Delhi’s air quality improves, may deteriorate again over Diwali weekend

Showing an improvement from the previous day, Delhi’s air quality dropped to the higher end of the “poor” category on Thursday morning. According to the Central Pollution Control Board data, the air quality index (AQI) reading at 6am stood at 299.

On Wednesday, the average 24-hour AQI reading was 344. The air quality had improved from the “severe” category to the “very poor” zone after six days.

Air quality enters the “very poor” category between 301-400 mark and crosses over to the “severe” zone after exceeding 400. “Severe” air quality can cause health impacts among healthy people and significant distress among those with existing health conditions.

Scientists from the India Meteorological Department (IMD) credited the improvement in air quality to change in wind direction and improved speed.

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Kuldeep Srivastava, head of IMD’s regional weather forecasting centre, said from Tuesday afternoon, the wind direction over Delhi changed from north-westerly — from the direction of agrarian states of Punjab and Haryana bringing in smoke from farm fires — to easterly.

“Because of the wind direction change, we did not have stubble-burning smoke adding to the local sources and deteriorating the air quality on Wednesday. The average wind speed was 12kmph, which was enough to disperse the accumulated pollutants,” Srivastava said.

He said on Thursday, too, the wind direction will remain easterly and there is a possibility of the AQI improving further into the better end of the “very poor” zone. But this respite will be short-lived as on the Diwali weekend (November 14), wind will slow down and change direction back to north-westerly.

Meanwhile, IMD has predicted a misty morning for Thursday with a mainly clear sky during the day. The minimum temperature at around 6.10am was 11.8 degrees Celsius and maximum temperature is predicted to be 29 degrees Celsius.

On Wednesday, the minimum temperature had dropped to 11.4 degrees Celsius, which was three degrees below normal and the maximum temperature was recorded at 29.9 degrees Celsius, which was one degree above normal.

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