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Learn how to use Health Impact Assessment to assess the health impact of potential community development or policy changes.


The Health Impact Assessment (HIA) is a tool that helps community leaders, legislators, and changemakers find out what health and safety impacts their proposed projects may have on area residents and community members. The HIA can be a valuable resource in anticipating the health effects of a projects, a long-term plan, or a new party. This section explores how to effectively conduct an HIA and use the results to improve communtiy projects and planning.

What is a Health Impact Assessment?

A consensus of those at a meeting of the World Health organization (WHO) held in Gothenburg, Sweden in 1999 defines HIA as “a combination of procedures, methods, and tools by which a policy, program [a series of projects over time], or project may be judged as to its potential effects on the health of a population, and the distribution of those effects within that population.” In simpler language, it’s a way of finding out whether and how a proposed action or policy will affect the health of people who are in some way exposed to it.

While there is obviously a difference between a single project and a series of projects, for the purposes of this section, we’ll lump the two together under the term “project.” We’ll consider a project as an activity that has clear physical consequences, as opposed to a policy, which may set guidelines for future action in any number of areas or sectors.

An HIA is intended not to determine, but to support decision-making. It helps decision-makers choose among options by predicting the health consequences of each option. Rather than having a set structure, HIAs are individually designed to match the needs and conditions of different locations and circumstances. They can be, and have been, used at the local, regional, national, and international levels, and have been applied to projects and policies in such sectors as agriculture, residential development, transportation, mining, industry, and recreation. HIAs can be helpful in making decisions in such areas as tax and foreign policy, employment strategies, and urban planning.

The actual practice of an HIA involves one or more practitioners – ideally both trained and experienced in conducting HIAs – studying the existing research on potential issues, and gathering background evidence from the people who are expert in the subject of the project or policy (agriculture, transportation, etc.), residents and other community members, officials from sectors involved, health professionals, etc.. In addition, the HIA practitioner might attend and/or conduct meetings among the various sectors, involve the community in meetings with developers or officials, and otherwise oversee the process, in order to collect as much information as possible about potential health effects and potential areas of health promotion associated with the proposed project or policy. Ultimately, the HIA practitioners prepare a report that should be presented to all involved, including the community. Decision-makers for the project or policy can then use the report – which includes recommendations for various options – to inform their decision.

An HIA may be commissioned by the government oversight agencies or policy makers concerned with the proposed project or policy; by the contractor(s) carrying out a project; by the local, regional, or national government; or by citizens or a citizen group, depending upon the circumstances. It generally carries the most weight when it has the authority of government behind it, regardless of who commissions it.

HIAs are generally conducted in one of three ways, depending on the time, resources, and personnel available.

  • Desktop. As the name implies, this HIA is essentially a sit-down process, focusing mostly on existing research and on phone contact with some stakeholders. It would probably be carried out by one or two people, and might take two to six weeks.
  • Rapid. A rapid HIA uses both existing research and rapid assessment techniques, thus including some fieldwork as well as literature research. Although it could be carried out by one or two researchers, it might also involve more, and might take about three months.
  • Comprehensive. A comprehensive HIA seeks to ferret out as much evidence as possible, using an extensive search of the literature and other existing evidence, in-depth interviews and community surveys, some original research if appropriate, and a good deal of contact with experts and agencies from the sectors involved in the project or policy under study. This type of HIA can take 6 months or more, and can require a team to conduct it.

The ideal HIA is planned through a participatory process that involves all stakeholders, and is carried out with the help of cooperation among all parties involved. In practice, that can mean encouraging various agencies--government agencies particularly--to work together and share information. It can also mean changing the culture of professionals to accept and welcome community participation.

Also in the ideal, HIAs are prospective – i.e., they look forward. An HIA, to be most useful, should be conducted before a project or policy is implemented (even better, before it’s fully planned), so that any health impacts, whether positive or negative, can be factored into the final design. In reality, HIAs are sometimes concurrent – running as the project or policy is being implemented – or retrospective – after completion. Concurrent or retrospective HIAs are better than nothing, and can result in adjustments that address health impacts. It’s more difficult, however, to change something that’s already built or in force than to adapt the plans for it. Where possible, HIAs should be conducted well before projects or policies are implemented.

HIAs are guided by four basic values:

  • Democracy. Wherever possible, all stakeholders affected by or taking part in a proposed action or policy should have a voice through an HIA and in its planning and development, and should understand its possible consequences.
  • Equity. HIAs should assess health impacts on the whole population, treating all fairly and equitably, with particular attention paid to the needs of the most vulnerable populations (children, elders, low-income people, etc.).
  • Sustainable development. Attention should be paid to both short and long-term impacts of a proposed action or policy, both obvious and not-so-obvious. That means that a major project or policy should be examined not only in light of current health impacts, but of possible impacts in the future as well.

We can look at this both as a health issue – Will the safeguards to health that we put in place today still be adequate in 10 or 20 or 100 years? – and as a larger societal issue related not only to individual health, but to the long-term health of the society. Do we develop an irrigation system that helps farmers now, but that will cause an aquifer to run dry in ten years? Do we build housing with construction techniques and materials that use renewable resources, allow it to stand indefinitely, and provide a healthy environment for inhabitants?

  • Ethical use of evidence. Research in the course of an HIA should be objective, and should deal in the reality, rather than seek and use research results to confirm a position already held. That means including all the legitimate information you find, whether or not it supports your position for or against a particular part of the proposed action or policy.

The ethical use of evidence concerns not only ethics, but also the effectiveness of an HIA. In general, there are four levels of HIA effectiveness:

  • Direct effectiveness: A project or policy is modified or cancelled as a result of an HIA.
  • General effectiveness: An HIA is properly conducted and adequately considered, but doesn’t result in any changes in original decision – either because changes are not necessary, or because the evidence was complete and weighed carefully, and the final decision was that any potential health impact was less important to community, regional, or national well-being than the potential results of the original proposal.
  • Opportunistic effectiveness: The HIA is used only to confirm or support the original proposal. This may result in evidence being slanted or suppressed, or in a legitimate HIA which is being conducted only for the wrong purposes.
  • Ineffectiveness: An HIA is conducted but ignored, or is conducted so poorly that it’s no help at all.

