Lahore again tops most polluted cities' list amid thickening smog

Punjab’s capital, Lahore, retained the top spot on the real-time list of the world’s most polluted cities on Monday, as pollution worsens in the metropolis with the arrival of winter.

Dense smog has engulfed Lahore once again with cooler temperatures taking hold as the city battles pollution each year in winter when mercury drops and cold air traps construction dust, vehicle emissions, and smoke. 

The air quality dropped to an AQI of 532 this morning, according to IQAir, a Swiss company. The provincial capital remained on top of the world's most polluted cities' list for almost a week, indicating a worsening smog situation.

On Sunday, the city had extremely bad air quality, with an AQI of 700, prompting the Punjab Environment Protection Department to issue a smog alert.

IQAir's air quality classification defines the atmosphere as "hazardous" to health once the AQI surpasses 300.

An AQI of 0-50 is rated "good," 51-100 is "moderate," 101-150 is "unhealthy for sensitive groups," 151-200 is labeled "unhealthy," 201-300 is "very unhealthy," and any reading above 300 is deemed "hazardous." 

The alert advised residents of Lahore to take precautionary measures to avoid the effects of air pollution. The citizens have been advised to keep air quality levels in check, keep their doors and windows closed, avoid going outside unnecessarily and wear masks in case they step out of their homes.

Meanwhile, all outdoor activities remain banned in schools across Punjab, with a change of school timings.

Traffic police has also warned commuters to practice caution while driving motorcycles as the visibility in the city is reduced due to rise in smog in Lahore.

Neighbouring India's capital New Delhi also retained the second slot on the pollution charts, with an AQI of 268 today.

The two cities are usually the most polluted in the world when winter season takes hold. Air quality deteriorates in cooler months, as temperature inversion traps pollution closer to the ground.

Meanwhile, Karachi also ranked among the top 10 most polluted cities today, with an AQI of 123. Here the air quality is "unhealthy" for sensitive groups and people with allergies.

According to an advisory issued by the Pakistan Meteorological Department on Tuesday (October 22), foggy and smoggy conditions are common from November to mid-December as the country enters winter season during these months.

Bad air quality is a major threat to the health as citizens in the polluted cities develop several medical issues, especially respiratory problems.

A report published last year flagging the growing burden of hazardous air on health, stated that rising air pollution can cut life expectancy by more than five years per person in South Asia, one of the world's most polluted regions.