Kolkata's air quality plunged to hazardous levels shortly after midnight following the widespread bursting of firecrackers during Kali Puja, in violation of government restrictions, IANS reported on Monday.

Source: IANS via The Freedom Press

According to data received at 2 am, the average Air Quality Index (AQI) across Kolkata was 437, a level the West Bengal Pollution Control Board termed 'Hazardous'. By midnight, a dense layer of smog had enveloped large parts of the city, with north Kolkata emerging as the worst-affected region.

437Kolkata average AQI at 2 am — 'Hazardous' (WBPCB)
662AQI at EE Block, Salt Lake — the city's highest reading
293 µg/m³PM2.5 concentration recorded in Kolkata
354 µg/m³PM10 concentration recorded in Kolkata

The situation in Bidhannagar (Salt Lake) deteriorated sharply: the AQI was recorded at 662 in the EE Block, 557 in the DJ Block and 490 in the Bidhannagar Municipal Corporation area. In north Kolkata, Kankurgachi recorded an AQI of 610, Nation Press reported, citing the same pollution data.

Source: Nation Press

The spike came despite restrictions on firecrackers during the festival. Kolkata Police arrested 341 people across the city during Kali Puja raids — 95 for bursting prohibited firecrackers and 246 for disorderly conduct — and seized 131.1 kg of banned firecrackers, according to police data reported by IANS.

Pollution had already been climbing before the festival night: on Sunday, PM2.5 levels reached 350 at Ghusuri in neighbouring Howrah, with environmentalist Somendra Mohan Ghosh attributing the deterioration to rule violations around firecracker use combined with unfavourable early-winter weather, IANS reported.