The air quality in Delhi-NCR was back to "severe-plus" or "emergency" category towards Monday evening and the monitoring agencies forecast a further rise in toxicity over the next few hours.
The levels of PM2.5 and PM10 continued to rise even as both central and Delhi governments claimed partial relief during the afternoon.
The average Air Quality Index (AQI) in Delhi on Monday at 4 p.m was 463, with PM2.5 recorded at 460 units.
For the entire Delhi-NCR, the average was 455 units, with PM2.5 at 452 units.
The international permissible limit for PM2.5 -- particles in air with diameter less than 2.5mm -- is 25 units (micro gram per cubic metre), while for India it is 60 units.
Ghaziabad was the most polluted city in the entire NCR, with PM2.5 at an astounding 848 units at 4 p.m -- 33 times the safe limit.
The System of Air Quality and Weather Forecasting And Research (SAFAR) initiative of the government said Delhi's air "may see increase in pollution levels" due to meteorological factors and that a clearer picture would emerge after Tuesday.
The Met office has forecast rains for November 15.
The Supreme Court-appointed Environment Pollution Control Authority (EPCA) said Delhi's air had "reversed" to "severe-plus" or "emergency" category after some signs of improvement on Friday and Saturday.
"On Friday (November 10) and Saturday morning, air quality had improved as there was some wind that allowed dispersion of pollutants. But by Saturday afternoon, this situation reversed. Pollution continued to rise and concentration levels have remained in the severe-plus over Sunday," it said.
However, an EPCA official claimed that the dispersal of pollutants had begun with the wind speed picking up again.
The "emergency" or "severe-plus" situation requires PM2.5 to remain above 300 units or PM10 above 500 units for 48 hours.
According to the Central Pollution Control Board (CPCB), Delhi's air quality was above the required limits for over 50 hours by 3.00 p.m on Monday.
The "emergency" situation was last witnessed from Thursday till Saturday morning. However, the pollutant levels fell below the red line for an hour on Saturday noon.
According to the Graded Response Action Plan (GRAP) of the EPCA, the measures to be enforced in "severe-plus" or "emergency" category include odd-even vehicular restriction scheme.
"Western disturbance is looming large over Delhi and its withdrawal is expected on November 16-17. This is likely to be accompanied by addition of moisture to Delhi's air and fall in the temperature which may result in an increase in pollution levels," said a forecast report prepared by Gufran Beig, Project Director of SAFAR.
But the report said that the rise could be marginal and nowhere near that caused by stubble burning and "Gulf dust storm", which is also a contributor to pollution in some parts of the country.
Delhi Minister Gopal Rai said on Monday that there was some improvement in Delhi's air quality in the morning.
"According to reports, there are fluctuations (in pollution levels). But in the past six hours, pollution levels are a little lower than before," Rai said in the afternoon.
He also claimed that the air pollution in Punjab and Haryana was worse than Delhi.
Union Environment Minister Harsh Vardhan said: "There is a declining trend in the levels of particulate matters at present, indicating improvement in air quality on account of efforts made by various agencies."
He also called for round-the-year efforts to tackle pollution.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)