Delhi experienced its cleanest air on Diwali eve since 2015, with the Air Quality Index (AQI) falling to 224 by 4 pm. The average AQI on Diwali eve was 220, compared to 259 last year. The improved air quality was attributed to consistent winds and unseasonal rains. However, the early warning system predicts that the air quality will deteriorate again on Sunday due to Diwali celebrations. Biomass burning contributed 10% to the overall PM2.5 levels on Saturday, but it is expected to rise to 29% on Sunday. The Delhi government issued an advisory urging people to take precautions and avoid exposure to polluted air.