Environmental effects

International estimates suggest that a total of between 125 000 and 146 000 km2 in Belarus, Russia and Ukraine are contaminated with radioactive cesium-137 at levels exceeding the maximum allowed level of caesium where restrictions do not apply. This is an area greater than that of the neighbouring countries of Latvia and Lithuania combined. At the time of the accident, about 7 million people lived in the contaminated territories, including 3 million children. About 350 000 people were resettled or left these areas. However, about 5.5 million people, including more than a million children, continue to live in the contaminated zones.

Most of the contaminated territory lies in Belarus, since up to 70 per cent of the total fallout was deposited here. Of the total area of Belarus, 22 per cent was contaminated with high levels of caesium-137. At the time of the accident, 2.2 million people lived in these areas, one fifth of the population of Belarus. Just over 7 percent of Ukraine's territory was contaminated following the accident, and 0.6 percent of the Russian Federation.

Because of variable weather conditions in the days following the accident, radiation also spread over large parts of Scandinavia, Poland and the Baltic States, as well as southern Germany, Switzerland, northern France and Britain.

Several days after the explosion a blanket of poisonous caesium fell over England, Wales and the south and west of Scotland. As a result restrictions were imposed on about 10,000 sheep farms that were unable to sell their sheep, costing the British taxpayer an estimated £13 million in compensation.

Twenty years after the accident, 200 000 sheep on 375 British farms still have to be monitored with radiation detectors before being sold for human consumption. Farmers were initially told restrictions would last about 30 days after the accident. Twenty years later no one knows when the restriction will actually be lifted.