India's toxic smog cuts off visibility in several areas

Toxic smog blanketed northern India on Thursday, becoming too thick to see through in several places, as high levels of pollution combined with humidity, low wind speed, and a drop in temperature, officials said.

The city of Lahore in neighbouring Pakistan ranked as the world's most polluted in winter's annual scourge across the region, worsened by dust, emissions, and smoke from fires burnt illegally in India's farming states of Punjab and Haryana.

However, operations at New Delhi's international airport were not affected by the smog, which weather officials expect to scatter during the day as breezes pick up.

Visibility remained at 300 m (980 ft), the airport operator, Delhi International Airport Limited (DIAL) said, while some airlines warned flights could be affected.

"Winter fog may impact flights" with Delhi, the city of Amritsar in Punjab, where authorities said visibility was zero, and the temple city of Varanasi in Uttar Pradesh, IndiGo said in a message on X.

New Delhi's international airport diverted some flights on Wednesday.

The minimum temperature in Delhi fell to 16.1 degrees Celsius (61°F) on Thursday from 17 degrees C the previous day, weather officials said.

Its pollution ranked in the 'severe' category for the second day in a row, with a score of 430 on an index of air quality maintained by the top pollution panel that rates a score of zero to 50 as 'good'. Pollution in New Delhi is likely to stay in the 'severe' category on Friday as well, the earth sciences ministry said, worsening to 'very poor' later, or an index score in the range of 300 to 400.

The number of farm fires to clear fields of paddy stubble in preparation for the planting of wheat in north India has risen steadily this week to almost 2,300 on Wednesday from 1,200 on Monday, the ministry's website showed.

In Pakistan, Lahore, the capital of the eastern province of Punjab, was rated the world's most polluted city on Thursday, in live rankings kept by Swiss group IQAir.

Authorities there have also battled hazardous air this month.

The province has already shut schools, halted some building work, banned most outdoor activity, and ordered early closures of some businesses in efforts to combat the problem.