[Concepts and theory of health impact assessment]

Health effects are often overlooked in the planning of policies, programmes or projects, which has led to international and national pressure for evaluation of potential influence. For this reason, Health Impact Assessment (HIA) has been emphasized by many national governments and international organizations such as the European Union and WHO. HIA is a helpful decision-making tool with methodology that was defined as "a combination of procedures, methods, and tools by which a policy, a program or a project may be judged as to its potential effects on health of a population and the distribution of effects within the population" in the WHO Gothenburg paper. In recent decades, many HIAs have been implemented for proposals including building new airports, dams, employment strategy, and housing policy. However, there is very little information on HIA in Japan, even among public health professionals and policy makers. In this review, we introduce basic concepts and theory, and discuss how to improve HIA activities in Japan.