The air quality in Delhi National Capital Region was back to "severe-plus" or "emergency" levels towards Monday evening and the monitoring agencies forecast a further rise in toxicity today.
The "emergency" or "severe-plus" situation means PM2.5 remains above 300 units or PM10 above 500 units for 48 hours.
The levels of PM2.5 and PM10 continued to rise even as both central and Delhi governments claimed during the afternoon that there was some improvement.
The hashtag #smog was the top trending on Twitter and Facebook this morning, as the people of Delhi continued to demand stronger measures to curb pollution.
The average Air Quality Index (AQI) in Delhi at 4 pm on Monday was 463, with PM2.5 recorded at 460 units. For the entire 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 (microgrammes per cubic metre), while has set it at 60 units.
Ghaziabad was the most polluted city in the NCR, with PM2.5 at 848 units at 4 pm - 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 today.
There is a forecast of rain on Wednesday. "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.
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.
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.
The CPCB report said that the rise could be marginal and would not compensate for by stubble burning in nearby states and a "Gulf dust storm", which is also a contributor to pollution in some parts of the country.