November 2008

Grant Results


From 2005 to 2006, staff at the University of California, Los Angeles, School of Public Health conducted a health impact assessment to investigate how public markets affect the health of communities. As its study site, staff selected the 60-year-old Trenton Farmers' Market in Trenton, N.J.

Health impact assessment is a multidisciplinary approach to evaluating the positive and negative health effects of policies and programs that are outside traditional public health concerns, such as urban development projects.

Key Findings
In Health Impact Assessment of Modifications to the Trenton Farmers' Market (available online), project team members identified five pathways through which changes to the market could impact health (nutrition, physical activity, economics, social capital and public health services). They then analyzed three alternative policy scenarios for their impact in these areas:

  • Policy One: no change or minor changes such as improved lighting, new wiring and new exterior doors — probably would not significantly impact health.
  • Policy Two: a major remodeling and expansion — could yield significant health benefits through its impact on the economy and social capital, but by itself probably would not improve consumption of healthy foods.
  • Policy Three: improving access to fresh fruits and vegetables through market outreach and satellite markets — was most likely to improve nutrition among market patrons.

The project team concluded that:

  • None of the alternatives is likely to change food consumption patterns unless augmented by other tactics to encourage behavior change, such as coupons and nutrition education.

The Robert Wood Johnson Foundation (RWJF) supported this project through an unsolicited grant of $126,785.

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Health Impact Assessments

Health impact assessment (HIA) is a multidisciplinary process that examines the positive and negative impacts of a policy or program by considering a broad range of economic, political, social, psychological and environmental factors. The value of this tool is its ability to identify and communicate potentially significant health impacts that are underrecognized or marginalized, such as the effects of wage policy or urban development projects.

Endorsed by the World Health Organization, health impact assessment has been used frequently in Europe, but less often in the United States. By the year 2000, however, interest in health impact assessment as a practical tool for promoting collaborative decision-making among diverse stakeholders was growing worldwide and in the United States.

Public Markets and Their Potential Health Impact

Studies by the Project for Public Spaces and others have demonstrated the potential of public markets and farmers' markets to revitalize communities economically and socially. These locally owned operations bring people of different ethnic and economic groups together; protect open spaces; and support small businesses, individual entrepreneurs and farmers.

Although these studies elucidated the nonhealth impacts of public markets, little research had focused explicitly on their potential for improving health, such as by increasing access to fresh fruits and vegetables.

The multidisciplinary focus of a health impact assessment made it particularly well suited for filling this gap in research. Its analytic tools can examine economics, geography, nutritional practices and numerous other sociocultural factors that shape the success of public markets and their impact on the health of the community.

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RWJF has invested in health impact assessment projects:

  • From 2001 to 2003, researchers at the University of California, Los Angeles, School of Public Health, worked under a subcontract from the Washington-based Partnership for Prevention to assess the feasibility and usefulness of health impact assessments in policy-making. Project staff created illustrative health impact assessments for two policy initiatives: the Los Angeles Living Wage Ordinance and the California Ballot Proposition 49 to increase after-school funding. The research team concluded that health impact assessments have potential to become a beneficial tool for persons involved in decision-making at all levels. (For more information, see Grant Results on ID# 040853.)
  • In 2004, RWJF and the Centers for Disease Control and Prevention convened a workshop of domestic and international experts on health impact assessment (see Grant Results on ID# 051172). Their recommendations, reported in the American Journal of Public Health (Dannenberg et al., 96[2]: 262–270, 2006, available online), were to conduct more U.S. health impact assessment pilot projects and to train more local public health officials in the procedure. (See the Appendix for more information on HIAs.)
  • From 2005 to 2007, the Georgia Institute of Technology's Center for Quality Growth and Regional Development worked with the Centers for Disease Control and Prevention to create a health impact assessment for the Atlanta BeltLine project, a 25-year plan to convert a 22-mile loop of largely abandoned freight rail right-of-way to parks, trails, transit and residential and commercial developments. See Grant Results on ID# 053546.

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From 2005 to 2006, a team from the Health Impact Assessment project of the University of California, Los Angeles, School of Public Health (UCLA) examined the linkage between public markets and community health.

The UCLA Health Impact Assessment project, a joint endeavor with the Washington-based Partnership for Prevention, funded by RWJF and the California Endowment, is the only research group in the United States dedicated to health impact assessment and training. It also conducted RWJF's project funded under Grant ID# 040853.

