2003 Power Failure Reveals Role of Power Plants in Air Pollution

Newswise — A new study by researchers at the University of Maryland shows that skies were dramatically bluer and the air was much healthier during the August 2003 blackout that hit the northeastern United States and southeastern Canada. The findings shed new light on the contribution of power plants to air pollution along the east coast of the United States.

Atmospheric measurements taken by the scientists some 24 hours after many power plants had essentially shut down found a 90 percent reduction in sulfur dioxide, a gas that leads to haze and acid rain, and a 50 percent reduction in smog, or ground-level ozone. The Maryland scientists also found that the amount of light scattering particles in the air dropped by 70 percent and visibility increased by some 20 miles.

A Clear Impact "The clean air benefit [of the blackout] was realized over much of the eastern United States," write researchers Lackson Marufu, Bryan Bloomer, Charles Piety, Bruce Doddridge, Jeffrey Stehr, and Russell Dickerson of the Department of Meteorology and Brett Taubman of the Department of Chemistry. "The improvement in air quality provides evidence that transported emission from power plants hundreds of kilometers upwind play a dominant role in regional haze and [smog]," they say.

Their paper, "The 2003 North American Electrical Blackout: An Accidental Experiment in Atmospheric Chemistry," will be published in the next issue of Geophysical Research Letters.

"What surprised us was not so much the observation of improved air quality during the blackout, but the magnitude of the observed improvement," says research scientist and lead author Lackson Marufu. "The improvement in air quality was so great that you could not only measure it, but could actually see it as a much clearer less hazy sky."

Co-author Russell Dickerson, professor and chair of the Department of Meteorology, said, "Scientists long have speculated about what would happen to air quality if all the power plants suddenly disappeared. The blackout performed for us an experiment that would have otherwise been impossible. The resulting clean air that we observed over large areas of rural PA was headed toward the Mid Atlantic, so cities from Washington to New York reaped the benefits of bluer skies, at least for a few days."

Fossil Fueled Pollution

Fossil fuel burning power plants account for more than half of electrical energy production in the United States, but also about 22 percent of the nitrogen oxides and about 69 percent of the sulfur dioxide emissions. In lower levels of the atmosphere, nitrogen oxides combine with volatile organic compounds in the presence of sunlight to produce ground-level ozone. Ozone found high above the earth in the stratosphere absorbs solar ultraviolet radiation to protect human health and the environment. However, the ground-level ozone found in the lower regions of the atmosphere is the main ingredient in smog.

In summertime, under a high pressure front, westerly winds carry power plant emissions from states like Ohio, West Virginia and Pennsylvania. These pollutants induce severe smog and haze events in the northeastern U.S., primarily comprised of ground-level ozone and sulfate-dominated fine particles. Both pollutants have been linked to adverse health effects, degradation of the environment, and global climate change.

For the current study, airborne measurements were made over Maryland and Virginia (outside the blackout area) and Pennsylvania (in the center of the blackout area) on August 15, 2003, approximately 24 hours into the blackout. The results were compared to measurements taken the previous summer in the same locations and under similar meteorological conditions when upwind power plants were operating normally.