Lahore’s 14 million residents spent six months breathing concentrations of PM2.5—tiny particles that can penetrate the lungs and bloodstream—at levels 20 times or more than recommended by the World Health Organization.
Those in Karachi, Pakistan’s biggest city, and the capital Islamabad were subjected to 120 days of the same choking pollution levels.
Experts say the pollution is primarily caused by factory and traffic emissions. It worsens in winter as farmers burn crop stubble and cooler temperatures and slow-moving winds trap the deadly pollutants.
This year, winter rains that typically bring relief did not arrive until late February, as climate change renders Pakistan’s weather patterns increasingly unpredictable.
The smog was so thick it could be seen from space and prompted authorities to close schools serving millions of students across the largest province Punjab, including its capital Lahore.