In order for an HIA to fall into either of the first two categories – the categories of real effectiveness – all the evidence has to be considered and presented, so that it paints as nearly complete a picture as possible of the situation. Only then can decision-makers make a truly informed decision. An opportunistic result, on the other hand, is an example of the unethical use of evidence – not mentioning information that conflicts with decision-makers’ assumptions, or actually changing statistics or other information to conform to the decision that those in authority want to see.

It should be noted that, while we usually think of unethical behavior as being indulged in by people in power to confirm their status, or by those who stand to gain financially from it, it can also be a product of ideology. It’s probably less common, but it’s not impossible that health advocates might ignore data that would contradict their objections to a project. No one is immune to trying to make sure that his philosophy prevails.

Like most of the other models we discuss in this chapter, HIA looks at health from a community perspective. It considers the social, economic, and political, as well as the physical determinants of health when examining the potential health effects of a proposal.

The WHO includes in these:

  • Biological factors (body type, other genetic factors).
  • Individual lifestyle factors (smoking, exercise, diet).
  • Social and community networks (family, friendship groups, clubs and associations, faith communities).
  • Living and working conditions (education, work environment, water and sanitation, housing).
  • General socioeconomic, cultural, and environmental conditions (income, physical environment, access to open space, status by gender or caste, etc.)

These factors may act alone, act in combination, or interact to determine the overall health and well-being of individuals, communities, and even whole nations.

This list of determinants matches up well with both the ten social determinants of health set out in “The Solid Facts,” a WHO publication by Richard Wilkinson and Michael Marmet, as well as with the nine necessary elements of a healthy community presented in the Ottawa Charter, a statement that emerged from a 1986 WHO conference in Ottawa, Canada.

From “The Solid Facts”:

  • The social gradient (Equity: the extent of the difference in wealth and opportunity between those with the most and those with the least.)
  • Stress
  • Early life experience
  • Social exclusion (the opposite of social connectedness)
  •  Work
  • Unemployment
  • Social support
  • Addiction
  • Food
  • Transport

From the Ottawa Charter:

  • Peace
  • Shelter
  • Education
  • Food
  • Income
  • A stable ecosystem
  • Sustainable resources
  • Social justice
  • Equity

The attention paid to social determinants greatly increases the breadth of what we might consider health impacts. While impacts on health are often seen in direct, medical terms – chemicals from an industrial plant or from farm run-off can poison water supplies, for example, causing specific types of cancer – they can also be indirect and far less visible.

Noise from increased traffic as a result of a faraway commercial development might disturb the sleep of residents in a community, and affect their immune systems...even though the development itself has no direct impact on their lives. Subsidies to industry or currency fluctuations on another continent might cause loss of income and severe stress to workers in a North American factory town, leading to substance use and a major public health problem.

That’s why an HIA can be so important. In the best case, it can directly prevent negative health consequences. Even where it can’t – a local project or policy can’t control the global economy – by predicting them, it can perhaps help to stave off their worst effects. At the very least, it can make policy makers and others in authority aware of the issue, and motivate them to consider ways to address it. For more information about Health Impact Assessment, see the National Research Council's report on Improving Health in the United States: The Role of Health Impact Assessment.

A note here: At this writing (2008), HIAs are still, on a world scale, not widely used.

The European Union has made a legal commitment to factoring in the health impacts of new projects, programs, and policies, but leaves it up to individual members – which, in turn, often leave it up to provinces or municipalities – to decide how this is to be done. The result is that there are places where stand-alone HIAs are regularly employed, others where HIAs are incorporated into environmental impact assessments (EIAs), and still others where there is precious little formal assessment at all.

The rest of the world is less committed to the HIA concept. HIAs have been used to some extent in Canada and Australia and in various parts of the developing world, but mostly in the context of projects that could have an obvious impact on health – water systems, dams, surface mining, and the like. In the U.S., the use of HIAs is still in its infancy, most often occurs within the confines of an environmental impact assessment, and may examine only obvious possible health problems (increase in asthma from increased traffic, for instance), rather than more subtle, long-term implications or the possibility of health promotion.

Why would you conduct a Health Impact Assessment?

HIAs, if done well, are painstaking and time-consuming. Why should you spend the time, money, and effort on them? There are a variety of answers to this question.

  • HIAs make for better decisions. An HIA provides decision-makers with as much of the best available information about the project or policy they’re about to embark on as possible. That means fewer, if any, surprises in the course of the work, and a lot fewer mistakes to fix afterward.
  • HIAs promote cross-sectoral cooperation. Government agencies and other institutions or organizations that represent particular sectors – health, agriculture, industry, education, transportation, housing, recreation, human services, etc. – seldom work together on planning and implementing projects, especially when those projects seem to be the province of only one of them. An HIA for a transportation project might bring together all or some combination of highway engineers, public health officials, environmental groups, citizens living near the current and proposed roads affected, water department officials, electricity providers, farmers with abutting property, landscape architects, trucking companies, and others to examine all aspects of the project. At least some of the intersectoral relationships developed are likely to carry over long after the HIA is finished, and have a positive effect on numerous other projects and policies as well.
  • HIAs raise the profile of health and health issues, and make it more likely that they’ll be considered in all circumstances. By bringing health impacts to the attention of government officials, developers, industry, and the public, HIAs increase general knowledge and establish health as an important factor to be considered whether or not an HIA is required in a particular situation.
  • HIA champions a participatory approach that values, includes, and empowers the community. This allows those affected by a project or policy to be consulted and listened to, or – even better – to participate in the planning and implementation of the HIA and, through it, of the policy or project itself. Such an approach increases the amount of knowledge and creativity brought to bear on solving problems and handling challenges, empowers and gives a voice to community members, increases community trust in the process, and encourages community support of the final result.
  • HIAs bring the community together. By emphasizing the importance of health impacts on all segments of the community, and by involving all segments in the HIA process, HIAs can unite communities and establish relationships among people who might otherwise have little contact with one another.

Through the participatory process, an HIA can also bring together community leaders and activists with government agencies, developers, and others to work out differences and build personal ties that will lead to collaboration in the planning and implementation of other projects and policies.

