Orange alert on weather; curbs back as AQI ‘severe’
Delhi experienced severe smog and low visibility on Sunday, with pollution levels reaching their highest this year. Over 400 flights were delayed, and schools were ordered to start classes after 9am. The weather office predicted further fog and cold temperatures for Monday and Tuesday. The city's air quality index worsened to its worst January level in three years, prompting restrictions on older vehicles and private constructions. Experts warned that the polluted air could cause serious long-term health issues for all residents and particularly vulnerable groups.
Delhi on Sunday was smothered in a thick smog that severely dented visibility and led to over 400 flights being delayed, as pollution levels soared into the dreaded “severe” zone for the first time this year and the minimum temperature fell to its lowest this season.
With schools set to reopen after the winter break on Monday despite the chill, the state government ordered institutions to begin all in-person classes only after 9am.
Little is likely to change on Monday and Tuesday at least, the weather office predicted, warning of yet another spell of impenetrable fog in the morning and more icy temperatures as it issued an orange alert for both days. An orange alert warns people to be prepared for inclement weather and consequent disruptions to everyday life.
The city’s 24-hour average air quality index (AQI) worsened to 447, according to the Central Pollution Control Board’s (CPCB) official 4pm reading, giving Delhi its worst January air in three years. This AQI was also significantly worse than 399 (very poor) on Saturday, a deterioration that pushed the Commission for Air Quality Management (CAQM) to once again clamp down on the use of older vehicles as well as on private constructions across the National Capital Region (NCR).
Such noxious air leaves even healthy people susceptible to serious long-term illnesses, while the outlook is even more bleak for children, the elderly and people with existing illnesses.
Meanwhile, the minimum temperature dipped to 3.5°C, four degrees below normal, keeping the city in the grip of a “cold wave” for a third straight day.
The India Meteorological Department (IMD) declares a “cold wave” when the minimum temperature is 4.5°C or more below normal. The agency can also declare a cold wave in the plains when the minimum reading is below 4°C, as has been the case in Delhi for three days. The temperature was 3.6°C on Saturday and 3.9°C the day before that.
The maximum temperature, however, was 20.6°C, a degree above normal and the highest this year.
Experts said the impact of local pollutants was being exacerbated by still winds and the relentless dip in temperatures, with the smoke mingling with fog and trapping Delhi in the worst smog episode so far in 2024.
This smog played havoc with mass transit operations, with chaos at the airport and across railway stations in the Capital.
For instance, visibility at the Indira Gandhi International (IGI) Airport dipped below 200m at 12.30am and then plunged to zero from 5am to 10am, with over 400 flights being delayed, 10 diverted and 20 cancelled, according to the airport’s website.
And even as the air cleared up around afternoon, the residual impact of the treacherous visibility meant flight operations into and out of the national capital were in disarray throughout the day.
Flightradar24, a portal that tracks flights across the world, said the average delay for aircraft taking off from or landingin Delhi between 7am and 11am was nearly 2.5 hours.
In a statement, IndiGo said: “Due to the low visibility and dense fog conditions across North India, IndiGo flight operations were impacted on Jan 14, 2024. This had a cascading effect on our operations throughout the day. Our staff kept passengers apprised of all delays and cancellations across airports and made every possible effort to facilitate the passengers. We sincerely regret the inconvenience caused to our passengers.”
Train services fared little better.
The Northern Railway reported that 22 trains originating from or heading to the Capital were delayed by at least one hour. These included the Puri-New Delhi Purushottam Express and the Kanpur-New Delhi Shramshakti Express.
Along with the cold and fog on Sunday, came Delhi’s worst air quality since December 23, when the AQI was 450. The hazardous pollution levels also mark the third, and usually final, phase of Delhi’s tryst with torrid winter air.
The city usually goes through three fortnights where the AQI is routinely in the severe zone: The first half of November, the second half of December, and then mid-January. During the first phase, the toxicity is fuelled largely by smoke from farm stubble fires in Punjab. The second and third phases are, however, down largely to local sources of pollution like vehicular and industrial emissions, which are in turn worsened by nearly still winds and dipping temperatures.
In fact, Sunday’s AQI was worse than it was in all of January last year. The last time Delhi breathed worse air in the month was when the AQI touched 460 on January 15, 2021.
The rapid deterioration in air quality prompted CAQM to invoke Stage 3 of the Graded Response Action Plan for the third time this winter. The measures include a ban on the use of BS-3 petrol and BS-4 diesel four-wheelers across Delhi, Gurugram, Faridabad, Ghaziabad and Gautam Budh Nagar, as well as an immediate ban on private constructions in the region.
Grap Stage 3 can be imposed when the AQI is 400 or higher, or expected to touch that range. Stage 4 or “severe plus” measures can be imposed when the AQI crosses 450.
In a statement, the CAQM sub-committee on Grap said the AQI jumped to 458 at 10am on Sunday. However, the panel said it did not impose Stage 4 of the curbs because the AQI was unlikely to stay above 450 for too long.
To be sure, the Stage 3 curbs exempt all work around rail services, Metro, airport, ISBT, national security or defence, projects of national importance and healthcare facilities. Linear projects such as highways, roads, flyovers, over bridges, power transmission and pipeline laying are allowed, in addition to sanitation projects, the order said.
Weather experts said there was a direct correlation between Delhi’s dipping temperatures and rising pollution levels.
Dipankar Saha, former head of CPCB’s air laboratory said the air can worsen this time of the year due to low temperatures, which makes the atmosphere stable. “This prevents dispersal of pollutants and winds also become calm. Add to that large-scale biomass burning and one can see a spike in pollution,” he said.