The air quality in many parts of Delhi and the National Capital Region turned severe on Thursday due to calm winds and high humidity.
The overall air quality index in the national capital was 356 at 9:30 am on Thursday.
The AQI at Rohini (411), Anand Vihar (411) and Bawana (404) entered the 'severe' category in the morning.
According to the India Meteorological Department, very low wind speed and high humidity due to a shallow fog in the morning has led to accumulation of pollutants.
A senior IMD scientist said the air quality is expected to remain in the 'severe' category on Thursday and Friday.
According to the government's air quality monitoring and forecasting body, Safar, relief is expected only on Saturday with an increase in wind speed, which will disperse pollutants faster.
Meanwhile, the minimum temperature was recorded at 12.5 degrees Celsius, normal for this time of year. The humidity level recorded at 8.30 am was 89 per cent.
