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,

Delhi's air-quality index, or AQI, shot up past 1,000 on Monday, more than five times higher than Sarajevo, the second most-polluted major city.

Toxic smog engulfed much of northern India on Monday and pollution readings in New Delhi hit their highest of this pre-winter season.