Sulfur dioxide emissions down by half since 2005
By Summit Voice
SUMMIT COUNTY — Sulfur dioxide levels in the vicinity of major coal power plants in the Northeast have fallen by nearly half since 2005, according researchers studying data compiled by instruments on NASA’s Aura satellite.
The new findings confirm ground-based measurements of declining sulfur dioxide levels and demonstrate that scientists can potentially measure levels of harmful emissions throughout the world, even in places where ground monitoring is not extensive or does not exist.
The results of the study suggest that the EPA’s 2005 Clean Air Interstate Rule, calling for deep cuts in emissions, is working.
“What we’re seeing in these satellite observations represents a major environmental accomplishment,” said Bryan Bloomer, an Environmental Protection Agency scientist familiar with the new satellite observations. “This is a huge success story for the EPA and the Clean Air Interstate Rule,” he said.
In response to that rule, many power plants in the United States have installed desulfurization devices and taken other steps that limit the release of sulfur dioxide. The rule put a cap on emissions, but left it up to power companies to determine how to reduce emissions and allowed companies to trade pollution credits.
Sulfur dioxide contributes to the formation of acid rain and can cause serious health problems. About two-thirds of sulfur dioxide pollution in American air comes from coal power plants. Geophysical Research Letters published details of the new research this month.
Scientists have used the satellite’s ozone monitoring instrument to observe sulfur dioxide levels within large plumes of volcanic ash and over heavily polluted parts of China in the past. This is the first time they have observed such subtle details over the United States, a region of the world that in comparison to fast-growing parts of Asia now has relatively modest sulfur dioxide emissions. Just a few decades ago, sulfur dioxide pollution was quite severe in the United States. Levels of the pollutant have dropped by about 75 percent since the 1980s due largely to the passage of the Clean Air Act.
The modeling technique based on the satellite data enabled the research team to pinpoint the sulfur dioxide signals from the 40 largest sulfur dioxide sources in the United States — generally coal power plants that emit more than 70 kilotons of sulfur dioxide per year. The scientists observed major declines in sulfur dioxide emissions from power plants in Alabama, Georgia, Indiana, Kentucky, North Carolina, Ohio, Pennsylvania and West Virginia by comparing levels of the pollutant for an average of the period 2005 to 2007 with another average from 2008 to 2010.
“Now that we’ve confirmed that the technique works, the next step is to use it for other parts of the world that don’t have ground-based sensors,” said Nickolay Krotkov, a researcher based at NASA’s Goddard Space Flight Center in Greenbelt, Md., and a coauthor of the new paper. “The real beauty of using satellites is that we can apply the same technique to the entire globe in a consistent way.”
The team plans to use a similar technique to monitor other important pollutants that coal power plants release, such as nitrogen dioxide, a precursor to ozone.