Delhi's air quality remained "very poor" for the second day this season, with several areas in the national capital nearing "severe" levels of pollution, according to the authorities.
The overall Air Quality Index (AQI) of Delhi was recorded at 315, same as Wednesday, according to the Centre-run System of Air Quality Forecasting and Research.
Faridabad, Ghaziabad, Gurgaon, Noida and Greater Noida all recorded very poor air quality.
The PM2.5 (presence in the air of particles with a diameter of less than 2.5 micrometres) touched a new high at 158, even as the authorities said it could increase further.
The PM2.5, also called "fine particulates," is a more serious health concern than PM10.
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".
A senior Central Pollution Control Board official said the situation is being monitored and depending upon the quality more stringent measures like increase of parking fees and a complete ban on construction activities would be imposed.
"We are hoping that with a slight improvement in meteorological conditions, the air quality would improve. But if it doesn't, we would impose stringent measures," he said.
On Thursday, Anand Vihar recorded an AQI of 315, Dwarka Sector 8 369, ITO 256, Jahangirpuri 337 and Rohini 368, according to the Central Pollution Control Board (CPCB).
The PM10 level (presence in the air of particles with a diameter of less than 10 micrometres) in Delhi stood at 297 and the PM 2.5 level was recorded at 140, according to the CPCB data.
Further deterioration of air quality has been forecast for the coming days with the PM10 level reaching 332 and the PM2.5 level 158.
The data released by the CPCB shows that the air quality in the last three years has not improved much but officials also said a clear picture would emerge by end of this month.
A CPCB official said a number of factors were responsible for the deteriorating air quality, including vehicular pollution and construction activities.