Gruinard island

At that time, there was an investigation by the British government into the feasibility of an attack using anthrax; either to test the vulnerability of Britain against a German attack, or the feasibility of such an attack against Germany. Eighty sheep were taken to the island, and a bomb filled with anthrax spores was exploded; the sheep began dying within days. The conclusion of the test was that a large scale release of spores could render a city unusable for decades: due to the durability of anthrax spores, decontamination was unsuccessful, and the island was quarantined, with no-one permitted to visit, other than an occasional check on the level of contamination. Beginning in 1986, a determined effort was made to decontaminate the island, with 280 tonnes of formaldehyde solution diluted in seawater being sprayed over all 520 acres of the island, and the worst-contaminated topsoil around the dispersal site being removed. A flock of sheep was then placed on the island, and remained healthy, and on April 24, 1990, after 48 years of quarantine, the then junior defence minister personally visited the island and removed the warning signs to announce its safety. As of January 2002, there have been no cases of anthrax in the island flock.