  • HIAs promote equity. One of the governing values of HIA concerns the promotion of equity and the particular consideration of health impacts on vulnerable populations. This promotes the fair treatment of everyone involved, with the needs of the most vulnerable addressed, and balanced against the needs of the general population. HIAs also give voice to community concerns, and thus promote equity in participation as well.
  • HIAs promote healthy behaviors and practices.The point of an HIA is not only to understand and prevent the negative, but to stimulate the potential positive health impacts of a project or policy. A new housing development, for example, can not only be built without volatile organic compounds (VOCs) – chemicals often contained in glues and solvents used in construction that can cause health problems in many people – but can include walking and bike paths and other features that encourage exercise and promote heart health. Thus HIAs can promote health both by forestalling possible hazards and by advancing healthy practices.
  • HIAs can be used in numerous and varied situations. HIAs can be, and are meant to be, adapted for use in individual local, regional, or national projects; long-term multi-project plans; and policy decisions that can cover anything from local economic development to national foreign policy. In addition, they can be designed individually for projects and policies in all sectors and in all different types of local, regional, or national circumstances. Because of the flexibility of the concept, HIAs can be a valuable tool for decision-making at any level.
  • Prospective HIAs provide information before the fact, leaving time to make adjustments in plans. HIA is meant to be prospective, and to give information that can guide decisions about how to implement projects and policies. This can eliminate problems down the road, deal with complaints or concerns, stave off potential legal battles and other conflicts, and generally make things go more smoothly. Even when an HIA is concurrent or retrospective, it can make it possible to correct problems or add features that promote health.
  • HIAs can promote sustainable development and environmental responsibility. Because sustainable development and concern for the environment are inextricably linked with the health of communities and populations (and are, in fact, specifically identified as determinants of health), HIA recommendations often link to them. Preservation of open space, alternative energy sources, environmental cleanup, non-toxic construction materials, curbs on pollution and noise, organic fertilizers and farming techniques – all of these may be elements of addressing health impacts, while addressing sustainability and environmental stewardship as well.
  • HIA is adaptable to the needs of many different groups. Local, regional, and state governments can employ HIAs to ensure that any projects or policies they undertake have the desired results without any unexpected negative side effects to health. Contractors and developers can make decisions about construction and other large projects that will avoid future problems and satisfy government requirements. Communities and community organizations can make sure that the health of the community is a major consideration in decision-making about projects and policies that affect them. Advocates for the disadvantaged or other vulnerable groups – children, people with disabilities, elders – can see to it that the needs of those groups are carefully considered when decisions are made.
  • HIA assists policy development. HIAs ensure that health is a concern when policies are considered, and that the potential health impacts of a policy are understood before it is implemented. This makes for better and more comprehensive policies, and helps to eliminate unintended consequences.
  • HIA helps the EU and some other policy makers address policy making requirements. In places where local, regional, national, or international laws and regulations dictate what must be included or considered when policies are developed and implemented, HIAs can provide decision-makers with the information they need in order to meet the requirements.
  • HIA recognizes that other factors besides health guide decisions. HIA can help decision-makers weigh all the factors that go into designing a project or developing policy. If there is a potential of adverse health effects for a very small number of people, versus a huge economic benefit for a very large number – many of whom may be lifted out of poverty – an HIA might serve to sway the decision away from making the health impact a priority...and that may be appropriate.
  • HIA is a proactive process that improves positive outcomes and decreases negative outcomes. An HIA affords decision-makers the opportunity to actively take steps to improve the health and well-being of the population in the course of accomplishing necessary and desirable projects or developing policy that enhances the community, the region, or the nation. Decision-makers can create a win-win situation in which everyone reaps the benefits.

When should you conduct a Health Impact Assessment?

As we discussed earlier, the timing of an HIA can take place before the project or policy is implemented (prospective), during the implementation (concurrent), or after the project is complete or the policy has become established (retrospective.) While any of the three can be valuable, it seems clear that the ideal is a prospective HIA. Getting all the facts and information before you start a project or implement a policy makes it much more likely that you’ll get it right, and not have to clean up a mess later. Some proponents of HIA feel that concurrent or retrospective HIAs aren’t really HIAs at all, but are simply monitoring or evaluating the project or policy.

The best time, therefore, to initiate an HIA is during the planning process, well before activity is scheduled to begin or policy put in place. A later HIA, whether concurrent or retrospective, can be useful, and can lead to correcting mistakes that are being or were made in the course of the activity. It’s much harder, however, to change a project or revamp a policy once it’s under way or – worse – completed than it would be to change plans beforehand. Furthermore, by the time a concurrent or retrospective HIA identifies a potential negative health impact, there’s a good chance that there will already be community or other groups calling attention to and perhaps protesting it. Considering impacts before the fact not only makes addressing them easier, but also avoids unnecessary conflict and distrust.

Who should be involved in conducting a Health Impact Assessment?

There are actually two ways to answer to this question. The first is a discussion of who needs to be included in a participatory HIA process and how. The second is a consideration of who should actually lead the process and conduct the assessment – a large amount of work, as we shall see, is involved; some of it is technical, and all of it requires a variety of skills. We’ll look at the second of these in the how-to part of the section, and limit the discussion here to who should be included in the process.

A truly participatory process is one in which all stakeholders are represented, and in which their role is significant, rather than just symbolic. That means that they actually take part in the planning and monitoring of the HIA, as well as in helping to formulate recommendations.

Stakeholders include:

