New Delhi, Jan 8 (IANS): Although the first spell of winter rain over the weekend brought down the pollution levels in the national capital, the Air Quality Index (AQI) is likely to remain in the "very poor" category due to adverse weather conditions, a Met official said on Monday.

"PM 10, which comprises fine particulate matter in the air with a diameter of less than 10 micrometres, have now been washed away and they are now oscillating between 'moderate' and 'poor' zone which was earlier in the 'severe' category. However, PM 2.5 is still in 'very poor' category," Mahesh Palawat, Director at private weather forecasting agency Skymet told IANS.

Delhi's AQI at 4 p.m on Monday was recorded at 333 (very poor), a relief from Saturday's "severe" air quality at 407.

In the National Capital Region (NCR), Faridabad at 346, Ghaziabad at 388, Greater Noida at 380 and Noida at 334 were in the "very poor" zone. However, Gurugram at 252 improved to "poor" air quality after the weekend rainfall.

The authorities have credited "additional rain and sufficient wind speed" behind slight improvement in Delhi-NCR's air quality. However, System of Air Quality and Weather Forecasting And Research (SAFAR), in its daily pollution analysis said that the air quality in Delhi is unlikely to improve further "as weather conditions are unfavourable for dispersion".

"There will be no immediate relief from air pollution and it will remain in the 'very poor' range for at least the next 3 days," Palawat said.

Across 35 areas in Delhi, where pollution is actively monitored, the average concentration of PM 2.5 and PM 10 was 173 and 266 microgrammes per cubic meters, respectively, on Monday at 6 p.m.

Concentration of PM 2.5 and PM 10 across 48 monitoring stations in the NCR stood at 167 and 258, respectively.