Strong winds in the capital brought the air quality index from 378 (very poor) on Tuesday to 282 (poor) on Wednesday — a difference of 96 points.
Delhi has been battling very poor air quality since November 23. The air quality also led to a Test match between Sri Lanka and India being suspended for a few minutes on Monday, with many players complaining of breathlessness. According to experts, the two episodes of severely polluted air were because of meteorological factors beyond Delhi.
“Any depression in any part of India and neighbouring areas restricts wind movement, disrupts wind pattern, increase or decrease in humidity, mixing height, temperature profile, etc affect air quality. In November, there was depression in coastal areas of Bay of Bengal, this time there was problem in the Arabian Sea. These factors restricted free air north or northwest to south or southeast. In both the cases, Delhi-NCR experienced very poor wind speed or calm conditions resulting in accumulation of dust at the local level and practically no dispersion of pollutants due to which we had prolonged ‘very poor’ AQI,” said Dipankar Saha, who heads the air quality laboratory at the CPCB.
“Now, the entire Indian sky is clear and wind is flowing from north to south with a speed of 4.5m/s, which has resulted dispersion of pollutants leading to improvement in air quality after a long pause,” Saha added.
According to the SAFAR forecast, the air quality might reach the very poor category again on Thursday and Friday as a dip in wind speed is expected. Mist is expected in the morning but will be followed by clear sky towards the afternoon. The maximum temperature is expected to be around 24 degrees Celsius.
Wind speed had not gone over 3 metres per second since November 23, which has led to accumulation of pollutants.