Delhi breathed cleaner air this Jan over last, more in store
As per the Central Pollution Control Board (CPCB) data, the average air quality index (AQI) value this January was 285.67, in the ‘poor’ category, a notch better than last January’s average of 327.70—‘very poor’ category.Updated: Feb 14, 2020 03:05 IST
Unusually high number of western disturbances (WDs), which led to windy days and good rainfall over northwest India, helped Delhi record significantly better air quality in January this year compared to the same period in 2019. Experts said that even though the average AQI till mid-February for both years was ‘poor’, conditions are likely to improve Saturday onward.
As per the Central Pollution Control Board (CPCB) data, the average air quality index (AQI) value this January was 285.67, in the ‘poor’ category, a notch better than last January’s average of 327.70—‘very poor’ category. Favourable meteorology also ensured the national capital experienced just two days of ‘severe’ air this January, five days fewer than last January, the CPCB data shows.
While the average AQI values till February 13 for both the years were in ‘poor’ category—281.6 in 2020 and 286.2 in 2019—meteorologists said air quality is likely to improve significantly in the next two to three days due to high wind speed of up to 30kmph.
On Thursday, too, the AQI was ‘poor’ (241).
“I think pollutants couldn’t accumulate mainly because of favourable weather conditions, which is reflected in the AQI. There were seven western disturbances in January, with at least three strong ones which brought rainfall to the northern plains. These wind systems created strong surface winds that helped in dispersal of pollutants. We also received moderate rainfall, especially around January 16, which too would have helped wash away the pollutants,” said Kuldeep Shrivastava, head of the regional weather forecasting centre.
According to Shrivastava, between January 1 and February 13, Haryana, Chandigarh and Delhi zones received 20% excess rain, and the average wind speed in January, in Delhi, was around 15 kmph, which often went up to 25kmph.
Shrivastava added, “In January 2019, the region experienced five western disturbances, which is above average, but the average wind speed was around 12 kmph,” he added.
“When a WD moves away, the wind direction is north-westerly and results in strong surface winds. If there are back-to-back WDs then wind speed is consistently good,” head of the national weather forecasting centre K Sathi Devi explained, adding that usually, WDs affect weather in the western Himalayan region, but this year they caused precipitation even in the plains.
Meanwhile, CPCB officials also attributed better air quality to policy action like Graded Response Action Plan and its on-ground enforcement. “There are two factors—meteorology and enforcement. Higher number of WDs may have aided dispersal. As per our data, there were no ‘severe’ air days in January 2017, 3 in 2018 and 7 in 2019,” said VK Shukla, head of CPCB’s air quality management division.
According to the models forecast by the Air Quality Early Warning System of the Union ministry of earth sciences, air quality will continue to be in the ‘poor’ category on February 14 but improve to moderate on February 15.
For February, four WDs were forecast by February 14; two hit on February 2 and 6. A WD was lying over west Iran and neighbouring areas and another WD was lying over north Pakistan and adjoining Jammu and Kashmir on Thursday.
“Fairly widespread light to moderate rain or snow is very likely over Jammu & Kashmir, Gilgit-Baltistan & Muzaffarabad and isolated light rain or snow likely over Himachal Pradesh during next 24 hours. Isolated light rain or snow is also very likely over Arunachal Pradesh, Assam, Meghalaya, Nagaland, Manipur and Sikkim during February 14 to 17” according to IMD’s Thursday bulletin. Strong surface winds (speed reaching 20-30 kmph) will affect the entire northwestern region according to the bulletin.