Dynamic healthy food accessibility in a rapidly urbanizing metropolitan area: Socioeconomic inequality and relative contribution of local factors

The socioeconomic status (SES) related disparities in healthy food accessibility have been heatedly debated. Theoretically, a gap remains in the literature about how healthy food accessibility changes over time and the relative contribution of local factors to the change. Methodologically, one main obstacle to this issue emerges on how to address the nested structural interactions among SESs across different levels. This paper first proposes a novel theoretical framework on healthy food accessibility from a spatiotemporally dynamic perspective. Guided by this framework, we employ the enhanced two-step floating catchment area model to examine the dynamic accessibility to four types of healthy food stores (i.e., vegetable markets, supermarkets, seafood markets, and fruit stores) from 2016 to 2018 across communities within the Hangzhou metropolitan area, China. The chain substitution method is further utilized to quantify the relative contributions of local factors, including population demand, healthy food supply, and transportation linkage. Multilevel regression is finally applied to analyze the associations between healthy food accessibility and the nested SESs across community and subdistrict levels. Results reveal that the dynamics of healthy food accessibility and the contributions of the local factors substantially vary depending on the type of healthy food stores and over time. Social inequality in accessibility to supermarkets and fruit stores is much greater than that to vegetable markets. The impact of the SES at the subdistrict level is greater than that at the community level. This study demonstrates a new methodological procedure and can offer new insights into healthy food accessibility in rapidly urbanizing metropolitan areas.