Ambient ozone in forests of the Central and Eastern European mountains.

Abstract Ambient ozone (O 3 ) concentrations in the forested areas of the Central and Eastern European (CEE) mountains measured on passive sampler networks and in several locations equipped with active monitors are reviewed. Some areas of the Carpathian Mountains, especially in Romania and parts of Poland, as well as the Sumava and Brdy Mountains in the Czech Republic are characterized by low European background concentrations of the pollutant (summer season means ∼30 ppb). Other parts of the Carpathians, especially the western part of the range (Slovakia, the Czech Republic and Poland), some of the Eastern (Ukraine) and Southern (Romania) Carpathians and the Jizerske Mountains have high O 3 levels with peak values >100 ppb and seasonal means ∼50 ppb. Large portions of the CEE mountain forests experience O 3 exposures that are above levels recommended for protection of forest and natural vegetation. Continuation of monitoring efforts with a combination of active monitors and passive samplers is needed for developing risk assessment scenarios for forests and other natural areas of the CEE Region.