NEW DELHI: Delhi's air quality turned 'severe' on Sunday, with the 24-hour average AQI recorded at 409, officials said.
The national capital's Air Quality Index (AQI) was recorded in the 'very poor' category with a reading of 370 on Saturday.
An AQI between zero and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.
The maximum temperature was recorded three notches above normal at 24.1 degrees Celsius.
The minimum temperature had settled a notch below normal at 7.3 degrees Celsius, the India Meteorological Department (IMD) said.
The city experienced fog in the morning, with humidity levels ranging between 68 per cent and 97 per cent, it said.
The IMD has forecast cloudy skies with light rain for Monday.
The maximum and minimum temperatures are expected to settle at 20 and 7 degrees Celsius, respectively.
GRAP 4 restrictions remain in place as air quality in Delhi-NCR continues to deteriorate. On December 16, the Centre's air quality panel imposed GRAP IV curbs as part of the winter air pollution control plan, which includes a ban on all construction activities.
Stage 4 restrictions also ban the entry of polluting trucks carrying non-essential goods into Delhi and mandate the shift of school classes, except for grades X and XII, to hybrid mode.
Under the revised GRAP schedule, classes for students in grades VI-IX and XI in Delhi, Gurugram, Faridabad, Ghaziabad, and Gautam Buddh Nagar must be conducted in hybrid mode (physical and online) during Stage 4.
Classes up to grade V are required to switch to hybrid mode under Stage 3. Parents and students can opt for online education where available.
(With inputs from PTI)