International Association for Impact Assessment

Health Impact Assessment

Edited By: Bridget

Overview & History


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." (Gothenburg Consensus Paper Page 4)

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:

  1. Screening - determining if an HIA is warranted/required
  2. Scoping - determining which impacts will be considered and the plan for the HIA
  3. 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
  4. Decision-making and recommendations - making explicit the trade-offs to be made in decision-making and formulating evidence-informed recommendations
  5. Evaluation, monitoring and follow-up - process and impact evaluation of the HIA and the monitoring and management of health impacts (refer to page on impact assessment follow-up)

The main objective of HIA is to apply existing knowledge and evidence about health impacts, to specific social and community contexts in order to develop evidence-based recommendations that inform decision-making. This is done in order to protect and improve community health and wellbeing. Financial and time constraints mean that HIAs do not always 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 - see for example the UK Acheson Report (1998) or the WHO Closing the Gap in A Generation (2008) reports).


The use of HIA can be seen as evolving from three origins:

  1. HIA as a part of environmental impact assessment
  2. HIA as an approach for intersectoral action on the broader determinants of health
  3. HIA as a mechanism to reduce and redress health inequities

Figure 1: Selective timeline of the development of Health Impact Assessment (Source: Harris-Roxas & Harris (2010))

World Wide

HIA is currently being used or developed around the world, most notably in Europe, North America, Australia, New Zealand and Thailand.

Numerous approaches to and models for Health Impact Assessment have been developed internationally. Many of these models and guidelines have been developed within the context of a country- or region-specific regulatory and policy framework. The focus of agencies, the scope of impact assessment and the interest of different disciplines influence these guidelines and models. As a result, HIA is treated as a distinct process in some regions or countries, while fully integrated with other forms of impact assessment in others.

The safeguard policies and standards of the International Finance Corporation (IFC), part of the World Bank, were established in 2006. These contain a requirement for health impact assessment of large project proposals. The standards have been accepted by most of the leading lending banks who are parties to the Equator Principles.

Health impact assessments are becoming routine in many large development projects in both public and private sectors of developing countries. There is also a long history of health impact assessment in the water resource development sector, principally on large dam and irrigation system proposals.


The 31th annual International Association for Impact Assessment conference will be held in Mexico in 2011. The 12th International HIA Conference (previously known as the United Kingdom and Ireland HIA Conference) will be held in Spain in 2011. The 3rd Asia Pacific HIA Conference is being held in Dunedin, New Zealand in November 2010.


Journal Articles

<ul> <li>Birley, M (2005), "<a href="" target="_blank">Health Impact Assessment in Multinational Corporations: A case study of Shell</a>", <em>Environmental Impact Assessment Review </em>25: 702-713.</li> </ul>

Journal Special Issues

<ul> <li>New South Wales Department of Health (2007), "<a href="" target="_blank">HIA in Urban Settings Special Issue</a>", <em>NSW Public Health Bulletin </em>18 (9-10).</li> </ul>

Resource Websites

<ul> <li><a href="" target="_blank">IMPACT - International Health Impact Assessment Consortium</a></li> </ul>

Government Websites

<ul> <li><a href="" target="_blank">Environmental Health Branch, New South Wales Health (Australia)</a></li> </ul>

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