NEW DELHI:  Pollution levels in Delhi increased slightly on Thursday morning with the air quality in the 'very poor' category, officials said.

At 9 am, Delhi's Air Quality Index (AQI) was recorded at 313, compared to a reading of 301 at 9 am on Wednesday, according to the Central Pollution Control Board (CPCB) data.

A thick layer of haze continued to blanket the national capital.

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'.

Of the 38 monitoring stations that recorded air quality data, none reported levels in the severe category, according to the CPCB data.

Meanwhile, the city's minimum temperature settled 0.2 notches below normal at 10.2 degrees Celsius, the India Meteorological Department said.

The IMD has forecast mainly clear sky during the day while the maximum temperature is expected to hover around 26 degrees Celsius.