and Seoul introduced public health actions such as testing, contact tracing, isolation and quarantine in a timely manner, and combined these with physical distancing and mask wearing.”
With this in mind, it appears to be the case that population density is not a leading factor in situations where quarantines are the norm. This may prove that lockdown measures are effective when implemented early and in cities with substantial healthcare infrastructure. However, across Indian cities where healthcare access is unequal, the effects of lockdown procedures may be diminished. Under normal circumstances where entire countries are not locked down, diseases have demonstrably spread faster in urban metros.
The article argues in favour of maintaining dense urban population centres as opposed to spreading into suburban regions. They claim that “over twenty years of research shows higher urban density is related to a lower risk of chronic diseases, such as obesity, diabetes and heart disease. This is largely due to people in higher-density communities being more physically active. Their local areas are more “walkable”, meaning that more often they can walk to nearby shops, schools and other services.”
Such an approach is multifaceted and difficult to quantify in terms of its impact on human health. It is true that where amenities are close to an individual’s home that walking may be the favoured option for transport. This is not the case in suburban housing sprawls in which a car or motor vehicle is all but a necessity to reach markets, schooling and amenities. In such cases where motor vehicles are common, pollution may become an issue.
However, dense urban housing has not freed Indian cities from the catastrophic impact felt through air pollution. India has some of the most densely-populated cities in the world, alongside many of the world’s most polluted cities. Motor vehicles, whether these be cars or bikes, are common to cities as well as rural regions. While it could be argued that investment into public transport infrastructure could improve the situation, this argument falls short when unprecedented situations such as the COVID-19 pandemic occur. Lockdowns have limited the capacity of public transport the world over and many are resorting to single-occupant vehicles to go back to work.
The article instead calls for a rethink of space allocation within cities, citing the need for greater abundance of public walkways and cycle paths. This would have a two-fold effect on occupants, allowing for more effective social distancing, as well as reducing noncommunicable disease risk through increased exercise rates. The primary issue with such a suggestion is the need for mass overhaul of the layouts of many dense urban metros across the world that have been built to occupy as many people as possible within a small space. In India, urban slums may never see such an overhaul.
Equality must be kept in mind with such changes, as infectious diseases such as COVID-19 could find reservoirs of individuals prone to infection in impoverished communities within cities. Should these areas never see improvements to infrastructure, diseases such as COVID, the flu, malaria, tuberculosis and others, may never be removed from India’s metros.