Kolkata’s air quality has deteriorated sharply this winter, with the city recording AQI levels worse than Delhi on several occasions this December — a rare and alarming trend for the eastern metropolis.
Last week, residents in Kolkata breathed air more toxic than that in the national capital, with the index entering the ‘very poor’ and ‘severe’ categories. On December 10, the Air Quality Index at Victoria Memorial was 347 (very poor), compared to Delhi’s 299 (poor). The following day, the AQI at the same location climbed to 351, while Delhi recorded 306.
The rise has triggered concern among environmentalists and public health experts, who warn that the city may continue to “gasp for breath” unless air quality improves. Winter conditions, including low wind speed and temperature inversion, trap pollutants closer to the ground.
Chairman of the West Bengal Pollution Control Board, Dr Kalyan Rudra, told The Indian Express, “In Victoria, the pollution level is high now due to the metro work. But a rise in AQI is due to several factors like if there is less wind speed, low temperature and meteorological factors.”
Environmental scientist Dr Swati Nandi Chakraborty said, “This is a climate disaster. The climate conditions are deteriorating mainly due to greenhouse. We are seeing that the temperatures and humidity are fluctuating. The carbon in the air is high and it has been noticed that at night, there is not much dew. All this is causing a rise in pollution. The lower the temperature, the higher the pollution level.”
Environmentalist and activist Naba Dutta said, “There are many reasons for this rise in pollution. There is construction going on all over the city and rules are flouted. All the things which need to be done, like planting trees and having water bodies, are not being done. We have seen that in the name of development, private individuals and the government have cut trees and several water bodies have been illegally filled.”
He also said that large-scale Metro construction has contributed “significantly.” “In order to reduce the pollution, there is spraying of water on the roads (as a measure), but that is hardly done.”
According to him, the “increase in population has led to a surge in waste generation, with inadequate recycling or reduction efforts”. He also alleged that while the city has 11 AQI monitoring machines, some are “not functioning” and some are positioned in “greener areas”, which may not show the state in localised pollution hotspots.
AQI levels between 301 and 400 — the category Kolkata entered this month — reduce lung capacity, inflame airways and can trigger frequent asthma attacks. Anything above 400 becomes severe and harmful to all.
In recent days, as temperatures marginally increased, AQI levels improved to around 100 in locations such as Fort William, Ballygunge and Jadavpur. But the Victoria Memorial zone continued to hover around 220, which environmentalists attribute to ongoing construction activity and heavy traffic congestion in the area.