DELHI'S WINTER SMOG AND THE CLOUD-SEEDING EXPERIMENT

In late October 2025, New Delhi awakened under a milky blanket of smog and fog, its skyline all but invisible.

- TDG NETWORK

Bar chart of AQI values at several Delhi monitoring stations on the morning of 30 Oct 2025 (8 AM). Colours indicate the AQI category, and dotted lines mark the thresholds for the “very poor” (301) and “severe” (401) categories.

After days in the “poor” category, the city’s Air Quality Index (AQI) plunged into the “very poor” range on October 30, with the overall AQI around 350-360 across the capital. Central Pollution Control Board (CPCB) monitors showed 32 of 38 stations in “very poor” (AQI 301-400), and several key localities in the “severe” range (AQI401-500)-Vivek Vihar at 415 AQI, Anand Vihar 409, Wazirpur 394. Across the region, visibility fell below 1km in the morning, confirming that weak winds and dense fog had trapped pollutants in the cold, stagnant air. By all measures, Delhi was among the worst-polluted cities in the world that day.

This post-Diwali smog crisis - nearly ten days after the October 20 festival - was a familiar winter menace. Each year the capital's pollution peaks as biomass burning in nearby states, vehicle emissions, coal use and firecrackers add toxic PM2.5 and NO₂ to the chill air. By late October, Stage-II of the city's Graded Response Action Plan (GRAP) had already been invoked: car usage curbs, doubled parking fees in municipal areas, restrictions on construction and non-compliant trucks. Still, on Oct 30, even these measures offered little relief. Thick haze engulfed the city overnight and pollutants became trapped by calm winds. The result was an AQI spike of 80 points since two days earlier. Public health alarms sounded: hospitals saw surges in breathing difficulties and eye complaints, while doctors warned of an impending emergency.