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North Carolina meets tougher federal standard for sulfur dioxide


RALEIGH – All air quality monitors in North Carolina now comply with the new, more stringent standard for sulfur dioxide, or SO 2, that the U.S. Environmental Protection Agency adopted for the noxious gas in 2010.

The EPA adopted a stricter one-hour standard of 75 parts per billion (ppb) for sulfur dioxide in June 2010 due to concerns about its effects on public health and the environment. One of the first regulated air pollutants, SO 2 is harmful to the respiratory system, particularly among those with asthma and other respiratory problems. It also can damage buildings, trees and other vegetation.

When EPA adopted the new standard, North Carolina had an air quality monitor near Wilmington in New Hanover County with SO 2 levels that exceeded the limit. Since then, the N.C. Division of Air Quality, or DAQ, has worked with local governments and industries to reduce SO 2 emissions, and measured levels have steadily declined over the past three years.

“This is a great example of the Division of Air Quality working with local governments and businesses to address a problem with serious economic and environmental implications,” said John Skvarla, secretary of the N.C. Department of Environment and Natural Resources. “Division staff took a proactive approach to reduce sulfur dioxide emissions in the Wilmington area, thus protecting public health and the environment while avoiding more burdensome federal permitting requirements for local industries.”

The EPA recently notified the state that its review of air quality monitoring data found no violations of the 2010 SO 2 standard in any areas in North Carolina. As a result, the EPA announced it would not designate any SO 2 non-attainment areas in North Carolina; non-attainment is the agency’s term for areas not complying with an air quality standard.

The Division of Air Quality worked to improve sulfur dioxide levels by analyzing wind patterns on days with high SO 2 measurements , indentifying large industrial sources near Wilmington, and working with key industries to reduce their SO 2 emissions. For example, DAQ issued a revised air permit for Invista in July 2012 that requires the company to increase the height of its emissions stacks and use low-sulfur fuel in its boiler and other equipment. Another SO 2 emissions source, Southern States Chemical, closed its plant near the monitor in December 2010 and gave up its air permit in November 2011.

In addition, Progress Energy is converting its coal-fired Sutton power plant, the largest source of SO 2 emissions in the area, to natural gas near the end of this year. When completed, that change will largely eliminate Progress Energy’s SO 2 emissions in New Hanover County.

“The improvement in sulfur dioxide levels has been a team effort involving numerous DAQ staff, local governments and businesses in the Wilmington area,” said Sheila Holman, director of the Division of Air Quality. “We expect to see further improvements once Progress Energy converts its Sutton coal plant to cleaner-burning natural gas.”

More information about DAQ’s efforts to reduce SO 2 emissions can be found at this page on division’s website: .

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