Photo by: PRABHASROY / iStock
Global warming particularly affects the health of residents in “dirty” industrial megacities (New York, Delhi), where the concentration of industries, waste and greenhouse gases is higher than in less densely populated areas. We tell you what the dangers of global warming are exacerbated in the “dirty” city.
Urbanisation as a catalyst for global warming
When the topic of global warming was on the agenda in the 1960s, researchers cited megacities as the source of climate problems. The growth and expansion of cities was a striking trend of the twentieth century. Once large cities turned into ‘monsters’ populated by a few million people overnight, and small towns into cities of a few hundred thousand. The main reason for people moving from the countryside to towns and cities was the intensification of agriculture, forcing rural inhabitants to look for new job opportunities. But what attracted settlers to the cities — comfort — turned out to be detrimental to the climate: ventilation systems, heating, air conditioning, petrol-powered transport had a negative impact on the ecological situation.
By the 1980s, there was a discourse that megacities were man-made “hotspots” and the first to cause increased global warming. And it has been shown, using the example of New York City, that the greenhouse effect of cities extends over an area much larger than the city itself. The results are grim. Numerous observations and studies confirm that the average temperature of the Earth has increased by 1-1.5 oC in recent decades. July 2021 was declared by the US National Oceanic and Atmospheric Administration (NOAA) the hottest July on record, when combined land and ocean surface temperatures worldwide were 0.93°C above the twentieth century average of 15.8°C. This is not the first year that the abnormally hot weather has been recorded, and this summer was also a record-breaking summer in many respects. The highest temperatures were recorded in June in Portugal, Spain, France and Germany. The culprits of such cataclysms are above all megacities, despite the fact that all the cities of the world together occupy no more than 2% of the Earth’s surface area.
Photo by: Bernd Lauter / Greenpeace
The ecology of megacities
The main problem environment of a “dirty” megacity is air, and a “dirty” megacity is identified by two main attributes: the city retains unmodernised large industrial plants, and authorities allow outdated models of public and private transport to operate — without controlling emissions (the classic example, of course, is Delhi).
As Mikhail Butusov, an expert in environmental technology and the commercialisation of scientific research, points out, the most obvious environmental problems in megacities include urban air pollution from transport (60-70%) and emissions from urban and suburban enterprises (15-20%), high levels of acoustic noise, water pollution by runoff and deliberate “dumping” of toxic substances from industrial plants, waste treatment plants, landfills and urban waste dumps, and leachates from technogenic urban soils, Thus, megacities create their own special microclimate.
How the environment of a metropolis affects the health of its inhabitants
For many people who moved to cities in the twentieth century on the wave of the ‘great rural exodus’, it was not obvious that their health could now get worse. But if the metropolis is among the ‘dirty’, it is. Environmentalists have been sounding the alarm for years, pointing to the environmental situation in industrial-type megacities and its impact on the planet as a whole as a factor not only in the increasing rate of global warming, but also in the deterioration of human health. In 2018, the UN Office for Disaster Risk Reduction (UNDRR) together with the Centre for Research on the Epidemiology of Disasters (CRED) released the Climate Change Research Report 1998-2017 “Economic Loss, Poverty and Natural Disasters”. It noted that due to climate change, an increasing number of people are suffering from respiratory (including chronic), cardiovascular and other diseases. Diagnoses such as asthma and chronic tonsillitis are on the rise. More and more people, but especially those living in megacities, are affected by various allergies.
- Allergies
Due to many circumstances, primarily related to the lifestyle and living conditions of inhabitants of megacities, people in large cities are more susceptible to various allergies. The most common causes of allergies are plant pollen, foodstuffs and insect bites. The lack of a green environment in cities without a greening strategy means that people living permanently in megacities have little contact with wildlife, rarely go into the woods, and therefore the organism becomes unaccustomed to such constant “irritants” as plant pollen or insect bites.
Scientists have been studying the causes of pollen allergies for decades, and global warming is also an issue here. Already today, the impact of global warming on the extension of the flowering season has been proven: American scientists’ observations of the pollen season in North America from 1990 to 2018 show that in recent years the flowering period has become 20 days longer and that the pollen concentration in the air has increased by 21%.
