Respite over? Delhi’s AQI on brink of ‘severe’ again
The forecast shows no significant change in meteorological conditions, with calm winds and no rain expected in the coming days.
The Capital’s air quality returned to the deep red zone on Thursday to end November on a sooty note as thick, grey haze shrouded Delhi’s sky, and calm winds negated the washout effect that helped drive out pollutants after rains at the beginning of the week.
Delhi’s 24-hour average air quality index (AQI) spiked rapidly on Thursday and touched the “severe” category, recording a grim 398 (very poor) at 4pm — an unswerving 100-point rise from Wednesday’s 290 at the same time. This further deteriorated to 401 (severe) at 7pm on Thursday, according to the Central Pollution Control Board.
The acute deterioration in air quality came a day after Delhi environment minister Gopal Rai directed to implement stages 1 and 2 of the Graded Response Action Plan (Grap) strictly. Stages 3 and 4 were withdrawn on account of brief but improved air quality, despite forecasts by the early warning system (EWS) that it was likely to remain “very poor” in the coming days.
The deterioration on Thursday prompted the Commission for Air Quality Management (CAQM) in NCR to call an emergency meeting. However, stage 3 measures of Grap were not invoked as the body has decided to “watch the situation for a day” before taking a decision. The body previously said that stages 3 and 4 of Grap were “disruptive in nature of restrictions impacting a large number of stakeholders and public.”
Forecasts showed there would be no significant change in meteorological conditions over the next three days making the beginning of December a far cry from breathable. The wind speeds would touch only around 5-6km/hour during the day and predominantly stay calm at night.
CPCB data at the end of the month showed that November recorded 18 “near-severe” or “severe” air days — the highest number of such days since the 13 days in November 2021 and 11 in November 2016.
Taking into account CPCB’s daily readings at 4pm, the Capital has recorded nine “severe” air days in November when the AQI was over 400, but it has also recorded another nine days when the AQI was on the brink of “near-severe” — between 390 and 400.
“The CAQM sub-committee noted that as per the air quality forecasts by IMD (India Meteorological Department) and the Indian Institute of Tropical Meteorology (IITM), Delhi’s average AQI will start showing improvement from Thursday itself. Therefore, after reviewing the overall air quality scenario and its relevant aspects, it was decided by the sub-committee unanimously to watch the situation for a day or more, before taking a decision on invoking stringent actions under Stage-3 of GRAP,” CAQM said in a statement.
CAQM also said a relatively low average wind speed of 4km/hour was recorded in Delhi in November, with long spells where winds were calm. It said an average wind speed of 10km/hour was desirable for effective dispersion of pollutants and attributed the month’s poor air quality to a slightly delayed paddy harvesting season and frequent spells of inversion — when low temperatures trap pollutants close to the surface.
“Paddy farm fires from Punjab and Haryana while being much lower than in the last three years, owing to highly unfavourable climatic and meteorological conditions as above, contributed significantly to the PM2.5 load in Delhi-NCR. The peak of the paddy harvesting activity in Punjab and Haryana coincided with the festival of Deepawali this year, further aggravating the air pollution scenario in Delhi-NCR,” CAQM said.
Even though clouds covered the city on Thursday, rain was recorded at only one station — Mungeshpur in northwest Delhi recorded 3mm of rainfall, IMD said.
“The western disturbance will gradually pull away now. After Tuesday, we are mainly seeing calm winds, with it picking up to 5-6 km/hr briefly. Cloudiness has persisted during day-time too, due to this western disturbance, which has not allowed the daytime temperature to rise either” said Kuldeep Srivastava, scientist at IMD.
Meanwhile, Delhi’s maximum temperature was recorded at 25.1 degrees Celsius (°C) — one degree below normal. The minimum was 12.6°C — two degrees above normal.
IMD said the wind direction will likely remain easterly on Friday, before changing to northwesterly on Saturday. Delhi’s minimum will remain around 13°C on Friday, before dropping to 12°C on Saturday and 11°C on Sunday. Delhi’s maximum will meanwhile hover around 25°C in the next three days.