Fall in minimum temperature and decrease in the speed of northwesterly winds coming from Punjab and Haryana, where stubble-burning is on the rise for the last three days despite the green court's order to the contrary, Delhi and the National Capital Region are likely to inhale toxic smog for a few more days.
"There is a possibility of stubble-burning being the reason of the rise in pollution levels in the region," said A Sudhakar, Member Secretary of the Central Pollution Control Board (CPCB).
Satellite images from the National Aeronautics and Space Administration (NASA) on Monday showed increased stubble-burning in parts of Haryana and Amritsar, Tarn Taran, Firozpur, Fazilka, Muktsar, Bathinda, Moga and Kapurthala districts in Punjab in the last two days.
"The average air quality of Delhi due to several reasons would range between 'poor' to 'very poor' for some days," A Sudhakar added.
According to the weather department, the wind speed in Delhi-NCR has slowed from 10-15 kmph on Sunday to 10 kmph or below on Monday, due to which it is not able to dissipate additional pollutant from the neighbouring states.
With a focus on long-term measures to tackle smog, the CPCB has directed the India Meteorological Department (IMD) to update their "inaccurate system" and develop an "early warning system" for issuing advance warning of air pollution.
"IMD is supposed to develop the early warning system to warn of the smog situation here or the possibility of a dust storm reaching Delhi through Afghanistan. The systems at IMD are not accurate as earlier they predicted that dust won't reach Delhi but it did... At least with early warning we will have time to prepare," A Sudhakar said.
According to the CPCB, the average air quality index (AQI) of Delhi-NCR on Monday at 5 pm was 316 points or "very poor", compared to 292 or "poor" on Sunday.
The average AQI of Delhi as monitored by 17 active stations of the CPCB at 5 pm was 324 points (very poor) against 292 (poor) on Sunday.
The major pollutant, PM2.5, or particles with diameter less than 2.5 micrometers, was recorded above the danger limit of 324 units on Monday in Delhi -- about 12 times the safe limit, against 290 units on Sunday.