In addition, an increase in average temperatures during the hot season poses an equally serious risk to the health of citizens — the likelihood of mould and fungi developing indoors. The abnormally hot summers of recent years have revealed the uneven distribution of precipitation over the Earth. For example, some regions have experienced drought, while in others torrential rains have resulted in flooding of cities. In places where there is a lot of rainfall during the heatwave, inhabitants should be particularly careful as dampness can lead to the growth of fungi and mould in houses. These can not only cause allergic reactions, but can also cause serious lung, skin and brain diseases.
- Diseases of the heart and circulatory systems
Air pollution, combined with high temperatures in industrial cities, causes heart disease by making the heart beat faster and leading to a risk of blood clots. The elderly are more likely to have heart attacks, but in recent years diseases such as hypertension, heart attacks and strokes have become considerably “younger”. Arrhythmias have become commonplace. According to the WHO, a third of deaths from stroke, lung cancer and heart disease are linked to air pollution.
- Cancer
If a metropolis, such as a city in South East Asia, regularly has high levels of soot or ‘black carbon’, it leads to lung cancer. Many countries have public service announcements and urban wellness projects to discourage people from smoking. But it has recently been found that concentrations of black carbon in metropolitan air are actually as harmful to the health of residents as smoking.
The incidence of lung cancer has been found to differ between continents and between genders. For example, the incidence of lung adenocarcinoma increases by 14% in women and 9% in men when air pollution levels rise. The same rates were found for squamous cell lung cancer, 14% and 8% respectively. In the Americas, the average increase in incidence was higher than in Europe, at 10% versus 7%.
Photo by: Manish Swarup / AP
- Diabetes mellitus
A study of the impact of polluted urban air on the health of residents has led to disappointing conclusions: even a short stay in a metropolis can cause insulin resistance. The emergence of any type of diabetes can be triggered not only by dirty city air, but also by a number of other causes (stress, genetic predisposition, lifestyle, etc.), but atmospheric pollution is not the least of these..
- Premature birth
High air temperature is a risk factor for preterm birth, which has been proven by several studies. Australian scientists monitored the pregnancy of several thousand women from 2005 to 2014 and concluded that a week before their expected due date, the risk of preterm birth increased for those in the hottest parts of the region. Although other factors such as the presence of diabetes, chronic diseases or smoking during pregnancy further increase the risk of preterm birth. Children born prematurely often suffer a lifetime of various chronic diseases and have weaker immune systems than those born on time.
- Insomnia
Scientist Kelton Minor from the Centre for Social Research at the University of Copenhagen has recently published a paper proving the link between elevated air temperatures and insomnia. In recent years, insomnia has become a growing problem for residents of megacities, but until now it has been linked to stressful situations or brain abnormalities. Minor has monitored the sleep quality of 47 thousand people around the world and has concluded that the higher the temperature, the worse people sleep. He estimated that people were sleeping 45 hours less per year. According to Minor’s findings, even if greenhouse gas emissions in cities could be stabilized, and the rate of global warming thus halted, by the end of the 21st century, people would be losing about 50 hours of sleep a year.
- Mental diseases
In addition to physical health, the megacity’s microclimate also affects the mental state of its inhabitants. It has been shown that when the air temperature rises, the number of cases of stress, mood and anxiety disorders, schizophrenia and substance use disorders increases. Dr Lawrence Wainwright of Oxford University notes that suicide rates increase by 1-2% during heat waves.
But even in the cold season, the psyche of the inhabitants of a metropolis is put to the test every day, such as lack of sleep, exposure to street noise, crowds of people in transport and on the streets, in offices and shops. Psychiatrist Polina Nosova says that digital reality accelerates the rhythm of life: frequent calls, messages, which often need to be answered immediately, which keeps people in a permanent state of stress. The constant stress causes headaches and increases the incidence of anxiety disorders, up to and including severe clinical conditions.
What people living in megacities should do to stay healthy
It is worth paying attention to your physical and mental health. Do not put off going to the doctor if you have any complaints. For people living in cities, doctors of various fields recommend getting outdoors more in urban parks or, if possible, going to the countryside, not eating too much junk food and sticking to a clear daily routine. Floating work schedules or ‘endless’ working hours have a negative effect on both your physical and mental wellbeing. If there are difficult periods, they should be diluted with days of ‘relaxation’ to keep you healthy.
Author: Catherine Lidskaya
Cover photo: Hindustan Times / Imago
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