Delhi was engulfed in a thick blanket of haze on Friday morning after the bursting of crackers on Diwali, with residents complaining of watery eyes and itchy throats, ANI reported.

The city’s overall air quality on Friday morning was 617 (hazardous), according to the System of Air Quality and Weather Forecasting And Research or SAFAR. The government-run monitoring agency reports real-time figures.

Air pollution in Delhi typically worsens in October and November due to farmers burning stubble in neighbouring states, unfavourable wind speed and emission of fumes by vehicles in the city. Firecrackers ignited for Diwali add to the problem.

In September, the Delhi Pollution Control Committee had banned the sale and bursting of firecrackers up to January 1, 2022.

Despite the ban and the deteriorating air quality, the residents of Delhi burst crackers on Diwali on Thursday.

People light firecrackers to celebrate Diwali in Delhi on November 4. [Sajjad Hussain/AFP]

At 9 am on Friday morning, the 24-hour average concentration of PM 2.5 in the air rose to 410 micrograms per cubic metre, which is nearly seven times the safe limit, PTI reported, citing the Central Pollution Control.

Particulate matter smaller than 2.5 microns, or about a ten-thousandth of an inch, is particularly dangerous to human health. Such particles are small enough to travel deep into the respiratory system, potentially impairing lung function.

In Delhi’s Janpath area, the concentration of PM 2.5 early on Friday was 655.07 micrograms per cubic metre.

The smog in Delhi and its neighbouring places led to a drop in visibility levels.

“Fog conditions this [Friday] morning have intensified in Delhi-NCR [National Capital Region] with visibility levels of 200-500 metres reported at its two airports – Safdarjung and Palam till 5.30 am,” India Meteorological Department scientist RK Jenamani told the Hindustan Times.

In the foggy conditions on Friday morning, six vehicles collided on a highway near Greater Noida, NDTV reported. Six people were injured in the accident. Two of them are reportedly in a critical condition.