What is HIA - Health Impact Assessment

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What is HIA

Overview of HIA - PDF (315 KB)

HIA Archive

HIAs conducted in the U.S. - PDF

What is HIA?

Health impact assessment (HIA) is
"a multidisciplinary process within which a range of evidence about the health effects of a proposal is considered in a structured framework, …based on a broad model of health which proposes that economic, political, social, psychological, and environmental factors determine population health."
Northern and York Public Health Observatory, 2001

HIA has the potential to:

Identify "those activities and policies likely to have major impacts on the health of a population in order to reduce the harmful effects on health and to increase the beneficial effects" (Northern and York Public Health Observatory, 2001).
Highlight potentially significant health impacts that are either unknown, under-recognized or otherwise unexpected.
Facilitate inter-sectoral action for health promotion by bringing a consideration of health issues into decision-making in other sectors, for instance in agriculture, education or economic policy.
Assess distributional effects between population sub-groups, including existing health disparities, as well as differential effects of policies on various population sub-groups.

Key elements of HIA
HIA is a new, rapidly evolving field. It has taken on a number of different forms as it is applied to wide range of issues in diverse social, political and bureaucratic environments. Variations in HIA practice have retained several common elements:
1. Analysis starts with proposed policies or projects;
2. Comprehensively examines potential health effects;
3. Based on a broad model of population health;
4. Employs a multidisciplinary approach to analysis;
5. Uses a structured framework to consider a range of evidence.

1. Analysis starts with proposed policies or projects, proceeding from a potential decision or series of decisions, such as whether to approve or not approve a proposal, whether an alternative might be preferable, or whether to modify a proposal. The goal of HIA is to provide unbiased information to policy-makers and the public, not to make decisions for them based on health criteria that would trump other social goals. HIA avoids giving a "thumbs up" or a "thumbs down" for a particular decision, but it will highlight areas of concern and compare the relative health benefits and costs of alternatives and/or modifications of the policy. Analyses may be based on existing data about current or past conditions and trends, HIA focuses prospectively on the potential consequences of a specific policy decision.

2. HIA comprehensively examines health effects. HIA looks squarely and explicitly at health outcomes. This of course begs the question "What is 'health'?" The World Health Organization has proclaimed that "'health' is not just the absence of disease; it is physical, mental and social well-being." Although scientific rigor can be maintained by narrowly defining research questions, outcomes and causal relations of interest, in HIA there is a competing demand for comprehensiveness that places a high value on addressing potentially significant outcomes even if they are difficult to ascertain. The appropriate balance between rigor and comprehensiveness needs to be determined in each HIA, based on the issue being analyzed, the state of knowledge about the relevant causal relations, the resources available to conduct the HIA and the information demands of the target audience(s).

3. HIA is based on a broad model of population health-one that recognizes the complex, interacting patterns of determinants that shape the health outcomes of groups of individuals and the distribution of outcomes within those groups. This implies several things. First, HIA must consider aggregate outcomes in the population. Second, HIA usually examines distributional effects. Third, and most significantly, HIA must take a broad, systems-based approach to understanding health outcomes and their determinants. While ultimately it is the individual that experiences good or poor health, the environmental determinants of health, along with the context of health outcomes must be considered.

4. Most approaches to HIA are multidisciplinary. As a broader range of health determinants is considered, it becomes necessary to draw from expertise in disciplines outside of health. In our work we have found that economics plays an especially significant role as a determinant or modifier of many policies' effects on health. A multidisciplinary focus is also necessitated by the fact that the most valuable HIAs examine the effects of proposals in sectors outside of health, such as agriculture, education and commerce, where health effects are typically not a major consideration in the policy-making process.

5. HIA uses a structured framework to evaluate a range of evidence. Due to variations in the types of outcomes considered and the substantial uncertainties involved in assessing potential effects, it becomes necessary to cobble together an assortment of evidence. Different kinds of criteria may be used to assess different kinds of evidence in different situations, which is discussed in the methodology section. What is always important is that the process for gathering and evaluating evidence is explicit, transparent and balanced.

HIA Archive
A list of Health Impact Assessments conducted in the United States, 1999 - 2007- PDF