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The Network for a Healthy California (Network) is a statewide social marketing initiative led by the California Department of Public Health, funded in part by the United States Department of Agriculture (USDA) to provide nutrition education to people who are certified as likely or potentially eligible for the Supplemental Nutrition Assistance Program (SNAP). The Network targets persons whose household income falls below 185% of the federal poverty level (FPL). An essential tool for the Network for identifying geographic areas of the state where large proportions of the target audience can be reached with program activities is a geographic information systems (GIS) application.
Geographic information systems is a powerful tool for interpreting data and planning program delivery because of its unique abilities to bring together the functions of computerized databases and the output of geographic-based, visual information into the form of maps. Geographic information systems is an example of information technology being used in public health to help foster collaboration among disciplines and social programs to find common integration points that potentially allow for merging diverse information streams. Geographic information systems is becoming an integral tool for public health practice and participatory research, and there are many examples in which GIS and geographic data are used for assessing access to health services; resource allocation and management; geographic distribution of social inequities and overall health status and health outcomes; and other health-related issues.
Neighbourhood food environment and area deprivation: spatial accessibility to grocery stores selling fresh fruit and vegetables in urban and rural settings.
Geographic information systems has been essential for the Network staff and contractors for quickly determining intervention site eligibility; viewing neighborhood characteristics and assets/deficiencies; producing maps as products with which to engage neighborhood and other local policy makers; and for increasing general work efficiencies for the program as a whole. The Network has had direct experience in improving communication with policy makers about issues and trends in California surrounding the geographic distribution of household poverty and food assistance program delivery, distribution of food retailers, and other community factors associated with nutrition education. The main objective of this article is to give the reader a general description of how a large public health program currently capitalizes on the unique aspects of GIS technology to enhance its program delivery and stimulate conversation across diverse audiences.
Program Applications for GIS
The Network GIS Viewer is quite versatile and has many possible uses. Although the current uses by Network contractors are very focused on nutrition education and intervention activities as described below, the system is also available in the public domain on the Internet, lending to broader public usage of the data and capabilities. The current examples provided demonstrate the possibilities of GIS as a useful tool for public health program and audience targeting as well as collaborative data management.
Network contractors use GIS to identify eligible census tracts in which contractors may carry out their work. The USDA requires that Network programs and funding be targeted primarily within approved census tracts, low-resource schools, and a variety of “proxy” community sites,
United States Department of Agriculture. Food Stamp Nutrition Education Plan Guidance FFY 2008. Alexandria, VA: Food and Nutrition Service Food Stamp Program; 2007.
such as food banks, employment centers, low-income housing, and supermarkets with a high volume of electronic benefits transfer sales. At least 50% of households in census tracts must have incomes less than 185% of the FPL for the census tract to be deemed eligible. Based on 2000 US census data for all races combined, there are 1,335 census tracts out of 7,049 (nearly 31% of the 2000 population) in California that meet this criterion. Being able to quickly identify these census tracts in a user-friendly Web application allows contractors, at the beginning of the year, to more efficiently direct their program activities and qualify for USDA reimbursement. Similar methodology is used to determine eligible census tracts based on areas where at least 50% of households of a specific racial or ethnic group are < 185% FPL. Thus, Network contractors working with a more specific target population can operate in a census tract that may be deemed eligible for a specific race/ethic group, but not for all races combined.
In the very rural areas of California, census tract geography and the USDA eligibility metric may not realistically represent population need owing to sparse population counts in census tracts with a large overall area. In these situations, census block groups, with smaller overall area and population averages of approximately 1,500 people,
can be used as an alternative, thereby identifying possibilities for disseminating minigrant funding to groups and organizations located in small, more densely populated areas of a rural geographic service area. The GIS Viewer also maintains counts of de-identified food stamp recipients (over 2.5 million unique food stamp users in California during federal fiscal year 2007), summarized at block group levels, for each federal fiscal year, which can serve as important additional information about the community and the eligible target population.
The statewide GIS Viewer also maps neighborhood assets in eligible census tracts. This feature can be used by local agencies to quickly and easily identify intervention sites within an approved census tract or block group. Examples of assets that may be used for intervention sites include: schools; parks; health facilities; Network-funded local and regional contractors; grocers that accept electronic benefits transfer or Special Supplemental Nutrition Program for Women, Infants, and Children vouchers; and locations of proposed programs in low-wage worksites (Figure 1). Some GIS Viewer users have used the data to research access to healthful food (assets) that is available to public school students based on geographic proximity, and describing transportation strategies to increase access to food retail options with a focus on identifying differences in access based on neighborhood income indicators and race/ethnicity indicators.
Figure 1Sample map demonstrating unique datasets: funded grantees (local incentive award recipients); Supplemental Nutrition Assistance Program-certified vendors; Special Supplemental Nutrition Program for Women, Infants and Children agencies; public schools; and census tracts with poverty ratio information.
