The Commission for Air Quality Management (CAQM) has convened a meeting at 1:30pm on Friday to discuss invoking Stage 4 of the Graded Response Action Plan (Grap) for enhanced anti-pollution curbs amid worsening air quality, which tipped into the severe category for the first time this season on Thursday.
The average Air Quality Index (AQI) of Delhi was 475 at 11am, worse than it was at its peak last year (450) and 2022 (471). In 2020, it was 477, and in 2019, 494. Two stations (Mundka and Punjabi Bagh) recorded an AQI of 499.
The rapid deterioration in air quality and fog plunged visibility to 600 metres at Safdarjung and 500 metres at Palam.
The pollution levels worsened on Thursday after Delhi recorded a 24-hour average AQI of 392 just short of the severe mark at 4pm. The average AQI barrelled up to 427 just before midnight.
Grap Stage 4 is invoked when the AQI crosses the 450 mark. The measures under it include a ban on the entry of trucks into Delhi as well as on construction activities on highways and roads, etc.
Measures under Grap’s Stage 3 include a ban on the use of older vehicles. They are supposed to kick in when the AQI is likely to touch the severe category. The authorities drew flak for reacting to the spike in pollution rather than pre-empting it.
CAQM ordered Delhi and the neighbouring states to restrict BS-III petrol and BS-IV diesel four-wheelers in Delhi, Gurugram, Faridabad, Ghaziabad, and Gautam Buddha Nagar. But no notifications asking for enforcement were issued until late on Thursday.
The worsening pollution levels also prompted the closure of schools for students in Classes 5 and below for two days on Friday and Saturday.
Greater Noida was on Thursday the worst off across the National Capital Region (NCR) with an AQI of 402 (severe) at 4pm. The AQIs in Gurugram and Ghaziabad were in the poor category at 297 and 286.
Delhi’s AQI was 362 (very poor) on Wednesday before calm surface-level winds exacerbated the impact of local sources of pollution. Delhi’s bad air was largely because of pollutants within the city even as farm fires in Punjab and Haryana continued to tick up and drive up PM2.5 levels.
A northwesterly current that the Capital was experiencing on Thursday brings smoke from farm fires into Delhi from Punjab and Haryana, which recorded 1,543 farm fires on Wednesday. On Tuesday, the two states recorded 1,556 farm fires. They were nearly double the 827 blazes that satellites tracked a week ago. The two states recorded 1,978 fires on November 1 last year, 2,477 in 2021, and 3,500 in 2020. Year-on-year data on stubble fires is not always comparable due to differences in cropping and harvest patterns.
PM2.5, a byproduct of combustion sources, was the prominent pollutant in Delhi’s air on Thursday. Delhi’s PM2.5 levels peaked at 242.7µg/m³ at 10pm. The PM10 peaked at 412µg/m³ also at 10pm. Both PM2.5 and PM10 were over four times India’s safe standards. India’s pollution norms are less stringent than global thresholds. Indian safe standard for PM2.5 is 60µg/m³. The World Health Organization’s (WHO) standard is a fourth of that at 15 µg/m³.
The air quality was likely to get worse as farm fires were nowhere near their peak. The temperatures were also set to plummet further in the run-up to Diwali none days later.