A Centre-run pollution agency has identified a late October dust storm in the Middle East and stubble-burning in northern states as the prime factors behind the ongoing air pollution crisis in the national capital, which is now showing signs of waning.
The dense smog layer, which kept the city shrouded since Tuesdday, thinned considerably and level of pollutants dropped steadily in Delhi today, with agencies forecasting that Delhiites can look forward to a better air quality over the weekend.
In its forecast, the System of Air Quality And Weather Forecasting And Research (SAFAR) said air quality is likely to remain in the 'severe' category tomorrow, but it may improve a shade and enter the 'very poor' zone on Sunday night.
"Since November 9 morning, upper air winds are consistently slowing down and have touched 5-7 km/hour and there is no trace of dust entering the Indian subcontinent, particularly the NCR region. Also the stubble-burning influx is marginal," the SAFAR report said.
The report said that a dust storm, which swept across Iraq, Kuwait, and Saudi Arabia in the last week of October and spilled onto the first week of November, severely affected Delhi's air quality.
"This dust storm was carried by relatively cool winds. As air temperatures dropped, wind and dust were likely to slowly diminish but by that time, it got into upper part of atmosphere where winds became very strong (15-20km/hour), with its direction being India. It affected large swathes of NCR and Delhi," the report added.
Meanwhile, the air quality index (AQI) remained in the 'severe' catgory for the fourth consecutive day, but the volume of PM2.5 and PM10 looked well on course to drop below the emergency level which calls for measures such as odd-even.
A 'very poor' AQI comes with the warning that people may develop respiratory illness on prolonged exposure while exposure to 'severe' air affects healthy people and seriously impacts those with existing respiratory or cardiovascular diseases.
According to the Central Control Room for Air Quality Management, around 5 pm, average concentration of ultrafine particulates PM2.5 and PM10 were 570 and 413 micrograms per cubic metre respectively.
These particulates were recorded over 850 and 600 micrograms per cubic metre in the intervening night of October 8-9, prompting authorities in the region to announce a sweeping set of measures including shutting schools, banning construction activities and introducing odd-even.
However, SAFAR warned that a fresh western disturbance (WD) was in the offing, which may impact the air quality adversely.
"After the withdrawal of WD, lots of moisture enter Delhi and temperature also cools down. This may bring down the inversion layer and air's holding capacity may increase from November 13. This may impact air quality adversely but we do not expect the repeat of this week," it said.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)