Data comprise radionuclide deposition, radioactivity dose measurements, radioactive particle activity and physical characteristic information from soil samples collected within and around the Chernobyl Exclusion Zone (CEZ) following the Chernobyl nuclear accident in 1986. Data include radiocaesium, radiostrontium and soil chemistry parameters from soils collected in 1997, plutonium isotope measurements in soil samples and soil layers collected in 2000 and 2001, 'Hot particle' dataset presenting radionuclide activity and some physical characteristics of 'hot particles' extracted from soils collected in the Ukraine and Poland between 1995 and 1997; and Ivankov region data (radionuclide activity concentrations and natural background dose measurements) from a survey of the Ivankov region, immediately to the south of the CEZ conducted in 2014. Funding for preparing this data set was provided by the EU COMET project (http://www.radioecology-exchange.org/content/comet) and TREE (http://www.ceh.ac.uk/tree) project funded by the NERC, Environment Agency and Radioactive Waste Management Ltd. under the RATE programme. Full details about this dataset can be found at https://doi.org/10.5285/782ec845-2135-4698-8881-b38823e533bf

Following the Fukushima accident in March 2011, grass samples were collected from 42 sites around Great Britain during April 2011. Iodine-131 was measurable in grass samples across the country with activity concentrations ranging from 10 to 55 Bq per kg dry matter. Concentrations were similar to those reported in other European countries. Rainwater and some foodstuffs were also analysed from a limited number of sites. Of these, I-131 was only detectable in sheep's milk (c. 2 Bq/kg). Caesium-134, which can be attributed to releases from the Fukushima reactors, was detectable in six of the grass samples (4-8 Bq/kg dry matter); 137Cs was detected in a larger number of grass samples although previous release sources (atmospheric weapons test and the 1986 Chernobyl and 1957 Windscale accidents) are likely to have contributed to this. All data and information for this sampling are available from this record. The data result from collaboration between CEH and the University of Stirling. Full details about this dataset can be found at https://doi.org/10.5285/1a91c7d1-ec44-4858-9af2-98d80f169bbd

Data comprise radiocaesium concentrations in soil, vegetation, wildlife and fungi analysed from samples collected from throughout Great Britain after the 1986 Chernobyl accident by the Centre for Ecology & Hydrology (CEH), formerly the Institute of Terrestrial Ecology (ITE). National level vegetation surveys were conducted in May 1986, October 1986 and Spring 1987. More intensive surveys of vegetation (grass and heather) and wildlife (grouse, fox, etc.) in restricted areas were carried out in Cumbria, Wales and North Yorkshire in 1989, 1990, 1991 and 1993. Surveys of fungi were carried out between 1994 and 1997. The data are suitable for interpolation to create spatially variable surfaces suitable for input into models. Full details about this dataset can be found at https://doi.org/10.5285/d0a6a8bf-68f0-4935-8b43-4e597c3bf251