 It became part of the World Meteorological Organization's Background Air Pollution Monitoring Network in 1982.Supplementary meteorological stations have also been established at middle elevation ( above sea level) and in the valley at .This has enabled scientists to measure a range of natural phenomena including the transport of air pollutants in the region and a marked decline since 1990 in the amount of atmospheric mercury pollution, an effect which has been attributed to the post-1989 closure of polluting factories in the former Eastern Bloc states.