New Delhi, Jan 23 : Delhi-NCR's air quality that improved due to intermittent rainfall will again deteriorate between "poor" to "very poor" category in the coming days, according to the System of Air Quality and Weather Forecasting And Research (SAFAR).
"The air quality had improved due to rain. However, it will deteriorate after the rain stops and settle between the lower end of the 'very poor' and the higher end of the 'poor' categories," Gufran Beig, Project Director, SAFAR, said, adding that under no condition will the air quality will enter the "severe" 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", then 401 and between 500 is considered "severe".
After a day of receiving intermittent rain, Delhi's air quality on Sunday improved significantly as its Air Quality Index (AQI) stood at 169, according to SAFAR estimates.
The level of both PM 2.5 and PM 10 pollutants stood in the "moderate" categories, even post noon.
Delhi's AQI has been recorded in the very poor category since the second week of January. It had improved and settled in the "moderate" category at the beginning of the month as the national capital received light rain.
SAFAR, in its bulletin, said that AQI improved significantly to "moderate" due to scavenging and wet deposition of particulate matter by Saturday's rain. Rain is likely to continue today leading to further improvement of AQI to the lower end of "moderate" or "satisfactory".
"A dust storm originated from Gulf region headed towards Gujarat coast and parts of Maharashtra, however it is unlikely to affect air quality of Delhi due to prevailing influence of western disturbance and associated intermittent drizzle/rain." "From 24th onwards fair weather conditions are likely to prevail with normal emissions from anthropogenic activity partially offset by moderate ventilation resulting in gradual accumulation of pollutants bringing AQI back to 'moderate' or 'poor'," it added.
The air quality and weather bulletin said, the predominant surface wind is coming from the southeast direction of Delhi with wind speed 08-16 kmph and partly cloudy sky on Sunday "The predominant surface wind is likely to be coming from the northwest direction of Delhi with wind speed 08 kmph, partly cloudy sky and moderate fog in the morning on Monday. The predominant surface wind is likely to be coming from the northwest direction of Delhi with wind speed 06-10 kmph, partly cloudy sky and moderate fog in the morning on January 25," it added.