W. Kevin Hicks,^* Johan C. I. Kuylenstierna,^** Anne Owen,^*** Frank Dentener,^**** Hans-Martin Seip,^***** Henning Rodhe<sup>******


*</sup>Kevin Hicks is a research associate at the Stockholm Environment Institute, based in the Department of Biology at the University of York. His research concentrates on air pollution impacts on terrestrial ecosystems and promoting the transfer of scientific knowledge to policy making. His address: Stockholm Environment Institute–York, University of York, Heslington, York YO10 5DD, UK. khicks@york.ac.uk
^**Johan Kuylenstierna is director of the York center of the Stockholm Environment Institute, based in the Department of Biology at the University of York. His research concentrates on regional assessments of air-pollution risks to ecosystems and on links between scientific information and policy making. His address: Stockholm Environment Institute–York, University of York, Heslington, York YO10 5DD, UK. jck1@york.ac.uk
^***Anne Owen is a research associate at the Stockholm Environment Institute based in the Department of Biology at the University of York. Her research concentrates on geographic information system (GIS) techniques and the calculation and communication of ecological and carbon footprints to aid policy making. Her address: Stockholm Environment Institute–York, University of York, Heslington, York YO10 5DD, UK. ao502@york.ac.uk
^****Frank Dentener is a senior scientist in the Climate Change Unit of the European Commission Joint Research Center, Italy. His current research focuses on global and regional photochemical and aerosol processes, air pollution and climate, the nitrogen cycle, and their interaction and representation in global atmospheric models. Model results are used to design optimized policy strategies to reduce both the emissions of climate gases and air pollution. His address: European Commission, Joint Research Centre, Institute for Environment and Sustainability, Climate Change Unit, I-21020 Ispra (Va), Italy. frank.dentener@jrc.it
^*****Hans-Martin Seip is a professor in chemistry at the University of Oslo and has a part-time position as a senior scientist at Center for International Climate and Environmental Research-Oslo. He has worked with environmental problems for about 30 y. A major research field has been effects of acid rain in Europe and in China. He studies how inclusion of regional and local benefits will affect cost-benefit analyses of measures primarily directed at reducing emissions of greenhouse gases. His address: Department of Chemistry, University of Oslo, PO Box 1033, Blindern, N-0315 Oslo, Norway. h.m.seip@kjemi.uio.no
^******Henning Rodhe is a professor of chemical meteorology at Stockholm University. His research interests include modelling of transport, transformation, and removal of chemicals in the atmosphere, with special emphasis on sulfur and nitrogen species. His address: Department of Meteorology, Stockholm University, S-10691 Stockholm, Sweden. rodhe@misu.su.se