The Health Protection Agency was a non-departmental public body in the United Kingdom. It was an organisation that was set up by the UK government in 2003 to protect the public in England from threats to their health from infectious diseases and environmental hazards. It did this by providing advice and information to the general public, to health professionals such as doctors and nurses, and to national and local government. There were four HPA centres - at Porton Down in Salisbury, Chilton in Didcot, South Mimms in Hertfordshire, and Colindale in NW London. In addition, the HPA had regional laboratories across England and administrative headquarters in Central London. On 1 April 2013, the HPA minus the South Mimms site became part of Public Health England, a new executive agency of the Department of Health (DoH).