The Air Quality Index (AQI) of Delhi improved by 100 points, with Thursday's AQI at 273 against 373 on Wednesday.

PM2.5, or particles with diameter less than 2.5mm, is still the dominant pollutant. However, with dry and cool north-westerly winds catching speed, Thursday saw good dispersion with average PM2.5 over 37 areas of Delhi recording 134 microgrammes per cubic meters, against 240 units on Wednesday.

The permissible limit for PM2.5 is 60 units by national standards and 25 units by international standards.

"North-westerly winds entered Delhi by Wednesday evening and gained speed on Thursday. These dry and cold winds will increase over the next two days, which will improve the air quality," said Mahesh Palawt, director, private weather agency Skymet.

However, pollution will rise from November 28 due to another western disturbance over the hilly regions, which will cut off the north-westerly winds and Delhi will receive moist easterly winds.

According to the System of Air Quality and Weather Forecasting And Research (SAFAR), the Air Quality at 11 regions which it monitors was under the 'very poor' category with AQI of 302.

"Air quality is in the lower range of 'very poor' and likely to improve further," SAFAR said.

SAFAR has advised people to avoid outdoor physical activities.

"If asthematics, keep relief medicine handy," the warning added.