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Health Impact Assessment (HIA)

Health impact assessment (HIA) is a process used to evaluate the potential health effects of transportation policies, plans, or projects on the community and to help integrate these considerations into the decision-making process. An HIA includes recommendations about enhancing health outcomes and mitigating potential negative health impacts. An HIA also considers the distribution and equity of health outcomes in relation to vulnerable populations. The main steps in conducting an HIA include screening, scoping, assessing potential impacts, developing recommendations, reporting findings to decision makers, and monitoring and evaluation. Stakeholder input should inform the HIA decision process. An HIA can help identify which strategies, such as those provided in this tool, to pursue in an effort to improve health.

Related Transportation and Health Tool Indicators

How can this strategy result in health benefits?

  • Address chronic disease (e.g., asthma, diabetes, heart disease)
  • Improve access to health-supportive resources
  • Improve equity
  • Increase physical activity
  • Improve safety
  • Reduce human exposure to transportation-related emissions
  • Reduce motor vehicle-related injuries and fatalities
  • Reduce transportation's contribution to air pollution

How has this worked in practice?

Seattle State Route 520 Bridge Replacement HIA

Seattle, King County, and the Puget Sound Clean Air Agency collaborated with the Washington State Department of Transportation to conduct an HIA of the State Route 520 bridge replacement project in Seattle. The HIA focused on raising awareness among decision makers about the relationship between health and the physical, social, and economic environment. It also encouraged decision makers to include health consequences in their deliberations. Recommendations focused on air quality, noise, green space, physical activity (bicycling and walking), safety, social capital, mental health, water quality, and emergency preparedness.

Where can I learn more?

CDC’s Healthy Community Design Initiative website provides extensive resources about HIAs, a basis for conducting them, and how-to help, including a toolkit for transportation practitioners.

The Health Impact Project website provides extensive resources about HIA and a database of more than 300 HIAs known to be completed or in progress in the United States. Approximately 50 of these HIAs relate to transportation projects and policies.

UCLA Health Impact Assessment Clearinghouse includes a library of completed transportation HIAs, links to training and information, and updates on related legislation.

Evidence base

Bourcier E, Charbonneau D, Cahill C, Dannenberg AL. Do health impact assessments make a difference? A national evaluation of HIAs in the United States. Seattle, WA: Center for Community Health and Evaluation; 2014.

Dannenberg AL, Bhatia R, Cole B, Dora C, Fielding JE, Kraft K, McClymont-Peace D, Mindell J, Onyekere C, Roberts JA, Ross CL, Rutt CD, Scott-Samuel A, Tilson HH. Growing the Field of Health Impact Assessment in the United States: An Agenda for Research and Practice. American Journal of Public Health 2006;96(2):262-270.

Fleming D, McLerran D. SR 520 Health Impact Assessment: A bridge to a healthier community. Seattle and King County Public Health with Puget Sound Clean Air Agency; 2008.

Harris-Roxas B, Viliani F, Bond A, Cave B, Divall M, Furu P, Harris P, Soeberg M, Wernham A, Winkler M. Health impact assessment: the state of the art. Impact Assessment and Project Appraisal; 2012;30(1):43-52.

National Research Council. Improving Health in the United States: The Role of Health Impact Assessment. Washington, DC: The National Academies Press; 2011.

Rhodus J, Fulk F, Autrey B, O’Shea S, Roth A. A Review of Health Impact Assessments in the U.S.: Current State-of-Science, Best Practices, and Areas for Improvement. Cincinnati, Ohio: U.S. EPA; 2013.