Your article shows hazy pictures from Great Smoky Mountains National Park and says the cause of the haze is “volatile organic compounds released by trees.” I’m the air-quality specialist in the park, and I know that 60 percent of the particle mass in the air is sulfate from power plants, not trees, and 80 percent of the haze is from sulfate, not trees. This article is misleading, and pictures of the park should not have been shown, especially if none of the work related to this story was done in the park.

Jim Renfro
Gatlinburg, Tenn.