Health Impact Assessment

About health impact assessments

A health impact assessment (HIA) is a process that examines the potential health effects of a plan, project, policy, or program. You should conduct an HIA before the plan, project, policy, or program is built or started.

HIAs allow decision-makers in other sectors—such as transportation and land use—to consider the potential public health effects of their efforts. HIAs provide practical recommendations designed to increase positive health effects and minimize adverse health effects.

HIAs can also assess whether certain populations are likely to be disproportionately affected. The goal of HIAs is to provide recommendations that will protect health and reduce health inequities.1

In the United States, HIAs are usually conducted voluntarily. Several local and state laws support examining health effects during the decision-making process. Some areas explicitly require use of HIAs.

Voluntary HIAs, like ones that public health officers use to provide information to planning agencies, are often simple. They are also less expensive and more accepted than regulatory HIAs. Less intensive voluntary assessments are sometimes called health reviews. Because they are less comprehensive, health reviews may be easier to do and are thus more common.

Regulatory HIAs, like those modeled on a required environmental impact statement, are more complex, more expensive, and often less accepted.

Health impacts can also be assessed within existing environmental impact assessment processes.

How HIAs are conducted

The six steps of HIAs are as follows:

• Screening: Identify the plan, policy, project, or program decisions for which an HIA would be useful.
• Scoping: Plan the HIA and identify which health risks and benefits to consider.
• Assessment: Identify affected populations and quantify the decision's health effects.
• Recommendations: Suggest practical actions to promote positive health effects and minimize adverse health effects.
• Reporting: Present results to decision-makers, affected communities, and other interested groups.
• Monitoring and evaluation: Determine how the HIA affects the decision and the subsequent health status of the affected populations.

The effect of HIAs

HIAs can:

• Influence some decisions.
• Improve collaboration among groups affected by or interested in the plan, policy, project or program.
• Increase awareness of population health issues among decision-makers.
• Give community members a stronger voice in local decisions.

The importance of community engagement

HIAs should engage affected populations, especially during the scoping and assessment steps. Community engagement can increase community buy-in to a proposed plan, policy, project, or program. Community engagement can also help identify relevant social and health issues.

Engage decision-makers and groups affected by or that are interested in the plan, policy, project, or program. Provide clear, feasible, and timely recommendations. This may likely contribute to an HIA successfully influencing decision-making.

HIA data sources

Recommendations from HIAs can be based on qualitative or quantitative data.

• Qualitative data are often easier to collect. They can be used to describe the direction of the predicted results but not the magnitude.
• Quantitative data require more resources to collect. These data can be used to describe both the direction and the magnitude of predicted results. Quantitative data are needed if cost-benefit information will be considered in the decision-making process.

Health in all policies

HIAs can also be used as part of a collaborative approach to decision-making called Health in All Policies (HiAP).2The HiAP approach helps groups collaborate and consider health in all policy areas. The goal is to create healthier communities and people. The HiAP approach recognizes that health is influenced by many factors beyond just health care and traditional public health efforts. The HiAP approach may also be effective in identifying evidence gaps and achieving goals.