AQI improves; forecast for Diwali still grim
Delhi’s pollution levels may rise to the “very poor” category by Diwali on October 31, and further deteriorate into the “severe” zone.
Strong, southeasterly surface winds on Monday led to a significant improvement in Delhi’s pollution levels, data from the Central Pollution Control Board (CPCB) showed, with the air quality dropping to the “poor” category, a day after rising to the “very poor” zone.
However, the relief is likely to be short-lived, with predictions for Delhi to be hit by a double-whammy around Diwali — the wind direction is likely to change to northwesterly, bringing pollutants from farm fires in northern states. This, combined with firecrackers that are likely to be burst on Diwali, will likely lead to the Capital’s air quality deteriorate to the “severe” zone, the Centre’s Early Warning System (EWS) for Delhi has forecast.
On Monday, Delhi’s 24-hour average air quality index (AQI) reading was 304 (very poor) at 4 pm according to CPCB. This further improved to 299 (poor) by 6pm and further to 288 at 10pm, the data showed. In comparison, the average AQI on Sunday at 4 pm was 356 (very poor).
The average AQI on Monday was calculated on the basis of data from 36 out of Delhi’s 40 ambient air quality monitoring stations. Of these, 21 stations were in the ‘very poor’ range, with the worst impacted station Burari (365), followed by Mundka (348).
Mahesh Palawat, vice president at Skymet meteorology said Delhi’s improvement in AQI is down to southeasterly winds at speeds of 10-18 kmph.
“We saw the wind direction change from northwesterly on October 26 and the contribution of stubble burning went down. Local wind speed, which was 10-18 kmph during the day on Sunday and even Monday, is likely to start dipping from Tuesday onwards,” he said.
Data from the Centre’s Decision Support System (DSS) showed the contribution of stubble burning to Delhi’s PM 2.5 concentration was around 3.34% on Sunday. This was down from around 5.5% on Saturday and 14.6% on Friday. The highest single day contribution of farm fires to Delhi’s PM 2.5 load this season has been 15.97% on October 23.
EWS predicted that Delhi’s pollution levels may rise to the “very poor” category by Diwali on October 31, and further deteriorate into the “severe” zone if firecrackers are burst on that day.
“Delhi’s air quality is likely to be in the ‘very poor’ category from October 29 till October 31. The air quality may reach the ‘severe’ category on October 31 in case of additional emissions from firecrackers and stubble fire,” said EWS on Monday, adding meteorological conditions were unfavourable for effective dispersion of pollutants.
The wind direction is also forecast to change by Diwali, which may further contribute to the bad air quality on the day. “By Thursday, we expect a change in wind direction back to northwesterly, which may increase stubble contribution again,” Palawat said.
Separately, the Commission for Air Quality Management (CAQM) in a statement on Monday said it has issued directions to the governments of National Capital Region (NCR) states and to Delhi, calling for measures specified under the Graded Response Action Plan (Grap) to be intensified, and for firecrackers and their respective regulations to be strictly enforced.
“NCR states and Delhi government were directed to further augment the capacity and intensify the use of mechanised road sweeping and sprinkling of water, identify more high-rise buildings for the installation of anti-smog guns, and deploy nodal officers specifically to address air pollution from hotspots, as per the action plan. The strict implementation of orders of the Supreme Court and related orders on firecrackers was highlighted, in view that festivals this year coincide with the peak paddy harvesting season in northern India,” said CAQM.
Meanwhile, the Capital recorded another balmy October day, with the maximum temperature on Monday at 34.4 degrees Celsius (°C) — three notches higher than the normal for this time of the year, and slightly above the 34.2°C a day earlier, according to India Meteorological Department (IMD) data.
The minimum on Monday was 20.4°C, four degrees above normal and a smidge above the 20.1°C a day earlier.
The mercury is unlikely to drop in the coming days — IMD has forecast the maximum to hover around 34-35°C till the end of the month, while the minimum is unlikely to dip below 20°C in the coming days.