The 20 most polluted cities in the world
According to the World Health Organization WHO, environmental factors are the major cause of disease and their impacts affect mainly the elderly and children from the poorest.
Air pollution has increased by 8% in the last 5 years. The World Health Organization estimates that pollution is the cause of 3 million premature deaths each year.
Data collected between 2011 and 2015 reveal that 98% of cities with more than 100,000 inhabitants cannot have air quality, according to the WHO standard.
The most polluted city in the world is Onitsha in Nigeria, Africa. Its levels are 30 times higher than recommended by WHO. Second is Peshawar in Pakistan, followed by Zabol in Iran. These cities are in countries which economy is growing rapidly and are located in the Middle East and Asia.
Four of the most polluted cities are in Nigeria, three in Saudi Arabia and three in India.
China has only one city on the list of most polluted: Shijiazhuang.
Among the mega-cities with over 14 million habitants, Delhi and Cairo have the highest levels of urban pollution.
With the worsening of air quality increases the risk of stroke, heart disease, lung cancer and chronic respiratory diseases, including asthma for people living with this level of pollution. The particulate matter originating from dust, smoke and soot penetrate the organism causing the diseases.
The graph shows the cities according to the particulate matter content.
Source: World Economic Forum, Wall Street Journal.