The air quality in Delhi remained in a severe category on Thursday morning, with the smoky haze lingering over the national capital for the third consecutive day becoming a serious health concern for the residents.
At 8 am, the city's overall air quality index stood at 408, a tad better than 415 at 8 pm on Wednesday.
Twenty-two of the 37 air quality monitoring stations across Delhi recorded the air quality in the severe category on Thursday morning.
Anand Vihar continued to be the most-polluted area with an AQI of 466, followed by Wazirpur with an AQI of 453.
An AQI between 0-50 is considered "good", 51-100 "satisfactory", 101-200 "moderate", 201-300 "poor", 301-400 "very poor" and 401-500 "severe". Above 500 falls in the "severe-plus emergency" category.
According to the Ministry of Earth Sciences' air quality monitor, SAFAR, the share of stubble burning in Delhi's pollution rose to 35 per cent on Wednesday, the season's highest, and the hazardous haze shrouding the city could "purely" be attributed to it.
Weather experts said the problem aggravated due to an unfavourable wind speed post-Diwali that led to the accumulation of pollutants. A relief is likely on the weekend, they added.
The city government has identified five "critically polluted" areas after examining the post-Diwali pollution data and asked the municipal corporations and the Delhi Pollution Control Committee to intensify actions at these locations.
The "critically polluted" areas are Wazirpur, Anand Vihar, Ashok Vihar, Vivek Vihar and Bawana.
In view of the hazardous pollution levels in the national capital, doctors advised people to take a lot of precautions, including wearing face masks and avoiding early morning and late evening walks as the concentration of pollutants is at its highest during this period.
Delhi Deputy Chief Minister Manish Sisodia said the decision to shut schools will be taken "when the need arises".
In November 2017, the government had shut schools for a few days due to deteriorating air quality.
This year, the government will start distributing 50 lakh N95 masks among school students in Delhi from Friday, Chief Minister Arvind Kejriwal said.
The AQI takes into account five chief pollutants -- particulate matter with a diameter of less than 10 micrometres (PM10), PM2.5, ozone (O3), nitrogen dioxide (NO2) and carbon monoxide (CO).
The higher the AQI value, the greater the level of air pollution and health concerns.