The situation got worse as over the years it has turned into a diesel vehicle capital with more vehicles running on diesel which is even dirtier than petrol. | Photo Credit: Thinkstock

Kolkata: After national capital, from past 72 hours the Kolkata's air quality has been deteriorating rapidly, making it country's most polluted metropolitan city. However, for both Delhi and Kolkata most prominent pollutant remains PM2.5.

According to a report in the Times of India, Kolkata has only one-fourth of vehicles that in Delhi. A comparison of the pollution data at the two stations in Kolkata- Rabindra Bharti University(RBU) and Victoria Memorial Hall- with Ashok Vihar, on the Delhi's most polluted area, shows that Kolkata's AQI has been constantly that of the national capital's.

Reportedly, in Delhi, there are 19 automatic stations to record the air quality index whereas, only two are in Kolkata. Environmentalist claimed that the data station RBU on BT Road is the air quality representative for Kolkata as the one at Victoria memorial hall shows the city's cleanest air. Meanwhile, the report mentioned that Kolkata's air quality routinely gets toxic during winter as the temperature traps finer particulate matter closer to ground.

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The Auto emission expert Somendra Mohan told the national daily, that Delhi goes with odd-even experiment but Kolkata has chosen to sit tight and ignore the issue. The situation got worse as over the years it has turned into a diesel vehicle capital with more vehicles running on diesel which is even dirtier than petrol.