Air raid shelter

Air raid shelters are structures for the protection of non-combatants as well as combatants against enemy attacks from the air. They are similar to bunkers in many regards, although they are not designed to defend against ground attack (but many have been used as defensive structures in such situations).^{[citation needed]}

Prior to World War II, in 1924, an Air Raid Precautions Committee was set up in the United Kingdom. For years, little progress was made with shelters because of the apparently irreconcilable conflict between the need to send the public underground for shelter and the need to keep them above ground for protection against gas attacks. In 1935, every city in the country was given a document to prepare air raid shelters. In February 1936 the Home Secretary appointed a technical Committee on Structural Precautions against Air Attack.

By November 1937, there had only been slow progress, because of a serious lack of data on which to base any design recommendations and the Committee proposed that the Home Office should have its own department for research into structural precautions, rather than relying on research work done by the Bombing Test Committee to support the development of bomb design and strategy. This proposal was eventually implemented in January 1939.

During the Munich crisis, local authorities dug trenches to provide shelter. After the crisis, the British Government decided to make these a permanent feature, with a standard design of precast concrete trench lining. Unfortunately these turned out to perform very poorly. They also decided to issue free to poorer households the Anderson shelter, and to provide steel props to create shelters in suitable basements.

During World War II, many types of structures were used as air raid shelters, such as cellars, Hochbunker (in Germany), basements, and underpasses. Bombing raids during World War I led the UK to build 80 specially adapted London Underground stations as shelters. However, during World War II, the government initially ruled out using these as shelters. After Londoners flooded into underground stations during The Blitz, the government reversed its policy. The UK began building street communal shelters as air raid shelters in 1940. Anderson shelters, designed in 1938 and built to hold up to six people, were in common use in the UK. Indoor shelters known as Morrison shelters were introduced as well.

Air raid shelters are still in use to some extent in various nations such as Spain, Switzerland, Israel, Singapore and Taiwan.

Air raid shelters were built to serve as protection against enemy air raids. Existing edifices designed for other functions, such as underground stations (tube or subway stations), tunnels, cellars in houses or basements in larger establishments and railway arches, above ground, were suitable for safeguarding people during air raids. A commonly used home shelter known as the Anderson shelter would be built in a garden and equipped with beds as a refuge from air raids.

Air raid trenches are forms of trenches that began to be constructed for defensive purposes around the world after the creation of bomber aircraft. They were especially prevalent during World War II, but have also been used in other wars.