The most heavily polluted cities

Leading the list of WHO's most polluted air is India, followed by cities in Pakistan.

The capital of India is the most polluted city in the world

Last week, the US Embassy in China reported the average density of dust particles equal to or less than 2.5 micrometers (PM2.5) in Beijing at 391µg / m ³ , nearly 40 times higher. the permissible level of the World Health Organization (WHO) is 10µg / m ³ . The Chinese Environmental Protection Agency advises people to stay indoors. According to a study published in the September 17 issue of Nature, air pollution kills about 3.3 million people a year, mostly in urban areas, more than HIV, malaria and influenza combined. In it, according to Guardian, the number of deaths due to air pollution in China is thought to be up to 1.6 million per year, especially in Beijing.

PM2.5 dust is the smallest dust in the atmosphere. They can cause respiratory infections and increase the risk of death of people with lung cancer and heart disease.

Ranking of polluted cities and units of µg / m ³ .(Photo: WHO).

Earlier this year, WHO published the results of data collection from monitoring stations located in 1,622 cities in 91 countries, of which 1/3 were cities with more than 100,000 people, from 2008-2013. Results showed that more and more people living in urban areas are at high risk of pollution.

The average annual pollution level in Beijing is 56 µg / m ³ , three times less than the most polluted city, Delhi with PM2.5 of 153 µg / m ³ . Air pollution causes serious lung damage in about 4.4 million Indian children, which cannot be completely cured. 8 million cars, small diesel generators, thermal power plants are the main sources of pollution here.

However, the above statistics have not fully reflected the truth. According to a WHO spokesman, they did not compare or rank many cities because they could not establish a monitoring system, for political reasons or not enough resources.

According to Gary Fuller, an expert in air pollution at Kings University, England, it is impossible to know where people on Earth are suffering from the highest levels of pollution. And if the air quality is not known, no measures will be taken to improve.

"When comparing pollution levels, we can only rely on measured data, focusing on major cities and developed countries. The first attempts to measure the pollution index by satellite have given see many areas of the world with high population density and high levels of air pollution, " he said.

"Cities that allow the collection and dissemination of air quality information should be praised. This is the first important step to start taking corrective actions , " said a WHO spokesman.

People in the Indian capital walk in the haze in October. (Photo: CNN).

"I think Delhi is noticeable because the air quality is measured. There are many similar cities but no one knows because it has not been tested, like in areas like West Africa or the Middle East , " said Professor Randall. Martin, the leader of the Spartan project, is currently improving the quality of satellite observations to help identify cities at high risk of contamination, said.

A study based on satellite data in August found that 96% of West Africans are living under WHO standards. Man-made smoke, mixed with Sahara desert sand and sea salt is dangerous for the lungs. In early 2015, Nigeria's Lagos capital began to be covered with smoke.

"Although people know that this situation is bad for their health, they still feel it is not dangerous enough and do not put pressure on the government to overcome , " Udeh Chiagozie, a Nigerian youth ambassador in the Topic. Eco-Generation project on the United Nations environment said.

"You can see a lot of cars that don't qualify for traffic on the streets. Generators, industries, especially oil and gas are discharging emissions into the city. It won't be surprising if the situation continued smoke, " Udeh Chiagozie said.

A five-month study in Lagos showed that five of the eight regions had PM2.5 figures that exceeded Delhi's annual index. Some places during that time even had the pollution index nearly double that of the Indian capital.

The map shows the number of cities where air monitoring stations are installed in color.The gray areas are completely free of data.(Photo: WHO).

Another problem is that in some countries, there are areas where pollution levels are much higher than the average. For example, the capital Ulaanbaatar of Mongolia, located in the natural basin with the average WHO pollution index is 68μg / m ³ , although it is bad but not too terrible. However, in 2012, the World Bank measured the pollution index in a neighborhood, with 175,000 households living in traditional tents and burning coal for heating, 200 to 350μ / m ³ , exceeding away from Delhi.

Blind smoke covering Delhi has forced politicians to act. The Indian government is seeking to adopt tougher regulations on car manufacturers and build a loop that does not pass through the city. In China, a recent poll showed that up to 94% of adults believe that the government should pay more attention to pollution issues. The Beijing government has launched a day-by-day, driver-based program. The closure of thermal power plants is also underway.

In addition to PM2.5, another cause of dangerous pollution is equally NO ₂ , discharged from cars . Germany's Volkswagen carmaker recently got into a scandal when cheating NO ₂ emissions test results. In London, England, this gas is more deadly than PM2.5. A non-governmental organization used data on air pollution to sue the British Government for the European Court of Justice, and the British government had to accept a penalty for failing to protect the people at 40. over 43 urban areas.

People in hundreds, and perhaps thousands of other cities, cannot do these things because the government does not install air quality monitoring systems.