A review of trends in health‐impact assessment and the nature of the evidence used

Developments at all levels between project and policy have a potential impact on human health. Health‐impact assessment (HIA) is a discipline that seeks to assess these impacts to safeguard and enhance human health. There is a growing consensus about the scope, methodology and context for HIA but there are also many unresolved issues. This paper reviews the main trends as they vary between the healthy public policy, environmental assessment and environmental epidemiology communities; and between retrospective and prospective, developed and developing economies and urban/industrial versus rural settings. There are unresolved issues associated with the nature of evidence, the link with economic appraisal, and with the core biophysical and social health determinants. The nature of the evidence used is examined and some resolutions are proposed. The growing number of guidelines testify to a demand by development agencies for HIA, but increased consensus is required to ensure that quality assessments are delivered.