Measurements of the built environment: A geospatial analysis of various density and proximity measures used to capture the tobacco retail environment

Background: Having appropriate measurement tools to gauge how the built environment influences health is imperative. For example, it is important to address environmental factors related to youth tobacco use onset, to better inform prevention efforts. Studies suggest that tobacco retailer density near schools is associated with increased teen smoking. However, measures of retail density have been crude, limited to counts of retailers near schools.

Methods: To better understand density and proximity measures, a review of existing measures was conducted. These existing measures will be evaluated using the same dataset, thus allowing direct comparison. Data from the 2007-2008 In-School Evaluation of TUPE Programs survey in 261 California schools are being examined to assess student tobacco use in relation to the geographic position of the retailers. In addition, schools will be linked to licensed tobacco retailers based on 2008-2009 California data.

Buffer zones surrounding each school were created to count the number of retailers around schools. In addition, more refined measures of tobacco retailer proximity and density are being developed. Examples include incorporating street-level data to account for actual physical access and reflecting ground barriers such as freeways, and cul-de-sacs. These new geospatial analyses account for the urban and rural landscape in the measurement of density and proximity, rather than assuming unrealistic straight-line distance. Hotspot analysis will also be done to identify areas high in retailer density.

The various measures will be compared using t-tests and chi-square analyses. Multilevel regression techniques will be used to estimate the association of these measures of retailer density and proximity with student smoking.

Conclusion: By comparing different measures, the best and most appropriate recommendations can be made. These geospatial analyses are expected to yield new insights into the impact of the built environment on student tobacco use, and on other health behaviors.