Between 1986 and 2012, the FSA has monitored the levels in sheep from the affected areas, managed controls on the movement of sheep to protect consumers and gradually removed controls where they were no longer required to protect food safety.
A maximum limit of 1,000 becquerels per kilogram (Bq/kg) of radiocaesium was applied to sheep meat affected by the accident to protect consumers. This limit was introduced in the UK in 1986, based on advice from the EURATOM Article 31 group of experts.
Under powers provided by the Food and Environment Protection Act 1985 (FEPA) (see the link on the top right of this page), emergency orders were used to impose restrictions on the movement and sale of sheep exceeding the limit, in certain parts of Cumbria in north-west England, North Wales, Scotland and Northern Ireland.
The emergency orders defined geographical areas, often termed 'restricted areas', within which the controls must be followed. Under the FEPA orders, sheep with levels of contamination above the limit were not allowed to enter the food chain.
A management system known as the 'mark and release' scheme operated in restricted areas. Under this scheme, a farmer wishing to move sheep out of a restricted area could have them monitored to determine the level of radiocaesium. A live monitoring technique was used, where a radiation monitor was held against the sheep. Any sheep that exceeded the monitoring pass mark were marked with a dye and not released from restrictions for three months. Those that passed were allowed to enter the food chain.