"Three years ago, the Forest Service sampled winter air in the gorge, and found visible haze 90 percent of the time, with 15 percent severe. While not yet harmful to people, the air damages sensitive plant life such as lichen, orchards, soil and probably Indian carvings called petroglyphs and pictographs. Acid found in the air pollution can change soils, destroy trees and dissolve rock over time. Those study results were reported by Mark Fenn of the Forest Service's Pacific Southwest Research Station." Read the rest at The Columbian online.