On season’s first ‘cold day’, AQI close to ‘severe’, dull grey pall over Delhi

With this, for the first time this winter, Delhi met the ‘cold day’ criteria, according to the India Meteorological Department (IMD). The IMD declares a ‘cold day’ when the minimum temperature is 10 degrees Celsius or less in the plains and 0 degree Celsius or less in the hills, and the maximum temperature is between 4.5 degrees Celsius and 6.4 degrees Celsius less than the normal.

The lowest maximum temperature recorded in December 2024 was 14.6 degrees Celsius, 15.9 degrees in 2023, and 15.6 degrees in 2022, according to IMD data.

Visibility was severely affected with the sky remaining shrouded in dull grey. The visibility recorded at Safdarjung airport at 8.30 am was 200 m and at Palam airport 350 m. It later improved to 400 m in Safdarjung and 600 m in Palam at 12.30 pm.

The IMD noted that cold day conditions prevailed at a few places in Delhi, accompanied by moderate to dense fog. Minimum temperatures fell by 1-3 degrees Celsius over the past 24 hours and were in the range of 6-8 degrees Celsius. Day temperatures remained markedly below normal at several locations, hovering between 16-17 degrees Celsius, it added.

According to Indian Institute of Tropical Meteorology’s Decision Support System, at 17.57%, the transport sector continued to be the largest local contributor to PM2.5 pollution in Delhi. Delhi and peripheral industries contributed around 8%, while residential emissions stood at 4.34%.

Pollution inflow from neighbouring regions also remained significant. Jhajjar again emerged as the highest external contributor, accounting for 16.51% of Delhi’s PM2.5 load. This was followed by Rohtak (4.3%), Bhiwani (4.2%), and Gurgaon (around 2%).