The project's objectives were to:

  • Develop a fuller accounting of the range of impacts that public markets have on communities and residents so that public and private resources for public markets can be targeted to maximize public benefit and to minimize harm.
  • Demonstrate the utility and limits of emerging health impact assessment methodologies.
  • Develop local capacity to conduct and use health impact assessments by training local agency staff members and involving them in preparation of the assessment.

Site Selection and Data Gathering

In the first phase of the project, the team selected a case study site in consultation with the New York City-based Project for Public Spaces, which was working to improve the economic viability of public markets in low-income communities around the country through its Public Market Program, supported by the Ford Foundation.

After reviewing multiple sites supported by the project, the team selected the Trenton Farmers' Market. Located approximately two miles outside of Trenton in Lawrence Township (Mercer County), the market had been operating year-round for 60 years and had a proven track record, economic sustainability and a large number of patrons and vendors. See Challenges for additional information on the site selection process.

Following site selection, the team gathered evidence for its impact assessment through:

  • Literature review on public markets.
  • Analysis of prior studies of the Trenton Farmers' Market conducted by the Project for Public Spaces and Rutgers University.
  • Direct observation of market activities.
  • Interviews and meetings with experts around the country as well as local stakeholders and the market's executive board.


Site selected was less than ideal. Despite a strong recommendation from the Project for Public Spaces, the Trenton Farmers' Market had several drawbacks as a candidate for HIA:

  • It did not serve a high-need, under resourced community.
  • Although it called itself a "Farmers' Market," its sales of fresh produce were limited during much of the year, making it difficult to examine potential nutritional benefits.
  • The market's executive board of directors was interested at most in relatively modest changes to the building, rather than major changes such as new locations or market expansion. The project team became aware of this position through meetings with board members after the assessment process began.

Aware of the board's position, the project team created alternative scenarios for modifications to the market that might have a greater impact on the health of the community. (See Conclusions.) According to the project director, this may not have been prudent since most health impact assessments restrict their analyses to proposals that are being considered by the community and do not attempt to create alternatives.

Detailed local data on health risks were not available. Since the reach of most public markets and farmers' markets is limited to a small population and small geographic area, detailed local information is needed to understand the potential health benefits. Most states, including New Jersey, do not have such local data. Statistical modeling techniques, such as small area estimation (SAE), can generate estimates but developing such a model is costly, and beyond the budget for this grant.

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  • The project team completed a health impact assessment and documented it in a report: Health Impact Assessment of Modifications to the Trenton Farmers' Market. According to the project team, this is the first health impact assessment of a public market in the United States. In addition to providing local stakeholders with site-specific information, it gives decision-makers in other locales a prototype they can apply in initiating or modifying farmers' markets. (Report available online.)
  • The project team produced a brief report on how to determine whether an in-depth health impact assessment is needed. In Lessons Learned for Screening for HIA: Selection of the Case Study Site for the Public Markets Health Impact Assessment, the project team identified minimum criteria that should be present before a project or policy is selected for a health impact assessment. See Lessons Learned for details.
  • Project team members educated staff from the Mercer County Health and Planning Departments, as well as market vendors and board members, in the purpose and value of health impact assessments. They also trained health department staff in the "scoping" process, which determines boundaries, data sources and a methodology for the health impact assessment. However, capacity-building efforts were hampered by limited personnel resources and competing priorities within the Planning Department, which was the lead agency involved in the HIA.


  • A profile of the Trenton Farmers' Market revealed that:
    • Although the market is called a "Farmers' Market," 27 of the 38 vendors sell primarily nonfarm products, including baked goods, meats, pizza, jewelry and household decorations.
    • The market attracts a higher proportion of mostly white middle to upper-middle income residents from surrounding Mercer County, and a much lower proportion of residents from central Trenton, who tend to be lower-income African Americans.
  • The project team identified three alternative policy scenarios for modifications to the Trenton Farmers' Market:
    • Policy One, favored by the executive board, involves no changes or minor changes to the market (i.e., improved lighting, new wiring and new exterior doors, with little or no change to signage, parking or the number and mix of vendors).
    • Policy Two, developed by Project for Public Spaces with input from community stakeholders, envisions a major remodeling and expansion of the market. It would change the market's outside appearance, improve signage and integrate it better into the community through a series of organizational and infrastructure changes.
    • Policy Three, developed by the project team, maximizes potential health benefits through outreach and improved access for the predominantly low-income, African-American residents of Central Trenton. Despite living only one to two miles away from the market, many area residents do not own cars and do not appear to frequent the market.

