Overview | How the Blue Ridge Mountains (Almost) Lost Their Blue | Season 1 | Episode 1 | PBS

The trees in the Blue Ridge Mountains are responsible for that dreamy blue haze on the horizon. Trees produce fine mists of volatile organic compounds (VOCs), which scatter blue light waves. In the mid-90s, the area had serious air quality issues. Not only was it dangerous to breathe, the hazy blue was disappearing from the horizon. But it wasn’t just the trees fault. Here’s what happened...