Health Impact Assessments

Conditions in the places where we live, work and play have a profound impact on our health. It is important to create conditions where we can easily and safely walk, run or bike; when we have clean air, healthy food and access to affordable housing; and when we are safe from things like violent crime, fires and lead poisoning. Policy makers outside of public health have opportunities to make choices that—if they took health into account—could help stem the growth of pressing health problems like obesity, injury, asthma and diabetes that have such a huge impact on our nation’s health care costs and on people’s quality of life.

Health impact assessment (HIA) is a fast-growing field that helps policy makers take advantage of these opportunities by bringing together scientific data, health expertise and public input to identify the potential—and often overlooked—health effects of proposed new laws, regulations, projects and programs.

Access Utilizing CDC Tracking Data for Health Impact Assessments Toolkit.  

What is HIA?

Health impact assessment (HIA) is commonly defined as “a combination of procedures, methods, and tools by which a policy, program, or project may be judged as to its potential effects on the health of a population, and the distribution of those effects within the population.”1 HIA is a practical tool that can:

  • provide a structured process to determine a policy or project’s impact on health;
  • bring both immediate and long-term health benefits;
  • and ensure that policy and project dollars are used efficiently to provide the greatest benefit.

The five principles and values of HIA are democracy, equity, sustainable development, scientific and robust practice, and a holistic approach to health.2 HIA continues to be one of the most important processes in public health, given its aim to influence decision-making processes in an open, multidisciplinary, and structured way.3

The HIA Process


The Screening phase is the first phase of an HIA process. It determines whether an HIA is feasible, timely and would add value to the decision-making process. The following elements should be evaluated during the Screening phase:

  • The potential for the decision to result in substantial health effects;
  • The potential for unequally distributed impacts;
  • Stakeholder interest/concerns about a decision’s health effects;
  • The potential for a decision to add new information that would be useful to decision-makers;
  • The potential for the HIA to result in timely changes to a policy, plan, program or project
  • The availability of resources, time and technical expertise


Scoping is the second phase of the HIA process. It determines what health impacts are going to be studied, which populations will be included in the study, and the methods that will be used to conduct an HIA. The following tasks should be performed during the Scoping phase:

  • Establish goals and anticipated outcomes of the HIA;
  • Establish the HIA scope; – Identify potential significant health and health equity impacts that will be studied; – Set geographic and demographic boundaries;
  • Create research questions;
  • Identify and select research methods to analyze each research question;
  • Determine an approach to evaluation and characterization of impacts and their distribution;
  • Engage stakeholders


Assessment is the third phase of the HIA process. It includes a summary of existing (baseline) conditions and analysis of potential health impacts. The following tasks should be performed during the Assessment phase:

  • Develop a profile of relevant health issues or factors that impact health (e.g., access to transportation, quality housing) and health outcomes (e.g., percentage of adults who have diabetes) among the affected communities;
  • Conduct assessment (e.g., literature review, data analysis, key-informant interviews, surveys or focus groups);
  • Describe the strength of evidence based on best practices for the relevant field; 
  • Create findings and characterize health impacts (e.g., direction, magnitude, likelihood)


Recommendations is the fourth phase of the HIA process. Recommendations are a way to suggest action that can enhance positive health effects and mitigate potential negative health effects related to the proposed plan/project/policy. The following tasks should be performed during the Recommendations phase:

  • Use criteria in developing recommendations including: – Responsiveness to predicted impacts; – Evidence-based (informed); – Technical and political feasibility; – Cost-effectiveness; and – Unaccompanied by additional negative consequences.
  • Create specific recommendations to address the health and equity impacts identified; Engage stakeholders and community members in developing recommendations and spearheading their future implementation.

Monitoring and Evaluation

Monitoring/Evaluation is the sixth phase of an HIA process. This phase helps determine future health impacts resulting from policy changes and assesses the HIA process, results and lessons learned. The following tasks should be performed during the Monitoring/Evaluation phase:

  • Conduct process, impact and outcome evaluations;
  • Develop a monitoring plan;
  • Make monitoring and evaluation results available to the public.


 1. European Centre for Health Policy, World Health Organization Regional Office for Europe. (1999). Health impact assessment: Main concepts and suggested approach. Retrieved October 22, 2015, from

2. UCLA School of Public Health. (2007). What is Health Impact Assessment? Retrieved October 22, 2015, from

3. Lock, K. (2000). Health impact assessment. BMJ: British Medical Journal, 320(7246), 1395.


Social determinants of health are an important part of HIAs. CDC has compiled scientific research into this area that can be used to provide guidance and resources.

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