1. ` 1 Source Attribution of Mobile Source Air Toxics Eric M. Fujita, David E. Campbell, William P. Arnott and Barbara Zielinska Division of Atmospheric Sciences Desert Research Institute University and Community College System of Nevada Reno, Nevada 2006 CRC MSAT Workshop Phoenix, AZ October 23-25, 2006

2. ` 2 Source Apportionment of SI and CI Exhaust to Ambient MSAT Concentrations Receptor Modeling – Chemical Mass Balance Correlations of MSAT with CO, NMHC, NOx or BC/EC. Multivariate regression of CO, NOx, PM 2.5 or BC with LDV and HDV traffic volumes Spatial variations ambient MSAT relative to known variations in LDV and HDV traffic volumes. Temporal variations in ambient pollutant concentrations (e.g., day of week).

3. ` 3 Acknowledgments Weekend Ozone Study – Sponsor: DOE’s Office of FreedomCAR and Vehicle Technologies, Dr. James Eberhardt and National Renewable Energy Laboratory, Dr. Douglas Lawson – Additional Support: South Coast Air Quality Management District Gasoline/Diesel PM Split Study – Sponsor: DOE’s Office of FreedomCAR and Vehicle Technologies, Dr. James Eberhardt and National Renewable Energy Laboratory, Dr. Douglas Lawson – Additional Support: U.S. Environmental Protection Agency. California Bureau of Automotive Repair, South Coast Air Quality Management District, Ralph’s Supermarket Distribution Center Assessing Exposure to Air Toxics in Microenvironments Dominated by Mobile Sources – Sponsor: Health Effects Institute, Dr. Debra Kaden – Additional Support: South Coast Air Quality Management District.

4. ` 4 Weekday Variations in CO and Black Carbon at Azusa, 9/30/00 to 10/8/00 Weekend Ozone Study

5. ` 5 Weekday Variations in CO and at Azusa, 9/30/00 to 10/8/00 Weekend Ozone Study

6. ` 6 Weekday Variations in NOx and Black Carbon at Azusa, 9/30/00 to 10/8/00 Weekend Ozone Study

7. ` 7 1-minute average Black Carbon (Photoacoustic) Sunday Weekday DOE Gas/Diesel PM Split Study

8. ` 8 Carbon Monoxide Health Effects Institute Project RFA03-1 405 110 60 710 605 91

9. ` 9 Black Carbon (Photoacoustic) Health Effects Institute Project RFA03-1 405 110 60 710 605 91

10. ` 10 Sampling Locations During the Phase II Field Measurements Weekend Ozone Study DS CV IH PO CO DOE Weekend Ozone Study

11. ` 11 Source Apportionment of Benzene Weekend Ozone Study Regional SitesFreeways DOE Weekend Ozone Study

12. ` 12 Source Apportionment of Toluene Weekend Ozone Study Regional SitesFreeways DOE Weekend Ozone Study

13. ` 13 Source Apportionment of Styrene Weekend Ozone Study Regional SitesFreeways DOE Weekend Ozone Study

14. ` 14 Source Apportionment of 1,3-Butadiene Weekend Ozone Study Regional SitesFreeways DOE Weekend Ozone Study

15. ` 15 Source Apportionment of MTBE Weekend Ozone Study Regional SitesFreeways DOE Weekend Ozone Study

16. ` 16 Source Apportionment of CO, NO, PM 2.5, and BC by Multivariate Analysis Using Traffic Counts Where: – Pe = estimated on-road pollutant concentration – V D = heavy-duty trucks per hour (a metric of diesel engine emissions) – V G = light and medium duty vehicles per hour (a metric of gasoline engine emissions) Source of uncertainty – Traffic volumes are annual hourly averages. – On-road measurements can be influenced by surrounding traffic. Health Effects Institute Project RFA03-1

17. ` 17 2005 Hourly Traffic Volumes Commute RoutesTruck Routes Health Effects Institute Project RFA03-1

18. ` 18 Contribution of SI and CI Exhaust to On-road CO, NO, PM 2.5 and BC Concentrations* Health Effects Institute Project RFA03-1 * Estimated from correlations of on-road measurements and traffic volumes.