  • Those who are directly affected by the proposed actions or policies. These folks might fall into several categories.
    • Members of the population at whom changes are aimed, where applicable.
    • Members of the population in closest physical proximity to proposed actions, and who will be directly affected by work to be done or other actions being carried out. Some examples are those living next to a proposed development site or irrigation project; those on a route between a major population center and an area to be developed; and those downwind or downstream of a proposed industrial development that could pollute their area, even if they’re relatively far away. (Heavy industry in the UK, Germany, and Poland is responsible for much of the acid rain in Norway, for example.)
    • Members of the most vulnerable populations that could be affected – children, elders, people with disabilities, language or other minorities, low-income groups.
    • Residents and officials of the communities or areas in which proposed projects or programs will take place (including neighborhood associations and the like.)
    • Residents and officials of communities that will be affected by the proposed actions or policies (e.g., communities subjected to heavier road traffic because of tourism development).
  • Those who are involved in carrying out the proposed actions or policies. These are the people responsible for actually doing the work of a project or implementing the details of a policy. Some possibilities:
    • Private developers and construction firms.
    • Local, regional, and national government agencies and officials.
    • Planners.
    • Police, firefighters, health workers, and other public service providers
  • Nonprofit and non-governmental organizations (NGOs) concerned with the issues and/or the populations affected. In many countries, particularly the U.S., these are often the groups that actually do the work of carrying out health and health-related policies, serving those with physical and mental health problems, and addressing violence prevention, environmental issues, and various other community challenges. They often see themselves as representing vulnerable populations, and may understand the needs of those populations more clearly than the government agencies that oversee them or the policy makers that decide their fates. It makes sense to involve them both for this understanding and because they are themselves affected by projects and policies.
  • Advocacy groups. Whether the subject of their advocacy is a cause or a population, these groups should be included in the HIA process from the beginning. If they’re included, they can be helpful in some of the same ways as NGOs. If they’re excluded, they’ll be (rightly) suspicious of the process, and can create problems for both the HIA and the project or policy it’s analyzing. With a seat at the table, they can work out any problems as they arise, and the process will go much more smoothly.
  • The decision-makers themselves. These are the people – government agencies, developers, architects, planners, local officials – who actually control the design and implementation of projects or policies. It goes without saying that they should be represented in the HIA process. First of all, they know the particulars of budget, time limits, and other factors that make a given option feasible or impossible. Just as important, the weight of the decision sits on their shoulders. It’s to their advantage – and to the advantage of a good decision – that they understand the true character of the evidence and its implications.
  • Government agencies that have responsibility for the issues and/or populations in question. It’s often up to agencies in the various sectors to carry out a project or policy. Not only should they be included for that reason, but because the better they understand the reasons for a project or policy being conducted in a certain way, the more likely they are to make that happen.
  • Representatives of other sectors that are affected by the proposal. An agriculture project, for example, may directly or indirectly affect water supply, transportation, the environment, and employment, to name but a few of the possibilities. Including the agencies or departments responsible for these areas will furnish better and more nearly complete information, foster inter-sectoral cooperation and communication, and keep all relevant sectors in the loop.
  • Health workers at local, national or international levels. These folks are the ones who are best situated to make judgments about health impacts and risks, and can add immeasurably to the usefulness of an HIA.
  • Employers and unions. As the people who will be responsible for and do the actual physical labor of a project, these groups can predict the feasibility of various options, and are affected by the choices of decision-makers. They may also have internal rules or contract conditions that dictate what can and cannot be done in the course of a project.
  • The commissioner(s) of the HIA – those who set it in motion (and pay for it, in many cases.) That could be a private developer – just as they often pay for environmental impact assessments as part of their permitting process – a municipality, the national government, an organization, etc.
  • Those who actually conduct the HIA. It goes without saying that the people who conduct the HIA are involved in its planning and implementation. That’s their job.

How do you conduct a Health Impact Assessment?

An HIA has both political and practical aspects, and they can’t really be separated. The political aspects have to do with the motivation and support for conducting an HIA, as well as its financing. The practical has to do with the mechanics and logistics of gathering the appropriate participants, putting together and implementing a plan, and coming up with information and potential courses of action. We’ll examine both of these – the political first, because at least some of the political elements have to be in place for an HIA to happen at all.

Political aspects of conducting an HIA

  • In order for HIA to become common, and particularly for it to be institutionalized, politicians and government agencies have to at least be willing to entertain some basic concepts:
    • That health is important enough to be integral to any project or policy that can have an impact on it.
    • That health is not an individual issue, but has to be viewed in a larger – community, regional, national, or international – context, depending on the scope of the project or policy proposed.
    • That health is more than the alleviation, elimination, or prevention of disease, injury, or medical conditions, but also includes the promotion, psychological implications, and other aspects of health.
    • That the social and other determinants of health are both real and crucially important to creating a healthy community and society.
    • That health transcends any one department or ministry – i.e., that more than public health agencies need to be involved in examining the health impacts of a project or policy, and that interdepartmental and inter-sectoral collaboration is necessary in order to fully understand the health impacts of projects or policies.
    • That they need the best, most accurate, most nearly complete information possible in order to make good decisions that take health impacts into account.
  •  HIAs won’t happen with any regularity or quality control unless they’re institutionalized by a legal basis of some sort – a law, an agency regulation, a clear policy, permit requirements, etc.. This legal basis has to set out clear standards for what an HIA needs to include and who should be involved, at whatever level it takes place. (A recent EU regulation, for example, requiring that any new project or relevant policy conduct an SEA – Strategic Environmental Assessment – specifies that population and health must be assessed alongside other factors.)
  • HIAs have to be paid for. Written into the governing legislation or regulations should be some consistent mechanism for financing them, or they won’t get done. This might be government funding out of a specific budget item, or out of the budget of the appropriate department or ministry. (A specific budget item makes more sense, since it eliminates the possibility of departments or agencies arguing over whose responsibility it is to pay for an HIA in an area where both have some oversight.)

Another possible financing method, at least for projects that are initiated by private firms, is to have the developer, corporation, or contractor pay for the HIA as part of the permit process, as they do in the U.S. for EIAs (Environmental Impact Assessments). Some combination of public and private funding might also be an option, at least in some cases. Although there are situations where citizens, an advocacy group, or an NGO might commission an HIA in order to protect a population at risk, funding, in general, should not have to depend on the people affected, but should be a government responsibility in some sense, as American EIAs are. (In that situation, the law specifies who pays for the EIA.)

  • Government agencies have to collaborate for an HIA to be of high quality. It usually takes the department or ministry of health, the governing agency of the sector the project or policy is directly related to, and often several other related ones as well to look at all the aspects of the proposal and to tease out all the potential implications for health embedded in them. A commercial development, for instance, might involve the departments of health, environment (air quality, noise, open space preservation, etc.), transportation (traffic patterns, new or improved roads), employment (economic factors), agriculture (effects on nearby cropland), and housing (displacement by the development), among others.

Government bureaucracies are often used to being competitive and secretive, rather than open and collaborative. For HIAs to work well, they have to understand that working together actually benefits all of them and makes their jobs easier.

  • Government has to be willing to involve, listen to (and heed) the concerns and advice of those who will be affected. Bureaucracies are often even more resistant to working with citizens than with other bureaucrats. The culture of government departments and agencies may need to change in order for that to happen. As with the necessity for collaboration among bureaucracies, bureaucrats need to see the advantages of public involvement (citizen buy-in, more trust in officials’ decisions, less aversion, reductions in post-project or -policy protests or lawsuits, etc.) before they’ll commit to it fully.

