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Delhi not ‘most polluted’, but dirty air fouls many cities

Early morning smog engulfing Delhi NCR region - a scene at Delhi Noida border, in New Delhi. Photo: V. Sudershan

Early morning smog engulfing Delhi NCR region - a scene at Delhi Noida border, in New Delhi. Photo: V. Sudershan   | Photo Credit: V_Sudershan

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Gwalior, Allahabad, Patna, Raipur in WHO’s global top 10 list

Delhi is no longer the most polluted city in the world, the latest air quality report from the World Health Organization (WHO) says.



The national capital which earned notoriety for the state of its environment now stands 11th among 3,000 cities in 103 countries in terms of fine particulate matter or PM 2.5. The ‘Global Urban Ambient Air Pollution Database (update 2016)’ released by WHO on Thursday placed the capital in 25th place based on bigger particulate or PM 10 levels. Particulate matter affects everyone but causes harm faster to children and senior citizens.



‘Positive trend’



Although Delhi improved its ranking, four Indian cities are among the world’s ten most polluted. Ten out of the top 20 are also in the country. The data are for 2013, but the Delhi government was quick to put out a statement exulting in a “definitive positive trend” in the city.



In 2014, Delhi was ranked the most polluted globally in terms of PM 2.5, for which the WHO had monitored 1,600 cities. Delhi’s place as the most polluted is taken by Zabol, in Iran. Gwalior and Allahabad, meanwhile, come a close second and third in terms of PM 2.5, while Patna and Raipur are ranked 6th and 7th.



WHO used data from government and research organisations to prepare the database. It is based on ground measurements of annual mean concentrations of particulate matter (PM 10 and PM 2.5) and “aims at representing an average for the city or town as a whole, rather than for individual stations. Years of measurements range from 2010 to 2015, unless the latest available data was older,” the report said.



PM 2.5 refers to atmospheric particulates with a diameter less than 2.5 micrometers. Exposure to fine particulates is linked to premature death from heart and lung disease. They trigger or worsen asthma, heart attack, bronchitis and other respiratory problems.



The WHO states that as urban air quality declines, the risk of stroke, heart disease, lung cancer, and chronic and acute respiratory diseases, including asthma increases.



More than 7 million premature deaths occur every year due to air pollution, and 3 million of these are due to outdoor air quality.



Maria Neira, head of public health, environmental and social determinants of health, WHO, praised the Centre for developing a national plan to deal with the problem when others have been unable to.



“Probably some of the worst cities that are the most polluted ones in the world are not included in our list, just because they are so bad that they do not even have a good system of monitoring of air quality, so it’s unfair to compare or give a rank,” she said.



Common causes of air pollution include diesel-fuelled vehicles, heavy construction activities, temperature control in large buildings and use of coal or diesel generators.

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Printable version | Apr 25, 2018 12:22:52 AM | http://www.thehindu.com/news/cities/Delhi/delhi-is-not-the-most-polluted-city-in-the-world-who/article8589775.ece