Rain Improves Delhi's Air Quality, But Regional Pollution and Farm Fires Remain Concerns

Delhi's air quality improved to the moderate category following overnight rainfall on Friday, with the Air Quality Index (AQI) dropping to 133 at 4 am. However, the official forecast indicated that pollution levels could return to the poor category from November 1.

The improvement came after the city's AQI remained in the poor category for two consecutive days, recording 222 on Thursday, compared with 229 on Wednesday, according to the Central Pollution Control Board (CPCB).

The Air Quality Early Warning System had forecast moderate air quality for October 30 and 31, followed by a deterioration to the poor category on November 1. Its outlook for the following six days also indicated poor air quality.

The India Meteorological Department (IMD) forecast partly cloudy skies for October 31, followed by mainly clear conditions from November 2. The Safdarjung weather station recorded 61.4 mm of rainfall during the overnight spell.

Weather conditions, particularly wind speed and atmospheric ventilation, are key factors affecting the dispersal of pollutants. The October 29 bulletin reported ventilation indices of 3,000 square metres per second for October 29 and 30, 5,500 for October 31 and 9,000 for November 1. A ventilation index below 6,000, along with average wind speeds below 10 kmph, indicates unfavourable conditions for pollutant dispersion.

Meanwhile, satellite observations detected 205 farm fires across six states on October 28. Punjab recorded 96 incidents, Rajasthan 57, Uttar Pradesh 20, Madhya Pradesh 16, Uttarakhand 10 and Haryana six. No farm-fire incidents were detected in Delhi on that day.

Between September 15 and October 28, a total of 2,472 farm-fire incidents were detected across the six states. Stubble burning contributed 0.9 per cent to Delhi's pollution levels in the reported assessment.

According to the Decision Support System for Air Quality Management in Delhi, transport emissions contributed 16.8 per cent to the city's pollution, making them a significant identified source alongside other urban and regional emissions.