1A Methodology for Quantifying Ozone Transport and Assessing the Benefits of Alternative Control Strategies Paper #933

The Ozone Transport Assessment Group (OTAG) has identified ozone transport as a contributor to ozone exceedances in the eastern U.S. EPA has issued the NOx SIP Call that requires deep NOx emission controls on major stationary sources (mainly utility sources) as a “cost-effective” approach for reducing ozone transport from upwind states on downwind “nonattainment”. However, the technical analyses on which EPA based their NOx SIP Call overstated the contributions of ozone transport, incorrectly evaluated the ozone contributions of the sources that were controlled in the SIP Call, inappropriately examined other levels of control, and used a measure of “cost-effectiveness ” that was not related to achieving any ozone reductions. In this paper we discuss a more detailed assessment of the role of transport on ozone exceedances in the eastern U.S. accounting for the state-specific contributions of elevated and low-level anthropogenic emissions in 2007 under a base case, NOx SIP Call, and several other alternative NOx emission control strategies. The Comprehensive Air-quality Model with extensions (CAMx) ozone source apportionment capability was utilized to assess the contributions of local versus upwind sources to ozone exceedances in eastern U.S. ozone nonattainment areas. The effects of the NOx SIP Call and alternative levels of NOx controls on ozone attainment and the contribution of ozone transport were examined. Finally, a true cost-effectiveness assessment was performed that analyzed the effectiveness of several utility NOx control strategies in terms of dollars per ppb ozone reduced under ozone exceedance conditions in nonattainment areas ($/ppb ozone reduced)