The Indian capital, Delhi, has been enveloped in a blanket of thick grey smog for the last week.
Millions of people in the city have been advised to stay indoors and refrain from an form of physical exercise.
Delhi is one of the world’s most polluted cities with more than 11 million people living there.
Visibility is poor as pollution levels reached 30 times the World Health Organization’s recommended limit in some areas.
The Indian Medical Association (IMA) declared “a state of medical emergency” after measures of airborne particles peaked at more than 750. A measure of 300 is the amount needed to start for air pollution warnings.
At levels over 300, entire populations can be affected. People with heart disease, respiratory problems and cardiopulmonary conditions are at risk of serious aggravation.