Tens of thousands of people are sick and Lahore has been shutdown, as toxic smog has engulfed the northern Pakistan city.
Authorities closed schools, markets and parks for four days due to the dangerous mist, officials said on Thursday.
Residents reported many people were coughing and having breathing problems.
Authorities in Pakistan’s Punjab province have imposed an “environmental and health emergency” in three cities - Gujranwala and Hafizabad as well as Lahore - until the situation improves, its chief minister Mohsin Naqvi said this week, CNN reports
The three cities have a combined population of more than 15 million people. Doctors have advised people to wear face masks and stay at home.
“Wearing of masks and staying at home are the two easiest solutions to avoid getting rushed to hospitals with respiratory-related diseases, infections in eyes and skin diseases,” said Lahore doctor Salman Kazmin.
He has been treating thousands of people suffering with such conditions at Lahore's main Mayo Hospital this week.
On Thursday, the concentration of PM 2.5, or particulate matter, in the air approached 450, which is considered hazardous.
Particulate matter contains microscopic solids or liquid droplets which are so small they can be inhaled getting deep in the lungs and bloodstream.
Particles which are less than 2.5 micrometers in diameter, also known as fine particles or PM 2.5, pose the greatest risk to health.
Lahore has repeatedly been ranked the world’s most polluted city.
Experts say the burning of crop residue at the start of the winter wheat-planting season is a key cause of the pollution.
Lahore was once known as the city of gardens, but rapid urbanisation and a surging population have left little room for greenery.
The pollution spike in Pakistan comes after neighboring India saw smog blanket its capital New Delhi last week, as colder temperatures trapped pollution particles, creating a toxic haze that reached hazardous levels.
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