4 of most polluted cities in India

WHO study places B'luru at 140, Delhi no longer on top of the list

Four of the world’s top 5 polluted cities are in India, says the World Health Organisation’s (WHO) latest urban air pollution database, with Delhi being divested of the “world’s most polluted city” tag.

Bengaluru is placed 140th among 2,976 cities worldwide, and 38th among Indian cities. Though the national capital continues to be highly polluted, it has ceded the pole position to the Iranian town of Zabol, where the PM-2.5 level stands at a whopping 217 micrograms per cubic metre.

But Zabol is followed by four Indian cities – Gwalior (170), Allahabad (170), Patna (149) and Raipur (144) – where the PM-2.5 level is extraordinarily high. The PM-2.5 level marks the concentration of very fine dust particles with 2.5 micron diameter in air.

Permissible limit

For comparison, the WHO permissible limit for PM-2.5 is 25 microgram per day.Bengaluru was placed 149th in the last WHO report released in 2014. In the latest report, Davangere and Hassan in Karnataka also find a place in the list of 122 Indian cities.

The annual mean PM-10 is 118 micrograms for Bengaluru (WHO limit is 50 micrograms for 24 hours) and PM-2.5 is 63 micrograms. PM-10 in Davangere is 75 micrograms (PM-2.5 is 40 micrograms). In Hassan, PM-10 is 36 micrograms and PM-2.5 is 19 micrograms.

The ranking of the 122 Indian cities is as per WHO report of 2012 along with Central Pollution Control Board (CPCB) data of 2014, said Lesley Onyon, Regional Advisor, Occupational and Environmental Health, WHO Regional Office for South-East Asia.

She said pollution in Bengaluru is not as high as in Delhi or Gwalior. Each city has a slightly different make of pollution, the local conditions and seasons play a vital role.

The database compiles air pollution data from 2,976 cities from all over the world. Out of the 122 Indian cities, 54 have very high levels of air pollution. Pollution is measured in terms of PM-2.5 and PM-10 level, which demonstrate the thickness of pollution blanket covering a habitat.

“We have overwhelming evidence of the impact of air pollution on stroke, heart disease, lung cancer, and chronic and acute respiratory diseases. Globally, in 2012, air pollution in urban areas is estimated to have caused 3.7 million deaths with more than one-third reported from the Southeast Asia Region,” said Poonam Khetrapal Singh, regional director of WHO South-East Asia region that covers India.
When it comes to the PM-10 level, the top five polluted Indian cities are Gwalior, Allahabad, Raipur, Delhi and Ludhiana.

In the past two years, the database – now covering 103 countries – has nearly doubled, with more cities measuring air pollution levels and recognising the associated health impacts. According to the latest database, 98% of cities in low and middle-income countries with more than 1,00,000 inhabitants do not adhere to the WHO air quality guidelines.