The most polluted cities in the world tend to be those with more than a million people living in them. A report on Air Pollution and Health in cities around the world was published last week by the Health Effects Institute's State of Global Air Initiative (HEI SoGA). This research to find the most polluted cities in the entire World has been done based on the "Fine Particulate Matter" (PM2.5) and 'Nitrogen Dioxide' in the air, which are the two most harmful pollutants in the atmosphere (NO2).
The cities on this list are where air pollution levels are highest, and where many people are exposed to dangerous levels of pollution every day. In some cases, these pollutants are emitted by factories and power plants; in others, they come from cars or trucks that burn fossil fuels like gasoline or diesel fuel or fossil fuel combustion. The world's most polluted cities are a grim reminder of the environmental impact humans have on our planet.
Please note, that most studies showed that PM2.5 should be at or below 12 μg/m3, which will be considered as healthy with less to no risk from exposure in the region. If the level increased to or above 35 μg/m3 during 24 hours, the air is considered unhealthy and toxic which can cause respiratory issues.
Here is the list of most polluted cities in the World:
1) Delhi, India
Capital of India, Delhi has been ranked number 1 in the entire world as the most polluted city Delhi is currently choking on its fumes by having the highest level of Fine Particulate Matter (PM2.5) and that is an average annual exposure of 110 micrograms per cubic metre (µg/m3).
2) Kolkata, India
The capital of the Indian state of West Bengal, Kolkata, is just a little behind Delhi and ranks number 2 on the list of most polluted cities in the whole world with an average annual exposure of 84 µg/m3 of dangerous fine particulate matter (PM2.5).
3) Kano, Nigeria
The second largest city in Nigeria after Lagos, Kano ranks third as the most polluted city around the world, which is a cultural, financial, and entertainment capital of Africa. Having a population of over 4 million, Kano in Nigeria noted as an annual average fine particulate matter (PM2.5) concentration of 83.6 micrograms per cubic metre (µg/m3).
4) Lima, Peru
With over 8 million people living, in South America's culinary capital, Lima ranks fourth on the list. Lima is the capital of Peru and is considered one of the largest cities in South America. Lima is having an average annual exposure of 73.2 micrograms per cubic metre (µg/m3) of PM2.5.
5) Dhaka, Bangladesh
The fifth most polluted city in the world Dhaka, the capital and largest city in Bangladesh has a population of over 18 million people. It recorded an annual average fine particulate matter concentration of 71.4 µg/m3.
6) Jakarta, Indonesia
A very famous tourist destination in Asia, Indonesia's capital Jakarta has recorded an annual average PM2.5 concentration of 67.3 micrograms per cubic metre (µg/m3). As per reports India and Indonesia have observed the most serious increase in fine particulate matter pollution.
There are many more cities followed by Delhi, Kolkata, kano, Lima, Dhaka, and Jakarta in the list of most polluted cities in the world including Lagos, Karachi, Beijing, Accra, Chengdu, Singapore, Abidjan, Mumbai, Bamako, Shanghai, Dushanbe, Tashkent, Kinshasa, and Cairo.