UNSCEAR - 2000: Report to the General Assembly, Annex J. The most recent information about Chernobyl from the UNSCEAR 2000 report The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) A full assessment of the Chernobyl accident is included in the UNSCEAR 2000 Report as Annex J "Exposures and effects of the Chernobyl accident". This web article reproduces that annex. The annex is well written and easy to read. But you will need some definitions, such as: t : metric tonne, 1000 kg GWd t-1 : gigawatt days per tonne, the amount of thermal energy produced from each tonne of nuclear reactor fuel PBq : peta becquerel, 10**15 becquerels um : micro meter, one millionth of a meter kBq m-2 : kilo becquerels per square meter MBq m-2 : mega becquerels per square meter Ci km-2 : curies per square kilometer Gy : gray Gy h-1 : grays per hour mSv : milli sieverts A "becquerel" (Bq) of radioactivity occurs if there is one nucleus decay event every second. So kBq indicates one thousand nucleus decay events every second, i.e. one thousand becquerels. MBq indicates one million becquerels. Associating this with a square meter gives a measure of the radioactivity of a land area. A "curie" (Ci) of radioactivity is 37 giga becquerels (GBq), i.e. 37,000,000,000 Bq. A "gray" (Gy) is a measure of an absorbed dose of radioactivity. A "sievert" (Sv) is a measure of a dose equivalent of radioactivity. A milli sievert is one thousandth of a sievert.