Short description
Tropospheric ozone (O3) is an important constituent of photochemical smog. Besides its harmful effect on human health, it is currently considered to be the most significant phytotoxic pollutant of the atmosphere. Recently, two types of approaches are available for assessing (O3) risk to vegetation: one is based on the exposure concentration and can theoretically be applied to all species of the plant kingdom and a second approach is based on the cumulative stomatal (O3) uptake. This applies to all stomatous target plants, and thus comprises all higher taxa of the plant kingdom, especially vascular plants. The standard reflects the current scientific knowledge, describes and defines critical levels for (O3) for crops, species-rich grassland, and forests, and derives target values using prediction intervals. Wheat, grassland species such as red clover or harebell, and beech are considered as (O3) sensitive representatives for the mentioned vegetation types. The risk assessment is based on the estimation of stomatal (O3) uptake using receptor-specific deposition models together with dose-response relationships established for the relevant effect indicators.