Criterion 2: Maintenance of Forest Ecosystem Health and Vitality: Indicator 2.1 Deposition and concentration of air pollutants

Annual sulphur and nitrogen throughfall deposition were generally higher in central and some southern and eastern parts of Europe. For the first time, tropospheric ozone concentrations in forests were also reported, with higher levels in southern and eastern Europe. Mean annual sulphur and nitrogen throughfall deposition decreased by about 60-70% and about 20-40% from 1997 to 2017, respectively. Mean ozone concentrations over the growing season (April- September) decreased by about 10% between 2000 and 2013. The thresholds for potential adverse effects on forests - critical loads and levels - are still exceeded at many ICP Forest monitoring plots, mainly in central parts of Europe for nitrogen, and over the majority of countries for ozone.