After India's biggest firework party of the year, Delhi woke up to a pollution hangover on Monday with the capital forced to breathe hazardous levels of toxic particles.
A thick smog engulfed landmarks such as the capital's Red Fort and India Gate while drivers had visibility cut by the haze that built up after the Diwali holiday weekend.
With the pollution threat growing over the past decade, the Supreme Court banned most fireworks for the Hindu festival of lights. However, few revellers followed the order.
Firecrackers and rockets lit up the night sky and left clouds of smoke, adding to emissions from cars and trucks and stubble fires by farmers around Delhi that have made it the world's most polluted capital.
Tens of thousands of people set off firecrackers into the early hours of Monday, pushing the government air quality index beyond the top recordable level of 999.
While the pollution was less serious than previous years, the amount of the most harmful PM 2.5 pollutants was still more than 20 times international safe levels at several locations in the city of 20 million people during commuting hours.
The government monitoring system said air quality was "very poor" on Monday morning.
The 2.5 particulate matter (PM2.5) measures less than 2.5 microns and can penetrate the lungs through the blood system, causing serious respiratory and heart diseases.