Practical aspects of conducting an HIA

There is no prescribed way to conduct an HIA. By definition, each is adapted to its context – the proposed policy’s location, sectors, and character, the amount of controversy it generates, the levels of government involved, etc. There is, however, a general, five-stage form to any HIA, and a set of logical, if not set-in-stone, guidelines that go with the stages that can help you conduct an HIA effectively.

The first step in the process is to choose assessors to conduct the HIA. The general, though not universal, consensus among HIA proponents is that people charged with this responsibility should be trained and/or experienced in HIA, regardless of what particular background – public health, social science research, public administration, or something else entirely – from which they come. Although not discussed widely, training probably should include a grounding in public health issues and in determinants of health, as well as in the broader perspective of health as a community (or wider) issue. Training should also encompass the mechanics of conducting an HIA – involving the community, including and conferring with all relevant agencies and organizations, generating options, etc., and perhaps some instruction/practice in reconciling opposing viewpoints, convincing sectors to work together, conflict resolution, and facilitation of discussion.

John Kemm, a leading HIA theorist and supporter, believes that training is less necessary than a general background in dealing with people and some ability to conduct research. He feels that HIA is so necessary that it’s more important to spread it widely as quickly as possible than to wait until a large number of people are expert at leading the process. Others feel that you’re setting yourself up for failure if you embark on the process without specific training and experience in conducting an HIA.

The author falls somewhere in between, as the next paragraph indicates. It seems reasonable to assume that a number of people have the skills – and personal characteristics – necessary to conduct a successful HIA as a result of the training and experience they already have. Training health impact assessors is certainly a good idea, but in a field as new as HIA, much of the expertise that’s needed will undoubtedly come through experience in any case. The best training may well be to understudy with someone who’s conducted successful HIAs in the past.

So who are the conductors of an HIA likely to be? Given the skills they need – the less training necessary, the more quickly they’ll be ready to undertake the task – they’d probably come out of one of the fields mentioned above, or perhaps others such as community psychology or the NGO world, where many of those skills are regularly needed and practiced. Other possible sources are universities, think tanks, and government. Wherever they come from, those who conduct HIAs should be able to relate to and communicate effectively and amicably with a broad range of people, be comfortable dealing with conflict and apparent contradictions, know how to navigate and negotiate government and other bureaucracies, understand research, and maintain their calm in the face of whatever comes their way.

There are political aspects to this choice as well. The most objective HIAs will obviously be conducted by people with no stake in the outcome and no connection to the agencies or other parties involved. Governments and other entities are often tempted, however, to have activities like HIAs conducted by people who are likely to favor their preferred course of action. There should be some guard against the employment of HIA practitioners who have particular biases, or who have obligations to those who commission the HIA. Both the need for the ethical use of evidence and the uselessness of an opportunistic HIA make the choice of practitioners an important one, and one that shouldn’t be dictated by politics.

HIA consists of five stages:

  • Screening
  • Scoping
  • Assessment
  • Reporting
  • Evaluation

We’ll look at each of these separately, and lay out some general guidelines within each to provide both a broader understanding of the HIA process and a series of steps you might take to conduct that process.

  • Screening. Each project or policy needs to be examined to determine whether an HIA is needed. There are at least two reasons why an HIA might not be needed. One is that the project or policy simply doesn’t have an impact on any area that affects health.

The second reason is that the project or policy already specifically takes health into account. This might be illustrated by a development that was designed to the LEED (Leadership in Energy and Environmental Design) gold standard – the highest rating from the U.S. Green Building Council – and used no toxic materials, in addition to setting aside several acres of its site for open space and recreation, creating bike and walking paths, and using a design that encouraged social interaction and group activity among residents.

Screening is the first – and sometimes the last – task in the conduct of an HIA. The identity of the screener can pose a problem. If you hire an individual or team to be the HIA assessor, he or they will have the knowledge and experience to judge whether an HIA would be valuable in a given circumstance. Unfortunately, he or they will also have a conflict of interest: if they decide an HIA is unnecessary, they’re out of a job. Leaving the task to the commissioner of the HIA can present a similar problem – HIAs are time-consuming, and involve dealing with the community and other sectors, neither of which the commissioner may be eager to do – as well as the danger that something important will be missed. A good option might be to hire someone with knowledge and expertise specifically to do the screening, and then to hire someone else to conduct the HIA if it’s needed.

  • Scoping. Scoping is the actual planning of the HIA. In this stage, you initially identify ways in which the decision in question could potentially affect health (positively or negatively) – the people who might be affected, how impacts should be assessed, whose expert opinion you need to get the full picture, what resources are needed to conduct the HIA, what kinds of evidence should be gathered, etc. At the end of the scoping process, you should have a complete plan for how to conduct the assessment.

As we’ve discussed, there’s no one way to conduct an HIA. It depends on the individual circumstances of each situation and place. What follows is one logical way to structure a scoping process, but should not be taken as the only way.

  • Using logic, prior knowledge, and the concerns of the community, make an educated guess about the possible health impacts of the proposed project or policy.
  • Determine the sectors, populations, groups, and individuals that need to be consulted and/or drawn into the process.
  • Assemble a team from among them to plan and do the groundwork for the HIA. This team should comprise representatives of as many stakeholders as possible, including those directly affected and those from or representing vulnerable populations.

The composition of this group may depend on time. If the timeline is short, it may not make sense to try to include the community on the planning team, although they do need to be consulted and kept informed. It is necessary to make sure that all relevant government agencies are included, or at least in the loop, both to avoid missing something important and to make sure that turf issues don’t interfere with the process.

An inclusive, participatory team is the ideal. Many HIA commissioners hire a consultant or a firm to conduct the HIA, and that individual or group may or may not make sure that all voices are heard. A short timeline makes it less probable that the process will actually be inclusive and participatory, but it should aim at those goals to the extent possible.

One point of using a team approach is that it gives everyone a chance to establish cross-sectoral personal relationships. These relationships not only make working together easier in the context of the HIA, but also improve relations among sectors for the future. HIAs, after all, aren’t the only processes that can benefit from various state agencies cooperating, or from collaboration between the government and the community.

