Toxic gray smog has sickened tens of thousands of people in Pakistan’s cultural capital of Lahore, forcing authorities to shut schools, markets and parks for four days, officials said Thursday. The decision came after the country's second-largest city was repeatedly ranked the world’s most polluted city. Doctors advised people to wear face masks and stay at home. Residents said many people were coughing and having breathing problems.
On Thursday, the concentration of PM 2.5, or tiny particulate matter, in the air approached 450, considered hazardous. AIR POLLUTION MORE DEADLY THAN SMOKING, NEW STUDY FINDS 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, which were ubiquitous during the Mughal era of the 16th to 19th centuries.