[en] Gas was sampled twice a year during the 1966 to 1975 period in Debrecen. Kr was extracted by the Linde method. Kr gas samples were measured without further purification. ⁸⁵Kr concentration was determined by beta detection using a GM counter with an effective volume of 136 cm³. In the years 1966 to 1969 an annual increase was found in ⁸⁵Kr to 1 pCi/m³ of air, in 1970 to 1973 the annual growth decreased to 0.4 pCi/m³ of air while in 1974 an increase to 1 pCi/m³ of air was again found. In 1975 the ⁸⁵Kr concentration was 17 pCi/m³ of air. The increased concentration after 1973 is attributed to the energy crisis which resulted in more intensive use of nuclear power and corresponding fuel reprocessing. Increased fuel reprocessing resulted in increased air contamination with ⁸⁵Kr. (J.P.)