5 days Ago
Delhi was enveloped under the blanket of moderate fog on Tuesday as the air quality remained ‘severe’, a day after restrictions under stages 3 and 4 of the Graded Response Action Plan (GRAP) were reimposed. Delhi’s air quality index (AQI) stood at 426 (severe) at 9am. The average AQI was 379 (very poor) at 4pm on Monday, but by 10pm, it had entered ‘severe’, touching 401.
Delhi’s last severe air day was November 23, when the AQI was 412 on the day. While initially, stage-3 was announced during the day on Monday, a steady increase in AQI prompted Commission for Air Quality Management (CAQM) to hold an emergency meeting late in the evening, with stage-4 also subsequently invoked with immediate effect in NCR. Also Read: Break from cold wave in Delhi, but not for long: IMD GRAP Stage 3 brings with it a ban on BS-3 petrol and BS-4 diesel four-wheelers in Delhi, Gurugram, Faridabad, Ghaziabad, and Gautam Budh Nagar, along with restrictions on the use of stone crushers, mining and associated activities.
It also restricts Delhi-registered diesel operated Medium Goods Vehicles (MGVs) to BS-4 standards or below, in Delhi, along with BS-4 and lower diesel operated light commercial vehicles registered outside Delhi from plying in Delhi. The only exception being vehicles carrying essential commodities or providing essential services. Further, as part of stages 3 and 4 of GRAP , all construction in NCR — both private and public projects are now halted.
Other vehicular restrictions in stage-4 include stopping entry of trucks into Delhi (except CNG, LNG, electric, BS-4 diesel or those involved in essential or emergency services) and a ban plying of BS-4 and lower Heavy Goods Vehicles (HGVs), unless they are involved in essential or emergency services. Further all classes in schools barring classes 10 and 12 in Delhi and its neighbouring districts will also have to shift to “hybrid” lessons, said the CAQM in a notification issued on Monday. Delhi’s average AQI has shot up rapidly in the last 24 hours, primarily due to a drop in wind speed, slowing dispersion of pollutants, meteorological experts said.
“We had strong surface northwesterly winds prevailing in Delhi-NCR till December 15, however, a drop was seen in the last 24 hours due to an approaching western disturbance. Winds which were between 10-15 km/hr till Sunday are now averaging less than 5 km/hr. They are also becoming calm at night-time, further trapping local pollutants,” said Mahesh Palawat, vice president at Skymet, stating intrusion of moisture also helps trap pollutants.
Palawat said winds should continue to remain slow on Tuesday, before picking up once again from Wednesday. “We may thus see an improvement in AQI from Wednesday,” he said. The India Meteorological Department (IMD) said mainly calm winds were prevailing in the region.
“Calm winds have brought down the minimum visibility of Delhi from 800m (shallow fog) over Palam on Monday to 350m (moderate fog) on Tuesday over Safdarjung,” said an IMD official, stating visibility should remain below 500m in the early hours till Thursday. Delhi’s minimum temperature meanwhile stood at 5.9°C, which was two degrees below normal.
It was at a season low of 4.5°C on Monday..
