Marius Thériault

Association between Activity Space Exposure to Food Establishments and Individual Risk of Overweight

Objective Environmental exposure to food sources may underpin area level differences in individual risk for overweight. Place of residence is generally used to assess neighbourhood exposure. Yet, because people are mobile, multiple exposures should be accounted for to assess the relation between food environments and overweight. Unfortunately, mobility data is often missing from health surveys. We hereby test the feasibility of linking travel survey data with food listings to derive food store exposure predictors of overweight among health survey participants. Methods Food environment exposure measures accounting for non-residential activity places (activity spaces) were computed and modelled in Montreal and Quebec City, Canada, using travel surveys and food store listings. Models were then used to predict activity space food exposures for 5,578 participants of the Canadian Community Health Survey. These food exposure estimates, accounting for daily mobility, were used to model self-reported overweight in a multilevel framework. Median Odd Ratios were used to assess the proportion of between-neighborhood variance explained by such food exposure predictors. Results Estimates of food environment exposure accounting for both residential and non-residential destinations were significantly and more strongly associated with overweight than residential-only measures of exposure for men. For women, residential exposures were more strongly associated with overweight than non-residential exposures. In Montreal, adjusted models showed men in the highest quartile of exposure to food stores were at lesser risk of being overweight considering exposure to restaurants (OR = 0.36 [0.21–0.62]), fast food outlets (0.48 [0.30–0.79]), or corner stores (0.52 [0.35–0.78]). Conversely, men experiencing the highest proportion of restaurants being fast-food outlets were at higher risk of being overweight (2.07 [1.25–3.42]). Women experiencing higher residential exposures were at lower risk of overweight. Conclusion Using residential neighbourhood food exposure measures may underestimate true exposure and observed associations. Using mobility data offers potential for deriving activity space exposure estimates in epidemiological models.

Modeling urban dynamics : mobility, accessibility and real estate value

For many decades, aggregate data (pertaining to zones) were used to study urban dynamics, using summary methods that rarely permitted the study of urban phenomena at the spatial process level [CLI 81]. Given the scarcity of data and lack of technology capable of processing data to model the details of the process, urban studies’ research was still able to obtain conclusive results with regard to the conceptual aspects of urban dynamics and modeling of interrelationships among a city’s basic elements, especially with regard to social and economic aspects. Partly hindered by issues of a modifiable area units problem [OPE 79] and ecological fallacy [ROB 50], this research rarely produced operational tools capable of modeling and simulating the detailed operation of the urban system. This made it difficult to plan for its development following overlapping social, economic and political change at various geographic levels (from the global village to the local neighborhood, and at the national level). Nevertheless, it is indispensible to evaluate the scope and relevance of urban planning and development undertaken by local authorities (cities, higher levels of government associations, etc.) or conducted by the private sector (households, land developers, firms, etc.) [GEE 03].