Development of a Voluntary Early Action Compact toControl Ozone Concentrations in the Austin, TexasArea

摘要

Since 1998, the design value for ozone concentrations averaged over 8 hours in Austin,Texas has exceeded or been close to National Ambient Air Quality Standard (NAAQS).In 2002, the area entered into an O3 Flex agreement, committing to voluntary emissionreduction measures intended to maintain compliance with the NAAQS for concentrationsaveraged over 1 hour. Subsequently, the Austin area has been in the forefront indeveloping a voluntary Early Action Compact (EAC) to reduce 8-hour averaged ozoneconcentrations below the NAAQS by 2007, three years before the date required fornonattainment areas. Activities undertaken by the local area pursuant to the EAC haveresulted in a voluntary clean air action plan (CAAP) that has been submitted to the TexasCommission on Environmental Quality (TCEQ) and the U.S. Environmental ProtectionAgency (EPA) for incorporation into the State Implementation Plan (SIP).The EAC has several advantages over the traditional process: it improves the air qualityearlier, it permits the local area to select control strategies instead of using EPAprescribed controls, it allows deferreral of nonattainment designation and relatedrequirements and transportation conformity and nonattainment new source review are notrequired. The EAC CAAP is based on enhanced emissions inventories andphotochemical modeling using the Comprehensive Air Quality Model with Extensions(CAMx). The air quality modeling for 2007 indicated that the area would be on the cuspof attainment or nonattainment of the NAAQS. Consequentially, in order to insure thatthe NAAQS is attained in the future, a suite of control measures have been adopted forimplementation in the area.This paper will describe the development of the emissions inventory and thephotochemical modeling. Results of the base case modeling will be provided.Sensitivity analyses will be described to assess the role of transport from other areas, the sensitivity to ozone precursors and ozone response to proposed controls. The ozoneprecursor control measures will be described.