Section 11. Health Impact Assessment

A Health Impact Assessment (HIA) is a tool that helps community leaders, policymakers, planners, and changemakers understand the possible health and safety effects of proposed projects, plans, programs, and policies on community members. An HIA can be a valuable resource for anticipating health effects before important decisions are made. This section explores how to conduct an HIA effectively and use the results to improve community projects, policies, and planning.

What is a Health Impact Assessment?

A consensus reached at a World Health Organization (WHO) meeting 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 may 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 sometimes group them under the term “project.” We’ll consider a project as an activity that has clear physical or practical 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 make a decision, but to support decision-making. It helps decision-makers consider options by anticipating the possible health consequences of each. HIAs are adapted to the needs and conditions of different locations and circumstances and can be used at the local, regional, national, and international levels. They have been applied to projects, plans, programs, and policies in such sectors as agriculture, residential development, transportation, mining, industry, energy, and recreation. HIAs can also be useful in areas such as employment, economic development, land use, and urban planning.

The actual practice of an HIA involves one or more practitioners – ideally people with appropriate training and/or experience – reviewing existing research and gathering evidence from people with expertise related to the project or policy, residents and other community members, public officials, health professionals, organizations, and others with relevant knowledge or experience. HIA practitioners may also attend or conduct meetings among different sectors, involve community members in discussions with developers or officials, and otherwise support the process in order to gather as complete a picture as possible of potential health effects and opportunities to promote health.

Ultimately, HIA practitioners prepare findings and recommendations that should be communicated to decision-makers and stakeholders, including people in the community who may be affected. Decision-makers can then use that information to help determine how to proceed.

An HIA may be commissioned by a government agency, policymakers concerned with a proposed project or policy, the organization or contractor carrying out a project, a local or regional government, a community organization, or another interested group, depending upon the circumstances. Regardless of who commissions it, the HIA should be conducted as independently, transparently, and objectively as possible.

HIAs can vary considerably in scope and intensity depending on the time, resources, evidence, and personnel available. Traditionally, they have sometimes been described in terms such as:

• Desktop. A relatively limited HIA that relies primarily on existing research, available data, and consultation with selected stakeholders.
• Rapid. An HIA that combines existing evidence with more direct consultation or field-based assessment and is generally conducted within a relatively limited time frame.
• Comprehensive. A more extensive HIA that seeks a broad range of evidence through literature review, interviews, community engagement, surveys, existing data, and, where appropriate, additional research.

The amount of time required for any of these approaches can vary widely depending on the complexity of the proposal, the information already available, the populations involved, and the decisions that need to be made. What matters most is that the scope of the HIA is appropriate to the decision and that the assessment provides useful information in time for decision-makers to act on it.

The ideal HIA is planned through a participatory process that involves stakeholders and encourages cooperation among the parties involved. In practice, this may require helping government agencies and organizations work across sectors and share information, while creating meaningful opportunities for community members to participate in the process.

Ideally, HIAs are prospective – that is, they look forward. An HIA is usually most useful when it is conducted before a project, plan, program, or policy is implemented, and preferably early enough that findings can influence its design. HIAs may also be conducted while implementation is underway or after a decision has been made, although at that point they function more as tools for identifying effects, informing adjustments, or contributing to future decisions. Where possible, an HIA should begin early enough to influence the decision it is intended to inform.

HIAs are guided by four basic values:

• Democracy. Wherever possible, people and organizations affected by or involved in a proposed action or policy should have meaningful opportunities to participate in the HIA, understand its possible consequences, and contribute their knowledge and perspectives.
• Equity. HIAs should examine how health impacts are distributed across the population, with particular attention to groups that may experience greater risks, barriers, or disadvantages.
• Sustainable development. Attention should be paid to both short- and long-term impacts of a proposed action or policy, including effects that may not be immediately obvious.

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 community and 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 using materials and construction methods that support both environmental sustainability and a healthy living environment over time?

• Ethical use of evidence. Research and evidence used in an HIA should be handled as objectively and transparently as possible. The purpose is not to search only for information that confirms a position already held, but to consider relevant and credible evidence whether or not it supports a preferred outcome.

