Integrating inventory with GIS platform 1 km or 100m grid cells

1. Emissions Inventory - Facilities • Integrating inventory with GIS platform • 1 km or 100m grid cells • Drill-in capability on selected sources

2. Emissions Inventory - On-Road Sources Wilmington Road Links, SCAG Models

3. Air Quality Modeling • Goal • Develop and evaluate methodologies to estimate annual average concentrations of pollutants released from multiple sources on a neighborhood scale • Micro-scale modeling • Focus on air toxics with defined unit risk factors or reference exposure levels and particulate • ISCST3, AERMOD, CALINE • Regional modeling • Focus on southern California • 30 toxic pollutants • Photochemical models (e.g. CMAQ and/or CALGRID) September 12, 2002 California Air Resources Board

4. Wilmington Wind Patterns Summer - daytime Summer - night-time Long Beach, Aug./Sept. • Typical coastal wind patterns • Daytime southerly and westerly flow September 12, 2002 California Air Resources Board

5. Model Evaluation - Overview • Assess accuracy of model results • Tracer studies • Received new contract between ARB, CEC, UCR to conduct a tracer release from an elevated stack in Wilmington • Use existing tracer data to evaluate model performance and improve model algorithms • Supplemental monitoring • Focus on diesel particulate, but there is currently no acceptable method for measurement • Uncertainty analysis • Assess uncertainty for a subset of facilities in the modeling domain: Diesel PM (DPM) and Hexavalent Chromium (CrVI) emissions September 12, 2002 California Air Resources Board

6. Model Evaluation - Tracer Study • Model performance evaluation - ensure model predictions are reliable • Develop database of tracer concentrations • Extend existing tracer database • Wilmington - elevated release (stack) • Improve dispersion algorithm • urban boundary layer conditions • large vertical gradients in wind speed and turbulence are present • Goal: improve model algorithms, incorporate into dispersion models (such as AERMOD) • Site: not yet chosen. Date: June 2003. September 12, 2002 California Air Resources Board

7. TRACER EXPERIMENTS IN WILMINGTON

8. Tracer Study - Dispersion Example

9. Model Evaluation - Toxics Monitoring • Diesel PM is major inhalation risk in Wilmington • No accepted methodology for measuring DPM • Elemental carbon as a surrogate does not work well in all cases • Major CMB studies provide conflicting results • Likely Approach - CMB Analysis with Polycyclic Aromatic Hydrocarbon measurement • Multiple sites over several weeks, June 2003. • Measure PM 2.5, OC/EC, SVOC PAH, elements • Evaluate differences between sites, between days, and correlation between pollutants • Looking for additional funding to expand study September 12, 2002 California Air Resources Board

10. Model Evaluation - Uncertainty Analysis • Provide context to estimated pollutant concentrations - evaluate assumptions • Uncertainty sources: emissions, spatial allocation of emissions, model options and release parameters, conceptual uncertainty in model physics • Approach • Focus on selected sources: CrVI and DPM • Evaluate range of possible emissions from each source through survey, databases, analysis of emission factors • Determine specific conditions of each emission release • Estimate range of inter-annual variability in meteorology • Assess range of acceptable model options and conduct sensitivity analysis • Use Monte Carlo statistical techniques to estimate confidence limits in modeling results

11. Health Risk Assessment • Evaluate inhalation health risk • Investigate alternative assessment methods • Goal: Provide perspective to inhalation health risk • Some pollutants have important multipathway component • Estimate differences in predicted health risks through evaluating multipathway contributions for selected pollutants • True inhalation exposure is a function of the amount of pollutant people breathe. • People spend time in microenvironments • Microenvironmental pollutant concentrations may be different than outdoor, ambient concentrations • May be possible to use existing data and models to compare ambient exposure to total exposure for selected pollutants September 12, 2002 California Air Resources Board

12. Expected Conclusions • Answer relevant policy questions • Which inventory sources are most important? • Do commercial facilities impact cumulative risk? If so which ones? • Can on-road emissions be accurately allocated to individual streets? If not, what can be done? • Which models are most appropriate for neighborhood assessment? Do approaches vary by pollutant? • How should models be improved? • How reliable are modeling results? • What is the impact of exposure to ambient air pollution relative to estimated personal exposure? September 12, 2002 California Air Resources Board