The GIS Viewer maps available health behavior data from several statewide health surveillance systems to various levels of geography throughout California. These data help local contractors and state staff set local priorities, complete annual needs assessments, and select special funding awards such as the regional Network contracts. The GIS Viewer includes individual school California Fitnessgram scores from 2004, 2005, and 2006 for grades 5, 7, and 9.
These data are delivered compiled and displayed as distinct map layers and their attributes as data reports. Other data layers in addition to those mentioned are arranged in 6 general thematic categories, shown in the Table.
TableCategories and Examples of Geographic Information System Data
Categories
Examples
Health, nutrition, education
Network for a Healthy California program sites, schools, nutrition intervention programs (federal, state, local, and non-profit)
Retail food channels
Food retailers (grocery stores, fast food, restaurants, convenience stores)
Worksite channels
Worksite wellness intervention sites
Administrative boundaries
US census boundaries, cities, zip codes
Communities
Parks, California Health Interview Survey data, healthy communities
The GIS Viewer can map selected indicators of healthful neighborhood food environments in low-income communities, similar to that found in the USDA Food Atlas,
USDA Food Environment Atlas. Economic Research Service, US Department of Agriculture Web site. http://ers.usda.gov/foodatlas/. Accessed February 7, 2011.
neighborhood-based study sites document the geographic accessibility to supermarkets and certified farmers’ markets, as well as the proximity of fast-food outlets to schools and parks (demonstrated by creating a half-mile circular buffer around the data point of interest) using the GIS system as a tool for 1 part of their assessment (Figure 2). These GIS-based methods that the sites use assist in describing a neighborhood food environment in relation to the types of food available to children on a daily basis. These methods are also augmented by more in-depth neighborhood surveys and qualitative data gathering in the field, to determine the types and quality of market produce available in retail food markets. The data from this study showed that a larger-than-expected number of small markets in low-income neighborhoods carried produce; however, it was of variable quality, leading the researchers to conclude that these types of stores did not reach a standard that could be considered as quality stores in low-income neighborhoods.
Figure 2View of a half-mile circular buffer created around a high school to show proximity to available food choices (eg, fast-food restaurants) for students, approximating a half-mile walking distance from the school.
Many data users have used existing GIS Viewer data either to describe their own communities in regard to access to healthful resources (nutrition and physical activity) or to research neighborhood and cultural factors (and differences among them) that may be associated with health outcomes, or they have proposed using these data to construct their own useful food environment indicator measures. The GIS Viewer currently has 122 layers from which to query and show on a map. The most frequently accessed layers include: the proportion of individuals (all races) at < 185% of the FPL; general grocery stores; the proportion of Hispanic individuals at < 185% of the FPL; fast-food, pizza, and sandwich establishments; convenience stores; farmers markets; and public schools. In the last half of 2009, the site received over 5,000 hits, representing 62 countries/territories, but over 90% of these hits originated from California. These measures serve as useful metrics for evaluation of usage of the GIS Viewer. In addition, the Network regularly surveys its GIS Viewer users in terms of overall site usability, functionality, user-friendliness, data appropriateness, and training needs. In the near future, new funding application materials will incorporate GIS Viewer components into scope of work activities by the contractors in an effort to more effectively track usage and accommodate Viewer updates.
Conclusion
The GIS Viewer gives the Network state staff, its contractors, and its partners an interactive data resource that can be adapted to specific program needs. The system greatly facilitates program planning and precise audience segmentation to help demonstrate the appropriate use of SNAP.
Notes
Because the GIS Viewer data are used to capture conditions present in the food environment rather than with humans as subjects of research, the project did not require institutional review by the common rule.
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Statement of Potential Conflict of Interest
This research project is funded in part by the USDA SNAP and Centers of Disease Control and Prevention through a contract with California Department of Public Health’s Network for a Healthy California (author MS) for the data collection, analysis, interpretation of results, and manuscript preparation. The opinions expressed are those of the author and do not necessarily represent the views or recommendations of their respective affiliations.
Funding/Support
This GIS project is funded in part by the USDA SNAP and Centers of Disease Control and Prevention through a contract with California Department of Public Health’s Network for a Healthy California.
References
Block J.P.
Scribner R.A.
DeSalvo K.B.
Fast food, race/ethnicity, and income: a geographic analysis.
Neighbourhood food environment and area deprivation: spatial accessibility to grocery stores selling fresh fruit and vegetables in urban and rural settings.
United States Department of Agriculture. Food Stamp Nutrition Education Plan Guidance FFY 2008. Alexandria, VA: Food and Nutrition Service Food Stamp Program; 2007.
USDA Food Environment Atlas. Economic Research Service, US Department of Agriculture Web site. http://ers.usda.gov/foodatlas/. Accessed February 7, 2011.
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