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If you've spent any length of time in colder climates, you're probably familiar with the phrase, “Don’t eat the yellow snow.” But there are other, less obvious things in snow you will also want to avoid.

Steven Fassnacht, professor of snow hydrology at Colorado State University, studies water availability by looking at how snow and environmental factors change over time and across different locations. He said most of the contaminants found in Colorado snow come from smokestacks and tailpipes.

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"If you’re downwind from a major industrial source of these, then the likelihood that you have these nitrogen, sulfur, etc., in the snowpack is a lot higher," Fassnacht explained.

Just like the snowflake you cut out from a sheet of paper in kindergarten, Fassnacht noted all the different angles create more surface area than rain, so snowflakes can pull more contaminants out of the air. Researchers are also studying how contaminants like "forever" chemicals, heavy metals and microplastics end up in snow.

If you are spending time in the mountains and rely on snow for your water supply, Fassnacht stressed there are ways to mitigate health risks.

"If you’re going to go out and eat snow all the time and have that as your water source, then you want to think about how you can filter some of these things out," Fassnacht urged. "Microfiltration is one of the good methods."

Fassnacht emphasized all this does not mean you should never catch another snowflake on your tongue. Just be aware of where the snow is coming from. He recommended avoiding snow from places hit by a recent forest fire or dust storm, and from nearby roadways or industrial areas.

"I’d go further away from industrial sources," Fassnacht advised. "I wouldn’t go right to the side of the road, because you have tailpipes. Hike in 100 feet or 200 feet, where you’re a little bit further away."

This story is based on original reporting by Stacy Nick for The Audit.