Air pollution is currently recognized as one of the most significant threats to the resources of the Sierra Nevada. Sources are local, regional, and in some instances, global. The National Park Service in cooperation with state and other federal agencies are making concerted efforts to reduce the damage caused by air pollution. This is done by an intensive monitoring program, support for research, and expanding the education of park visitors and those concerned about the future of Yosemite National Park.

Air quality has a dramatic impact on visibility in the Yosemite Valley. Move your pointer over the image to see a clean-air day in the Valley. NPS Photos.