Euclidean Buffers Research Articles

Development and validation of a nationwide walkability index for the Netherlands using transport survey data

BACKGROUND AND AIM: Neighbourhood walkability indices have been developed and linked to behavioral and health outcomes elsewhere in the world, but not yet in the Netherlands. We aimed to compose a theory-based walkability index for the Netherlands and elucidate its cross-sectional association with adults’ walking behaviours. METHODS: The Dutch walkability index consists of seven components: population density, retail- and service destination density, land-use mix, street connectivity, green space, sidewalk density and public transport density. These components were composed and aggregated to three Euclidean buffer sizes (150m, 500m and 1000m) around every postal code and to every administrative neighbourhood. The normalized walkability index is the sum of its componential z-scores and scaled between 0-100. Data on self-reported demographic characteristics and walking behaviors of adult participants (aged 18-65, n=15716) were extracted from the Dutch National Travel Survey 2017. Using censored regression analysis (tobit model) adjusted for individual and survey-related confounders, we assessed the association between walkability index and total time spent walking, for non-discretionary and discretionary purposes. The main association was also examined across various urbanization degrees, socioeconomic levels, age groups and sexes. RESULTS:In fully-adjusted models, a 1% increase in walkability was associated with 0.49 minutes increase in walking (95%CI: 0.4-0.58), corresponding to 37 meters (95%CI: 29-44). This association was consistent across buffer sizes and between discretionary and non-discretionary walking. Stratified results showed that associations for minutes of walking were stronger in rural (0.90, 95%CI: 0.54-1.26) compared to highly urbanized areas (0.41, 95%CI 0.23-0.59), for discretionary walking in females (0.53, 95%CI: 0.38-0.67), and non-discretionary walking in males (0.64, 95%CI: 0.44-0.84). CONCLUSIONS:The walkability index was associated with walking behaviours of people in the Netherlands, indicating its value for further use in the Netherlands. KEYWORDS: walkability, built environment, travel behaviours

Associations of changes in neighbourhood walkability with changes in walking activity in older adults: a fixed effects analysis

BackgroundSupporting older adults to engage in physically active lifestyles requires supporting environments. Walkable environments may increase walking activity in older adults, but evidence for this subgroup is scarce, and longitudinal studies are lacking. This study therefore examined whether changes in neighbourhood walkability were associated with changes in walking activity in older adults, and whether this association differed by individual-level characteristics and by contextual conditions beyond the built environment.MethodsData from 668 participants (57.8–93.4 years at baseline) across three waves (2005/06, 2008/09 and 2011/12) of the Longitudinal Aging Study Amsterdam (LASA) were used. These individuals did not relocate during follow-up. Self-reported outdoor walking activity in minutes per week was assessed using the LASA Physical Activity Questionnaire. Composite exposure measures of neighbourhood walkability (range: 0 (low)-100 (high)) within 500-m Euclidean buffer zones around each participant’s residential address were constructed by combining objectively measured high-resolution Geographic Information System data on population density, retail and service destination density, land use mix, street connectivity, green space density, and sidewalk density. Fixed effects linear regression analyses were applied, adjusted for relevant time-varying confounders.ResultsChanges in neighbourhood walkability were not statistically significantly associated with changes in walking activity in older adults (β500m = − 0.99, 95% CI = -6.17–4.20). The association of changes in neighbourhood walkability with changes in walking activity did not differ by any of the individual-level characteristics (i.e., age, sex, educational level, cognitive impairment, mobility disability, and season) and area-level characteristics (i.e., road traffic noise, air pollution, and socioeconomic status).ConclusionsThis study did not show evidence for an association between changes in neighbourhood walkability and changes in walking activity in older adults. If neighbourhood walkability and walking activity are causally linked, then changes in neighbourhood walkability between 2005/06 and 2011/12 might have been not substantial enough to produce meaningful changes in walking activity in older adults.

