A day after showing a slight improvement, Delhi's air quality was recorded 'poor' on Wednesday due to unfavourable meteorological conditions, authorities said.

According to the Central Pollution Control Board (CPCB) data, the overall Air Quality Index (AQI) in the city was 246, which is in the 'poor' category.

An AQI between 100 and 200 comes under the 'moderate' category, 201 and 300 is considered 'poor', 301 and 400 'very poor', while that between 401 and 500 is 'severe'.

Twenty nine areas in Delhi recorded 'poor' air quality, while one gauged 'very poor', it said.

In the National Capital Region, Ghaziabad, Faridabad, Gurgaon and Noida recorded 'poor' air quality, the CPCB said.

The overall PM2.5 level (fine particulate matter in the air with a diameter of less than 2.5 micrometers) in Delhi was recorded at 115 while the PM10 level was at 206, the CPCB said.

Authorities said the 'poor' air quality is due to unfavourable meteorological conditions as expected rainfall did not occur.

According to the Centre-run System of Air Quality and Weather Forecasting (SAFAR), "Under the influence of two successive western disturbances, the region is covered by shallow clouds without much rain. Expected rain and wet deposition has not occurred and has led to deterioration of air quality instead of improvement".

The air quality is expected to slightly improve and register in moderate to poor category for Thursday. No further deterioration is expected for next three days, the SAFAR said.

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