From 60 to 261 in two days: Delhi's smog season opens on schedule

On Friday, after heavy rain and strong winds, Delhi recorded an air quality index of 60, “satisfactory”¹. On Saturday it was 117. On Sunday the official 24-hour average reached 261, “poor”, and it kept climbing through the evening: 272 at 6pm, 287 at 10pm, 290 at 11pm local time¹. It is the worst reading since 17 April, the Times of India notes, and the highest in 198 days². Of the city’s 57 reporting stations, 22 were in the “very poor” band; Jahangirpuri was worst at 378, not far below the “severe” line at 401².

The weather did not cause the smoke. It stopped carrying it away. Delhi’s minimum on Sunday was 18 degrees, 1.9 below the seasonal average, and a Hindustan Times reading of the Safdarjung weather balloon found the day’s pollution mixed only 1,100 metres up, in winds averaging 10 km/h; on a typical early-November afternoon it is about 1,300 metres and 13 km/h¹. A lower lid and a slower breeze: the same emissions, less room.

The model view tells the same story in fine particles. Open-Meteo’s CAMS series for a central Delhi grid point shows PM2.5 near 80 µg/m³ early last week, a dip to 28.8 on Friday after the rain, and a return to 81.0 by Sunday³. Desk arithmetic: the rain bought roughly two days.

Where it comes from matters more than the number. The government’s decision-support system put stubble burning at 18.57% of Delhi’s pollution on Sunday, up from 5.33% on Saturday; transport inside the city was 16.4%^1,2. One analyst told the HT that two-thirds of the fine particles come from outside the city¹. A city cannot legislate its neighbours’ fields, which is why the answer is a calendar, not a speech.

That calendar started on Sunday. Non-Delhi vehicles below BS-VI standards are barred, dust-generating outdoor construction is banned until 31 January, parking charges are doubled until 28 February, and offices are capped at 50% attendance². It brought queues at the borders and grumbling online². Rules that inconvenience people on the first day are usually the ones that are actually enforced.