1. National Center for Environmental Assessment Office of Research and Development U.S. EPA Washington D.C. 20460 USA
2. Air Resources Division National Park Service Lakewood Colorado 80225 USA
3. Resources for the Future Washington D.C. 20036 USA
4. Western Ecology Division Office of Research and Development U.S. EPA Corvallis Oregon 97333 USA
5. Appalachian Laboratory University of Maryland Center for Environmental Science Frostburg Maryland 21532 USA
6. Office of Air and Radiation, Office of Air Quality Planning and Standards U.S. EPA Research Triangle Park North Carolina 27709 USA
7. Pacific Southwest Research Station USDA Forest Service Riverside California 92607 USA
8. Washington Office‐Water Wildlife Fish Air and Rare Plants USDA Forest Service Washington D.C. 20250 USA
9. Environment Centre Wales Centre for Ecology and Hydrology Deiniol Road Bangor LL57 2UW United Kingdom