The radioactivity of coloured rain in Thessaloniki, Greece.

The radioactivity of coloured rain precipitated over Thessaloniki, Greece, on 4-5 April 1988 was determined. The long-lived fission product radionuclides such as 137Cs, 134Cs, 144Ce, 106Ru and 125Sb were identified in dust originating from the Sahara desert which was precipitated with the rain to produce coloured rain. Caesium-137 concentrations reached 1000 Bq kg-1, resulting in a deposition of 3.03 Bq m-2, which is four orders of magnitude lower than measured on 5-6 May 1986 after the Chernobyl reactor accident.