On December 19, Lucknow was enveloped in a stupendous sheet of fog (or smog) and the city-ites are evidently worried. If you've been coughing up more than usual today, with irritation in the nose and strained eyes, there's a specific reason behind it.

The Lucknow Air Quality Index (AQI) has deteriorated and has been declared as severe with the current fine particulate matter or PM2.5 concentration 10.3 times above World Health Organisation's recommended limit. The recorded AQI in the city's bustling areas of Lalbagh and Gomti Nagar was high, with Lalbagh reaching a 372 AQI, deemed as "very poor". Remember, when AQI values cross 100, air quality is unhealthy.

In the last 24 hours, Lucknow's AQI peaked at 411 at 10 PM last night.

With the public facing hardships during normal activities like driving, jogging, and even walking, here are accounts of some of their experiences.

"The road was not visible more than a distance of 10 metres," informed Sagar, a localite travelling from Bahraich to Lucknow this morning. "I had to drive extremely slow and with increased caution in order to not meet with an accident," he added.

Accidents on highways/expressways have also been reported due to the aggravated conundrum of lack of visibility.

"It was like walking into the clouds, and not in a good way," shares Hazratganj resident Mahi, who takes her dog for walking at 8:30 AM around her house.

"On the road behind Fun Republic, we could only see ahead when we were switching off the headlight of the car. On switching it on, the road was so foggy, there was no visibility," informed another resident of Gomti Nagar, on the streets on Lucknow at 11:30 PM.

Other Northern India cities like Ghaziabad (with 614 AQI) and New Delhi (with 590 AQI) also peaked in terms of the AQI. Bihar's Begusarai (523 AQI) and Saharsa (523 AQI), too, have reported extreme levels of pollution in the past 24 hours.

"Any exposure to the air, even for a few minutes, can lead to serious health effects on every body. Avoid outdoor activities," advised a weather website.