According to data from the Central Pollution Control Board (CPCB), Delhi's average Air Quality Index (AQI) was recorded at 349 as of 6 a.m. NCR cities also witnessed poor air quality, with AQI readings of 196 in Faridabad, 266 in Gurugram, 276 in Ghaziabad, 289 in Greater Noida, and 269 in Noida.

The highest AQI reading within Delhi was at Aya Nagar, where levels reached a "severe" 406, with many other parts of the capital recording AQI levels between 300 and 400.

According to IQAir, a Swiss-based air quality monitoring organisation, Delhi's AQI had even reached 1,133 in certain areas earlier, categorising the pollution as "hazardous," with PM2.5 identified as the main pollutant.

The thick smog, accompanied by moderate fog and mist, caused poor visibility in the early hours. Experts anticipate the hazy conditions will persist into the evening, posing heightened health risks for residents, particularly those with respiratory concerns.

Delhi's AQI has remained "very poor" since October 30, with levels initially recorded at 307. The seasonal spike in pollution levels is largely attributed to stubble burning in Punjab and Haryana, as farmers clear fields post-harvest in October and November.

Air quality levels in parts of Punjab and Haryana were also concerning, with many areas recorded in the "poor" range and Chandigarh, the shared capital, in the "very poor" category with an AQI of 349 as of Tuesday night. Punjab saw 83 new instances of farm fires, bringing the season's tally to 7,112.

The CPCB classifies AQI as follows: 0-50 is "good," 51-100 "satisfactory," 101-200 "moderate," 201-300 "poor," 301-400 "very poor," 401-450 "severe," and above 450 as "severe plus."