The ethical use of evidence concerns not only ethics, but also the effectiveness of an HIA. One way of thinking about HIA effectiveness identifies several possibilities:

• Direct effectiveness: A project or policy is modified or reconsidered as a result of the HIA.
• General effectiveness: The HIA is properly conducted and meaningfully considered, even if it does not result in changes to the original decision. Changes may not have been necessary, or decision-makers may have considered the evidence and concluded that another option provided the greater overall benefit.
• Opportunistic effectiveness: The HIA is used primarily to confirm or justify a decision that has already been made, rather than to examine the evidence openly.
• Ineffectiveness: An HIA is conducted but largely ignored, or is conducted so poorly that it provides little useful information.

For an HIA to be genuinely useful, relevant evidence should be considered and presented as completely and accurately as possible. Only then can decision-makers make a truly informed decision. Selecting only evidence that supports a preferred outcome undermines both the ethics and the value of the process.

Bias can come from many directions. Government officials, businesses, community organizations, advocates, researchers, or others may all hold strong views about a proposal. The responsibility of the HIA process is to distinguish advocacy or preference from evidence and to present uncertainty, disagreement, and limitations clearly.

Like most of the other models discussed in this chapter, HIA looks at health from a community perspective. It considers social, economic, environmental, and political conditions, as well as more direct physical influences on health, when examining the potential effects of a proposal.

Factors that may influence health include:

• Individual and biological factors, such as age, genetics, and other personal characteristics.
• Individual behaviors and circumstances, such as physical activity, nutrition, smoking, and other health-related behaviors.
• Social and community networks, including family relationships, friendships, community organizations, and faith communities.
• Living and working conditions, such as education, employment, workplace conditions, water and sanitation, transportation, and housing.
• Broader socioeconomic, cultural, political, and environmental conditions, including income, access to resources and open space, environmental quality, and social conditions.

These factors may act alone, work in combination, or interact in ways that affect the health and well-being of individuals, communities, and whole populations.

This broad view of health is consistent with longstanding public-health approaches to social determinants of health and with the conditions for health described in documents such as WHO’s The Solid Facts and the Ottawa Charter.

Themes discussed in The Solid Facts include:

• The social gradient – differences in resources, opportunity, and health across socioeconomic conditions
• Stress
• Early life
• Social exclusion and social connection
• Work
• Unemployment
• Social support
• Substance use and related harms
• Food
• Transport

The Ottawa Charter identifies basic conditions and resources for health including:

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

Attention to social determinants greatly increases the breadth of what we might consider a health impact. Some impacts are direct – industrial emissions or contaminated water, for example, may contribute to specific health problems. Others are indirect and may be less immediately visible.

Increased traffic resulting from a development may raise noise levels, affect sleep, increase injury risk, or change opportunities for walking and bicycling. A major economic change may affect employment, income, stress, housing stability, or access to services. These effects may then influence health even though they are not medical interventions themselves.

That’s why an HIA can be so important. In the best case, it can help prevent or reduce negative health consequences and strengthen positive ones. Even when a project or policy cannot control every factor involved, identifying possible effects can help decision-makers plan for them, reduce harm where possible, and consider opportunities to improve health.

HIA is now an established approach used in many settings around the world. It may be conducted as a stand-alone process or incorporated into environmental, strategic environmental, social, or other forms of impact assessment. How frequently it is used, whether it is voluntary or required, and how formally it is incorporated into decision-making vary across countries and jurisdictions.

Why would you conduct a Health Impact Assessment?

HIAs, particularly comprehensive ones, can require considerable time, effort, and resources. Why invest in them? There are a variety of answers to this question.

• HIAs can support better decisions. An HIA provides decision-makers with relevant information about the potential health effects of the project or policy they’re considering. Identifying likely effects ahead of time can reduce surprises and make it easier to address problems before they become harder or more expensive to correct.
• HIAs promote cross-sector cooperation. Government agencies and other organizations concerned with health, agriculture, industry, education, transportation, housing, recreation, human services, and other areas may not routinely plan together. An HIA can bring these sectors together around a common decision.

An HIA for a transportation project, for example, might bring together highway engineers, public health officials, environmental organizations, residents near existing and proposed routes, water or utility agencies, farmers or property owners, planners, businesses, and others to examine different aspects of the proposal. Some of the relationships developed through that process may continue after the HIA is complete and support collaboration on future issues.

