Recent Research by Eco Experts on global levels of pollution for air, light and noise, ranks the most and least toxic cities in the world. Cairo tops the worst ten lists according to their unique criteria, followed by Delhi, Beijing, Moscow, Istanbul, Guangzhou, Shanghai, Buenos Aires, and Paris. Los Angeles is the only American city in the top ten lists and comes in tenth. On the other hand, Zurich is the cleanest city in the world.

Pollution, of all kinds, can have a real impact on the health and well-being of everyday people. According to the WHO, 9 out of 10 people around the world breathe polluted air. We seem to just accept it now as part of life.

Furthermore, WHO estimates that about 7 million people die every year from exposure to fine particles in polluted air that penetrate deep into the lungs and cardiovascular system, causing diseases like stroke, heart disease, lung cancer, chronic obstructive pulmonary diseases and respiratory infections, including pneumonia.

We have always known that high pollution levels can have devastating impacts on both physical and mental well-being, leading to obesity, insomnia and depression. What is unique about the Eco Experts’ report is that it includes not just air pollution but artificial light pollution and noise pollution as well.

These last two have dramatic effects on sleep and circadian rhythms, which in turn have effects on mental and physical well-being in ways we did not understand until recently.

This Eco Experts’ report names Cairo as the most polluted city in the world, again according to their unusual criteria, scoring in the bottom three for air pollution (284 PM10), light pollution (14,900 μcd/m2) and noise pollution (1.7).

Chinese cities dominate the most polluted 10 - Beijing is 3rd, Guangzhou is 6th and Shanghai is 7th. Beijing scored badly for toxic air (73 PM2.5), the third highest air pollution score in the study and over 7 times the WHO safe level.

Los Angeles is the most toxic city in America, the tenth in the world, with the 7th highest PM10 air pollution levels at 57 PM10, and a light pollution score of 10,900 μcd/m2. Chicago and New York ranked in 21st and 26th place, respectively.

On the other side, Zurich, the largest city in Switzerland, is the cleanest city in the world, scoring in the bottom five across all pollution types, with light pollution levels of only 2,170 μcd/m2 and the lowest noise pollution of all cities studied, probably because the Swiss have a tradition of ‘Quiet Hours’, usually between 10 PM and 6 AM, noon to 1 PM and all day Sundays.

 Source

https://www.forbes.com/sites/jamesconca/2018/08/23/the-ten-most-polluted-cities-on-earth/#7b104f2a18cc