Rapid industrialization that swept most parts of Asia in the past few years has helped the economy tremendously. However, this booming industrialization has done a lot of harm to the environment and public health. Here’s a rundown on the top 10 most polluted cities on Earth.
In the countries of Asia, Africa and Europe that are most severely hit, a rapidly growing manufacturing sector and the emerging middle-class have led to lethal air pollution levels that often exceed 10 times the approved safety standards set by the World Health Organization.
Particulate matter: The villain of the piece
One particular type of air pollution seen here is called particulate matter 2.5 micrometers or PM2.5 for short. It is extremely harmful to human health. To give an example, if the diameter of one human hair follicle is about 50-70 micrometers, the particles in air that are 2.5 micrometers or smaller in size are extremely fine and easily inhalable.
Causes of polluted air: Combustion from automobiles, factories or fires generate PM2.5. The air pollution caused by it leads to a series of health problems such as lung infection, asthma, heart attacks and premature deaths.
Other contributors to polluted air include heavy industrialization and a standard of living that’s always on the rise. In some polluted cities, particulate matter is generated due to non-existent sewage systems.
Effects of air pollution: All kinds of pollution have a real effect on the health and safety of people. The WHO states that nine out of every 10 people worldwide breathe polluted air. However, for us, it’s part of everyday life.
The WHO also found that nearly seven million people die of exposure to particulate matter that penetrate their cardiovascular systems and lungs, resulting in heart disease, stroke, lung cancer, pneumonia and chronic obstructive pulmonary diseases. Apart from these medical conditions, poor air quality leads to insomnia, obesity and depression.
Most polluted cities in the world: According to researchers, globally there are 10 cities that are most affected by air pollution. These are:
- Cairo:This city is No. 1 in the 10 most polluted cities worldwide. Here, on a regular day, people inhale air laced with PM2.5, 11.7 times more dangerous than what the WHO stipulates for clean air. It also has the world’s second highest PM10 levels, at 284 ug/m3 on average, nearly 14.2 times more than the safe limit.
Where noise pollution is concerned, this is the No. 3 noisiest city in the world. On average, people are exposed to 85 decibels per day.
Causes: Air pollution in Cairo is so severe that it’s between 10 to 100 times normally accepted standards internationally. The causes of air pollution here include lack of rain, its layout of narrow streets and tall buildings which do not allow for good ventilation and result in trapping pollutants.
Here, PM is also a big reason for air pollution caused by industries, transportation and open-air burning of waste matter. These pollutants cause a series of respiratory diseases and cancer from inhaling these particulates, which include hydrocarbons, soot, dust and heavy metal compounds.
- Delhi: Air pollution in Delhi, India’s capital city, is a huge threat to the health and well-being of its citizens and to its flora and fauna. One of India’s most populated cities, Delhi records one of the country’s highest levels of PM pollution.
The air quality of this city varies from moderate (101-200) level between January to September to hazardous (500+) levels between October to December, due to factors such as lighting of crackers at Diwali, stubble burning and the approaching winter.
Causes: The causes of air pollution in Delhi include overpopulation, reduced water resources, dusty roads, industries, unclean two-stroke and three-stroke engines of automobiles, and the winter season. During winters, the pollutants in the air reach ground level, thereby increasing air pollution.
- Beijing: Various forms of pollution have affected Beijing’s environmental and people’s health drastically. Over the past few decades, China has witnessed stellar economic growth, resulting in the middle class investing in automobiles.
Today, it has more than five million cars on the roads, polluting the air from its engines. Automobile emissions contribute to more than 70% of Beijing’s air pollution levels, with sulphur dioxide, nitrogen dioxide, carbon monoxide and PM reaching PM10 levels.
Causes: Other causes of air pollution in Beijing include population growth, manufacturing output, and the city’s nearby topography and seasonal weather. The huge population that has swelled to 16 million is another factor. Coal-burning factories that throw up smog is another big factor. The consequences of poor air quality on the Chinese are shorter average life spans by five to six years, lower birth rates, increase in cases of lung cancer and higher adult mortality rates due to respiratory diseases.
- Moscow: With the people here leading luxurious lives, there are many more cars on the roads now, causing terrible traffic congestion. This throws up a lot of air pollutants that cause respiratory diseases, among other medical problems. Every day, 3 million cars drive on Moscow’s streets.
Causes: Burning of fossil fuels is the largest contributor to air pollution in this European city, followed by traffic. People are kept longer on the streets, which results in the release of toxic carbon monoxide from automobiles. Plus, it also has 65 big and small heating stations that cause air pollution, and being highly industrialized with over 3000 factories, that cause the air to be polluted.
All these factors go to make Moscow’s air quality about 10 to 20 times the legally acceptable limit.
- Istanbul: Sudden and rapid urbanization, increased use of automobiles and industrialization are the three key reasons for Istanbul’s poor air quality. When people of Turkey moved from rural areas to cities, and work in factories that give off deadly emissions, air quality began to suffer.
Causes: Apart from the above factors, Istanbul’s contributory factors to poor air quality are an improper division of urban land into smaller lots based on the topography and meteorological factors, low quality of fuel used that send CO, NOx, HCs, lead and VOC into the air, lack of green areas and unhygienic and primitive methods of waste disposal. They shoot air pollution levels to three times higher than standard WHO levels.
- Dhaka: The air quality has been dramatically reducing over the past few years, particularly during the winters. In January 2018, Dhaka was on top of the list of most polluted cities worldwide, at an AQI of 556. The air quality begins to drop in October each year when hundreds of brick kilns begin to operate, increasing air pollution and health concerns.
There are five air pollution-related causes of death in Dhaka–lung cancer, stroke, lower respiratory infections, chronic obstructive pulmonary disease and ischemic heart disease.
7) Ulaanbaatar: In the Mongolian capital of Ulaanbaatar, the yearly average PM level is 14 times higher than what the WHO advocates. Its poor air quality is attributed to industrialization, desert dust blowing, open soil surfaces, unpaved roads, ash, lack of greenery, and coal, vehicles, boilers and power plant emissions.
Causes: In the winters, wood and coal burning in homes for heating and cooking add to poor air quality levels shooting up. These cause chronic bronchitis, heart disease and other problems among children and adults.
8) Hong Kong: An extremely polluted island nation, Hong Kong’s air pollution levels were about 12 to 14 times worse than acceptable standards of WHO. Here, poor air quality is translated into low visibility on 20% of occasions.
Causes: Air pollution is manifest here as vehicular pollution. Here, people live and work very close to the major roads, causing toxic gases to pervade the air.
9) Riyadh: Rated as one of the world’s most polluted cities, the root cause here are sandstorms.
Causes: Secondary causes of air pollution in Riyadh comprise air pollutants from traffic and industrial effluents.
10) Los Angeles: America’s most toxic city, Los Angeles ranks No. 10 in air pollution levels worldwide with a rating of 57 PM10.
Causes: Its high car ownership causes a thick layer of smog to top the cityscape. Its mountains also act as a natural trap for pollutants.
Large cities need to take stringent steps to implement long-term and foolproof methods of getting rid of air pollution so that their citizens breathe pure air and freely too.