New Directions: A new generation of ozone critical levels for the protection of vegetation in Europe

摘要

Ozone is the most important air pollutant affecting vegetation. In Europe, the AOT40 index, based on cumulative exposure of ambient ozone concentrations above 40 ppb, has been adopted for use within the United Nations Economic Commission for Europe (UNECE) Convention on Long-Range Trans-boundary Air Pollution (CLRTAP) and the European Union. However, the limitations of indices based on external concentrations have long been recognised. At the CLRTAP workshop in Gothenburg, 2002 (Bull et al., 2003, at http://www.ozoneworkshop.ivl.se/wsreport. htm), two alternative approaches were considered, based on modeled stomatal ozone flux and on the maximum permissible ozone concentration (MPOC). Here we present an assessment of the strengths and weaknesses of each approach from the scientific perspective, as well as from a perspective of continental-scale regional risk assessment and policy evaluation.