In terms of sulfur dioxide air pollution caused by fossil fuels, İstanbul is the seventh most polluted city in the world, while Ankara ranks 26th.
According to the “World Development Indicators 2012” report, just published by the World Bank, which includes data on pollution in cities around the world, air pollution in Ankara and İstanbul exceeds the maximum acceptable limit set by the World Health Organization (WHO).
The WHO's limit value for air quality is annual mean concentrations of 20 micrograms per cubic meter for particulate matter less than 10 microns in diameter (Ankara is 35 mcg, İstanbul 42 mcg), 40 micrograms for nitrogen dioxide (Ankara 46 mcg, İstanbul was not included in the report), and daily mean concentrations of 20 micrograms per cubic meter for sulfur dioxide (Ankara 55 mcg, İstanbul 120 mcg).
Particularly in terms of sulfur dioxide concentration, which is described as a pollutant resulting from the consumption of coal, diesel fuel and gasoline containing sulfur, Turkey's two largest cities İstanbul and Ankara are placed rather high on the list of most polluted cities: İstanbul is ranked seventh and Ankara 26th out of 97 cities. In the top 10 list of most polluted cities with regard to sulfur dioxide are six cities from China, with Guiyang (424 mcg) and Chongqing (340 mcg) leading the list. Tehran is third (209 mcg), Rio sixth (129 mcg), Moscow ninth (109 mcg) and Mexico City 19th (74 mcg).
Regarding nitrogen dioxide, which is known to cause irritation in the nasal cavity, Ankara ranks 45th out of 86 cities. On the top 10 list, which is also crowded by Chinese cities, Milan comes first with 248 micrograms, Guangzhou second with 136 mcg, Mexico City third with 130 mcg, Sofia and Beijing fourth and fifth with 122 mcg, Sydney 12th with 81 mcg, while New York and London rank 15th and 16th with 79 and 77 micrograms, respectively.
The other pollutant in the report is particulate matter with a diameter less than 10 microns. The report gives the rate of such matter based on measurements carried out in 1990 and 2009. Although both İstanbul and Ankara have decreased the amount of particulate matter in the air by half within the 19-year period, in 2009 İstanbul still holds 39th place, while Ankara is 48th out of 111 cities on the list. The top 10 are dominated by cities from China and India. Delhi comes first with 118 micrograms per cubic meter, Xi'an second with 115 mcg, Cairo third with 112 mcg, Calcutta sixth with 101 mcg, Buenos Aires seventh with 92, Beijing 14th with 73, and Santiago and Shanghai 24th and 25th, respectively, with 60 micrograms. Among the luckiest cities on the list are Stockholm (with 9 mcg), Paris (10 mcg), and Auckland, Vancouver and Melbourne, all with 11 micrograms.
After noting that pollutant concentrations are sensitive to local conditions, and even in the same city different levels of pollution may be registered, the report cautions that the data should be treated as a general indicator of air quality. According to the WHO, air pollution is a major risk to health, and it's possible to reduce the cases of respiratory infections, heart disease and lung cancer by reducing air pollution levels. Chronic exposure to particulate matter contributes to the risk of developing cardiovascular and respiratory diseases, as well as lung cancer.
Long-term exposure to nitrogen dioxide, major sources of which are combustion processes such as heating, power generation and engines in vehicles and ships, causes the symptoms of bronchitis to increase in asthmatic children. It is also associated with reduced lung function growth. As to the effects of sulfur dioxide, overexposure may cause problems in the respiratory system and lungs, and eye irritation. When combined with water, sulfur dioxide forms sulfuric acid, the main component of acid rain.
According to the WHO findings, air pollution in cities is estimated to cause 1.3 million deaths a year globally. The WHO Air Quality Guidelines demonstrates that by reducing particulate matter pollution from 70 to 20 micrograms per cubic meter, it is possible to decrease air quality-related deaths by around 15 percent.