• HIAs raise the profile of health and health issues, making it more likely that health will be considered in decisions outside the health sector. By bringing health impacts to the attention of government officials, developers, businesses, organizations, and community members, an HIA can reinforce the idea that decisions about transportation, housing, employment, land use, and other areas can also be health decisions.
• HIA supports a participatory approach that values community knowledge and involvement. People affected by a project or policy can contribute information about local conditions, concerns, and priorities and, where possible, participate in planning the HIA and developing recommendations.

Meaningful community participation can increase the amount and variety of knowledge brought to the process, identify issues that might otherwise be missed, strengthen transparency and trust, and make it more likely that people understand how a final decision was reached.

• HIAs can bring people and organizations together. By examining health impacts across different parts of a community and involving people from different sectors and perspectives, an HIA can build relationships among people who might otherwise have little opportunity to work together.

Through a participatory process, an HIA can bring community leaders and advocates together with government agencies, developers, businesses, and others to discuss differences, identify shared concerns, and build relationships that may support collaboration on other projects and policies.

• HIAs promote equity. One of the governing values of HIA is attention to how health effects are distributed. An overall improvement in health can still leave some groups carrying a disproportionate share of negative impacts. An HIA asks not only, “What is the health effect?” but also, “Who experiences the benefit, and who experiences the harm?”
• HIAs can promote healthy conditions and practices. The point of an HIA is not only to identify and prevent negative effects, but also to identify opportunities to strengthen positive ones. A new housing development, for example, might reduce exposure to harmful building materials while also including safe walking and bicycling routes, accessible green space, and other features that support health.
• HIAs can be used in many different situations. HIAs can be adapted for individual local, regional, or national projects; long-term plans; programs; and policy decisions. Because the process is flexible, it can be used in a wide variety of sectors and circumstances.
• Prospective HIAs provide information before a decision is finalized, leaving time to adjust plans. This can help address concerns earlier, reduce avoidable harm, identify opportunities for improvement, and potentially prevent later conflict or costly changes.
• HIAs can promote sustainable development and environmental responsibility. Because the physical environment, climate, natural resources, and community conditions influence health, HIA recommendations may address open space, transportation, energy, pollution, noise, building materials, land use, and other environmental factors.
• HIA is adaptable to the needs of many different groups. Governments can use HIAs to understand potential health consequences of proposed decisions. Contractors and developers can use them to identify health-related risks and opportunities before projects are finalized. Communities and community organizations can use them to make health a more visible part of decisions that affect them. Advocates can use the HIA process to make sure the experiences and needs of groups likely to experience greater effects are considered.
• HIA assists policy development. An HIA helps ensure that health is considered when policies are developed and that possible intended and unintended consequences are examined before implementation.
• HIA can help decision-makers meet impact-assessment requirements. In jurisdictions where laws, regulations, permits, or planning processes require consideration of health or related impacts, HIA methods can help decision-makers gather and organize the information needed.
• HIA recognizes that health is one of several considerations involved in many decisions. Economic, environmental, logistical, social, legal, and other factors may also matter. The purpose of an HIA is to make health consequences visible so they can be considered openly alongside those other factors – including who receives the benefits and who bears the risks.
• HIA is a proactive process intended to strengthen positive outcomes and reduce negative ones. It gives decision-makers an opportunity to consider health and well-being while a project, plan, program, or policy is still being shaped.

When should you conduct a Health Impact Assessment?

As discussed earlier, an HIA may be prospective – conducted before the project or policy is implemented – or may be used concurrently or retrospectively to examine an action already underway or completed. The ideal for decision support is a prospective HIA. Gathering and analyzing information before a decision is finalized makes it more likely that findings can influence the outcome.

The best time to initiate an HIA is therefore during the planning and decision-making process, before implementation has advanced so far that meaningful alternatives are no longer possible. Later assessment can still provide useful information and may lead to corrections or improvements, but changing a project or policy after implementation is generally more difficult than improving it beforehand.

Who should be involved in conducting a Health Impact Assessment?

There are actually two ways to answer this question. The first concerns who should be included in a participatory HIA process. The second concerns who should actually lead and conduct the assessment – a substantial amount of work, some technical and some relational. We’ll look more closely at the second question in the how-to part of the section and focus here on who should be included in the process.

A truly participatory process is one in which relevant stakeholders have meaningful opportunities to contribute rather than being included only symbolically. Depending on the scope of the HIA, stakeholders may help identify concerns, contribute evidence and local knowledge, review findings, participate in planning, and help formulate recommendations.

