A haze engulfed Calcutta on Saturday as the air quality deteriorated with the AQI ranging from poor to very poor.
Besides burning of crop residues in the neighbouring districts, celebrations with firecrackers ahead of Kali Puja aggravated the situation, officials said.
At 4 pm, the Air Quality Index (AQI) at Ballygunge, Victoria Memorial and Bidhan Nagar was 300 (very poor). In Rabindra Sarobar, it was 243 (poor), while Jadavpur and Fort William recorded 268 (poor).
An AQI between zero and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.
Environmentalist SM Ghosh said the pollution level shot up after sunset as celebrations with fireworks began in different parts of the city.
"If the pollution level aggravates, it will cause respiratory problems," he said.
"We recommend sprinkling water on plants in the evening to reduce the effect of pollution," he added.
Illegal fireworks will certainly cause a greater degree of air pollution over the next two days, said Naba Dutta, the general secretary of NGO Sabuj Manch.
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