Delhi-NCR chokes on ‘severe’ air

NCR cities Ghaziabad, Greater Noida, and Noida face severe air pollution, while Delhi's air quality nears danger. Conditions expected to worsen.

Only three cities in the country were in the throes of “severe” air on Wednesday – Ghaziabad, Greater Noida and Noida – while Delhi hovered just short of the danger zone, missing the threshold by only nine points as a thick, immovable haze settled across the National Capital Region (NCR).

Ghaziabad recorded the worst AQI on the day, with a reading of 422. (Sakib Ali/HT Photo)

Data from the Central Pollution Control Board (CPCB) showed Ghaziabad topping the national pollution charts with an air quality index (AQI) reading of 422, plunging it deep into the “severe” category. Greater Noida followed at 420, with Noida close behind at 409. Delhi’s 4pm reading stood at 392 — “very poor”, but alarmingly close to the next stage.

In fact, all 10 of India’s most polluted cities on Wednesday were part of NCR, underscoring once again how the country’s air pollution battle remains concentrated in the region. After the top three came Hapur, Rohtak, Meerut, Bulandshahr, Baghpat and Bhiwadi.

Gurugram and Faridabad fared marginally better, both registering readings in the “poor” category at 300 and 265 respectively.

The trend, officials and analysts pointed out, is not new. Ghaziabad, Noida and Greater Noida have been the worst-hit towns in the country on at least three days of the first 19 days of November. Of the remaining 13 days, NCR towns topped the list 11 times, CPCB data shows. Between November 1 and 19, Noida recorded three “severe” air days; Greater Noida five; Ghaziabad four; and Delhi three.

Weather experts said low wind speed was at play. “Due to very slow wind speed, pollutants have accumulated and are not getting dispersed. This condition is likely to prevail for the next two to three days. Further, there is no forecast of any western disturbance or rainfall for the next week,” said Mahesh Palawat, vice president for meteorology and climate change at Skymet Weather.

Forecasts by the Centre’s Air Quality Early Warning System (EWS) for Delhi predicted the Capital’s AQI to stay “very poor” on November 20 and 21, but then deteriorate to “severe” on November 22 as meteorological conditions largely remain unfavourable. “The outlook for the subsequent six days from November 23 onwards shows the air quality is likely to be between ‘severe’ and ‘very poor’ category,” said EWS in its daily bulletin.

CPCB classifies air as “good” when the AQI is 0-50, “satisfactory” between 51 and 100, “moderate” between 101 and 200, “poor” between 201 and 300, “very poor” between 301 and 400, and “severe” above 400.

Data from the Decision Support System (DSS) over the past few days indicated that the impact of stubble burning is reducing in the region, due to a change in wind direction. The contribution of stubble burning to Delhi’s PM2.5 was 3.88% on Wednesday. It was 5.43% on Tuesday and 16.13% on Monday.

NCR is already in the grips of curbs under Stage-3 of the Graded Response Action Plan (Grap), with non-essential construction and demolition, alongside private four-wheelers (BS3 petrol and BS4 diesel) banned. Stage-3 curbs were implemented on November 11, when Delhi’s AQI first touched “severe” this year.

Sunil Dahiya, founder and lead analyst at the think-tank Envirocatalysts, said the population load, combined with unfavourable meteorological conditions and geographical factors, makes NCR a pollution hub. “Due to high pollution, there is a high consumption of energy, high vehicular load, waste generation and lots of industries which all generate a high emission load. If winds are low and temperatures dipping, it leads to stagnation. Geographically, the Aravallis and Himalayas also create a corridor for pollution to come to NCR from Punjab and Haryana during stubble burning, which can stretch as far as the Indo-Gangetic plains,” he said.

Delhi’s base weather station at Safdarjung on Wednesday logged a minimum temperature of 10.2°C, which was two degrees below normal. It was 9.6°C on Tuesday. The minimum is likely to oscillate between 10 and 12°C till Friday as conditions marginally become milder. The maximum in Delhi, meanwhile, was 28.3°C, a degree above normal. The maximum is forecast to hover between 26 and 28°C till Friday.