Grand Canyon National Park, visibility

Mazurek, M., K. A. Hallock, M. Leach, M. C. Masonjones, H. D. Masonjones, L. G. Salmon, and G. R. Cass, Visibility-Reducing Organic Aerosols in the Vicinity of Grand Canyon National Park ... 

A fourth example of data showing the particle distribution was a study that used the DRUM sampler at Grand Canyon National Park in 1984 (22). Recording the size distribution of sulfur was necessary in helping to understand the effects of sulfur on visibility degradation because there were two size modes one near 0.3 xm and one around 0.1 xm. These modes were not present simultaneously but appeared somewhat anticorrelated (see August 14 in Figure 7). 

The United States Clean Air Act of 1977 set as a national goal the prevention of any future degradation and the reduction of any existing impairment of visibility in mandatory class I federal areas caused by anthropogenic air pollution. The Clean Air Act Amendments of 1990 reinforce the support of these goals. (See Chapter 22 foj a discussion of federal classes of areas.) These areas include most of the major national parks, such as the Grand Canyon, Yosemite, and Zion Park. This portion of the Clean Air Act ad-... 

Atmospheric Effects. The presence of fine particles (0.1-1.0 mm in diameter) or N02 in the atmosphere can result in atmospheric haze or reduced visibility due to light scattering by the particles. The major effect of atmospheric haze has been degradation in visual air quality and is of particular concern in areas of scenic beauty, including most of the major national parks such as Great Smoky Mountain, Grand Canyon, Yosemite, and Zion Parks. 

The visibility problem that has resisted solution is that caused by photochemical smog, particularly in the national parks of the western United States. Environmentalists have called this phenomenon the graying of the West. Even though the absolute diminution of visibility in the Grand Canyon may be less than that experienced in eastern U.S. cities, a much higher aesthetic premimn is placed on maintaining the scenic value of such important landmarks. 

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