Stakeholders may include:

• People directly affected by the proposed action or policy. These may include several groups:
  • Members of the population a proposed intervention or change is intended to reach, where applicable.
  • People living, working, studying, or spending time near a proposed project who may be directly affected by construction, traffic, environmental changes, displacement, noise, or other effects.
  • Populations that may experience greater health risks or barriers, such as children, older adults, people with disabilities, people with lower incomes, and communities that have historically been underrepresented in decision-making.
  • Residents, community organizations, and officials in the areas where proposed projects or programs would take place.
  • Residents and organizations in neighboring communities that could also experience effects, such as changes in traffic, employment, pollution, housing, or use of public resources.
• Those involved in carrying out the proposed actions or policies. These are people and organizations responsible for implementing the project or policy. Some possibilities include:
  • Private developers and construction firms
  • Local, regional, tribal, state, or national government agencies and officials
  • Planners
  • Public safety, health, and other public-service providers
• Nonprofit and nongovernmental organizations (NGOs) concerned with the issues or populations affected. These organizations may have direct experience providing services, working with communities, or understanding local conditions. Their knowledge can help identify potential effects that might otherwise be overlooked.
• Advocacy groups. Whether their focus is a particular issue, population, or community, advocacy groups may have relevant evidence, experience, or perspectives and should have opportunities to contribute where appropriate.
• The decision-makers themselves. These are the agencies, developers, planners, officials, boards, or others who control the design or implementation of the proposal. They understand such practical considerations as budgets, timelines, regulatory requirements, and the range of options actually available.
• Government agencies with responsibilities related to the issue or populations involved. Their involvement may be important both for the evidence they hold and for the role they may have in implementing decisions.
• Representatives of other sectors affected by the proposal. An agriculture project, for example, may affect water, transportation, employment, housing, land use, or the environment. Including relevant sectors helps create a fuller picture of possible consequences.
• Public-health and health professionals at the appropriate local, regional, national, or international levels. They can contribute expertise related to health impacts, population health, health data, and the interpretation of health risks and benefits.
• Employers, workers, and labor organizations. People who understand workplace conditions and the practical realities of implementing a project may provide useful information about feasibility, occupational health, and potential effects on workers.
• The commissioner or commissioners of the HIA. These are those who initiate and, in many cases, fund the assessment. They might include a government, developer, organization, agency, or partnership.
• Those who actually conduct the HIA. The practitioners carrying out the assessment are obviously involved in its planning, evidence review, analysis, reporting, and communication.

How do you conduct a Health Impact Assessment?

An HIA has both institutional and practical aspects, and they can’t really be separated. The institutional aspects concern whether decision-makers support the process, how it relates to existing decision-making procedures, how it will be funded, and whether agencies and organizations are willing to cooperate. The practical aspects concern gathering participants, planning the process, obtaining and analyzing evidence, and communicating findings and recommendations.

Institutional aspects of conducting an HIA

• For HIA to become a routine and useful part of decision-making, public officials, agencies, organizations, and other decision-makers need to recognize several basic concepts:
  • Health is important enough to be considered in projects and policies that may affect it.
  • Health is not only an individual matter, but can be influenced by community, regional, national, and international conditions.
  • Health involves more than the absence or treatment of disease and injury; it also includes mental, social, and broader aspects of well-being.
  • Social, economic, environmental, and other determinants of health can be important to individual and community well-being.
  • Health often crosses the boundaries of any one agency or sector. Understanding health impacts may require collaboration among public health, transportation, housing, environment, planning, education, economic development, and other sectors.
  • Good decisions depend on the best and most complete information reasonably available.
• Institutional support can help make HIA more consistent. HIAs can be voluntary or may be incorporated into laws, regulations, planning requirements, permitting processes, or organizational policies. Where HIAs are formally required or routinely used, clear standards can help define when an HIA should be conducted, what it should include, and how affected communities and other stakeholders should be involved.
• HIAs have to be paid for. A reliable way of financing an HIA is important if it is expected to be conducted thoroughly and independently. Funding might come from a public agency, the entity proposing a project, a dedicated public budget, or another appropriate source.

When a developer, corporation, contractor, government agency, or other interested party funds an HIA, safeguards should be in place to protect the independence and credibility of the assessment. Who pays should not determine what the evidence says.

