Transboundary environmental assessment: lessons from OTAG. The Ozone Transport Assessment Group

The nature and role of assessments in creating policy for transboundary environmental problems is discussed. Transboundary environmental problems are particularly difficult to deal with because they typically require cooperation among independent political jurisdictions (e.g., states or nations) which face differing costs and benefits and which often have different technical capabilities and different interests. In particular, transboundary pollution issues generally involve the problem of an upstream source and a downstream receptor on opposite sides of a relevant political boundary, making it difficult for the jurisdiction containing the receptor to obtain relief from the pollution problem. The Ozone Transport Assessment Group (OTAG) addressed such a transboundary problem: the long-range transport of tropospheric ozone (i.e., photochemical smog) across the eastern United States. The evolution of the science and policy that led to OTAG, the OTAG process, and its outcomes are presented. Lessons that are available to be learned from the OTAG experience, particularly for addressing similar transboundary problems such as regional haze, are discussed.