All elementary schools in India's capital New Delhi are being closed indefinitely due to the increasing smog in the metropolis and its surrounding areas, where over 30 million people live.
Instead, children will be taught online.
Farmers in other parts of India who burn their fields before next year's sowing, as well as emissions from factories and traffic, are believed to be behind the deadly high pollution levels. Cooler temperatures and slower winds keep the hazardous substances in the air for longer periods between October and January, and schools often need to be closed during the worst weeks of the annual smog crisis.
Last month, India's Supreme Court ruled that clean air is a fundamental human right and that both the government and state authorities must take action against the high pollution levels.