India's capital was left gasping this week as air pollution smog reduced visibility to near zero and raised air quality levels more than 130 times safe limits.

Residents in India's northern states woke up to another day of poor air quality on Tuesday, as a layer of dense fog shrouded most of the region, and pollution in the capital Delhi remained severe.

India’s capital region, Delhi, has virtually come to a halt as air pollution levels reached a “severe plus” category, creating what officials have described as a public health emergency.