Levels of industrial pollutants in Central Europe have been declining with a simultaneous increase in the importance of photochemical pollutants, e.g., ozone since the late 1980s. Since the early 1990s ozone injury symptoms have been observed on vegetation indicating that the pollutant poses a threat to forests and other ecosystems of the Carpathian Mountains. A new study sponsored by the USDA Forest Service International Programs has been initiated to characterize air pollution distribution and its potential effects on vegetation diversity in the Retezat National Park, Romania. Specific objectives for the study are: (a) characterize spatial and temporal distribution of ozone, sulfur dioxide, ammonia and nitrogen dioxide, (b) evaluate incidence and severity of air pollution injury to vegetation, (c) select native indicators of air pollutants with a special emphasis on ozone, (d) evaluate effects of ozone and other pollutants on forest health and biodiversity, and (e) evaluate effects of various land management practices on mountain ecosystems. This new study will establish an important environmental/ecological database for any potential collaborators interested in studying other long-term changes in the Retezat Mountains.