Measuring Food Access in Urban Areas

Motivated by concern about rising obesity rates, researchers have begun to map the neighborhood " food environment " and examine its association with the risk of overweight or obesity. Some argue that " food deserts " – areas with little or no provision of fresh produce and other healthy food – may contribute to disparities in obesity, diabetes, and related health problems. When access to healthy food is limited, households must expend more time and/or money in order to eat a nutritious diet; more resource-constrained households may be especially likely to respond by substituting unhealthy for healthy food, leading to elevated rates of overweight and obesity. Recent studies have sought to explain socioeconomic or race/ethnic disparities in diet and body size using measures of proximity to food outlets such as supermarkets, convenience stores, or fast food restaurants. This research takes advantage of geographic information systems (GIS) technology and more widely available spatially referenced data to develop precise and objective measures of the local food environment. GIS measures have enabled a significant expansion of research on disparities in the food environment and their implications for health. More attention to conceptual and methodological issues would enhance the value of this research for science and public policy. This paper contributes to this broader agenda by examining the measurement of the food environment in urban areas. It opens with an overview of research on the food environment, drawing from epidemiology as well as urban planning and the social sciences. This discussion highlights two key categories of conceptual and methodological questions: how to define the relevant neighborhood and how to characterize the food environment within that neighborhood. Second, using an extensive collection of GIS data, we examine the spatial accessibility of healthy food in New York City. These analyses include fruit and vegetable markets and farmers' markets as well as supermarkets. As part of this empirical exercise, we conduct a series of sensitivity analyses to examine how adjustments for spatial variation in characteristics such as vehicle ownership, 2 crime, and public transit access affect measured disparities in the accessibility of healthy food. Lastly, we review recent food access initiatives in New York City and discuss the extent to which they are responsive to the disparities identified in our empirical analysis.