Health impact assessment (HIA) is defined as "a combination of procedures, methods, and tools by which a policy, program, or project may be judged as to its potential effects on the health of a population, and the distribution of those effects within the population." Overview HIA is intended to produce a set of evidence-based recommendations to inform decision-making . HIA seeks to maximise the positive health impacts and minimise the negative health impacts of proposed policies, programs or projects. The procedures of HIA are similar to those used in other forms of impact assessment, such as environmental impact assessment or social impact assessment. HIA is usually described as following the steps listed, though many practitioners break these into sub-steps or label them differently: Screening - determining if an HIA is warranted/required Scoping - determining which impacts will be considered and the plan for the HIA Identification and assessment of impacts - determining the magnitude, nature, extent and likelihood of potential health impacts, using a variety of different methods and types of information Decision-making and recommendations - making explicit the trade-offs to be made in decision-making and formulating evidence-informed recommendations Evaluation, monitoring and follow-up - process and impact evaluation of the HIA and the monitoring and management of health impacts The main objective of HIA is to apply existing knowledge and evidence about health impacts, to specific social and community contexts, to develop evidence-based recommendations that inform decision-making in order to protect and improve community health and wellbeing. Because of financial and time constraints, HIAs do not generally involve new research or the generation of original scientific knowledge. However, the findings of HIAs, especially where these have been monitored and evaluated over time, can be used to inform other HIAs in contexts that are similar. An HIA's recommendations may focus on both design and operational aspects of a proposal. HIA has also been identified as a mechanism by which potential health inequalities can be identified and redressed prior to the implementation of proposed policy, program or project . A number of manuals and guidelines for HIA's use have been developed (see further reading). Determinants of health The proposition that policies, programs and projects have the potential to change the determinants of health underpins HIA's use. Changes to health determinants then leads to changes in health outcomes or the health status of individuals and communities. The determinants of health are largely environmental