Modelling critical levels of ozone for the forested area of austria modifications of the aot40 concept

Ozone is the most important air pollutant in Europe for forest ecosystems and the increase in the last decades is significant. The ozone impact on forests can be calculated and mapped based on the provisional European Critical Level (AOT40 = accumulated exposure over a threshold of 40 ppb, 10,000 ppb.h for 6 months of one growing season calculated for 24h day^sup -1^).

For Norway spruce, the Austrian main tree species, the ozone risk was assessed in a basis approach and because the calculations do not reflect the health status of forests in Austria, the AOT40 concept was developed.

Three approaches were outlined and maps were generated for Norway spruce forests covering the entire area of Austria.

* The 1^sup st^ approach modifies the AOT40...