Delhi recorded its best air quality on Diwali day in eight years on Sunday, with its 24-hour average AQI settling at 218 at 4 pm. However, the bursting of firecrackers till late Sunday night led to a spike in pollution levels amid low temperatures.

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’, 401 and 450 severe’ and above 450 severe plus’. “It’s evident that the spike in pollution levels post Diwali is due to two factors — firecracker bursting and farm fires — with fireworks being the predominant reason in this case,” an official of the Commission for Air Quality Management (CAQM), a statutory body responsible for formulation of strategies to reduce pollution in Delhi-NCR, told PTI.

According to a system developed by the Pune-based Indian Institute of Tropical Meteorology to identify the contribution of different pollution sources, stubble-burning accounted for 12 per cent of the air pollution in the capital on Tuesday. It is likely to be 14 per cent on Wednesday and 6 per cent on Thursday. Delhi recorded an AQI of 312 on Diwali last year, 382 in 2021, 414 in 2020, 337 in 2019, 281 in 2018, 319 in 2017 and 431 in 2016, according to CPCB data.