Some areas recorded AQI levels as high as 474. (File)
Delhi's air quality deteriorated on Sunday with the 24-hour average Air Quality Index (AQI) reaching the 'severe' category at 409 at 4 pm, Central Pollution Control Board (CPCB) data showed.
On Saturday, the AQI was recorded at 370, placing it in the 'very poor' category.
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 capital on Sunday experienced dangerously high levels of PM2.5, the primary pollutant, with 37 out of 39 monitoring stations reporting air quality in the 'severe plus' category.
Some areas recorded AQI levels as high as 474.
PM2.5 particles, which are 2.5 micrometres or smaller in diameter, can penetrate deep into the lungs, posing significant health risks.
Delhi remains under Stage IV of the Graded Response Action Plan (GRAP), which includes stringent anti-pollution measures such as a complete ban on construction activities and restrictions on non-essential polluting trucks entering the city.
Meanwhile, the weather office has forecast cloudy sky with light rain on Monday, with temperatures expected to range from a high of 20 degrees Celcius to a low of 7 degrees Celcius.
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