List of Sites of Special Scientific Interest by Area of Search
Sites of Special Scientific Interest in the United Kingdom are areas of conservation, consisting of protected areas, recognised for their biological or geological significance. In Northern Ireland an SSSI is called an area of special scientific interest.
An Area of Search is a geographical area used in the selection of these sites. In England these are largely based on the counties of England|1974-1996 administrative counties]. In Scotland they are largely based around the 1975 - 1996 districts, whereas in Wales they are based on districts or counties. The individual AOSs are between 400 km2 and 4,000 km2 in size. There are 59 AOSs in England, 12 in Wales, and 44 in Scotland.
Until the 2010s, Natural England, which maintains the database of English SSSIs, kept the listing of counties as it was in 1974, but by 2015 they had updated their lists to reflect some later changes. However, two counties abolished in 1996 are still used as areas of search by Natural England: Avon and Cleveland.