Current Design Value Status of Monitored Texas Areas Area2008 YTD 4 th High2006-2008 YTD DV Dallas/Ft Worth8491 Marshall/Tyler/Longview7178 EL Paso8781 Waco7172 Beaumont/Port Arthur7881 Austin7477 Houston/Galv/Brazoria8391 San Antonio7478 Corpus Christi7071 Rio Grande Valley6864 Laredo5658
State Implementation Plan Elements Determine compliance and design value with monitors Count precursor emissions in the region (EI) Model an historical ozone episode(s) Test alternative control strategies to determine most effective control path and strategies Adopt rules
Ambient Ozone Monitoring Houston is the most densely monitored region in the nation. Monitored data used for public health notification, determination of compliance, understanding of precursor emissions and trends, and modeling inputs. Challenges include expense, political concerns and public explanatory capability.
Emissions Inventory Observations Must understand precursor sources, amounts, species, and where and when emitted. Concerns about use of EPA calculation methods to represent dynamic processes for point sources. Some source monitoring replacing calculation methods for NOx and HRVOCs from certain sources. Related concerns about on-road and non-road mobile, area and biogenic sources.
Photochemical Modeling Observations Perform photochemical modeling to allow predictions of ozone in attainment year based on growth/controls. Modeling has been particularly challenging in Houston due to land-sea interaction and emissions. Model episodes to date seem more “stiff” and not as responsive to controls (esp. VOCs). Numerous field studies yield useful data, but not always well tied in to modeling needs.
Control Strategy Testing in Houston Model is tool to chart overall path forward, but EPA recognizes it’s not appropriate to use as only test of attainment. EPA developed weight of evidence guidance implemented earlier—states can bring other evidence to support model predictions that are close to attainment.
Control Strategy Adoption Experience Ozone effectiveness, emissions inventory, data analysis and cost of control supposed to help prioritize new controls, but Houston has usually had to adopt “all of the above”. Point sources now highly controlled—Houston looks more like a “typical” urban area in emissions profile. States are federally pre-empted from adopting separate new engine standards—behavior changing rules often only alternative. But politics and public acceptability are often key issues— some behavior changing rules have been repealed after adoption.
New Technologies/Programs Driving Reductions New IR camera in Houston not SIP rule. Used for safety, enforcement, compliance, leak detection, etc., and has made significant reductions in VOCs. Voluntary “best practices” exchange by trade associations helps drive reductions. Also not “on the books”. Engines/fuels improvements still coming on board, will enable progress in these OR/NR sectors for years to come. TERP funding accelerates reductions from new engine technologies. Area sources will need more attention.