We've all heard the saying, "don't eat yellow snow" – But what about black snow? Or green snow?

In truth, you probably shouldn't be ingesting snow of any color but green snow could be particularly toxic. And that is bad news for residents of Pervouralsk, Russia, where the snow has turned the unusual hue.

So, what exactly is causing the snow to turn green? The number one suspect here is a chrome factory based in Pervouralsk, a city in the central region of Sverdlovsk Oblast with a population of 125,000. But they have denied claims that the chemicals in the snow could cause harm to the health of the public.

"It’s a routine situation for residents that should not cause alarm," Vsevolod Oreshkin, a spokesperson for the factory, told local reporters.

"[The snow] does not threaten lives or health of adults and children. It’s Pervouralsk. There are a whole variety of industrial enterprises here. If we take samples of snow in any place we will see a multitude of dangerous substances."

However, the city's parents and teachers disagree, telling reporters that children have been falling ill since green snow started to drop near to the nursery.

“The children got sick, they had a cough and their skin turned red, rashes on their faces. This is after the walk, when snow covers of yellow color were noticed,” Natalya Solovey told local reporters.

Sadly, this isn't an uncommon occurrence. Locals say they see green snow like this every year. For example, in 2016, when an overflowing pipe leaked out chromium-tainted water.

While elsewhere, coal plants have turned the snow a more gothic color: black. Officials even attempted to cover it up – literally, by coating it in white paint.

Unsurprisingly, people are not happy with the current situation. Protests have broken out in response to the government's lax attitude towards waste management and residents in Sibay have even gone so far as to start legal action over the smog that has smothered areas in the southern Urals.

According to reports, this is just the latest in a long list of environmental problems thought to be hurting Putin's popularity.