Unusual smog-like conditions prevailed in Karachi on Wednesday morning, causing poor visibility and difficulty for drivers in various parts of the city, along with exacerbating respiratory issues in people suffering from asthma.

Regional Meteorological Centre Karachi Director Shahid Abbas, while explaining the weather in the metropolis, said that fog or smog is formed "when minimum temperature falls rapidly".

"Right now, the land and sea temperature are almost the same, due to which the wind has stopped blowing," he said, adding that this was why "smog has formed in Karachi".

"It will remain for the next two or three days until winds from Quetta start blowing here. Then the smog will disperse and it will get two to three degrees colder," he said.

Take a look: Punjab authorities are responding to help manage the smog, but is it enough?

He ruled out the possibility of rain in Sindh over the next few days.

"There are rains in parts of Punjab ─ Sialkot, Gujranwala ─ but the [weather] system is passing overhead and there is no chance of rain in Sindh," he explained.

However, "the air temperature will lower and dry winds will begin blowing, which will clear the atmosphere."

Earlier, a Met official, requesting anonymity, told Dawn.com that the ratio of humidity in the air is around 32 per cent. He added that Nawabshah, Sukkur, Dadu, Hyderabad, Jackobabad, and Sakrund are also affected due to the situation.

Smog has become a common feature of the winter season in parts of the country, particularly Punjab. The condition has been attributed to the burning of crop stubble, and pollution from factories and traffic in the province. Burning of crop stubble across the border has also aggravated the situation locally.

A global list of the 50 worst air pollutant emission hotspots in the world by Greenpeace which analysed the satellite data generated by European Space Agency’s new satellite ranked Lahore and its surrounding area at 30th place.