Delhi's air quality index remained in the 'severe' category on Sunday with the maximum temperature settling at 31.5 degrees Celsius, a notch above the season's average.

According to the data shared by the Central Pollution Control Board (CPCB), the air quality index (AQI) was 448 at 7 pm.

No relief is likely on Monday as the India Meteorological Department (IMD) has forecast no rainfall in the city which could improve the AQI by forcing down air pollutants.

According to the IMD, there will be shallow fog on Monday morning and the maximum and minimum temperatures are likely to settle around 31 and 15 degrees Celsius.

The city's air quality index worsened from 415 at 4 pm on Saturday to 463 at 3 pm on Sunday due to unfavourable meteorological conditions and a spike in stubble-burning incidents in neighbouring states.

An AQI between 0-50 is considered "good", 51-100 "satisfactory", 101-200 "moderate", 201-300 "poor", 301-400 "very poor" and 401-500 "severe". An AQI above 500 falls in the "severe plus" category.

Earlier in the day, the Centre ordered a ban on construction work related to linear public projects in Delhi-NCR and the entry of pollution trucks and commercial four-wheelers into the capital.

These measures constitute the final stage, Stage IV, of the Centre's air pollution control plan, which is activated at least three days before the Air Quality Index surpasses the 450 mark in the capital.

Meanwhile, the Delhi Fire Service pressed 12 fire engines to spray water at several locations to curb air pollution.

The Delhi government has announced the closure of all primary schools for two days in an effort to safeguard young children from health-threatening pollution.

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