Dangerous radioactive particles have been detected in seven different European countries and scientists can’t explain where they have come from.
Traces of Iodine-131 were found in Norway, Finland, Poland, Czech Republic, Germany, France and Spain in January, but the public were not immediately alerted.
These radioactive particles are produced by atomic bomb explosions or nuclear disasters such as Chernobyl or Fukushima.
They appear to be emanating from Eastern Europe, but experts have not been able to say exactly what produced them.