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Calcutta tops toxic pollutant rate chart

Foul air

By JAYANTA BASU in Calcutta
  • Published 15.05.18

Calcutta: The city had the highest rate of rise in the level of PM 2.5, an ultra-fine toxic pollutant, among the metros between 2014 and 2016, according to a World Health Organisation report.

The level is almost twice that of the national permissible limit and eight times the WHO prescribed limit.

The report, published a few days ago, found the annual PM 2.5 level in Calcutta was 74 microgram in a cubic metre of air. That's a rise of about 21 per cent compared to the previous WHO report published in 2016.

The national permissible limit is 40 microgram, while that of WHO is 10 microgram.

The global air pollution database of WHO covers 4,300 cities from 108 countries, including more than 130 cities from across India.

The organisation analyses PM 10 (fine particulate) and PM 2.5 (ultra-fine particulate) pollutants.

Between the two, PM 2.5 is considered more toxic because it can reach the crevices of lungs and trigger a host of pulmonary and cardiovascular diseases.

The PM 2.5 level in Delhi - 143 microgram - was higher than that of Calcutta in the 2016 WHO report. Compared with this year's report, the national capital has seen a 17 per cent rise in the level of PM 2.5.

Chennai, too, has seen a rise of 17 per cent while Mumbai has remained almost unchanged.

Bangalore has seen a downward trend, though.

The annual PM 2.5 level in Calcutta is second to Delhi that tops the list of metros, according to this year's WHO report.

"Ultra-fine particulate matter comes mainly from diesel combustion," Anumita Roy Choudhury, air pollution expert from the Centre for Science and Environment, said.

The emission from the huge fleet of old and often ill-maintained commercial vehicles in the city are responsible for the rise in the PM 2.5 level, Roy Choudhury said.

"Calcutta, being the diesel capital of country, needs to quickly replace diesel vehicles with those that run on environment-friendly compressed natural gas."

City-based environmentalist S.M. Ghosh said more than 95 per cent of commercial vehicles in the city run on diesel.

"The state government is not interested in reducing toxic air pollution from vehicles; or else they would have been more proactive in bringing eco-friendly CNG to the city," environment activist Subhas Datta claimed.