Comparison between the radiological situations in the Czech Republic after the Chernobyl accident and due to irradiation from natural sources

An overview of the radiological situation in the Czech Republic following the Chernobyl accident is presented. Particular attention is paid to the radioactivity of artificial radionuclides found in the environment and their time dependence. The doses observed during the first year and their development in the ensuing years are described, as are the countermeasures taken. The exposure to the Chernobyl radionuclides are compared to the exposure to radon and other natural radionuclides. The estimated mean annual effective dose received by people in the Czech Republic after the Chernobyl accident (in 1986) is 0.2 mSv, i. e. 6% of the mean annual dose (or 0.2% of the mean lifelong dose) received by the public from radon and other natural radionuclides. (author)