Tuovinen J-P - Ozone flux modelling for risk assessment: status and research needs

Introduction In Europe, the development of air pollution abatement strategies is founded on the ef­ fects-based approach, which includes the ozone-induced plant injury as one of the key effects to be minimized. Within this frame­ work, the risk of ozone damage to vegetation is related to numerical exposure and dose in­ dices (UNECE 2004b, Simpson et al. 2007, Tuovinen et al. 2007). Both types of index are presently defined within the risk assess­ ment methodology adopted within the Con­ vention of Long-range Transboundary Air Pollution of the United Nations Economic Commission for Europe (UNECE 2004b). However, there is increasing evidence for the superior biological basis of the dose ap­ proach (Matyssek et al. 2007). The exposure and dose indices differ in that exposure can be evaluated from ozone concentration data alone, while for the calcu­ lation of ozone dose the stomatal uptake by vegetation must be modelled. In this paper, we will discuss some shortcomings involved in the modelling of ozone fluxes in the con­ text of local-scale risk assessment, especially as related to the data collected within the In­ ternational Co-operative Programme on As­ sessment and Monitoring of Air Pollution Effects on Forests (ICP Forests UNECE 2007). We will also suggest an enhanced monitoring strategy that would provide a sounder basis for the development, valida­ tion and application of risk assessment mod­ elling tools.