New Delhi, Jan 7 (IANS): Following a rain spell, Delhi's air quality improved significantly on Friday and settled under the 'moderate' category, with the Air Quality Index (AQI) recorded at 149, according to the System of Air Quality and Weather Forecasting And Research (SAFAR) estimates.

The level of both PM 2.5 and PM 10 have settled in the moderate 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'; 401 and 500 'severe'.

"The air quality is likely to improve further and remain in the moderate category on January 8. The air quality is likely to remain in the moderate to a poor category on January 9," said the air quality and weather bulletin.,

However, the air quality is likely to remain largely in the poor category afterwards.

"The predominant surface wind is likely to be coming from Southeast direction of Delhi having wind speed 08-15 kmph with a generally cloudy sky, very light rain/drizzle on Friday, which will be coming from Southeast direction of Delhi with wind speed 12-18 kmph with a generally cloudy sky, very light rain to moderate rain/ thundershowers accompanied with gusty winds (speed 30-40 kmph) on January 8," the bulletin said.

The predominant surface wind is likely to be coming from the northwest direction of Delhi with wind speed 05-08 kmph with a partly cloudy sky, the possibility of very light rain/drizzle, shallow fog in the morning on January 9, it added.