On April 26, 1986, at 1:23 a.m., a chain reaction occurred in the Chernobyl reactor, creating explosions that blew off the reactor’s heavy steel and concrete lid. From Chernobyl in the former Union of Soviet Socialist Republics (now in the Ukraine), radiation spread across Europe in perhaps the most catastrophic industrial event in the planet’s history. Radioactive particles remained suspended in the atmosphere for many days and were distributed as far as Scandinavia, the United Kingdom, and Greece.
Distance between Chernobyl and Stockholm is greater than one thousand miles, see figure 1, but Sweden was more polluted than neighboring to Belarus countries because of the radioactive rain several days after the catastrophe.
Sweden and Belarus. Sweden is shown in yellow and cesium data are displayed over the Belarus territory. Dark gray indicates low value of radiocesium soil contamination, blue shows territories with relatively low contamination, and warm colors indicate high contamination.
Wind direction over the Belarus territory in April 1986. Using filtered kriging, Byelorussian districts are colored according to the probability that thyroid cancer rates in children exceeded one case per 10,000. Red represents the highest probability and cycles through the spectrum to blue, the lowest probability.
The full article is here: http://www.esri.com/library/whitepapers/pdfs/chernobyl-consequences.pdf