Health impact assessment: a tool to help policy makers understand health beyond health care.

Health impact assessment (HIA)--a combination of methods to examine formally the potential health effects of a proposed policy, program, or project--has received considerable interest over the past decade internationally as a practical mechanism for collaborating with other sectors to address the environmental determinants of health and to achieve more effectively the goals of population health promotion. Demand for HIA in the United States seems to be growing. This review outlines the common principles and methodologies of HIA and compares different approaches to HIA. Lessons learned from the related field of environmental impact assessment and from experience with HIA in other countries are examined. Possible avenues for advancing both the field and the broader goals of population health promotion are outlined.