On Tuesday morning, Delhi’s air quality remained in the “severe” category with an AQI of 427, while the minimum temperature dropped to 5.9°C, two degrees below normal. Out of 35 monitoring stations, 28 recorded “severe” air quality, with some stations surpassing the 450 mark, falling into the “severe plus” category. The remaining seven stations reported air quality in the “very poor” range, according to the Sameer app, which provides real-time data from the Central Pollution Control Board.

An AQI of 400 or higher is considered “severe” and poses risks to both healthy individuals and those with underlying health conditions. The weather department noted that calm winds over the past 24 hours contributed to the poor visibility, which decreased from 800 meters in shallow fog at Palam on Monday to 350 meters in moderate fog at Safdarjung on Tuesday morning. Moderate fog conditions are expected to persist for the next two days due to calm or easterly surface winds.

Humidity levels were reported at 97% at 8:30 am, and temperatures are expected to fluctuate between a maximum of 24°C and a minimum of 5°C.

In response to the hazardous air quality, the Centre’s air quality panel for Delhi-NCR imposed strict Stage 4 curbs under the winter air pollution control plan. These measures include a ban on all construction activities, restrictions on the entry of polluting trucks carrying non-essential goods, and the mandatory shift of school classes, except those for X and XII, to hybrid mode.

Stage 4 curbs were introduced after Delhi’s AQI breached the 350 mark, triggering restrictions under the Graded Response Action Plan (GRAP). The GRAP system categorizes air quality into four stages: Stage I (Poor, AQI 201-300), Stage II (Very Poor, AQI 301-400), Stage III (Severe, AQI 401-450), and Stage IV (Severe Plus, AQI above 450).