Sunlight, wind speed pull Delhi’s air out of ‘emergency’ category

New Delhi

New Delhi

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Delhi breathed relatively easier on Saturday, with the air quality recovering slightly from the ‘severe’ category and the city getting a respite from the dense blanket of smoke and haze that has enveloped it for the past four days.

The double layer of cloud cover and smoke gave way to bright sunshine and strong winds flushed out pollutants that had stagnated over the past few days.

With the air quality finally improving to ‘very poor’ after remaining in the ‘emergency’ zone for more than 86 hours, the Central Pollution Control Board (CPCB)-led taskforce on Saturday reviewed pollution levels and lifted the ban on operation of polluting industries.

While air quality is expected to improve further on Sunday, it may dip again slightly on November 18.

“Industries that run on coal in NCR towns of Faridabad, Gurugram, Ghaziabad, Noida, Greater Noida, Sonepat and Bahadurgarh may now commence operations subject to taking adequate control measures and compliance to prescribed environmental norms,” read the minutes of the CBCB-led taskforce meeting on Saturday.

However, hot mix plants and stone crushers shall remain closed till further orders. Besides, the pollution watchdog directed the pollution control boards of Delhi and NCR towns to remain “on alert” and ensure surveillance and necessary action on polluting activities.

The Supreme Court in its November 4 order had directed a blanket ban on construction activities in Delhi-NCR till further orders.

The curbs had come into force under the ‘severe and ‘severe plus’ categories of the Supreme Court-enforced Graded Response Action Plan (GRAP) to deal with different levels of pollution throughout the year. Under ‘severe plus’ or ‘emergency’ category, other measures such as odd-even road rationing policy and shutting down of schools come into effect depending on a decision from government agencies.

The Air Quality Index (AQI), as per the CPCB’s 4 pm bulletin on Saturday was 357 (very poor), as against 458 (severe) on Friday.

“Strong surface winds helped improve air quality. It is likely to strengthen further till November 18, when AQI may fall in the low end of ‘very poor’ or towards the higher side of ‘poor’ category,” VK Soni, senior scientist, India Meteorological Department (IMD) informed the taskforce, as per the minutes.

The AQI was in ‘severe’ zone even till around 8am on Saturday.

The levels of ultra-fine particulate matter with diameter less than 2.5 microns, had remained above ‘emergency’ mark of 300ug/m3 since Tuesday 12pm. The levels started dropping below the emergency mark after 5am on Saturday when it was recorded as 294. It dropped significantly only by 5pm when it was 182ug/m3, as per CPCB.

PM 10 (coarse particles) concentration too inched close to the emergency mark of 500ug/m3 till Friday midnight and started falling only in the morning.

If either particulate matter remains above emergency mark for 48 hours or more, air quality is considered in ‘severe plus’. Prolonged exposure to PM is known to cause respiratory distress. PM 2.5, in particular, can enter the blood stream and lungs, causing harm to internal organs.

On Saturday, the fresh contribution from crop stubble burning in neighbouring Haryana and Punjab to overall pollution in Delhi was 5%, which was less than 10% on Friday, as per the System of Air Quality and Weather Forecasting and Research (SAFAR), the pollution forecasting wing of the union Ministry of Earth Sciences.

“The high surface winds in Delhi are forecasted to continue for the next two days and will consistently improve the air quality. The effect from stubble burning will reduce further to not more than 2% on account of good winds on Sunday. Pollution levels could again spike from November 20,” said a senior SAFAR scientist.

According to scientists at the India Meteorological Department, the cloud cover reduced on Saturday and good sunlight and strong winds dispelled the layer of pollutants.

“Wind speed on Saturday was 24-25 kmph from the north and north-westerly direction. On Sunday we are expecting wind speed between 25-30 kmph and on November 18 it might go down slightly to 20-25 kmph. Also, sufficient sunlight was available for 7-8 hours with high intensity today, which is much better in comparison to the diffused sunlight of 1-2 hours between November 12-14. On Friday, it was slightly better at 4-5 hours,” said Kuldeep Srivastava, head, regional weather forecasting centre (RWFC), IMD.

The increase in wind speed is expected to disperse air pollutants and improve air quality significantly, he added.

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