The Small Area Health Statistics Unit (SAHSU) was established in 1987 following a recommendation from the Black Enquiry into the incidence of leukaemia in children and young adults near the Sellafield nuclear power plant for an organisation to coordinate centrally the monitoring of small area statistics around major installations producing discharges that might present a carcinogenic or mutagenic hazard to the public. In this way early warning of any untoward health effect could be obtained.
The Unit was initially established at the London School of Hygiene and Tropical Medicine but in 1996 transferred to Imperial College London. The Unit now forms a core part of the MRC-PHE Centre for Environment and Health held jointly between Imperial College London and King's College London set up in 2010.
The main role of SAHSU is to assess the risk to the health of the population from environmental factors by using routinely collected health and population data at a small area scale. To this end, SAHSU holds comprehensive computerised sets of health and demographic data and a range of environmental datasets at high spatial resolution.