Delhi woke up on Sunday to hazardous air quality, marking the second-worst December air day on record. A thick layer of smog shrouded the city, causing breathing difficulties for residents. The overall Air Quality Index (AQI) in Delhi reached a "severe" level, hitting 491 out of 500.
The Central Pollution Control Board (CPCB) data indicated a significant deterioration from Saturday evening's reading of 441. This prompted the Commission for Air Quality Management (CAQM) to invoke Stage IV of the Graded Response Action Plan (GRAP), the highest level of response to combat severe pollution. The air quality of several other cities of North India, including Baghpat, Bahadurgarh, Noida and Greater Noida, was also in the 'severe' category.
Under GRAP Stage IV, authorities have implemented several measures, including restricting the entry of older diesel trucks into Delhi, halting construction activities (including public projects), and implementing hybrid schooling. Residents, particularly children and those with respiratory or heart conditions, are advised to remain indoors and wear masks if venturing outside is necessary.
The CAQM attributed the worsening air quality to high humidity and a change in wind direction, preventing pollutant dispersion and contributing to smog formation. The ventilation index is likely to be 5000 m2/s on December 15, 2025, 5800 m2/s on December 16, 2025, and 5500 m2/s on December 17, 2025, over Delhi. A ventilation index lower than 6000 m2/s with average wind speed less than 10 kmph is unfavorable for dispersion of pollutants.
The India Meteorological Department reported that Safdarjung Airport recorded the lowest visibility of 200 meters at 08:00 hours IST on December 14, 2025, which improved to 400 meters by 08:30 hours IST. Palam Airport experienced similar conditions, with visibility at 350 meters at 08:00 hours IST, improving to 400 meters at 08:30 hours IST.
The "Air Quality Early Warning System for Delhi" forecasts that air quality is likely to remain in the "Very Poor" category from December 15 to December 17, 2025. The outlook for the subsequent six days suggests that the air quality will likely persist in the "Very Poor" category.
The deterioration in air quality has raised concerns among health professionals, who report an increase in pollution-triggered coughs and respiratory ailments. Doctors are advising people to take necessary precautions and avoid prolonged exposure to the polluted air.
While authorities are implementing emergency measures to mitigate the pollution levels, long-term solutions are crucial to address the root causes of air pollution in Delhi. These include controlling vehicular emissions, regulating construction activities, managing industrial pollution, and promoting cleaner fuels.