Socioeconomic inequalities in food outlet access through an online food delivery service in England: A cross-sectional descriptive analysis

Online food delivery services facilitate ‘online’ access to food outlets selling food prepared away-from-home. Online food outlet access has not previously been investigated in England or across an entire country. Systematic differences in online food outlet access could exacerbate existing health inequalities, which is a public health concern. However, this is not known. Across postcode districts in England (n = 2118), we identified and described the number of food outlets and unique cuisine types accessible online from the market leader (Just Eat). We investigated associations with area-level deprivation using adjusted negative binomial regression models. We also compared the number of food outlets accessible online with the number physically accessible in the neighbourhood (1600m Euclidean buffers of postcode district geographic centroids) and investigated associations with deprivation using an adjusted general linear model. For each outcome, we predicted means and 95% confidence intervals. In November 2019, 29,232 food outlets were registered to accept orders online. Overall, the median number of food outlets accessible online per postcode district was 63.5 (IQR; 16.0–156.0). For the number of food outlets accessible online as a percentage of the number accessible within the neighbourhood, the median was 63.4% (IQR; 35.6–96.5). Analysis using negative binomial regression showed that online food outlet access was highest in the most deprived postcode districts (n = 106.1; 95% CI: 91.9, 120.3). The number of food outlets accessible online as a percentage of those accessible within the neighbourhood was highest in the least deprived postcode districts (n = 86.2%; 95% CI: 78.6, 93.7). In England, online food outlet access is socioeconomically patterned. Further research is required to understand how online food outlet access is related to using online food delivery services.

Associations of traffic-related air pollution and greenery with academic outcomes among primary schoolchildren

BackgroundThere is preliminary evidence that greenery/greenspace around schools may be positively associated with children's cognitive development and academic outcomes, whereas traffic-related air pollution (TRAP) may have a detrimental effect. Few studies have examined pathways between both exposures and academic outcomes. This study aimed to assess associations between greenery, road traffic density (a proxy for TRAP) surrounding primary (elementary) schools, and academic achievement of primary schoolchildren in Melbourne, Australia. MethodsThis cross-sectional study examined mean academic scores in Years 3 and 5 for primary schools (n = 851) in Greater Melbourne. Scores were from the 2018 ‘National Assessment Program – Literacy and Numeracy’ (NAPLAN) in five domains: ‘Reading’; ‘Writing’; ‘Spelling’; ‘Grammar & Punctuation’ and ‘Numeracy’. Greenery was measured within school boundaries and surrounding Euclidean buffers (100, 300, 1000 and 2000 m) using the Normalized Difference Vegetation Index (NDVI). Measured TRAP proxies were weighted road density (WRD) within the buffers and distance to a major road. Generalised Linear Models were used to examine associations of greenery and TRAP with academic scores (adjusted for school socio-educational status), and to identify mediating pathways. ResultsGreenery was positively associated with Reading scores in Year 3 (all buffers except 2000 m) and in Year 5 (all buffers), with Numeracy in Years 3 and 5 (all buffers) and with Grammar & Punctuation in Year 5 (all buffers). WRD was inversely associated with Reading scores in Year 5 (all buffers), with Numeracy in Year 3 (all buffers) and Year 5 (300 and 1000 m buffers), and with Grammar & Punctuation in Year 3 (100 and 300 m buffers) and Year 5 (all buffers). Distance to a major road was not associated with any score. TRAP partially mediated associations of greenery within 300 m with Numeracy in Year 3 and Grammar & Punctuation in Year 5, and within 2000 m for Reading in Year 5. ConclusionsPreliminary evidence indicated that greenery around primary schools was positively associated with Reading, Numeracy and Grammar & Punctuation scores, with TRAP mediating some associations. Further research is required to improve TRAP exposure assessment around schools to verify these findings and inform town/school planners and educators regarding optimal school locations and environments for promoting learning.

