As a result of the Chernobyl disaster on April 26, 1986, part of the territory of Bryansk Oblast has been contaminated with radionuclides (mainly Gordeyevsky, Klimovsky, Klintsovsky, Krasnogorsky, Surazhsky, and Novozybkovsky Districts). In 1999, some 226,000 people lived in areas with the contamination level above 5 Curie/km2, representing approximately 16% of the oblast's population.