  • Become familiar with the current state of the project or policy, and with the decisions that can and/or must be made. Can any or all aspects of the project or policy be cancelled or changed, and if so, which ones? Are there other projects or policies dependent on this one, or vice versa, and what are they? What is the project or policy meant to accomplish? What are its benefits expected to be, and to whom? Does it affect any vulnerable populations or groups?
  • Determine what evidence is needed. Different HIAs will need different types of evidence. Some may rely to a large extent on local first-hand accounts and interviews. Others may require monitoring of such things as water pollution or traffic flow. Still others may rely in part on epidemiological studies (broad-based examinations of health problems from many angles). Almost all will need some combination of evidence types. Types of evidence that might need to be sought out include:
  • Existing evidence. Studies of the issue that are relevant to the current situation, studies of the population(s) and geographical area(s) to be affected, statistics, etc.. These may be available from the various agencies involved, or from consultants, or may need to be found in professional journals, in libraries, or on the Internet.

Proponents of HIA emphasize that it’s important to search both the existing literature – i.e., published research – and “gray literature,” evidence that’s been gathered but not published. This may be statistical data that’s been gathered for funders; physical evidence, such as soil samples, that’s been taken and kept for other purposes (checking on the best places to plant a particular crop); interviews done in the course of undergraduate courses; etc.. Often, studies and evaluations conducted internally by NGOs or government agencies fall into this category as well: they’re meant not for publication, but merely to guide the work of the organization or agency.

  • Evidence that needs to be gathered. There are several types of evidence that can be useful here. One is conditions on the ground – the physical state of the geographic area, logistics (transportation, power, water, etc.), proximity to residences and frequented areas (schools, churches, parks, commercial districts), and the situation of the affected population. (Once again, agencies might be helpful here, as will experts in the field.) Another type of evidence lies in information from key informants and the community at large – community leaders or spokespersons, advocacy groups, people with an understanding of the area’s history, and people affected by the project or policy under scrutiny. A final type of evidence consists of studies or statistics that need to be conducted or gathered by the HIA, particularly on vulnerable populations. This work may be done by consultants or, where appropriate, by assessors or other members of the team.
  • Assign responsibilities for all parts of the HIA. Everyone should understand clearly just what her role is – planning and oversight, accomplishing specific tasks, attending meetings, contacting or interviewing people, etc. – and the time frame it entails. The assessors are generally responsible for overseeing the whole process, in addition to whatever other specific tasks they take on, and making sure that team members fulfill their commitments and meet deadlines.
  • Assessment. Up to this point, you’ve been planning. Now it’s time to perform the actual assessment – gather and study the evidence, and identify the nature, size, and targets of potential impacts under different options. The steps here aren’t really steps, in that most can be undertaken at the same time, if there are a number of people involved in the assessment.
    • Review existing evidence. This is largely a matter of tracking down and reading through studies and statistical reports, both published and unpublished. It might be assigned to one experienced researcher while others work on other tasks. (It may involve digging in university libraries and in the files of government agencies and departments – that’s where good relationships with people from many sectors come in handy.) The reviewer carries the responsibility to determine the reliability of studies and other existing evidence. Not every study is constructed or conducted well, and not all conclusions drawn are necessarily logical or accurate. It is the task of the reviewer to decide whether the study was constructed so that it would actually measure what it proposed to, and whether the researcher’s interpretation of the results bears up under scrutiny. If not, the evidence shouldn’t be used, or should be presented with the explanation that it’s suspect in some way.

Key steps in undertaking an objective and methodical review are:

  • Using a standard approach to guide the process.
  • Being systematic.
  • Focusing on a specific question.
  • Assessing the quality of the studies included in the review.
  • Analyzing and combining findings.
  • Presenting clear conclusions and recommendations

Following these steps will result in an unbiased consideration of findings, and will bolster one of the key values behind HIA: the ethical use of evidence.

  • Familiarize yourself with the proposed project or policy. Visit worksites, natural areas, factories, mines, farmlands, roads, etc., that the proposed (or current, if that’s the case) project or policy affects and learn all you can about it. Obtain and study blueprints, maps, proposed routes, and the like. Get to know the neighborhood, region, etc., which the project or policy will affect, what the residents’ circumstances are, what the geographic and social boundaries of the project or policy are, what connections they have to other neighboring or farther-away geographic and social areas. Understand the intentions of the decision-makers – their assumptions about the costs and benefits of the project or policy, its intended effects, etc. Be clear on the differences between the proposed project or policy and what currently exists. Research all the relevant laws and regulations. Understand what, if anything, would have to change if the project or policy were implemented. Know what areas the proposed project or policy might affect in addition to the particular one it concerns.
  • Learn what the range of options is. Some projects or policies may be open to cancellation, or to any changes that need to be made in them in order to address health impacts (we don’t need this road so badly that we’ll risk adverse health effects to build it.). Others may be modified only in certain ways (the road has to be built – the question is where to put it.). Still others may be severely limited in the changes they can absorb (the road has to go through here, but we want to soften the health effects of its construction and use on the local population.). If there are defined options – the road can go here, here, or here (Options 1, 2, or 3) – be aware of what they are, and of whether they are the only options possible, or whether others could be considered if they were practical.
  • Conduct individual and group interviews, hold meetings, administer surveys, etc., to gather other evidence and obtain community input.

The community or population should be kept informed throughout the process. Whether or not there’s a participatory planning group, the community should know that HIA exists, who is involved, and who they represent. The HIA should be described to them at the beginning, and they should be kept current on its progress. This will help to keep citizens from feeling that the government or big business or the government-corporate conspiracy is simply doing whatever it wants under a cloak of secrecy, and will find and decide whatever it pleases (and will also keep it from doing just that.)

  • Gather or compile statistics and other evidence currently unavailable which is necessary for a full picture of the situation. In some cases, when time and resources permit, that may involve conducting a study specifically for the HIA.
  • Gather information available from the various agencies, NGOs, think tanks, businesses, institutions, and other groups whose responsibilities or concerns are directly or indirectly relevant to the HIA or the issue, sector, geographic area, or population potentially affected. Evidence here may include such things as SES (socio-economic status) data, health and demographic statistics, scientific information, etc.
  • Assess the impacts of the proposed project or policy on the health of populations affected. This is, in some sense, the meat of the HIA. Once the evidence has been gathered and studied, it needs to be analyzed to understand possible health impacts. This can be a complex exercise, involving not only immediate effects on health in medical terms – air pollution that can cause or aggravate respiratory illnesses, for example – but also social determinants of health.

