ISLAMABAD: Swiss air monitor index IQAir ranked Pakistan’s eastern city of Lahore as the most polluted in the world on Monday, recording its Air Quality Index (AQI) at 563, considered as “hazardous.”

Lahore, the capital of Pakistan’s most populous Punjab province, faces worsening smog every winter. Cold air traps vehicular emissions, industrial pollution and residue from crop burning due to which thick smog chokes the city.

Thick smog every winter threatens public health and daily life. It can cause sore throats, eye irritation, and respiratory illnesses, while long-term exposure increases the risk of stroke, heart disease and lung cancer.

“PM2.5 concentration is currently 79.8 times the World Health Organization annual PM2.5 guideline value,” the Swiss monitoring index wrote.

Mongolia’s Ulaanbaatar ranked at number 2 on the list with an AQI of 177 while India’s capital New Delhi was ranked third with an AQI of 174, followed by Kolkata with 173.

Pakistan’s commercial hub and southern port city of Karachi was ranked at number 20 on the list with an AQI of 92, which is considered by the index as “moderate.”

Smog season begins in late October, peaks from November to January and lasts through February.

In October 2025, the Punjab government conducted its first anti-smog gun operation, which helped lower the city’s unhealthy air quality levels. Anti-smog trucks sprayed fine water mist across the city to help settle dust and pollutants.

Pakistan’s main urban centers routinely rank among the most polluted cities in the world, with vehicular emissions remaining one of the top contributors to air pollution.