New Delhi: The Commission for Air Quality Management (CAQM) on Friday rolled back Stage 3 pollution restrictions in Delhi following a brief improvement in air quality driven by strong surface winds. The decision, which allows construction, mining, and other restricted activities to resume, comes even as forecasts indicate that air pollution levels are likely to worsen again by Sunday and remain in the “very poor” category for at least the following week.

This marks the second time in ten days that emergency pollution measures have been lifted shortly after weather-driven improvements, only to be followed by a rapid deterioration in air quality. On December 25, the CAQM had revoked Stage 4 restrictions just hours after the Air Quality Index (AQI) briefly improved to “poor” levels due to favourable winds, only for the AQI to spike again into the “very poor” range within days.

Delhi’s 24-hour average AQI dropped from 380 at 4 pm on Thursday to 236 at the same time on Friday — an improvement of 144 points — largely attributed to surface winds of 15–20 km/h. By 7 pm on Friday, the AQI further improved to 213, prompting the commission to ease Stage 3 measures.

Under Stage 3 of the Graded Response Action Plan (GRAP), private construction, demolition, mining, and allied operations, as well as certain vehicular restrictions on older BS-3 petrol and BS-4 diesel vehicles, are temporarily suspended to curb pollution. With the rollback, these activities have resumed immediately. However, Stage 1 and Stage 2 measures, such as the continued restriction on the entry of interstate buses from NCR states (except electric, CNG, or BS-6 diesel vehicles), remain in force.

Experts have expressed concern over the timing of the withdrawal, warning that the temporary improvement may not be sustained. Sunil Dahiya, founder of the environmental think tank Envirocatalysts, stressed the need for caution. “The entire concept of GRAP should be focused on forecasting. Ideally, we can conditionally revoke GRAP if AQI reaches a certain threshold for a sustained period,” he said. “We have seen multiple instances where forecasts were ignored and GRAP measures were invoked late, leading to avoidable exposure to severe air pollution.”

Dahiya added that the winter meteorological conditions in Delhi make air quality highly volatile. “Due to changing weather, the AQI can deteriorate quickly. Authorities should wait for a sustained period of clean air before lifting restrictions to ensure public health is protected,” he said.

Dipankar Saha, former head of the Central Pollution Control Board’s air laboratory, echoed this view. “Winter extremities and unpredictable weather are more pronounced in the first half of the season. By January, forecasts are more reliable, but even then, waiting longer to remove GRAP restrictions is advisable. Acting based on a day’s improvement can give a false sense of safety,” he said.

CAQM, in its statement justifying the rollback, cited the “prevailing trend of air quality” and the significant improvement in readings. “The AQI of Delhi, which was recorded at 380 yesterday, has significantly improved to 236 today at 4 pm, exhibiting a declining trend,” the commission said on Friday evening.

Despite this temporary relief, the Air Quality Early Warning System (AQEWS) forecast indicated that the improvement would be short-lived. According to AQEWS, air quality in Delhi is expected to remain in the “poor” category through Friday and Saturday but is likely to return to “very poor” from Sunday through Tuesday, suggesting at least eight consecutive days of hazardous air starting Sunday.

Meteorologists attribute the brief respite to strong northwesterly winds, which not only dispersed pollutants but also cleared fog in the early hours. Visibility had fallen to 800 metres in the morning before bright sunshine improved conditions by afternoon. Mahesh Palawat, Vice President of Skymet Weather, explained that these winds are expected to continue for another one to two days, providing a temporary improvement, but no western disturbance is anticipated until the second week of January, meaning sustained relief is unlikely.

The cold wave accompanying the wind shift has caused minimum temperatures in Delhi to fall to between 6 and 8 degrees Celsius over the weekend, from 9.1 degrees on Friday — two degrees above normal. Maximum temperatures hovered around 17.4 degrees Celsius on Friday, slightly above Thursday’s 17.3 degrees but still two degrees below normal. The extreme cold has pushed power demand to above 5,500 MW since Wednesday, with a peak of 5,603 MW recorded on January 1, the third-highest winter peak demand on record. Power distribution companies Tata Power DDL and BSES reported meeting this demand successfully, and peak consumption is expected to approach 6,000 MW over the coming days.

The temporary improvement has also impacted transportation. Delhi airport experienced disruptions, with 66 flights cancelled and over 500 delayed on Friday, mainly due to low visibility at northern airports. The India Meteorological Department (IMD) has issued a yellow alert for moderate to dense fog across Punjab, Haryana, Chandigarh, Uttar Pradesh, Bihar, and Odisha for the next 5–7 days, with similar conditions expected in parts of Jammu, Himachal Pradesh, Uttarakhand, Rajasthan, northern Madhya Pradesh, and northeast India over the next 4–5 days.

Under GRAP protocols, Stage 3 measures are generally triggered when AQI crosses 400, while Stage 4 is imposed if AQI reaches or exceeds 450. The Central Pollution Control Board classifies air quality as “moderate” when AQI is 101–200, “poor” at 201–300, and “very poor” at 301–400. Beyond 400, air quality is termed “severe,” highlighting the health risks posed by high pollution days.

Delhi Environment Minister Manjinder Singh Sirsa attributed the recent improvement to government efforts under the Chief Minister’s leadership, citing persistent ground-level interventions and monitoring. However, public health experts warn that reliance on short-term weather-driven improvements is risky, given the recurring spikes in pollution levels over the past weeks.

Looking ahead, experts emphasise the importance of forecasting and sustained enforcement of GRAP measures. The winter months in Delhi are characterized by low temperatures, stagnant air, and frequent inversion layers that trap pollutants near the surface. Combined with emissions from construction, vehicles, and industrial activity, these conditions can rapidly deteriorate air quality despite temporary interventions.

In summary, the rollback of Stage 3 restrictions on Friday has provided a brief window for construction and industrial activity to resume in Delhi. Yet meteorologists and environmental experts caution that the improvement is likely temporary. Strong winds may have cleared the air for now, but forecasts suggest that very poor air quality will return within days, highlighting the need for continued vigilance, sustained GRAP enforcement, and public awareness about the health risks of winter pollution in the capital.

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