The harmful public health and ecological impacts from the nation's older coal- and power plants are numerous and significant. Electric power plants are, by most measures, the nation's largest industrial source of air pollution. Indeed, power plant emissions are the largest contributor to the largest environmental risk to public health: disease and premature death due to inhalation of fine particles.
Power plant air emissions cut a broad swath of damage in terms of human health as well as the global environment. Unhealthy levels of smog trigger millions of asthma attacks each summer; fine particles shave years off people's lives and damage lungs; acid rain damages forests, lakes, bays, and crops; mercury contaminates fish and wildlife; shrouds of haze cloak our national parks; extraction of fuel despoils the environment; and improper disposal of solid and liquid wastes from power plant operations contaminates groundwater. These are just some of the major problems associated with the nation's fossil electric generating fleet.
If we hope to reverse this trend, we must achieve major reductions of the major power plant pollutants: sulfur dioxide, nitrogen oxides, mercury, carbon dioxide, and other air toxins.
The effects of sulfur dioxide include damage from acid rain, fine airborne particles that harm lungs, and the haze that obscures scenic vistas in national parks and urban areas. Power plants contribute about two-thirds of the sulfur dioxide emitted in the United States each year. Reductions of sulfur dioxide emissions of 75 percent or more will be necessary to allow ecosystems to recover from acid rain damage by mid-century.
Science has proven that the problem of acid rain has not been solved and that the acid rain provisions of the 1990 Clean Air Act Amendments will not be sufficient to fix the problem. More than 150 years of sulfur deposition have taken a serious toll on ecosystems. Although sulfur emissions have declined somewhat in recent years, they remain high when compared with historic background levels.
Lakes and streams and the aquatic life they contain are experiencing the most widespread impact from high concentrations of acidity. The most sensitive water bodies are those that are located atop soils with a limited ability to neutralize acidity. Sensitive areas in the United States include the Adirondack Mountains, Mid-Appalachians, southern Blue Ridge, and high-elevation western lakes. (1)
Water bodies are affected not just by the chronic acidification that occurs from cumulative deposition but also by episodic acidification that occurs when pulses of highly acidic waters rush into lakes and streams during heavy downpours of rain and periods of snow melt when acids collected in snow over the winter are released.
In some places, chronic and episodic acidification together have completely eradicated fish species. For example, some acid-sensitive fish populations have disappeared, and others have been reduced in Pennsylvania streams where they formerly occurred in large numbers. Acidification, together with high levels of aluminum leaching, is blamed for the reduction in fish diversity in many Pennsylvania streams over the past third of a century. (2)
Acid rain also saps calcium from the needles of trees, weakening the cell membranes and making the trees susceptible to damage from diseases, insect outbreaks, and freezing in winter. (3) Acid rain depletes soil nutrients--largely calcium and magnesium--needed for healthy forest growth. The U.S. Geological Survey has shown that calcium in forest soils has decreased at locations in the Northeast and Southeast, and acid rain is one of the major factors contributing to this depletion. (4)
Although most evidence shows that conifers tend to be more vulnerable than hardwood trees, acid rain also harms deciduous trees. Detection of patches of dead trees in hardwood forests of the Southern Appalachians has been attributed to the interactions of many stressors, including declining air quality. (5)
Beyond the Amendments
Scientists believe that cuts called for in the 1990 Clean Air Act Amendments will not be adequate to protect surface water and forest soils of the northeastern United States from acidification. (6) Recent work by scientists with the Hubbard Brook Research Foundation found that an additional 80-percent reduction in sulfur from levels that went into effect in 2000 under the acid rain program of the Clean Air Act Amendments of 1990 would be needed for biological recovery to begin by mid-century in the northeastern United States. (7)
Meanwhile, model simulations in the Shenandoah mountains illustrate that a greater than 70-percent reduction in sulfate deposition from 1991 levels would be needed to increase viability of brook trout. A 70-percent reduction would simply prevent further increase in Virginia stream acidification. (8) In Great Smoky Mountains National Park, two separate ecosystem models have concluded that sulfate reductions of 70 percent are necessary to prevent an increase in acidification impacts. (9)
Canadians in the Acidifying Emissions Task Group have called for a 75-percent reduction in U.S. sulfur emissions that went into effect in 2000 under the acid rain program of the Clean Air Act Amendments. (10)
Clearly, nothing short of an overall 75-percent reduction will solve the problems associated with acid rain. Tighter, targeted cuts may be necessary for sources directly affecting sensitive areas. And the longer we wait for the reductions to begin, the longer we will await recovery of these systems.
Cost in Lives
If the damage to ecosystems weren't compelling enough to warrant cuts in sulfur dioxide emissions, consider this: research indicates that a 75-percent reduction in power plant sulfur dioxide emissions will avoid more than 18,000 particulate-related premature deaths. (11)
One of the air pollutants most carefully studied in the 1990s is particulate …