• Government agencies and other sectors often have to collaborate for an HIA to provide a complete picture. A commercial development, for instance, might involve health, environmental quality, transportation, employment, agriculture, housing, utilities, land use, and other sectors.

Agencies and organizations have different mandates and responsibilities, and cooperation does not always happen automatically. An HIA can provide a structure for sharing relevant information and examining how decisions in one sector may affect another.

• Decision-makers and agencies should create meaningful opportunities to hear from people who will be affected. Community involvement can contribute information that professional or administrative sources may not contain, improve transparency, identify potential problems early, and strengthen trust in the process.

Practical aspects of conducting an HIA

There is no single prescribed way to conduct an HIA. Each assessment should be adapted to its context – the proposal, the population and geographic area affected, the sectors involved, available evidence, the time before a decision must be made, and the level of public concern.

Current HIA guidance sometimes divides the process into four, five, or six stages. The differences are largely a matter of whether such activities as recommendations, reporting, monitoring, and evaluation are separated or combined. For consistency with this section, we’ll use five broad stages.

The first task is to determine who will conduct the HIA. Ideally, those responsible should have appropriate HIA training or experience or have access to people who do. Useful backgrounds may include public health, planning, environmental health, social science research, public administration, community development, or related areas.

HIA practitioners also need skills that aren’t simply technical. They should be able to communicate with people from different backgrounds, work across agencies and organizations, understand and evaluate research, facilitate discussion, deal constructively with disagreement, and communicate uncertainty clearly.

Experience matters as well. Working alongside someone who has conducted a successful HIA can provide practical knowledge that is difficult to gain through written guidance alone.

Independence is important. Those conducting an HIA may be funded by or connected to organizations involved in the decision, but the assessment should include safeguards against pressure to reach a particular conclusion. Potential conflicts of interest should be identified and handled transparently.

For this section, HIA consists of five broad stages:

• Screening
• Scoping
• Assessment
• Reporting and recommendations
• Evaluation and follow-up

We’ll look at each separately and describe some general guidelines that can help you understand and carry out the process.

• Screening. A proposed project, plan, program, or policy is examined to determine whether an HIA would be useful. An HIA may not be needed when health effects are negligible, already well understood and appropriately addressed, or when the assessment would arrive too late to influence the decision.

Screening is the first – and sometimes the last – task in the HIA process. Whoever performs the screening should be able to judge the health relevance of the proposal while avoiding conflicts of interest. If the same consultant who would be paid to conduct the HIA also decides whether one is necessary, for example, that potential conflict should be recognized and managed.

• Scoping. Scoping is the planning stage of the HIA. Here, you identify the ways the decision could potentially affect health, the people and groups who may be affected, the health impacts that should be examined, the evidence and expertise needed, the time and resources available, and how the assessment will be conducted. At the end of scoping, you should have a clear plan for the HIA.

As we’ve discussed, there’s no one way to conduct an HIA. What follows is one logical way to structure the scoping process, but it shouldn’t be taken as the only way.

• Using existing knowledge, early evidence, and community concerns, identify possible positive and negative health impacts of the proposed project or policy.
• Determine the sectors, populations, groups, and individuals that need to be consulted or involved.
• Assemble an appropriate group to help plan and guide the HIA, with meaningful participation from people affected by the proposal whenever possible.

An inclusive and participatory process is the ideal. The amount and form of participation may vary with the timeline and scope of the HIA, but a short deadline shouldn’t be used as a reason to ignore the knowledge and concerns of affected communities.

One advantage of a team approach is that it can build relationships across sectors. Those relationships may make the HIA easier to conduct and may also support cooperation in future work.

• Become familiar with the current state of the project or policy and the decisions that remain open. Can the proposal be changed? Are some parts fixed? Are there alternatives? What is the proposal intended to accomplish? What benefits are expected, and for whom? Which populations could experience positive or negative effects?
• Determine what evidence is needed. Different HIAs will need different kinds of information. Some may rely heavily on interviews, local knowledge, and existing data. Others may require environmental monitoring, traffic analysis, epidemiologic evidence, geographic information, or other specialized information.
• Existing evidence. This may include research, population and geographic data, statistics, previous assessments, agency records, planning documents, and other information available from professional publications, libraries, agencies, institutions, or online sources.

