Improvement in Delhi's Air Quality Post-Diwali
Delhi's air quality index (AQI) showed significant improvement after Diwali, moving out of the 'Very Poor' category for the first time. This improvement is attributed to several key factors:
Contributing Factors to Improved AQI
- Stronger Northwesterly Winds: These winds helped disperse pollutants accumulated in previous days. Typically, they carry smoke from Punjab and Haryana to Delhi, worsening pollution. However, this trend reversed this year.
- Reduced Farm Fires: The number of farm fires in Punjab and Haryana was significantly lower this year due to:
- Recent rain and flooding delaying harvesting.
- Punjab reported 512 fires, over 90% lower than the average since 2020.
- Haryana had 58 incidents, around 95% lower than the average.
- Warmer Conditions:
- The average minimum temperature in Delhi was recorded at 20.6°C, among the warmest since 2015, preventing pollutants from being trapped near the ground.
- Warmer nights improve ventilation, preventing sharp PM2.5 spikes.
- Wind Patterns: Predominant northwesterly winds prevented smoke from Uttar Pradesh from worsening Delhi's air, as Uttar Pradesh reported the highest residue burning events this season.
Statistics and Observations
- Delhi recorded an AQI of 275 ('Poor') on Friday, improving from 305 ('Very Poor') on Thursday.
- The fastest post-Diwali AQI improvement, excluding the pandemic year 2020, with historical data since 2015.
- Stubble burning contribution to Delhi’s pollution is less than 2% as per the Decision Support System (DSS).
Historical Comparisons
- In 2020, AQI improved from 414 on Diwali to 221 in two days.
- In 2017, a similar pattern was observed with AQI improving by over 70 points post-Diwali.