Kolkata's air quality turns more toxic than Delhi's

KOLKATA: The city's air turned especially toxic on Tuesday-literally-as the air-quality index hovered around 245, a figure worse than that of Delhi, known to be the worst polluted city, where the figure stood closer to 240. The index is significant given that it represents the measure of the most prominent pollutant, PM2.5, the tiniest particulate matter that goes straight into the lungs, forcing experts to press the health alarm button.


The figures published by the Central Pollution Control Board (CPCB) found that automatic air quality monitoring station at Victoria Memorial Hall (VMH) showed PM2.5 count ranging from 153g/m³ and 313g/m³ (microgram per cubic meter), five times the permissible limit. At Delhi ITO, the AQI was 240, though PM2.5 count went up to 500g/m³ and dropped to 82 g/m³.

Why this sudden spurt of PM2.5 count in the city? "The source apportionment study of pollutant can ascertain their sources definitively. In absence of that, we can only say that massive human activities and influx of huge automobile traffic could be the reasons for such a spurt. Durga idol immersion is still continuing and often involves bursting of fireworks," said a senior scientist at National Environmental Engineering Research Institution (NEERI). "But the reason for the sudden rise in pollutants has to be seriously investigated." Another NEERI scientist pointed out that there was no surety whether stubble burning-burning of crop stubble-was taking place in Bengal or not. "This is the period when stubble burning in Uttar Pradesh pollutes Delhi's air," the scientist said. NEERI is conducting source apportionment study of city's pollutants, which was commissioned by state's pollution control board .

While there is a fluctuation in Delhi's PM2.5 count, Kolkata's count remained static. "It means either the dispersal of pollutants is slow or the constant presence of a source of air pollution, which we are not aware of. This can be the fallout of excessive rise in the number of vehicles in the city. These figures certainly cause worry and warrant drastic action as they are strong enough to announce health emergency for citizens," said auto-emission expert Somendra Mohan Ghosh. According to experts, Kolkata is at a disadvantageous position than Delhi, given that it does not have as many air-quality monitoring stations as in Delhi and Kolkata has the least open space, least road space and dwindling green space. "One of the reasons might be four coal-fired thermal power station nearby," said Sudipto Bhattacharya, an environment scientist.