The Impact of Three Recent Coal-fired Power Plant Closings on Pittsburgh Air Quality: A Natural Experiment
Creators: name: Russell, Marie C.
name: Belle, Jessica H.
name: Liu, Yang
Publisher: name: Taylor & Francis
Year: 2016
Subjects: subject: Biophysics
subject: Biotechnology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: FOS: Earth and related environmental sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: FOS: Chemical sciences
subject: Ecology
subject: FOS: Biological sciences
subject: FOS: Biological sciences
subject: 69999 Biological Sciences not elsewhere classified
subject: Plant Biology

description: Relative to the rest of the US, the region of southwestern Pennsylvania, including metropolitan Pittsburgh, experiences high ambient concentrations of fine particulate matter (PM<sub>2.5</sub>), which is known to be associated with adverse respiratory and cardiovascular health impacts. This study evaluates whether the closing of three coal-fired power plants within the southwestern Pennsylvania region resulted in a significant decrease in PM<sub>2.5</sub> concentration. Both PM<sub>2.5</sub> data obtained from EPA ground stations in the study region and aerosol optical depth (AOD) data retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard the Terra and Aqua satellites were used to investigate regional air quality from January 2011 through December 2014. The impact of the plant closings on PM<sub>2.5</sub> concentration and AOD was evaluated using a series of generalized additive models. The model results show that monthly fuel consumption of the Elrama plant, which closed in October of 2012, and monthly fuel consumption of both the Mitchell and Hatfield’s Ferry plants, which closed in October of 2013, were significant predictors of both PM<sub>2.5</sub> concentration and AOD at EPA ground stations in the study region, after controlling for multiple meteorological factors and long-term, region-wide air quality improvements. The model’s power to predict PM<sub>2.5</sub> concentration increased from an adjusted R<sup>2</sup> of 0.61 to 0.68 after excluding data from ground stations with higher uncertainty due to recent increases in unconventional natural gas extraction activities. After preliminary analysis of mean PM<sub>2.5</sub> concentration and AOD showed a downward trend following each power plant shutdown, results from a series of generalized additive models confirmed that the activity of the three plants that closed, measured by monthly fuel consumption, was highly significant in predicting both AOD and PM<sub>2.5</sub> at 12 EPA ground stations; further research on PM<sub>2.5</sub> emissions from unconventional natural gas extraction is needed. ImplicationsWith many coal-fired power plants scheduled to close across the US in the coming years, there is interest in the potential impact on regional PM<sub>2.5</sub> concentrations. In southwestern Pennsylvania, recent coal-fired power plant closings were coupled with a boom in unconventional natural gas extraction. Natural gas is currently seen as an economically viable bridge fuel between coal and renewable energy. This study provides policymakers with more information on the potential ambient concentration changes associated with coal-fired power plant closings as the nation’s energy reliance shifts towards natural gas. With many coal-fired power plants scheduled to close across the US in the coming years, there is interest in the potential impact on regional PM<sub>2.5</sub> concentrations. In southwestern Pennsylvania, recent coal-fired power plant closings were coupled with a boom in unconventional natural gas extraction. Natural gas is currently seen as an economically viable bridge fuel between coal and renewable energy. This study provides policymakers with more information on the potential ambient concentration changes associated with coal-fired power plant closings as the nation’s energy reliance shifts towards natural gas.