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

Why is north India blanketed by smog every winter? Why has smog appeared earlier this year? We explain the basics and beyond.

The smog, a toxic blend of smoke and fog, happens each year in winter as cold air traps dust, emissions, and smoke from illegal farm fires in some surrounding states. Visibility dropped to 100 m (109 yards) in Delhi and Chandigarh,

Air pollution in India's capital Delhi has soared to extremely severe levels, choking residents and engulfing the city in thick smog. Monitors recorded pollution levels of 1,500 on the Air Quality Index (AQI) at 15:00 IST (09:30 BST),

Delhi recorded air pollution more than 17 times above an acceptable level as worsening smog triggered curbs on trucking and shuttered construction sites and schools.

Authorities in India’s capital shut schools, halted construction and banned non-essential trucks from entering the city on Monday after air pollution shot up to its worst level this season. Residents of New Delhi woke up to thick,

Delhi ’s government imposed the most stringent set of restrictions on the movement of vehicles and people as the toxic smog enveloping the Indian capital worsened on Monday. The city’s average air quality index was 457 in the morning,