Delhi woke up to a blanket of moderate fog on Tuesday, as the city continued to grapple with severe air pollution. The air quality index (AQI) stood at 426 at 9 am, classified as ‘severe,’ prompting the reimposition of restrictions under stages 3 and 4 of the Graded Response Action Plan (GRAP). This comes a day after the AQI crossed into the ‘severe’ category, marking an alarming rise from 379 (very poor) at 4 pm on Monday to 401 by 10 pm.
The last time Delhi experienced such severe air quality was on November 23, when the AQI touched 412. The deteriorating air quality has led to the activation of emergency measures by the Commission for Air Quality Management (CAQM). Initially, Stage 3 restrictions were enforced, but with the AQI continuing to worsen, Stage 4 was invoked late Monday night for the entire National Capital Region (NCR).
Under Stage 3 of GRAP, several restrictions have been implemented, including a ban on BS-3 petrol and BS-4 diesel four-wheelers in Delhi, Gurugram, Faridabad, Ghaziabad, and Gautam Budh Nagar. Stone crushers, mining activities, and certain other industries have also been restricted. Furthermore, Delhi-registered diesel Medium Goods Vehicles (MGVs) must comply with BS-4 standards, and only essential vehicles are exempt from the restrictions.
Stage 4, which brings stricter measures, has led to a complete halt in all construction activities in NCR, affecting both public and private projects. In addition, truck entry into Delhi has been restricted, except for those that run on CNG, LNG, or electricity, or meet BS-4 diesel standards, with exceptions for essential and emergency services.
The impact of the severe air quality is also being felt in schools, where all classes except for those in grades 10 and 12 have been shifted to a “hybrid” mode of learning. This measure is part of efforts to reduce exposure to the hazardous air for students.
The sharp deterioration in Delhi’s air quality is largely attributed to the drop in wind speed, which has slowed the dispersion of pollutants. Meteorological experts note that strong northwesterly winds had been prevailing till December 15, but these winds have significantly weakened in the past 24 hours due to an approaching western disturbance. Wind speeds, which had been between 10-15 km/hr, have now fallen below 5 km/hr, further trapping pollutants in the atmosphere, especially during the night when winds are calm. The intrusion of moisture has also contributed to the trapping of pollutants.
Visibility in Delhi has taken a hit due to the fog, with the India Meteorological Department (IMD) reporting a reduction from 800 meters (shallow fog) on Monday to 350 meters (moderate fog) on Tuesday morning at Safdarjung. Officials predict that visibility will remain below 500 meters during the early hours through Thursday.
As the wind speeds are expected to pick up again from Wednesday, experts hope for an improvement in the AQI, although the situation remains critical for now.
The rising pollution levels and reduced visibility have raised concerns about public health and safety, with authorities continuing to monitor the air quality closely and urging residents to take necessary precautions.
Sources By Agencies
