Record-high air pollution in Pakistan's cultural capital of Lahore is sending more people to hospitals and private clinics and the city authorities warned a complete lockdown could be imminent if residents fail to don face masks and follow other guidance related to smog.

A toxic cloud of smog has swept over Pakistan and India, causing one of Pakistan's major cities to put schools on lockdown. On Sunday, the capital of the Punjab region of Pakistan, Lahore, held the real-time top spot as the world's most polluted city,