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 battles air pollution every winter as cold,

Around 38% of the pollution in New Delhi this year has been caused by stubble burning - a practice where stubble left after harvesting rice is burnt to clear fields - in the neighbouring states of Punjab and Haryana, according to SAFAR, a weather forecasting agency under the ministry of earth sciences.