Residents of India's capital, New Delhi, found themselves surrounded by a blanket of smog on Friday as the air quality plunged to "hazardous" levels.
The Air Quality Index (AQI) figure, as reported by the Swiss group IQAir at 0100GMT, stood at a "hazardous" 545.
IQAir had previously named New Delhi the world's most polluted capital just last year.
Local resident Nitin lamented the dire situation, saying masks were necessary when leaving the house and the air quality meant his elderly parents were housebound and his children's schools were shut.
The toxic smog has left many suffering from burning sensations in their eyes, sore throats, and shortness of breath.
Despite the implementation of anti-pollution measures, the capital struggles to rein in its escalating pollution crisis.
Each winter, the city grapples with smog - a lethal cocktail of smoke and fog - as cold air traps dust, emissions, and smoke from unauthorized agricultural fires.
(Reuters)