Accessibility Analysis of Primary Healthcare Services in Mysore District Using Geospatial Techniques

The accessibility of healthcare centers is one of the most important indicators for measuring the efficiency of a healthcare system. Accessibility is a complex indicator that reflects the number of health care institutions, their geographical distribution and the impact of different types of barriers social, Economic and culture (1). Primary health centre which acts as the first level of contact between the population and health centers. It acts has a cornerstone of rural health services. Primary healthcare is affordable, accessible and appropriate care for the particular needs of a given population especially in rural areas. The main objectives of the study are to study the spatial distribution pattern and delineation of service area of primary health centers; to identify the gap between the availability and accessibility of health services. The base map of study area has been geo-referenced and digitized using ARC GIS software. The Global positioning system (GPS) was adopted to take the coordinate of all the existing primary health centers in the study area. Simple Euclidean buffers are mapped and analyzed to define the service area, Thiessen polygon and Nearest Neighbour Technique was used here to identify the availability of health services in Mysore district. The results reveal that, the spatial variation in the distribution of PHC’s, which were not evenly distributed across the study area and there is scarcity in the availability of workforce among the study area.

Harvesting spatially dense legacy soil datasets for digital soil mapping of available water capacity in Southern France

Although considerable work has been conducted in recent decades to build soil databases, the legacy data from a lot of former soil survey campaigns still remain unused. The objective of this study was to determine the interest in harvesting such legacy data for mapping the soil available water capacities (SAWCs) at different rooting depths (30 cm, 60 cm, 100 cm) and to the maximal observation depth, over the commune of Bouillargues (16 km2, Occitanie region, southern France).An increasing number of available auger hole observations with SAWC estimations – from 0 to 2781 observations – were added to the existing soil profiles to calibrate quantile regression forests (QRFs) using the Euclidean buffer distances from the sites as soil covariates. The SAWC was first mapped separately for different soil layers, and the mapping outputs were pooled to estimate the required SAWC. The uncertainty of the SAWC prediction was estimated from the estimated mapping uncertainties of the individual soil layers by an error propagation model using a first-order Taylor analysis.The performances of the SAWC predictions and their uncertainties were evaluated with a 10-fold cross validation that was iterated 20 times. The results showed that the use of a quantile regression forest that was fed with auger hole observations and that used the Euclidean buffer distances as soil covariates considerably augmented the performances of the SAWC predictions (percentages of explained variance from 0.39 to 0.70) compared to the performance of a classical DSM approach, i.e., a QRF that solely used soil profiles and only environmental covariates (percentages of explained variance from 0.04 to 0.51). The analysis of the results revealed that the performances were also dependent on the spatial patterns of the different examined SAWCs and was limited by the observational uncertainties of the SAWCs determined from auger holes. The best performance tended to also provide the best view of the uncertainty patterns with an overestimation of uncertainty.Despite these gains in performance, the cost-efficiency analysis showed that the augmentation of soil observations was not cost efficient because of the highly time-consuming manual data harvesting protocol. However, this result did not account for the observed gain in map details. Furthermore, the cost efficiency could be further improved by automation.

Urban street tree biodiversity and antidepressant prescriptions

Growing urbanisation is a threat to both mental health and biodiversity. Street trees are an important biodiversity component of urban greenspace, but little is known about their effects on mental health. Here, we analysed the association of street tree density and species richness with antidepressant prescribing for 9751 inhabitants of Leipzig, Germany. We examined spatial scale effects of street trees at different distances around participant’s homes, using Euclidean buffers of 100, 300, 500, and 1000 m. Employing generalised additive models, we found a lower rate of antidepressant prescriptions for people living within 100 m of higher density of street trees—although this relationship was marginally significant (p = 0.057) when confounding factors were considered. Density of street trees at further spatial distances, and species richness of street trees at any distance, were not associated with antidepressant prescriptions. However, for individuals with low socio-economic status, high density of street trees at 100 m around the home significantly reduced the probability of being prescribed antidepressants. The study suggests that unintentional daily contact to nature through street trees close to the home may reduce the risk of depression, especially for individuals in deprived groups. This has important implications for urban planning and nature-based health interventions in cities.

