Modified Retail Food Environment Index (mRFEI) Map By Census Tract Identifying Food Deserts and Food Swamps of Bexar County, Texas, 2015

BACKGROUND: Centers for Disease Control and Prevention (CDC) created a modified retail food environment index (mRFEI) which identifies food deserts and food swamps by combining them into a single measure within census tracts for every state. Although the state-wide mRFEI was created by census tracts level, large static mRFEI maps for each state could not identify small communities within the state. In Texas, Bexar County needed to pilot test a retail food environment assessment intervention. The objective of this study was to create mRFEI maps by census tract that could better identify counties specifically Bexar County to inform the pilot test of retail food environment assessment of this county.

METHODS: North American Industry Classification Codes (NAICS) were utilized to categorize retail food businesses as healthy or less healthy. Retail food data was purchased from Environmental Systems Research Institute (ESRI) and was current as of January 2015. The mRFEI ranges from 0 to 100 and was calculated as the number of healthy food retailers divided by the sum of the number of healthy food retailers and less healthy food retailers and multiplied by 100. Lower scores indicate that census tracts contain a higher number of less healthy retailers than healthy retailers. The mRFEI was calculated based on food retailers within a census tract and within a half mile buffer of a census tract boundary, identified using geoprocessing tools including clip, buffer, count, and spatial join with ArcGIS 10.3 and Pywin 32. Classification of the mRFEI used the same methodology as CDC’s original maps: 0 (no healthy food retailers), 0.1–5 (fewer less healthy food retailers), 5.1–10, 10.1–37.5, and 37.6–100 (more healthy food retailers).

RESULTS: 63 healthy food retailers and 1,218 less healthy food retailers were geocoded in Bexar County. By including a half mile buffer of each census tract boundary to count the retailers, 270 healthy food retailers and 4,811 less healthy food retailers were used to calculate mREFI which ranged from 0 to 50 for each census tract. Among 366 census tracts of Bexar County, 54.1% had no healthy food retailers, 8.7% fell within 0.1–5, 20.5% within 5.1–10, 15.3% within 10.1–37.5, and 1.4% within 37.6–100.

CONCLUSIONS: The mRFEI maps of Bexar County offered a user-friendly method to visualize and identify food desert and food swamp on smaller geographic areas than whole state. These results will inform the pilot test for retail food environment assessment of the county.