      This alternative would bring the market to the people who could benefit most by selling produce from mobile vans or organizing satellite markets at locations convenient and familiar to central-city residents.
  • The team identified five major pathways through which these modifications to the market might impact the health of the affected populations:
    • Nutrition. Markets can increase access to fresh fruits and vegetables, particularly in low-income communities, but improved access alone does not change consumption behavior. Evidence suggests that additional programs, such as coupons and education, are necessary.
    • Physical activity. The market has the potential to increase physical activity by encouraging more patrons to travel to the market on foot or by bicycle instead of by motor vehicle, stimulating the development of a more walkable neighborhood and providing a venue to educate people on the value of physical activity.
    • Economics. Farmers' Markets can have an indirect impact on health by generating income for individual vendors and producers and by stimulating economic development in the surrounding neighborhood.
    • Social capital. The amount of formal and informal social networks, group membership, trust, reciprocity and civic engagement in a neighborhood has been shown to benefit both subjective and objective measures of health.
    • Public health services. Markets can serve as venues for providing the community with preventive health services, such as health screenings, healthy-cooking demonstrations and nutrition education.

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The project team drew the following conclusions regarding the potential health benefits of the three alternatives.

  • The first policy (no or minor changes) would probably not impact health significantly.
    • Even within the limited scope of this scenario, the team recommended ways the market could improve potential health benefits and minimize harm. For example:
      • Setting up vendor stalls, particularly those selling fresh fruits and vegetables, with EBT (electronic benefits transfer) machines to take government benefit cards could help encourage low-income patrons to increase purchases of fruits and vegetables.
      • Ensuring that all food vendors offer healthy foods and pricing them competitively could result in healthier nutrition choices. With the existing plethora of unhealthy food choices, buying food at the market may be less healthy than buying from a supermarket.
  • The second policy, with its broader changes could yield significant health benefits through its impact on the economy and social capital, but by itself it probably would not improve consumption of healthy foods.
    • Project for Public Spaces estimates that more than $7.5 million in annual sales could be generated if local, low-income residents began shopping at the market, with daily sales per square foot comparable to an existing farmers' market in a low-income community.
    • In addition, $3 million has been projected in other sales from specialty shops, neighboring retailers and others.
    • Simply attracting more patrons could actually harm health if buyers primarily patronize the many unhealthy food options available in the market, such as pizza, fried chicken and deli sandwiches.
    • Long-term recommendations to improve pedestrian and bicycle infrastructure would improve the walkability and bikeability of the area around the market.
  • The third policy has the best likelihood for improving nutrition by increasing access to fresh fruits and vegetables.
    • Even this alternative, however, is not likely to change food consumption patterns unless augmented by other tactics to encourage behavior change, such as coupons and nutrition education.
    • Maximizing health benefits in other areas — for example, physical activity, economics and social capital — could be achieved by coupling this alternative with the modifications proposed under the second policy alternative.
  • Given the executive board's preference for policy one, it is likely that near-term changes to the market will be minor with little impact on health. In retrospect, the project team concluded that "modifications to the market that would likely yield significant health benefits may have been beyond the realm of what the market was willing to consider."

    Although the alternative scenarios for maximizing health benefits may not have much utility for the Trenton Farmers' Market, the project team concluded that "they still can serve as a guide to elucidating the potential health impacts of other Farmers' Markets, including other Farmers' Markets that might be organized in the Trenton area."

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  1. Screen a policy or program first to determine whether an in-depth health impact assessment is necessary or relevant. Screening is the first and most fundamental step of the assessment process, according to the project team. Based on lessons learned from working with the Trenton Farmers' Market, the team recommended that all candidates for an HIA should at a minimum be significant, evidence-based, feasible and able to add value or new information to the decision-making process. (Project Staff)
  2. Let partners and stakeholders know the limitations of HIA, especially when the scenario is less than ideal. Although the project team advocated careful screening, it did not recommend that decision-makers proceed with health impact assessments only when circumstances are ideal. A locality may be interested in pursuing a "good-enough" HIA with less-than-ideal information, but in those situations, partners should know exactly what an HIA can and cannot do. (Project Director/Cole)
  3. When selecting a site for an HIA, try to find one for which detailed local data are available. In retrospect, the project team wished it had "pushed harder" for its partner, Project for Public Spaces, to select a site for which fine-grained, local health risk data (e.g., fruit and vegetable consumption) were already available. Having this information for the Trenton Farmers' Market might have resulted in a more effective health impact assessment — and helped both to make a better case for HIAs in general and to serve as a better model for others to emulate. (Project Director/Cole)
  4. Create partnerships with local stakeholders to improve the process of conducting the health impact assessment and perhaps its long-term prospects for influencing decision-makers. The Planning Department was helpful in facilitating the assessment process, but since health outcomes were outside its purview, its investment in the result was limited to a consultative capacity.

