Air Quality Issues of Electricity Production:
Ozone (Smog) and Fine Particulates

While Climate Change and Acid Rain impact the general environment on a regional or global scale, air emissions from fossil fuel power plants also have direct impacts on human health. Most especially, human health is jeopardized from the formation of ozone (or "smog") and fine particles that result from fossil fuel combustion technologies. Ozone is formed as a result of chemical reactions of nitrogen oxides emitted into the atmosphere; fine particulates may form either in power plant smokestacks or in the air as a result of the emissions of any of the three primary gasses from fossil generation plants - carbon dioxide, sulfur dioxide or nitrogen oxides. Both ozone and fine particulates pose health risks within the vicinity of the emitting power plants or may travel hundreds of miles and pose health risks far from the sources of the precursor emissions.

Ozone

What is ozone?

Ozone is a molecule comprised of three oxygen atoms linked together. Stratospheric ozone provides a vital protective shield against the sun's ultraviolet radiation and occurs naturally in the upper reaches of the atmosphere. Tropospheric ozone, in contrast, can be extremely harmful to human health and the environment as it becomes a major pollutant when created at ground level.

Ozone is not emitted directly into the environment. It is produced by a complex chemical reaction when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight. NOx is produced when cars and trucks, electric power plants and industrial processes burn fossil fuels. VOC's are unstable and easily-evaporated organic compounds present in vehicle exhaust, paint fumes, and industrial process waste. The interaction between these two chemicals create ozone pollution, the primary harmful ingredient in urban smog.

Weather conditions are critical to ozone formation, which is greatest during the summer, when long hours of sunlight and high temperatures speed the photochemical reactions that produce ozone. These chemical reactions take place while the pollutants are being blown through the air by wind. What this means is that ozone pollution can be far more severe many miles away from the original power plant site that generates the NOx precursors. As a result, tall smokestacks that emit NOx can contribute to air pollution build-up in downwind states located hundreds of miles away.

What are the consequences of ground level ozone?

At ground level, ozone can damage humans, green plants and everyday materials.

Human Health Effects
Ozone reacts readily with membranes lining the lung's air passages as well as the eye. Mounting scientific evidence links ozone to a number of short- and long-term respiratory and visual problems:

• Decreased ability of the lungs to function properly, increasing respiratory illness, especially in children that are active outdoors.
• A long list of breathing problems: shortness of breath, coughing, wheezing, chest tightness, headaches and nausea.
• Pronounced allergic reactions.
• Increased hospital admissions for respiratory problems, especially for children with pre-existing conditions such as asthma.
• Reduced ability to exercise resulting in poor athletic performance.

Plants and Crops
Ozone interferes with the ability of green plants to convert sunlight into useful energy. This interference with the normal photosynthesis process causes damage to agricultural crops, commercial timber and natural forest ecosystems, ornamental plants (grass, flowers, shrubs, trees) and other natural flora. The EPA estimates that ground-level ozone pollution is responsible for several hundred million dollars in annual losses from reduced crop yields.

Materials
Ozone damages rubber products, dyes and paints, fabrics, plastics and electrical components. The damage comes in the form of corrosion, fading and cracking.

How does electricity production contribute to ozone formation?

Electric power plant emissions account for about one-third of all NOx released into the atmosphere from human sources. As noted, NOx is the major precursor of ground-level ozone.

NOx emissions rates can vary significantly among generating companies, individual power plants and geographic regions. A 1997 study conducted by the Natural Resources Defense Council, Public Service Electric and Gas and the Pace Energy Project found that the emissions per unit output of electricity varied by a factor of ten between the highest and lowest polluting power companies. The study concluded that much of the difference in pollution rates is directly attributable to air emission control requirements, which can vary immensely depending upon any specific power plant's vintage and precise location. Many electric generators in the Midwest and Southeast release largely uncontrolled NOx, emissions. Tighter NOx emissions limits prevail in areas currently out of compliance with air quality standards - such as the Eastern U.S. On top of that, disparate air quality regulations allow many older coal-fired generators to emit NOx at a rate five to ten times that of a new coal plant and 20 to 30 times that of a new natural gas electricity generator.

EPA has recently taken several steps to limit NOx emissions from power plants: the issuance of stricter air quality standards for ozone; requirements to retrofit power plants with control technology under provisions of the acid rain program; and a requirement that states contributing to the non-attainment, or interfering with attainment of air quality standards in downwind states, submit new air quality plans focused on limiting interstate pollution. EPA's effort to control the environmental and health effects of ozone has been dealt a setback, however, by the Appellate Court for the District of Columbia, which struck down EPA's revised ozone standard. This decision is being appealed.

How can consumer electricity choice address ground-level ozone?

The advent of competition in the electricity business presents both risks and opportunities for those concerned about the air quality and public health impacts of electricity generation. Competition has already led to increased use of high-polluting coal-fired power plants that are exacerbating the air quality problems outlined above. If concerned about ozone pollution, consumers can "vote" with their pocketbooks and switch to power products consisting of non-polluting renewable energy sources. Even supply portfolios made up, in whole or in part, of electricity generated by traditional fossil-fuels (coal, oil, natural gas) exhibit a wide range of environmental performance. A well-informed consumer would identify and select those electricity suppliers whose sources have taken steps to greatly reduce harmful NOx emissions.

References:

The Energy Project, Land and Water Fund of the Rockies, How the West Can Win: A Blueprint for a Clean and Affordable Energy Future (1996).

ESEERCO, New York State Environmental Externalities Cost Study Vol. 1 (1995).

National Resources Defense Council (NRDC), Benchmarking Air Emissions of 100 Largest Electric Generation Owners in the U.S.
http://www.nrdc.org/air/energy/util/index.asp

Pace University Center for Environmental Legal Studies, Environmental Costs of Electricity (1990).

Washington University in St. Louis, Effects of Ozone Pollution (last modified Apr. 14, 2000)