The national capital recorded its air quality in the "moderate" category on Saturday morning, while a government forecasting agency predicted that it will turn "poor" by Monday.
At 9.30 am, Delhi's air quality index (AQI) was 168, which falls in the "moderate" category. On Friday, it recorded a 24-hour average AQI of 134.
An AQI between 0 and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.
The Ministry of Earth Science's air quality monitor, SAFAR, said dust from arid regions in the southwest has started affecting Delhi.
"Farm fires have begun in Amritsar, Punjab, and neighbouring border regions and are likely to influence the city's air quality," it said.
The farm fire count on Friday was around 40, according to the System of Air Quality and Weather Forecasting and Research (SAFAR).
"Deterioration in air quality index is expected on Saturday. Further deterioration -- from the higher end of the moderate category to poor category -- is expected on September 27 and September 28," it said.
Pawan Gupta, a senior scientist at Universities Space Research Association, NASA, said the forecast shows high PM2.5 levels across the Indo-Gangetic plains over the next 2-3 days.
"It appears a combination of smoke, dust and weather is playing a role," he said.
