A thick dusting of toxic, black snow has coated several towns in Siberia, transforming them into “post-apocalyptic” landscapes, according to Russian media.

The inky snowfall is the result of open coal pits in the Kuzbass Basin, which is home to 2.6 million people and sits on one of the world’s largest coal reserves spanning 10,000 square miles.

Residents in the towns of Prokopyevsk, Kiselyovsk, and Leninsk-Kuznetsky have been posting surreal footage of grayscale snowdrifts, trees, and icicles to social media.

“No cleansing systems, all the waste, dust and dirt, coal lay in the area,” one resident remarked, according to the Siberian Times on Friday. “Our children and us are breathing it. It’s just a nightmare.”

“The future of our children is terrifying,” another reportedly said.

Anatoly Volkov, director general of the Prokopyevskaya coal factory, told local TV that “a shield” (possibly a covering used to contain the dust) had malfunctioned. Prosecutors in the region are allegedly investigating the cause.

The open-air coal pits of Kuzbass are a known health risk, CBS News reported on Monday, and the region was called “the coal heart of Russia” in a 2015 report by the Russian environmental advocacy group Ecodefense. According to Ecodefense, Kuzbass supported 120 mining facilities and 52 enrichment plants at the time. Ninety percent of the coal exported to Britain in 2017 originated in Kuzbass, The Guardian stated on Friday.

Last year, Russian authorities tried to conceal black snow in the town of Mysky with white paint. The ruse was exposed when a woman touched the snow only to find her hand covered in paint, the Moscow Times reported.

“It’s harder to find white snow than black snow during the winter,” Vladimir Slivyak of Ecodefense told The Guardian. “There is a lot of coal dust in the air all the time. When snow falls, it just becomes visible. You can’t see it the rest of the year, but it is still there.”

Not only are coal plants a powerful driver of climate change, coal production can be detrimental to human health. Heavy metals and silica contained in coal dust can trigger asthma and inflammation, and have been linked to lung cancer, stroke, and heart and respiratory disease.

Ecodefense found that Kuzbass has abnormally high rates of tuberculosis, cerebral palsy, and certain cancers compared to other parts of Russia. Life expectancy in the region is also 3 to 4 years shorter than the country’s average, according to the group.