The UV observations weighted for the plant action spectrum are rather limited. The activities in the UV ground-based measurements mainly focused on the human erythemal effects. Our objective is to find the long-term variations in the UV radiation weighted by the plant effects using the data (erythemal UV irradiance and total ozone measurements) collected at in the period of 1992–2003. The transfer function from the erythemal weighted UV radiation to the UV radiation convolved with the plant action spectrum is constructed using total ozone observations (from the Brewer spectrophotometer) and UV spectral and UV erythemal data (from the Brewer spectrophotometer and the broadband UV biometer SL 501 for the erythemal effects) taken during the intercomparison campaign of the spectrophotometers in Warsaw, May 2004. The long-term variations in the reconstructed data are discussed concerning the impact of total ozone and cloudiness fluctuations on the UV radiation for the period of 1992–2003 (Belsk [52N,21E], Poland).