Air quality is fundamentally important to the preservation of natural and cultural resources and values. Shenandoah is located downwind from and near major industrial and urban areas. Monitoring and research projects confirm that human-caused air pollution has impaired the park's air quality, visibility, stream-water chemistry, soils, native fish and vegetation.
Air pollution, particularly during the summer season, has significantly degraded the distance, color, contrast and landscape details of park views from Skyline Drive, the Appalachian Trail, and high points in the park. Acid deposition has adversely impacted the acid-sensitive blacknose dace and acid-tolerant Appalachian brook trout at the individual, population and community levels. Despite improvements in air quality under the Clean Air Act, the park's visibility and most sensitive aquatic systems are still degraded relative to estimated natural or pre-industrial background conditions. In addition, the park does not currently meet ground-level ozone standards set by the U.S. Environmental Protection Agency to protect public health and welfare. The park registers some of the highest ground-level ozone measurements recorded at all national parks. Foliar injury caused by ground-level ozone has impaired the aesthetics of many of the park's 40 known ozone-sensitive plant species. Scientists are also concerned about potential ground-level effects on forest growth and the health of several species.
The National Park Service is committed to upholding its affirmative resource stewardship responsibilities under the Clean Air Act through continuation of a strong monitoring and research program, and through resource-efficient regional planning. The Service is also involved in educational efforts, implementation of environmental leadership activities, and providing review and comment on proposed new or modified sources of air pollution.