The National Park Service has a responsibility to protect air quality and resources that might be adversely affected by air pollution under the NPS Organic Act and the Clean Air Act (CAA). The Organic Act directs the NPS to conserve the resources and values of parks in a way that will leave them "unimpaired" for the enjoyment of future generations. One of the purposes of the CAA is "to preserve, protect, and enhance the air quality in national parks" and other areas of special national or regional natural, recreational, scenic or historic value. The CAA includes special programs to prevent significant air quality deterioration in clean air areas, and to protect visibility in major national parks and wilderness areas. The CAA provides some tools and many opportunities to protect park resources. In some cases, the CAA gives the federal land manager a special role in decision-making when park air quality might be affected. These laws provide the basis for the NPS's general policy (Management Policies, 4.7.1) of promoting and pursuing measures to safeguard park resources and values from the adverse effects of air pollution.