A development or policy that displaces people from a neighborhood and thereby disrupts families and social networks may have as much of an effect on their health as air pollution or the dumping of carcinogens. An industrial development may impact air pollution many hundreds of kilometers away, either through actual emissions, or in the form of increased truck traffic. It may also upset the economic balance of an area, throwing people on the financial edge into poverty, or lifting them out. The latter circumstance creates a dilemma, since it leaves the decision-makers weighing the positive health impact of economic security against the negative of increased medical risks.

But this is the purpose of an HIA. It isn’t meant to tell decision-makers what to do, but rather to give them the whole picture so they can make an informed decision. If that decision is difficult, and involves contradicting factors, it is even more important that they make it with their eyes open, and are able to explain the reasoning behind it.

It should be noted that HIAs can also serve to guide policy or projects outright in a positive direction. Karen Lock, in a BMJ online article (see Resources), cites a regional development plan that was designed around an HIA conducted to determine what kind of development would provide the strongest positive (and, one assumes, the weakest negative) impact on the health of the area’s population.

  • Determine the impacts that come with different options. Again, this can be complex, and isn’t guaranteed to be 100% accurate. How accurate it is depends on the expertise and experience of those conducting the HIA, as well as how much they consult with others in related fields to make sure they know all they can about the possible consequences of various courses of action. It also depends on whether options are predetermined or whether they can be generated by the HIA team, based on the evidence.

There are some basic questions that you can ask to help think about options and their impacts. If a negative health impact comes with the plan of the project or policy as it exists, how could it be eliminated? Are alternatives practical? Are they affordable? Who will they benefit? Who will the plan benefit if it is left as it is? Is there an option that turns the negative into a positive? (Creating a pedestrian-only space in a development may both eliminate the threat of injury and illness to children playing outside, and create an area where people can create social bonds and exercise as well, thus promoting healthy practices.)

Asking these kinds of questions and weighing the answers should give you a base for providing options and making recommendations, the next stage in the process.

  • Reporting and recommendations. Once the evidence has been analyzed and the assessment completed, the HIA team delivers a report to the commissioners of the process, the community, and the various agencies, organizations, and institutions involved. The report has two parts: The first describes the proposed project or policy, the HIA process, the evidence gathered, the conclusions drawn, and the options considered. The second consists of recommendations to minimize negative and enhance positive consequences for each option. Where it’s appropriate, recommendations should either present predetermined options in priority order or suggest other options (also prioritized) based on their analysis of the situation.

The recommendations should be generated based on the evidence. This means being non-political and objective, using all the relevant and reliable evidence, analyzing it scientifically where possible, and trying to understand and reconcile (or explain) conflicting conclusions where they exist. It also means weighing all the factors involved, not only health. While an HIA is meant to assess health impacts, one of the assumptions behind the process is that there may be several conflicting purposes – often all positive – and that in some cases, you can’t have your cake and eat it, too. The decision-makers may have tough choices, and the HIA process can help them.

The report should be framed so that everyone involved can understand it. If there are complex scientific, engineering, or other considerations, they should be included in the full report, but there should be a summary that’s understandable for the average person that explains the evidence and the conclusions drawn from it. It’s particularly important that those affected by the project or policy have a clear understanding of what was reviewed, what the conclusions and recommendations were, and to what extent their concerns were addressed. If they trust the process, they’ll be much more apt to support the final decision.

The report should be presented directly to decision-makers, and conclusions and recommendations explained at length and in person by those who conducted the HIA. It’s crucial that decision-makers understand the report completely, so they can use the information in it to best advantage.

The report should also be available to all stakeholders, and not just as a public record that they can find at the town hall or in the national archives. It should be easily accessible – sent to all affected households, if that’s a manageable number, for instance, and/or published in the newspaper or distributed to public libraries. It could also be sent to organizations that serve the affected population, or presented at public meetings. However it’s done, efforts should be made to ensure that the community knows that an HIA has been conducted, and what it’s found.

It’s also important that everyone – from decision-makers to the general public –understand that HIA is not a directive, but a tool to help decision-makers reason out the best course of action. They may choose not to take all or any HIA recommendations, but they should be able to explain why, and to defend their decisions with counterarguments.

  • Evaluation of the HIA’s effectiveness. As we’ve discussed, HIAs can be directly effective (the HIA resulted in changes to the original project, plan, or policy); generally effective (the HIA was conducted and considered, but didn’t result in any changes); opportunistically effective (the HIA was used only to confirm or support the original proposal); or ineffective (the HIA was ignored, or so poorly conducted as to be useless.) The HIA process, its results and conclusions, its recommendations, and its effect on decision-makers all need to be considered in an evaluation, in order to understand whether it was effective, and why or why not.

The process can be evaluated along several lines. How well did it reflect HIA’s guiding values of democracy, equity, sustainability and ethical use of evidence? How participatory and inclusive was it, and how well did it do at convincing stakeholders to participate? How successful was it at encouraging inter-sector cooperation? How well were responsibilities divided (if there was more than one person involved in conducting the HIA)?

Did the conclusions consider all the evidence? Did they accurately reflect the information contained in that evidence? Did they take into account all the determinants of health involved? Did they consider the feelings, fears, and opinions of the people affected? Did they acknowledge and describe conflicting health concerns (air quality vs. financial security, for example)?

Did the recommendations follow from the conclusions? Were they reasonable, considering such factors as expense, bureaucracy, logistics, hardship to citizens, etc.? Were the impacts on vulnerable populations given serious consideration and priority?

Were recommendations followed? If not, why not? If so, how were they implemented (e.g., was there a law passed, were actions modified, different materials substituted, a different route chosen, etc.)? How helpful was the HIA to decision-makers from their point of view?

The outcomes of the project or policy might be considered as well, but would be more likely to fall under an evaluation of the project or policy itself. That evaluation would be ongoing, and, ideally, would involve revisiting and perhaps revising some of the original recommendations of the HIA, as well as providing feedback on the effectiveness of the HIA process.

