Humidity levels fluctuated between 96 and 76 per cent during the day. (File)
The air quality index continued to fluctuate between the "severe" and "very poor" categories in Delhi.
The city's 24-hour average air quality index, recorded until 4 pm on Sunday, was 318 (very poor), improving rom the severe category recorded the previous day when it was 412, according to data from the Central Pollution Control Board (CPCB).
None of the 38 monitoring stations in Delhi recorded AQI in the severe category on Sunday, compared to 20 stations that recorded severe air quality the previous day, according to the SAMEER app, which provides hourly updates on the National Air Quality Index.
An AQI between 0 and 50 is considered "good," 51-100 "satisfactory," 101-200 "moderate," 201-300 "poor," 301-400 "very poor," 401-450 "severe," and above 450 "severe plus." CPCB data identified PM2.5 as the primary pollutant, with its levels recorded at 138 at 3 pm.
PM2.5 particles, measuring 2.5 micrometers or smaller (approximately the width of a human hair), pose significant health risks as they can penetrate deep into the lungs and enter the bloodstream, according to the CPCB.
The Centre's Decision Support System (DSS) for Air Quality Management estimated that vehicular emissions contributed 18.1 per cent to Delhi's pollution on Sunday. Stubble burning, another major factor, accounted for 19 per cent of Delhi's pollution on Saturday.
The DSS provides daily estimates for vehicular emissions, while data on stubble burning is typically released the following day.
Delhi's air quality plunged into the hazardous category last Sunday morning, with the AQI crossing 450 for the first time this season.
It worsened further on Monday, recording the season's highest average Air Quality Index (AQI) of 495. In response, Stage 4 restrictions under the Supreme Court-mandated Graded Response Action Plan (GRAP) were implemented across the city to address the escalating air pollution crisis.
According to data, the city's air quality remained in the severe category from Monday to Wednesday. While there was a slight improvement on Thursday and Friday, it returned to the severe category on Saturday.
Meanwhile, a thick layer of mist and smog blanketed the city during the morning and evening hours, reducing visibility.
The daytime temperature was recorded at 29.1 degrees Celsius, two notches above the seasonal average, according to the India Meteorological Department (IMD).
Humidity levels fluctuated between 96 and 76 per cent during the day.
The IMD has forecast moderate fog for Monday, with maximum and minimum temperatures expected to be around 28 and 12 degrees Celsius, respectively.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)