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LINKING CHANGES IN UTILITY NO X EMISSIONS TO CHANGE IN OZONE AIR QUALITY
Citation:
PORTER, S., E. GEGO, E. ZALEWSKY, A. GILLILAND, J. IRWIN, AND S.T. RAO. LINKING CHANGES IN UTILITY NO X EMISSIONS TO CHANGE IN OZONE AIR QUALITY. Presented at NOAA/EPA Golden Jubilee Symposium, Durham, NC, September 20 - 21, 2005.
Impact/Purpose:
The framework of accountability is based on measuring environmental outcomes using an integrated environmental assessment model - - assessing and documenting relationships between emissions, air quality, atmospheric deposition, and effects to public health and ecosystems. Work in AMD will focus on relating changes in emissions to changes in environmental conditions prospectively, and the retrospective attribution of observable improvements in environmental conditions to specific emission control strategies.
1.Emission reductions observed in ambient air and atmospheric deposition
Since the 1990 Clean Air Act Amendments, a greater number of stationary sources of SO2 and NOx emissions have installed continuous emissions monitoring systems. Improved systems for tracking emissions from mobile sources have also been developed. At this level, an accountability framework provides a bridge between measured emission reductions and changes in the ambient environment. Resources under this initiative would be applied to analyze specific primary and transformed emission products in ambient air and in atmospheric deposition (e.g., nitrogen oxide, particle nitrate) over relevant geographic areas.
2.Predicted air quality and atmospheric deposition improvements
Resources would be applied to enhance the predictive capability to address whether emissions reductions have resulted in the expected improvements in air quality and deposition, for example:
Reduced ozone, PM2.5 concentrations
Reduced deposition of NOx transformations (e.g., wet and dry deposition of nitrate)
Diagnostic species (e.g., peroxides, nitric acid, ammonia) useful for model evaluations and interpreting dynamic changes in the atmosphere associated emissions reductions
In addition to assessing whether the improvements have occurred, this would also entail assessing whether these improvements can be attributed to specific emission control strategies.This team's objective is to research and develop analytical tools that will quantify the effect of regional NOx emission reductions on ambient air quality, thus providing a measure of control stategy accountability.
Description:
The NOx State Implementation Plan (SIP) Call was designed to reduce Northeastern U.S. NOx emissions from utilities. With these reductions, it was anticipated that the amount of ozone attributed to transport from other states would in turn be reduced. In this study, ozone time series data are analyzed at several Northeastern U.S. sites from 1995 through 2004 to consider whether a ozone reduction can be seen. Results show observed ozone reductions at the sites, especially when only considering time periods when the site is downwind of the Ohio River Valley, which had substantial NOx reductions as part of the NOx SIP call.