Violations of the Supreme Court order were reported from nearly all across the city and the satellite cities of Noida and Gurgaon.
While seven people were detained for allegedly flouting the apex court's guidelines and bursting crackers after the 10 pm deadline, Mirror spotted hordes of residents on Carter Road, Marine Drive and Worli Seaface, who disregarded the order, sending noise and air pollution levels skyrocketing with their pyrotechnics.
"At present, it continued to be in "severe" but likely to improve further and will become "very poor" by afternoon and will improve further by Saturday". Levels from 0-50 is considered "good", 51-100 "satisfactory", 101-200 "moderate", 201-300 "poor", 301-400 "very poor", and 401 and above is "severe".
A "severe plus emergency" AQI essentially means that even healthy people may suffer from respiratory illnesses on prolonged exposure.
Experts said a significant drop in temperature and reduced wind speed have also aggravated the situation.
In 2017, the AQI of Delhi two days after Diwali was 389 or "very poor".
The overall AQI Thursday was recorded in the "severe plus emergency" category at 642, according to the data by SAFAR. The Air Quality Index (AQI) readings of Major Dhyan Chand National Stadium; ITI Shahdra, Jhilmil Industrial Area; PGDAV College, Sriniwaspuri; Mother Dairy Plant, Parparganj; Mandir Marg and Anand Vihar showed 999, the highest measurable figure on the AQI.
The Supreme Court ruled last month that only environmentally friendly crackers - that emit less smoke and soot - can be sold in Delhi, in a bid to cut the smog that has scarred the city's global reputation.
PM2.5 - small particles predominantly dust, that are 2.5 microns in size, can penetrate deeper into the lungs and enter the bloodstream.
The highest levels of PM 10 and PM 2.5 were recorded between 11 pm and 5 am on the intervening night of November 7 - 8. It is expected to rise to 165 µg/m3 on Thursday and then decline to 121 µg/m3 on Friday.
The court also said firecrackers could only be set off between 8:00 pm and 10:00 pm.
With maximum fire counts from stubble burning in neighbouring states - 2,100, which is four times higher than a year ago, on Thursday, Delhi and areas around it on Friday were found more polluted than Thursday, a day after Diwali. The good news, however, is that this year's Supreme Court-mandated restriction on crackers has seen pollution levels being almost 33% lower than the festivities of 2017.