Indians celebrate festival in toxic, foam-covered river

STORY: The foam came from sludge and untreated waste, according to a former adviser to the Delhi government, who added that the city's water board was spraying a food-grade chemical to control it.

The devotees were celebrating Chhath Puja, in which families visit rivers holy in Hinduism to mark the festival. It requires them to stand in the river for long periods and take a dip as they make offerings to the setting and rising sun.

The sight of the foam-covered Yamuna River comes amid the Indian capital’s annual battle on polluted skies this month.

Delhi's air pollution gets worse in winter, when wind speeds drop and cooling air traps pollutants spewed by vehicles, industry and farmers burning agricultural waste in surrounding states to prepare for new planting.