The variability of solar irradiance in the UV-B spectral region, is studied at two European stations operating well calibrated spectroradiometers during the period 1991-97. It is confirmed that total ozone is the controlling factor in long-term changes of solar irradiance below 315 nm at ground level. This is supported by the similar long-term variability under clear sky and all sky conditions during the past seven years. Upward trends at UV-A wavelengths are associated with decreasing trends of the pollution in the area, as it appears from the long-term columnar SO2 measurements. The observed changes in solar irradiance (in % per year) are verified with model calculations performed with a radiative transfer model.