HIA practitioners often consider both published research and “gray literature” – useful evidence that has not been formally published in an academic journal. Gray literature might include government reports, internal program evaluations, technical reports, community assessments, planning documents, data collected by organizations, or other credible sources.

• Evidence that needs to be gathered. This might include information about physical conditions, transportation, utilities, proximity to homes or community spaces, local economic and social conditions, or experiences of affected community members. Interviews with community leaders, residents, organizations, workers, and others may provide information not available in existing data.
• Assign responsibilities for each part of the HIA. Everyone should understand their role – planning and oversight, specific research or data tasks, community engagement, meeting participation, interviews, analysis, or other responsibilities – and the time frame involved.
• Assessment. Up to this point, you’ve been planning. Now it’s time to gather and analyze the evidence and estimate the nature, direction, magnitude, likelihood, and distribution of potential health impacts.
  • Review existing evidence. Track down and evaluate relevant studies, reports, data, and other available evidence. The reviewer has a responsibility to consider the quality of the evidence and whether conclusions are supported by the methods and data used. Weak or uncertain evidence should not automatically be discarded, but its limitations should be clearly identified.

Key steps in undertaking an objective and methodical review include:

• Using a clear and consistent approach to guide the process
• Being systematic
• Focusing on specific questions
• Assessing the quality and relevance of the evidence
• Analyzing and combining findings
• Presenting clear conclusions, uncertainties, and recommendations

Following these steps supports one of the key values behind HIA: the ethical use of evidence.

• Familiarize yourself with the proposed project or policy. Where appropriate, visit sites and affected areas. Study maps, plans, proposed routes, technical documents, and other relevant materials. Learn about the communities involved, local conditions, connections with neighboring areas, applicable laws and regulations, the goals of the proposal, and the assumptions being made about its expected benefits and costs.
• Learn what the realistic range of options is. Some proposals may be open to major changes or even cancellation. Others may have fewer alternatives. Be clear about which parts of the proposal are fixed, which can change, and whether additional options could reasonably be considered.
• Conduct individual and group interviews, hold meetings, administer surveys, and use other appropriate methods to gather evidence and obtain community input.

People affected by the decision should be kept informed throughout the process. They should know that an HIA is being conducted, who is involved, how they can participate, what questions are being examined, and how findings will be communicated. Transparency helps people understand the process and reduces the likelihood that decisions will appear to be made behind closed doors without their knowledge.

• Gather or compile additional data necessary for a fuller picture of the situation. Where time and resources permit, this might include conducting additional research specifically for the HIA.
• Gather relevant information from agencies, nonprofit organizations, businesses, institutions, research organizations, and other groups with knowledge related to the geographic area, population, sector, or issue under review.
• Assess the potential impacts of the proposed project or policy on affected populations. This is, in some sense, the meat of the HIA. Once the evidence has been gathered, it needs to be analyzed to understand possible positive and negative health effects, who may experience them, how significant they may be, and how certain the available evidence is.

A development or policy that displaces people from a neighborhood and disrupts social networks may affect health through housing instability, stress, loss of social support, or economic change. An industrial development may affect air quality locally or farther away, while also creating employment or other economic opportunities. These effects can point in different directions and may not be distributed evenly across the population.

That is one reason an HIA can be useful. It is not meant to tell decision-makers automatically what to do, but to make the different potential effects visible so that decisions can be made with a fuller understanding of their consequences.

An HIA can also help guide a proposal in a positive direction by identifying alternatives or design choices that strengthen potential health benefits rather than simply reducing harm.

• Determine the potential impacts associated with different options. Predictions will rarely be perfect. Their usefulness depends on the quality of the evidence, the expertise involved, the assumptions made, the amount of uncertainty, and how carefully different perspectives and forms of evidence have been considered.

Some basic questions can help in thinking about options. If the current plan carries a possible negative health impact, can that impact be reduced or eliminated? Are alternatives practical? What do they cost? Who benefits from each option? Who may experience harm? Can a negative effect be turned into a positive one?

Creating a pedestrian-oriented area in a development, for example, might reduce traffic-related injury risk while also supporting walking, physical activity, social interaction, and community connection.

Asking these kinds of questions and weighing the answers provides a base for developing options and recommendations.

• Reporting and recommendations. Once the evidence has been analyzed, findings should be communicated to the people who commissioned the HIA, decision-makers, stakeholders, and affected communities. The report should explain the proposal, the HIA process, evidence, findings, uncertainties, options considered, and recommendations for reducing negative health effects and strengthening positive ones.

