It sounds innocuous enough: traveling to a tributary of India's Ganges to bathe as part of a Hindu ritual. But as CNN reports, some sections of the Yamuna River were far from ripe for bathing in this week. What's being described as white toxic foam currently cover portions of the sacred river, but that didn't keep people from entering the water Wednesday as part of Chhath Puja, a four-day festival tied to the sun god Surya. The AP reports hundreds of people as going knee-deep, with others dunking themselves under. "It's a sewer," one devotee tells the New York Times. "But the sun deity says: 'Even if you stand in a gutter and make an offering, I will protect you for the rest of the year.'"
The foam is thought to be a mix of sewage and industrial waste dumped in the Yamuna from New Delhi-area industries and is believed to contain problematic levels of ammonia and phosphates. Exposure to them can cause respiratory and skin problems. The AP reports the Yamuna is one of the world's most polluted rivers; the city's air is no better, ranking as among the most polluted on the planet. Authorities did try to employ boats and bamboo-stick barricades to deal with the foam, and even tasked workers with spraying fresh water on the river via hose. Still, "the foul odors were inescapable," per the Times. (More India stories.)