The air quality in the national capital remained in the 'very poor' category on Sunday with the minimum temperature settling at 8.7 degrees Celsius and a thin layer of smog affecting visibility.
The air quality index (AQI) is expected to remain in the higher-end of the 'very poor' category on Monday because of cold weather and calm winds allowing accumulation of pollutants.
According to the Centre-run System of Air Quality and Weather Forecasting And Research (SAFAR), the overall AQI of the capital on Sunday was docked at 377.
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.
The levels of PM 2.5-- particulate matter so small that they can enter the lungs and even the bloodstream-- shot up to 220 micrograms per cubic metre, around four times the safe limit of 0-60, by 6 pm.
The AQI, which is expected to deteriorate slightly on Monday will remain within the higher-end of very poor category while the maximum temperature is likely to settle at 24 degrees Celsius.
The calm surface wind condition is likely to continue until Monday. "The air quality over Delhi and NCR is likely to worsen further due to light winds, high humidity and low temperatures over the area," tweeted Skymet Weather, a private forecaster.
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