19. ` 19 Correlations with CO at Los Angeles-N. Main 1990-95 and 1996-02 Data from ARB Air Toxic Monitoring

20. ` 20 Total Carbon Source Contributions DOE Gas/Diesel PM Split Study

21. ` 21 Variations in Source Contribution Estimates (Percent of Total) Azusa and Los Angles Weekday Ambient Samples

22. ` 22 Summary Ambient levels of volatile organic MSATs in the SoCAB were mainly associated with SI vehicle exhaust. However, SI and CI contributions were comparable for styrene. Evaporative contributions to volatile organic MSAT in the SoCAB were minor. CI and SI apportionments varied with location and time. – CI vehicles were the dominant mobile source of EC and TC at Azusa and LANM. – More equal apportionment at other locations that are more regionally representative. – SI vehicles were the dominant mobile source of OC and EC in locations and times with minimal truck traffic. – EC is a reasonable surrogate of PM emissions from CI vehicles in the SoCAB. Short-term on-road exposures (few minute or less) can be substantially higher and depend on proximity of high gasoline emitters and diesel trucks. Over half of the organic carbon during summer in the SoCAB could not be apportioned to directly-emitted PM emissions from motor vehicles.

23. ` 23 References Fujita, E.M., W.R. Stockwell, D.E. Campbell, R.E. Keislar and D.R. Lawson (2003). Evolution of the Magnitude and Spatial Extent of the Weekend Ozone Effect in California’s South Coast Air Basin from 1981 to 2000. J. Air & Waste Manage. Assoc. 53:802-815 Fujita, E.M., D.E. Campbell, B. Zielinska, J.C. Sagebiel, J.L. Bowen, W. Goliff, W.R. Stockwell, and D.R. Lawson (2003). Diurnal and Weekday Variations in Source Contributions of Ozone Precursors in California’s South Coast Air Basin. J. Air & Waste Manage. Assoc. 53: 844-863. Fujita, E.M. and D.E. Campbell (2006). Spatial and Temporal Variations in Exposure to Air Toxics in the South Coast Air Basin. Draft final report submitted by Desert Research Institute to the National Renewable Energy Laboratory, Golden, CO, August 31, 2006. Fujita, E.M., D.E. Campbell, B. Zielinska, W.P. Arnott and J.C. Chow (2006). Exposure to Air Toxics in Mobile Source Dominated Microenvironments. Draft report submitted by Desert Research Institute to the Health Effects Institute, Boston, MA, July 27, 2006. Fujita, E.M., B. Zielinska, W.P. Arnott, D.E. Campbell, L. Rinehart, J.C. Sagebiel and J.C. Chow (2006). Gasoline/Diesel PM Split Study: Source and Ambient Sampling, Chemical Analysis, and Apportionment Phase. Final report submitted to the U.S. Department of Energy National Renewable Energy Laboratory, Golden, CO, January 19, 2006. Data are available at: http://www.nrel.gov/vehiclesandfuels/nfti/feat_split_study.htmlhttp://www.nrel.gov/vehiclesandfuels/nfti/feat_split_study.html Fujita, E.M., B. Zielinska, D.E. Campbell, W.P. Arnott, J. Sagebiel, L. Reinhart, J.C. Chow, N. P.A. Gabele, W. Crews, R. Snow, N. Clark, S. Wayne and D.R. Lawson. Variations in speciated emissions from spark-ignition and compression ignition motor vehicles in the California's South Coast Air Basin. In Press. Fujita, E. M., D. E. Campbell, W. P. Arnott, B. Zielinska. Evaluations Of Source Apportionment Methods for Determining Contributions Of Gasoline and Diesel Exhaust to Ambient Carbonaceous Aerosols. Submitted.