The bioavailability of (137)Cs and (239+240)Pu in soil, dust and aerosols has been determined by applying a fractional extraction procedure. In aerosols, 47-57% of (137)Cs was found to be easily exchangeable. This differs significantly from soil and deposited dust samples collected on a nearby street as well as on grassland where (137)Cs was quantitatively found in the acid-soluble fraction and the residue. A similar difference was observed for (239+240)Pu: 47% of (239+240)Pu in aerosols was associated with the organic fraction, while in soil and deposited dust from grassland 63-75% of (239+240)Pu was found in the acid-soluble fraction. In deposited street dust, 53% of (239+240)Pu was associated with the oxide fraction.