Delhi's air quality deteriorates to 'very poor' on Diwali as pollution peaks; Grap-2 imposed

As Delhi prepares for Diwali, the city is engulfed in thick smog and the pungent sting of pollution, prompting the Commission for Air Quality Management (CAQM) to implement Stage 2 measures under the Graded Response Action Plan (GRAP). Residents are bracing for another festive season overshadowed by toxic air. The air quality index (AQI) at 4pm was registered at 296 (poor), up from Saturday’s 268, according to the Central Pollution Control Board (CPCB). The number continued to climb post-sunset, crossing the ‘very poor’ mark and reaching 310 by 11pm. Experts predict the situation won’t improve until the week’s end. This marks the first time since February 2 that Delhi’s AQI has entered the ‘very poor’ zone.

The Air Quality Early Warning System (AQEWS) forecasts that Diwali will see AQI levels move into the 'very poor' zone, due to an increase in firecracker emissions. Experts are concerned that these pollutants, combined with local emissions and smoke from stubble fires in Punjab and Haryana, will persist in Delhi’s air throughout the week, as low surface winds hinder dispersal. Stage 2 measures under Grap include tighter controls on diesel generators, restrictions on interstate buses (except EVs, CNG, and BS-VI diesel), and hikes in parking fees to limit private vehicle use.

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The toxic air is the result of multiple factors: stagnant winds, low temperatures, vehicle emissions, and the burning of firecrackers. Experts also point to crop burning in neighboring states as a significant contributor. According to the Decision Support System (DSS), Delhi’s AQI deterioration on Sunday (October 19) was largely due to pollution from surrounding NCR towns, which contributed to 67.89% of the city’s total PM2.5 levels. The remainder came from local sources. “The air quality is expected to remain ‘very poor’ on Monday, Diwali day, and will likely enter the ‘severe’ category by Tuesday due to the increase in firecracker pollution,” the AQEWS said in its report.

The CPCB’s AQI classification runs from ‘good’ (0-50) to ‘severe’ (401-500), with values above 300 marking ‘very poor’ conditions. Data on pollution sources revealed that outside Delhi, the largest contributors to pollution were categorised as ‘unaccounted sources’ (26.7%), with stubble fires accounting for only 2-3%. Without wind to disperse the pollutants, these harmful particles are trapped in the city’s air, worsening the already high levels of local emissions.

This year, Diwali arrived earlier than usual, while the peak of stubble burning tends to occur in mid-November. On Sunday, Punjab reported 67 stubble fires — the highest single-day count for the season — while Haryana saw seven. So far this season, Punjab has registered 308 farm fires, and Haryana has logged 38. Despite the Supreme Court’s permission for only ‘green’ firecrackers, the bursting of both green and traditional firecrackers was widespread in Delhi.