Satellite observations show drop in NOx emissions in eastern US

Washington (Platts)--8Dec2006

New satellite observations show that emissions of nitrogen oxides -- a
major smog-forming pollutant -- are declining over the eastern US, researchers
with the National Oceanic and Atmospheric Administration and the University of
Bremen, Germany, said Friday.

The researchers said the new satellite observations mark the first time
space-based instruments have detected the regional impact of pollution
controls implemented by coal-burning electric power plants in the 1990s.
The findings were published this month in Geophysical Research Letters, a
publication of the American Geophysical Union.

NOAA and the university said high-precision instruments aboard European
satellites have detected a 38% drop in nitrogen dioxide in the Ohio River
Valley and nearby states between 1999 and 2005.

Nitrogen dioxide and nitric oxide are two gases that form a group of
pollutants known as nitrogen oxides, which are created primarily through
burning fossil fuels. When combined with other gases and sunlight, they form
ozone, the major urban air pollutant in smog. Ground-level ozone harms human
health and vegetation and is a key pollutant targeted by the US Environmental
Protection Agency, the researchers said.

"The reduction in NOx emissions from these large eastern power plants is
dramatic," says Greg Frost, an author of the study and a scientist in the NOAA
Earth System Research Lab and the Cooperative Institute for Research in the
Environmental Sciences, in Boulder, Colorado. "With these new data, model
results predict lower ozone pollution across much of the eastern US."

Computer model results show the nitrogen oxide emission reductions should
decrease ozone levels in the six states of the Ohio River Valley -- Illinois,
Indiana, Ohio, Pennsylvania, Kentucky and West Virginia -- as well as in North
Carolina, Virginia, Georgia and Texas.

Home to many large electric power plants, the Ohio River Valley produced
a third of all US nitrogen oxide emissions from power plants during the 1990s,
the study said. The region's nitrogen oxide emissions drift downwind,
producing ozone in urban areas hundreds of miles away and hindering their
compliance with EPA standards, especially in the Northeast. In response, the
EPA mandated reductions of stationary sources of nitrogen oxide emissions,
primarily eastern US coal-fired power plants.

After implementing pollution controls, utility companies reported a 45%
decline in nitrogen oxide emissions from individual power plants in 2004
compared with 1990 levels, even though electricity production increased
during this period, NOAA said, adding that the study is the first to verify
from space that these single-point reductions have had a measurable impact on
the atmosphere across the entire region.

The authors reported much smaller decreases in satellite measurements of
atmospheric nitrogen dioxide in the northeastern states, where the primary
source is fossil fuel combustion in cars and other vehicles. The highest
nitrogen dioxide levels occurred in areas with combined urban, industrial and
power plant sources, such as the Northeast urban corridor, Chicago,
Pittsburgh, Detroit, Toronto, Atlanta, Dallas and Houston.

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