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Additional firecracker emissions on Diwali day could push the air quality into the ‘severe’ category on Monday and the day after, according to a forecast issued by SAFAR (System of Air Quality and Weather Forecasting and Research).
Three factors that are crucial in determining air quality around this time of the year are likely to “act together” resulting in deterioration of air quality — wind speed and direction that favours transport of stubble burning smoke from the northwest, calm local weather conditions that trap pollutants, and firecrackers, if any.
The contribution of stubble burning-related emissions in Delhi is likely to increase from October 24 onwards, the forecast indicates. The forecast has been issued considering current fire counts and trend recorded over past years, as per Gufran Beig, founder project director, SAFAR.
According to the forecast, “even a smaller increase in additional local emissions due to firecrackers is likely to have a significant deterioration impact during October 24-25 and may put AQI in the severe category on October 25 if stubble fire is not controlled.”
Since stubble burning fire counts have remained low so far and transport level winds have been slow and unfavourable for carrying the smoke into Delhi, contribution of crop-residue burning to Delhi’s air has remained low — below 5% — so far this season. However, the fire count in Punjab has been on the rise.
On Saturday, Punjab recorded the highest single-day fire count of 582 so far this harvest season, according to the Indian Agricultural Research Institute’s monitoring system based on NASA satellite data.
Transport level winds from Punjab, Haryana and Western Uttar Pradesh towards Delhi are set to pick up from October 24 onwards, as per the forecast, and the contribution of stubble burning to PM 2.5 levels in Delhi could rise from around 5% on October 23 to 8% on October 24, and 16% to 18% on October 25.
To add to this, calm conditions and little ventilation are expected over the next three days, making dispersion of pollutants difficult. Stable conditions trap pollutants near the surface.
Even if there are no firecracker emissions, the city’s PM 2.5 level could be in the ‘very poor’ category on Diwali day, the forecast says. However, if weather conditions bring firecracker-related emissions from “surrounding regions of Delhi” and there are zero firecracker emissions in Delhi, the AQI could still hit the lower end of the ‘severe’ category on October 25 with around 15% to 18% of contribution from stubble burning.
If there are firecracker emissions in Delhi as well similar to what was seen last year, the AQI is set to be in the ‘severe’ category on Diwali day and the day after, according to the forecast.
Beig added that the forecast has been issued without factoring in any measures that may be imposed to “put a break” on the way that pollution levels are rising. The forecast also mentions that the impact of control measures has not been factored in and that if fire counts reduce, AQI may improve.
On Saturday, Delhi’s AQI was 265, in the ‘poor’ category.
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