National parks, visibility

Committee on Haze in N ational Parks and Wilderness Areas, N ational Research Council, Protecting Visibility in National Parks and Wilderness Areas, National Academy Press, Washington, D.C., 1993. 

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-... 

A survey by national park personnel indicates that large areas of the United States are subject to varying degrees of visibility degradation (1). The middle portion of the eastern half of the country and the Florida Gulf Coast are subject to widespread hazy air masses associated with stagnation conditions. Large portions of the western half of the country are subject... 

Other Titles - The Clean Air Act Amendments of 1990 continue the federal acid rain research program and contain several provisions relating to research, development and air monitoring. They also contain provisions to provide additional unemployment benefits through the Job Training Partnership Act to workers laid off as a consequence of compliance with the Clean Air Act. The Act also contains provisions to improve visibility near National Parks and other parts of the country. Strict enforcement of the Clean Air Act Amendments is the driving force behind pollution abatement. Non-compliance is simply not an option, since there are both financial and criminal liabilities that outweigh any benefits derived from a business. 

Protecting Visibility in National Parks and Wilderness Areas (1993)... 

One place this problem has become especially severe is the nation s national park system. Visitors to national parks have found their enjoyment of the natural scenery compromised by poor air quality that leaves famous and noteworthy features only barely visible. For this reason, one section of the 1977 Amendments to the Clean Air Act provided for a program of monitoring and pollution control in the nation s 156 national parks and wilderness areas. Poor visibility resulting from high particulate concentration has safety effects also. Automobile drivers and airline pilots may find that they are able to see shorter distances and less clearly, increasing the likelihood of accidents involving other vehicles and aircraft. 

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). 

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. 

Figure 1 Impairment of visibility by aerosols. Photographs at Yosemite National Park, California, USA. (a) Low aerosol concentration (particulate matter of aerodynamic diameter less than 2.5 p,m, PM2.5 = 0.3 p,g m particulate matter of aerodynamic diameter less than 10 p,m, PMio = 1.1 ag m estimated coefficient of light scattering by particulate matter, (r p, at 570 nm = 12 Mm ). (b) High aerosol concentration (PM2.5 = 43.9 p,g m PMio = 83.4 p,g m estimated (r p at 570 nm = 245 Mm ) (reproduced by permission of National Park Service,...

This book reviews methods for measuring airborne compounds and includes recent developments from experts in the field. Topics range from optical remote sensing to VOC sampling and analysis to visibility research in national parks. 

CSA repeals or significantly weakens many provisions of existing law that have protected health and the environment since the enactment of the 1970, 1977, and 1990 Clean Air Act (CAA) amendments, including Interstate air pollution protections New Source Review requirements Air Toxics controls applicable to the electric power industry Provisions designed to bring air quality into attainment with national standards and to protect areas from air quality degradation The deadlines by which states must attain national air quality standards and Visibility protections for National Parks. ... 

Finally, particulate matter (PM), or the solid and liquid particles that are released into the atmosphere, comes from both the actual emissions of particulates and the reaction between atmospheric molecules and SO2 or NO. Particulate matter can be divided based on the size of the particle. Health effects include respiratory distress as well as cancer and permanent lung damage. Fine particulate matter (<2.5 microns in size, PM 2.5) is a major cause of reduced visibility, or haze, in many parts of the country. The EPA notes visibility in several of our nation s national parks and wilderness areas has been negatively affected by high particulate levels in the air. Particulate emissions that are not the result of other pollutants or natural causes come primarily from the industrial sector (EPA 1995). 

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. 

Regional Haze Haze produced by a multitude of sources and activities that emit fine particles and their precursors across a broad geographic area. National regulations require states to develop plans to reduce the regional haze that impairs visibility in national parks and wilderness areas. 

An important application of the theory of light scattering and extinction is the study of visibility in the atmosphere, the most striking feature of particulate pollution. This subject has received considerable attention in the United States since the passage of the Clean Air Act of 1977, which mandated the protection of visibility in American national parks and wilderness areas. 

---