    Partnering with a stakeholder group (e.g., health agencies, community-based organizations, market vendors and farmers) would have increased the sense of ownership of the HIA and the potential use of its results in addressing health issues through other programs and policies, regardless of whether they affected decisions to modify the farmers' market. (Project Director/Cole)
  5. A health impact assessment has the potential to inform policy or decision-makers, but, as this project shows, it is important to have buy-in from the local community group responsible for making a decision. In this case, the board members for the Trenton Farmers' Market were interested in minimal investments and maximum economic benefit. They did not appear to have a major interest in improving health outcomes or in recognizing that they could make investments in the structure and product offerings that would benefit a low-income community only one to two miles away. (Program Officer/Bazzarre)
  6. Make sure the health impact assessment team is located near enough to the project that there is realistic time to build relationships with local stakeholders. In this case, the assessment team was from the West Coast and that affected its ability to develop a working relationship with the target community. (Program Officer/Bazzarre)
  7. The project demonstrates that without a behavioral education program supported by incentives such as coupons, the proposed changes to the market are unlikely to increase the intake of fresh fruits and vegetables significantly. (Program Officer/Bazzarre)

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The project team has begun work on developing a health impact assessment of the potential effects of the federal Farm Bill on farmers' markets when it comes up for consideration in Congress again in 2012.

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Using Health Impact Statements to Increase Understanding of the Linkages between Public Markets and Community Health


University of California, Los Angeles, School of Public Health (Los Angeles,  CA)

  • Amount: $ 126,785
    Dates: September 2005 to December 2006
    ID#:  053545


Jonathan E. Fielding, M.D.
(213) 240-8117
Brian Cole, Dr.P.H.
(310) 206-4253

Web Site

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Appendix 1

Health Impact Assessment: Definition and Methods

Although there is no single definition of a health impact assessment, the World Health Organization (WHO) identifies the following as the "main" definition:

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.

WHO identifies the following as the main stages of an HIA:

  1. Screening (or scanning) quickly establishes the "health relevance" of the program or policy. Is the HIA necessary?
  2. Scoping identifies key health issues and public concerns and sets boundaries.
  3. Appraisal or impact assessment is a rapid or in-depth assessment of health impacts using available evidence.
  4. Report provides conclusions and recommendations to remove/mitigate negative influences on health or to enhance positive influences.
  5. Monitoring involves action, when appropriate, to monitor actual impacts on health to enhance the existing evidence base.

Additional information on HIA, with toolkits to help conduct the procedure and case studies of completed HIAs are available from the WHO Web site and from the UCLA Health Impact Assessment Web site.

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(Current as of date of this report; as provided by grantee organization; not verified by RWJF; items not available from RWJF.)


Cole BL and Fielding JE. Lessons Learned for Screening for HIA: Selection of the Case Study Site for the Public Markets Health Impact Assessment. Los Angeles: UCLA Health Impact Assessment Group.

Cole BL, Hoffman S, Shimkhada R, Rutt C, Fielding JE and Kaufman N. Health Impact Assessment of Modifications to the Trenton Farmers' Market (Trenton, New Jersey). Los Angeles: UCLA Health Impact Assessment Group, 2008. Available online.

World Wide Web Sites The Web page of the Health Impact Assessment project of the University of California, Los Angeles, School of Public Health. This provides access to health impact assessments conducted by the Health Impact Assessment Group, including the Trenton Farmers' Market project and two other HIAs conducted with funding from RWJF. The site also has information on HIA in general and links to toolkits for conducting HIAs.

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Report prepared by: Robert Crum
Reviewed by: Jayme Hannay
Reviewed by: Molly McKaughan
Program Officer: Pamela G. Russo