Recommendations should follow from the evidence. This means making clear distinctions between evidence, interpretation, and preference; using relevant and credible information; acknowledging uncertainty and conflicting findings; and considering practical issues such as feasibility, resources, timing, and the broader goals of the proposal.

HIA may reveal competing interests or tradeoffs. That is not a failure of the process. Sometimes the evidence does not point to one obvious answer. The HIA’s job is to make the health implications of those choices as clear as possible, including how benefits and harms may be distributed across different groups.

The report should be understandable to the people who will use it. Technical information may need to be included in the complete report, but findings and recommendations should also be communicated in accessible language. People who may be affected by the proposal should be able to understand what was examined, what was found, what uncertainties remain, and how their concerns were considered.

Findings should be presented directly to decision-makers in a way that allows questions, discussion, and clarification.

The report should also be easy for stakeholders and community members to access. Depending on the size and nature of the HIA, that might mean posting the report online, providing summaries through community organizations and libraries, sharing information at public meetings, or using other appropriate communication channels.

It’s also important for everyone – from decision-makers to the general public – to understand that an HIA is not a directive. Decision-makers may accept, modify, or reject recommendations, but the process is most transparent when they explain how the HIA was considered and why particular decisions were made.

• Evaluation and follow-up. The HIA itself should be evaluated to understand how well it was conducted, whether it influenced decision-making, how recommendations were handled, and what could be improved in future assessments. Follow-up can also include monitoring whether agreed-upon recommendations are implemented and, where feasible, examining actual health effects after the decision takes effect.

The HIA process can be evaluated along several lines. How well did it reflect the guiding values of democracy, equity, sustainable development, and ethical use of evidence? How inclusive and participatory was it? Were stakeholders meaningfully involved? Did it encourage cooperation among sectors? Were responsibilities clear?

Did the analysis consider relevant evidence? Did conclusions accurately reflect what the evidence could and could not show? Were social, economic, environmental, and other determinants of health considered? Were the experiences and concerns of affected people taken seriously? Were competing health considerations acknowledged?

Did the recommendations follow logically from the findings? Were they realistic in terms of resources, logistics, law, policy, and feasibility? Did they consider who might experience greater benefits or harms?

Were recommendations adopted or acted upon? If not, why not? If they were, how were they implemented? How useful did decision-makers and community stakeholders find the HIA?

The actual health outcomes of the project or policy may also be monitored, although this may become part of the evaluation of the project or policy itself. Ongoing evaluation can help determine whether original assumptions were accurate and whether recommendations should be revisited or revised.

Conditions, populations, technology, environments, and economic circumstances change, and health effects may change with them. New information can emerge, new risks may appear, and old assumptions may prove incomplete. Continued monitoring and attention to HIA findings can help projects and policies remain responsive to the health and well-being of the communities they are intended to serve.

In Summary

Health Impact Assessment (HIA) is a process for understanding and making recommendations about the possible health impacts of projects, plans, programs, and policies. It draws on scientific evidence, local knowledge, community perspectives, and information from the different sectors involved in a decision.

An HIA is not meant to dictate what decision-makers must do. Rather, it provides information about possible health consequences – positive and negative, direct and indirect – and about how those consequences may be distributed across different populations. Decision-makers can then consider that information alongside the other factors involved in the decision.

HIAs are guided by the values of democracy, equity, sustainable development, and the ethical use of evidence. They work best when they are conducted early enough to influence a decision, when affected communities and other stakeholders can participate meaningfully, and when findings, limitations, and recommendations are communicated transparently.

This section presents the HIA process in five broad stages:

1. Screening – determine whether an HIA would be useful.
2. Scoping – decide what the HIA will examine, who should be involved, and how the assessment will be carried out.
3. Assessment – gather and analyze evidence about potential positive and negative health effects and their distribution.
4. Reporting and recommendations – communicate findings and recommend ways to reduce harm and strengthen health benefits.
5. Evaluation and follow-up – assess the quality and influence of the HIA and, where appropriate, monitor implementation and health effects over time.

A well-conducted HIA can contribute not only to better-informed projects and policies, but also to stronger communication, cross-sector collaboration, meaningful community participation, greater attention to equity, and decisions that more fully consider the health and well-being of the people they affect.