Wilmington Air Quality Study Modeling for Neighborhood Assessment

1. Wilmington Air Quality StudyModeling for Neighborhood Assessment Todd Sax Vlad Isakov September 12, 2002 California Air Resources Board

2. Neighborhood Assessment • Program Objective • “Develop source-receptor based, cumulative impact/risk assessment methodologies suitable for evaluating neighborhood-scale air pollution impacts and for comparing neighborhood exposures within a region” (NAP Work Plan) • Develop tools for evaluating local scale impacts and targeting risk reduction strategies September 12, 2002 California Air Resources Board

3. Wilmington • Identified by MATES-II as one of the most impacted areas of the Los Angeles region • Located near • Freeways • Refineries • Ports • Local Traffic • Manufacturing • Local Facilities MATES-II Health Risk Wilmington September 12, 2002 (source: MATES-II, pg. ES-12)

4. Wilmington Study Domain September 12, 2002 California Air Resources Board

5. Wilmington Air Quality Study • Project Objectives • Improve assessment methodologies • Evaluate model results • Develop recommendations for policy development • Communicate results and risks to the public • Project Components • Emissions Inventory • Dispersion Modeling • Model Evaluation • Health Risk Assessment • Exposure Assessment September 12, 2002 California Air Resources Board

6. Wilmington Neighborhood Assessment - Conceptual Plan • Emissions • Point Sources • Industrial • Metal platers • Refineries • Manufacturing Facilities • Other sources: Cr6+, DPM • Commercial • Gas stations • Dry cleaners • Autobody shops • Warehouses • Industrial diesel • Welding facilities • On-Road Sources • Link-based inventory • Evaluate with vehicle • counts • Off-Road Sources • Marine - Port, ARB • Dockside - Port, ARB • Railroads - ARB, Port • Health Risk • Modeling Results • Inhalation health risk • calculation • Multi-media health risk • calculation • Health risk assessment • Exposure • Microscale Modeling • ISCST3 • AERMOD • CALINE4 • Regional Modeling • CALGRID and/or CMAQ • Model Evaluation • Tracer Studies • June 2003 • Powerplant elevated release • Toxics Monitoring • Multiple sites, June 2003 • Focus on diesel particulate • Coordination with POLA • Uncertainty Assessment • Focus on diesel and Cr6+ • Estimate range of pollutant • concentrations possible using • Monte Carlo techniques • Inventory Analysis • Focus on diesel and Cr6+ • Examine by source and release point • Estimate range of possible emissions • using Monte Carlo techniques • Compile by release location

7. Emissions Inventory • Goal: comprehensive emissions inventory • Industrial and Commercial Facilities • Comparing multiple inventory sources (Federal, State, Local) • Conducting on-site surveys of large and small facilities • On-Road Mobile Sources • Building link-based inventory using SCAG light and heavy duty travel demand models • Off-Road Mobile Sources • Supplementing off-road inventories with facility-specific emissions identified by survey • Working with Ports of Los Angeles and Long Beach in inventory development for sources of diesel PM • Integrating spatially allocated off-road emissions from multiple sources September 12, 2002 California Air Resources Board

8. Emissions Inventory - Facilities • Over 2500 businesses in modeling domain • 195 facilities in CEIDARS • Multiple inventory databases • 240 facilities surveyed, ~50% have emissions • More surveys planned

9. Emissions Inventory - Facilities • 195 facilities in CEIDARS • Corrected geo-locations • Integration with existing HRAs • Improved release locations and parameters • Sampled for data quality evaluation

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

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

12. 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

13. 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

14. 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

15. 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

16. TRACER EXPERIMENTS IN WILMINGTON

17. Tracer Study - Dispersion Example

18. 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

19. 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

20. 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

21. 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