Migration and health impact assessment.

Government policies, programmes and projects can have a significant impact on health. Health impact assessments (HIAs) seek to estimate this impact, but they often do so by measuring intermediate or proxy indicators and factors that act to determine health. These measures frequently assume a static population. However, regeneration policies can work hard for several years to no apparent effect. One explanation could be migration. Families who have benefited move from the area and other, perhaps more deprived, families move in. Conversely, healthy, prosperous families may move into an improved area, giving the impression that the health of the population has changed, when in fact it is the actual population that has changed. Census data in England and Wales show that a positive correlation exists between migration within wards and deprivation scores. This paper explores the possible implications of migration for HIA. The census, NHS central register, electoral register, labour force survey, central index of the Department of Social Security, council tax database and other data sources are examined to identify what migration data are available at a local level. Factors that determine rates of migration at a local level have been reviewed, with special reference to the differences between population subgroups. The paper concludes with recommendations to take account of residential mobility and changes in migration patterns when carrying out HIAs.