Air quality turns ‘moderate’, Delhi breathes easiest since October 15

NEW DELHI: Delhi’s air quality improved remarkably and turned ‘moderate’ with a clean sky and cool north-westerly winds making it a soothing Tuesday.

The air quality index (AQI), on a scale of 0 to 500, was 177 as against 218 a day earlier and 306 on Sunday. This is the cleanest air the city has breathed since October 15 when the AQI was 186. This is also the cleanest December day in at least two years, as none of the days in December 2021 saw moderate air quality. On December 14, 2020, the AQI was 160.

According to pollution monitoring agencies, the air quality may improve further due to persistent winds and clear sky, which support ventilation of pollutants.

“The relatively stronger winds and better ventilation conditions are likely to prevail from December 13 to 15. The air quality is likely to improve further and remain in the moderate category on December 14. It may deteriorate marginally but remain in the same category on December 15. It will reach the poor category on December 16,” stated the air quality early warning system.

The meteorological conditions are likely to become highly unfavourable for dispersion of pollutants from December 17, it added.

On Tuesday, the wind speed was in the range of 12-16 kmph. It may be around 12 kmph on Wednesday. The ventilation index is likely to be 7,500 sqm per second on Wednesday, 5,400 on Thursday and 3,500 on Friday over Delhi. The ventilation index lower than 6,000 with average wind speed less than 10 kmph is unfavourable for dispersion of pollutants, according to the early warning system.

Meanwhile, the maximum temperature on Tuesday hovered around 26 degrees Celsius, four degrees above normal, while the minimum temperature was recorded at 8.9 degrees Celsius, the season’s average.

According to a weather scientist, the minimum temperature is likely to fall December 15 onwards due to the impact of a western disturbance.

“The minimum temperature currently remains around 9 degrees Celsius. A slight drop is likely due to cooler north-westerly winds. Though not much decline is expected on Wednesday, after December 15, the minimum temperature is likely to drop,” said VK Soni, senior scientist at India Meteorological Department.