Measurements of sulfur pollutants at stations in the Norwegian Arctic, 1977-1983, show persistent annual variations with maximum values in the winter season. These are mostly due to low-level transport of polluted air from industrial areas in northern USSR. The pulsating character of the air pollution episodes is related to the synoptic scale pressure variations. Aircraft measurements in March 1983 show the presence of thin stratified layers of polluted air at elevated tropospheric levels. In summer the Arctic air is generally very clean, and elevated concentrations are mainly due to a direct transfer from source areas in northwestern Europe across the Norwegian Sea. The aircraft measurements show that the Arctic aerosol has a narrow and very homogeneous size distribution, indicating a stable aerosol that is not subject to chemical reactions and further growth.