Delhi’s air quality remained in the ‘severe’ category on Sunday, a day after the Commission for Air Quality Management (CAQM) invoked Stage 4 measures of the Graded Response Action Plan (Grap). The sharp drop in air quality was attributed to calm winds from a prevailing western disturbance and fog.
Delhi’s AQI, which stood at 354 at 4 pm on Friday, rose to 400 at 4 pm on Saturday, before surging further to 434 (severe) at 11 pm. It continued to rise on Sunday, with the average AQI standing at 444 (severe) at 9 am, even as Delhi grappled with dense fog.
Visibility remained zero at Safdarjung for around six hours, between 2:30 am and 8:30 am, while it was down to 100 metres at Palam, the India Meteorological Department (IMD) said. A yellow alert is in place for the city, with isolated dense fog expected to persist in the eastern part of the city till forenoon, it said.
The minimum temperature was logged at 5.3°C — two degrees below normal but 0.9°C higher than Saturday’s minimum.
Data from the Central Pollution Control Board’s Sameer app showed that 37 of the city’s 40 stations were active at 9 am, with 33 in the severe range. This included readings as high as 493 at Anand Vihar and 488 at Rohini.
Forecasts by the Centre’s Air Quality Early Warning System for Delhi (EWS) show AQI may improve marginally ahead and return to ‘very poor’ by Monday.
“Delhi’s air quality is likely to be in the severe category from January 17 till 18. The air quality is likely to be in the ‘very poor’ category from January 19 till 20,” said the EWS on Saturday evening.
In a statement on Saturday, CAQM said, “The AQI of Delhi which was recorded as 400 today (January 17) at 4 pm exhibited a sharp increasing trend and has been recorded 428 at 8 pm, owing to western disturbance, highly unfavourable weather/ meteorological conditions, calm winds and lack of dispersal of pollutants. Keeping in view the prevailing trend of air quality and relevant factors and in an effort to prevent further deterioration of air quality in the region, the CAQM sub-committee on Grap unanimously decides to invoke all actions as envisaged under Stage-IV of the extant Grap with immediate effect, in the entire NCR, as a proactive measure.” It said.
Under Stage 4, entry of BS-IV truck traffic into Delhi is restricted. All construction and demolition work is prohibited, while schools up to Class 10 must shift to hybrid lessons, with only Classes 10 and 12 continuing in-person instruction.
Stage 3 measures of Grap were invoked on Friday, which bans BS-3 petrol and BS-4 four-wheelers in Delhi, Gurugram, Faridabad, Ghaziabad and Gautam Budh Nagar; blanket curbs on private construction and demolition, restrictions on stone crushers and mining operations, and hybrid lessons for schools up to Class 5 in Delhi and neighbouring districts.