Don't Eat The Yellow Snow

There is a lot of industrial mining activity in that region. Smelters with high sulfur emissions can produce such an effect. There are even "dead zones" around industrial settlements as the heavy metal fallout turned the tundra and soils so acidic everything died off.

Similar events happened in Sudbury Ontario at the giant INCO smelter. When NASA was training astronauts for moon landings, they sent them to Sudbury. It's about the only moonscape environment with a - barely - breathable atmosphere.

INCO built the "superstack" starting in 1972, which at 1,247 ft is the tallest chimney in North America and indeed the world until 1987, when the GRES-2 powerstation in Kazakhstan built their own superstack.

Ironically though the superstack greatly reduced the environmental decimation of Sudbury, it has become the largest single point source of acid rain for all of North America. In Ontario alone up to 7,000 lakes have been severely affected by the superstack emissions.