Drone footage shows toxic foam floating on the Yamuna River in Delhi – video

Toxic foam has been shown floating over India's Yamuna River in Delhi amid the country's annual battle with air pollution. In the winter months, wind speeds drop and cooling air traps pollutants from vehicles, industry and farmers burning agricultural waste. The foam on the river comes from untreated waste, according to a former adviser to the government. Delhi, home to about 33 million people, is regularly ranked the most polluted city in the world

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