Toxic grey smog has sickened tens of thousands of people, mainly children and elderly people, since last month when the air quality started worsening in Lahore, the city bordering India.

Lahore AQI: Pakistan blames India for worsening smog in Lahore and urges serious action as the air quality index hits a record high.

Pakistani officials say dangerously poor air quality has forced the provincial government in Lahore to close primary schools for a week.