Conditions, populations, and economic circumstances change, and health impacts may change with them. New information surfaces and some new health threats appear, while former ones disappear. When that happens, there should be adjustments that reflect the changes and work to continue to support healthy communities. HIAs, and paying continuing attention to their conclusions and recommendations, can help projects and policies to remain dynamic, and to respond to the real health needs of the community, region, or nation they’re meant to benefit.

In summary

Health Impact Assessment (HIA) is a process that attempts to understand and make recommendations about the possible health impacts of local, regional, national, and international projects, plans, and policies. It involves all the players – government agencies in several sectors, contractors and developers, local officials, civic institutions, people affected by the proposed action or policy, etc. – to at least some extent in the planning and carrying out of the HIA, and is meant to inform them of its results as well.

An HIA is not meant as a directive for what decision-makers should do, but rather as a tool to give them the best and most accurate information possible to work with. They aren’t bound to its recommendations, but can use them to weigh competing interests and goals, and to make decisions that seem to carry the most overall public benefit, and the least potential for conflict.

HIAs are guided by the values of democracy, equity, sustainability, and the ethical use of evidence. If these values are practiced, a well-conducted HIA that is carefully considered by decision-makers can result in not only a well-planned and well-executed project or effective and equitable policy, but in community buy-in and support, and in a project or policy that truly protects and enhances public health and contributes to the creation of a healthy society.

Online Resources

APHA's Health Impact Assessment Fact Sheet. A tool to ensure that health and equity are considered in transportation policy and systems.

Health Impact Project offers a full page of assessment case studies from around the United States.

The Chronicles of Health Impact Assessment (CHIA) is an open access online journal. This peer-reviewed periodical has been created with the intent to serve the public health profession and encourage health in all policies. The journal strives to give expression to health impact assessment research and scholarship to serve public health and planning professionals.

Growing the Field of Health Impact Assessment in the United States: An Agenda for Research and Practice. (U. of California, Berkeley, School of Public Health). Andrew L. Dannenberg, MD, MPH, Rajiv Bhatia, MD, MPH, Brian L. Cole, DrPH, Carlos Dora, PhD, Jonathan E. Fielding, MD, MPH, Katherine Kraft, PhD, Diane McClymont-Peace, MS, Jennifer Mindell, MBBS, PhD, FFPH, Chinwe Onyekere, MPH, James A. Roberts, PhD, CEP, Catherine L. Ross, PhD, Candace D. Rutt, PhD, Alex Scott-Samuel, MB, CHB, MCommH & Hugh H. Tilson, MD, DrPH. From the American Journal of Public Health, February 2006, Vol 96, No. 2, pp. 262-270.

A Guide for Health Impact Assessment by the California Department of Public Health.

Health Impact Assessment (HIA) is a key strategy that supports organizations and governments to identify and integrate health-promoting policies and practices so that health becomes a key component in all community decision-making.

The Health Equity Impact Assessment from the Lawrence-Douglas County Health Department is an assessment tool used to identify unintended impacts of an existing policy on equity issues. The pdf version can be accessed here.

Health Impact Assessment and Housing: Guidance for health and housing professionals is a set of issue briefs that highlight ways to integrate the consideration of health into housing policy and projects through the use of HIAs.

Health Impact in the United States. This website offers an interactive map of Health Impact Assessments in several sectors that have been implemented all over the United States.

Health Impact Project.

Health Impact Project's Toolkits and Guides.

Health Inequalities Impact Assessment - An approach to fair and effective policy making: Guidance, tools and templates contains a guidance document (HIIA: An approach to fair and effective policy making), information about legislative requirements, a workbook for workshop participants and a summary version of the workbook, guidance for workshop facilitators and a document with key issues to consider, a process workplanner and templates for the scoping workshop scribe, and the workshop report and the final report, from NHS Health Scotland, a national Health Board working with public, private and third sectors to reduce health inequalities and improve health.

Improving Health in the United States: The Role of Health Impact Assessment. This book from the National Research Council and Committee on Health Impact Assessment, available for free online, offers guidance to officials in the public and private sectors on conducting Health Impact Assessments.

The report presents a six-step framework for conducting Health Impact Assessment of proposed policies, programs, plans, and projects at federal, state, tribal, and local levels, including within the private sector. In addition, the report identifies several challenges to the successful use of Health Impact Assessment, such as balancing the need to provide timely information with the realities of varying data quality, producing quantitative estimates of health effects, and engaging stakeholders. In addition to the guidance on evaluating public health consequences of proposed decisions -- such as those to build a major roadway, plan a city's growth, or develop national agricultural policies -- the report also suggests actions that could minimize adverse health impacts and optimize beneficial ones.

Is Health Impact Assessment Effective in Bringing Community Perspectives to Public Decision-Making? from the PEW Charitable Trusts. Lessons from 4 case studies in California

While geared toward its own region, the Mid-Michigan Health Impact Assessment Tool Kit is available to professional planners and the public and includes documentation that allows users within the region to download, replicate, and adapt HIA as a practice in their communities.

New Guides Help Bring Health Considerations Into Industrial Projects from the PEW Charitable Trusts. Tools can boost community health and businesses’ bottom lines.

UCLA Health Impact Assessment Clearinghouse. UCLA offers several completed HIAs for transportation policies.

U.S. Centers for Disease Control HIA page, with a number of references.

The U.S. Environmental Protection Agency offers case studies, tools, and policies related to Health Impact Assessments.

Use of Health Impact Assessment in the U.S. 27 Case Studies, 1999–2007. Andrew L. Dannenberg, MD, MPH, Rajiv Bhatia, MD, MPH, Brian L. Cole, DrPH, Sarah K. Heaton, MPH, Jason D. Feldman, MPH, Candace D. Rutt, PhD. This CDC publication looks at HIAs conducted on 27 varied projects and programs in a number of states.

Wikipedia article on HIA, including a number of references.

The World Health Organization website on HIA.

Print Resources

Wilkinson, R., & Marmet, M. (eds.). (1998). The Solid Facts: Social Determinants of Health.” World Health Organization: Copenhagen.

Wismar, M., Blau, J.,  Ernst K., & Figueras, J. (eds.). The Effectiveness of Health Impact Assessment: Scope and limitations of supporting decision-making in Europe. World Health Organization 2007, on behalf of the European Observatory on Health Systems and Policies.