Key Facts

The Central Pollution Control Board's Air Quality Index has six bands, from Good (0-50) to Severe (401-500); 201-300 is classed Poor. Under the Supreme Court's order and Tamil Nadu's guidelines, crackers could be burst on Deepavali only from 6-7 a.m. and 7-8 p.m. Chennai's average AQI was 213 (Poor) per CPCB data; 1,654 people across Tamil Nadu were injured by firecrackers on Sunday and Monday, with 204 hospitalised. Chennai police booked 237 cases, 148 of them for bursting crackers outside the permitted hours. In Delhi, pollution rose to about 200 times the WHO limit on Diwali night, with several air sensors reporting PM2.5 exceeding 1,000; Delhi's five-day average AQI rose from about 350 before Diwali to 376 afterwards in 2026, compared with 298 to 358 in 2024 and 259 to 315 in 2025.

GK Context

The Air Quality Index, developed by the Central Pollution Control Board (CPCB), aggregates eight pollutants including PM2.5, PM10, NO2, SO2 and CO into a single number for public communication. The Supreme Court had granted a temporary relaxation to the cracker ban ahead of Deepavali 2026, prompting debate over whether 'green crackers' developed by CSIR-NEERI (which only cut emissions by 30-45% under lab conditions) meaningfully reduce pollution. PM2.5 refers to particulate matter smaller than 2.5 micrometres, which can penetrate deep into the lungs and bloodstream.