35. "Particulate Matter in and from Agriculture", International Conference, Braunscheweig, Germany, September 3-4, 2007.

34. Meeting Co-chair, “Air Quality in the Agricultural Landscape: Measurements,
Modeling, BMPs, and Emerging Regulations”, ASA-CSSA-SSSA International Annual Meetings in Indianapolis, November 13-16, 2006.

33. Workshop Chair, “Workshop on Agricultural Air Quality: State of the Science”, Potomac, MD, June 5-8, 2006.

32. “International Perspectives in Agricultural Air Quality”, Workshop on Agricultural Air Quality: State of the Science, Potomac, MD, June 5-8, 2006.

31. “Deposition”, Particulate Matter Supersites Program & Related Studies, An International Specialty Conference Sponsored by the American Association for Aerosol Research, Atlanta, GA, February 7-11, 2005.

30. “Estimates of N and S Deposition”, 2004 National Atmospheric Deposition Program -Scientific Symposium, Halifax, Nova Scotia 22-24 September 2004.

29. “Deposition of Air Pollutants”, 13 th World Clean Air and Environmental Protection Congress and Exhibition, London, U.K., August 22-27, 2004.

28. “Ozone Precursors, Fugitive, Workplace, and Area Source Monitoring”, Symposium on Air Quality Measurement Methods and Technology, Research Triangle Park , NC , April 19-22, 2004 .

27. “Dust Storms and Their Effects on Human Health”, Sino-US Workshop, Raleigh , NC , November 25-26, 2002 .

26. “Airborne Water Pollutants and Atmospheric Water”, Water Resources Institute Annual Meeting, Raleigh , NC , April 9, 2002 .

25. “Atmospheric Issues Related to Nitrogen”, Future Directions on Air Quality Research, Research Triangle Park , NC , February 12-15, 2001 .

24. “Air-Surface Emissions and Gas Fluxes”, 2000 Annual Meeting and International Conference of the American Institute of Hydrology, Research Triangle Park, NC, November 5-8, 2000.

23. “Ammonia Emissions”, International Symposium on the Measurement of Toxic and Related Air Pollutants, Research Triangle Park , NC , September 12-14, 2000 .

22. “Photochemical Oxidants,” The Sixth International Conference on Air-Surface Exchange of Gases and Particles, Edinburgh , UK July 3-7, 2000 .

21. “Workshop on Air Quality Index and Emission Inventory Development for Delhi ”, New Delhi , India , June 6-8, 2000 .

20. "Atmospheric Nitrogen Compounds II: Emissions, Transport, Transformation, Deposition, and Assessment”, Chapel Hill , NC , June 7-9, 1999 .

19. “Ozone,” EPA/AWMA International Symposium on Measurement of Toxic and Related Air Pollutants, Cary , NC , September 1-3, 1998 .

18. “Air Quality Modeling,” 91 st Air & Waste Management Association Annual Meeting, San Diego , CA , June 14-18, 1998 .

17. "Project NOVA — Natural emissions of Oxidant precursors: Validation of techniques and Assessment," American Geophysical Union Fall Meeting, San Francisco , CA , December 8-12, 1997 .

16. "Ozone", EPA/AWMA International Symposium on Measurements of Toxic and Related Air Pollutants, Research Triangle Park, NC, April 29 - May 1, 1997.

15. "Natural emissions of Oxidant precursors: Validation of techniques and Assessment, (Project NOVA)", EPA/AWMA International Symposium on Measurements of Toxic and Related Air Pollutants, Research Triangle Park, NC, May 7-10, 1996.

14. "Atmospheric Ammonia: Emission, Deposition and Environmental Impacts", Department of the Environment, U.K. , Oxford , England , October 2-4, 1995 .

13. " North Carolina Ozone State Implementation Plan - Measurements and Modeling Studies," EPA/AWMA International Symposium on Measurements of Toxic and Related Air Pollutants, Research Triangle Park , NC , May 14-19, 1995 .

12. " North Carolina Ozone State Implementation Plan - Measurements and Modeling Studies," EPA/AWMA International Symposium on Measurements of Toxic and Related Air Pollutants, Durham , NC , May 2-6, 1994 .

11. "Regional Photochemical Measurements and Modeling Studies - Photochemical Reaction Products," Air and Waste Management Association International Specialty Conference, San Diego , CA , November 7-12, 1993 .

10. "Oxidants in the Atmosphere," EPA/AWMA International Symposium on Measurements of Toxic and Related Air Pollutants, Durham , NC , May 3-7, 1993 .

9. “Tropospheric Oxidant Formation and Chemistry”, American Geophysical Union Western Pacific Meeting, Hong Kong , August 17-21, 1992 .

8. "Southern Oxidant Study - Photochemical Observations in the Rural Atmosphere" American Chemical Society National Meeting, Atlanta , Ga. , April 15-19, 1991 .

7. "Atmospheric Dispersion. Computer Models for Risk Analysis", Chairman, Indo-US Workshop on Environmental Risk Analysis, New Delhi, India,
December 12-16, l989.

6. "Global Climate Change", Chairman, American Institute of Chemical Engineers Annual Meeting, San Francisco , California , November 5-10, 1989 .

5. "Global Climate Change", Chairman, Feature Mini Symposium at American Institute of Chemical Engineers Annual Meeting, Washington, D.C.,
November 25 - December 2, 1988.

4. "Environmental Impact of Natural Emissions", Technical Program Chairman, International Specialty Conference, Air Pollution Control Association, Research Triangle Park , NC , March 7-9, 1984 .

3. "Natural Emissions of Hydrocarbons, Halocarbons, Sulfur, and Nitrogen Gases into the Atmosphere", 75th Air Pollution Control Association Annual Meeting, New Orleans , June 20-25, 1982 .

2. "Natural Emissions of Hydrocarbons, Halocarbons, Sulfur, and Nitrogen Gases into the Atmosphere", 74th Air Pollution Control Association Annual Meeting, Philadelphia , June 21-26, 1981 .

1. "Biogenic Emission of Sulfur, Hydrocarbon, and Nitrogen Gases into the Atmosphere", 73rd Air Pollution Control Association Annual Meeting, Montreal , Canada , June 22-27, 1980 .