Spatiotemporal Trends in Discarded Needle Reports in San Francisco Over a 10-year Period, 2010-2019

BackgroundTo describe the geographic and spatiotemporal distribution of needle reports in San Francisco, and examine spatial relationships between needle reports and needle disposal boxes, needle disposal kiosks, and homeless shelters. MethodsWe conducted multiple geospatial analyses of a crowdsourced database of non-emergency service requests. We describe changes in discarded needle and bulky item reports across San Francisco between 2010 and 2019, and compared changes in the reporting patterns of these items, while 200-meter Euclidean buffers captured needle reports in close proximity to needle deposit boxes, needle deposit kiosks, and homeless shelters in 2019. Results34,912 needle reports were included. Yearly needle reports increased by 3827.1%, with a markedly different geospatial distribution from bulky item reports. 45.6% of needle reports originated in the five downtown neighborhoods with the highest needle report density, and 33.8% were identified within 200 meters of boxes, kiosks, or homeless shelters. ConclusionsReports of discarded needles in San Francisco increased dramatically over the last decade, and more than one third of 2019 reports were adjacent to harm reduction and homeless shelter locations. Needle reports provide an opportunity to understand changes in public injection drug use and target harm reduction services.

GIS-modelled built-environment exposures reflecting daily mobility for applications in child health research

BackgroundInaccurately modelled environmental exposures may have important implications for evidence-based policy targeting health promoting or hazardous facilities. Travel routes modelled using GIS generally use shortest network distances or Euclidean buffers to represent journeys with corresponding built-environment exposures calculated along these routes. These methods, however, are an unreliable proxy for calculating child built-environment exposures as child route choice is more complex than shortest network routes.MethodsWe hypothesised that a GIS model informed by characteristics of the built-environment known to influence child route choice could be developed to more accurately model exposures. Using GPS-derived walking commutes to and from school we used logistic regression models to highlight built-environment features important in child route choice (e.g. road type, traffic light count). We then recalculated walking commute routes using a weighted network to incorporate built-environment features. Multilevel regression analyses were used to validate exposure predictions to the retail food environment along the different routing methods.ResultsChildren chose routes with more traffic lights and residential roads compared to the modelled shortest network routes. Compared to standard shortest network routes, the GPS-informed weighted network enabled GIS-based walking commutes to be derived with more than three times greater accuracy (38%) for the route to school and more than 12 times greater accuracy (92%) for the route home.ConclusionsThis research advocates using weighted GIS networks to accurately reflect child walking journeys to school. The improved accuracy in route modelling has in turn improved estimates of children’s exposures to potentially hazardous features in the environment. Further research is needed to explore if the built-environment features are important internationally. Route and corresponding exposure estimates can be scaled to the population level which will contribute to a better understanding of built-environment exposures on child health and contribute to mobility-based child health policy.

Service environment link and false discovery rate correction: Methodological considerations in population and health facility surveys.

BackgroundGeospatial data are important in monitoring many aspects of healthcare development. Geographically linking health facility data with population data is an important area of public health research. Examining healthcare problems spatially and hierarchically assists with efficient resource allocation and the monitoring and evaluation of service efficacy at different levels. This paper explored methodological issues associated with geographic data linkage, and the spatial and multilevel analyses that could be considered in analysing maternal health service data.MethodsThe 2016 Ethiopia Demographic and Health Survey and the 2014 Ethiopia Service Provision Assessment data were used. Two geographic data linking methods were used to link these two datasets. Administrative boundary link was used to link a sample of health facilities data with population survey data for analysing three areas of maternal health service use. Euclidean buffer link was used for a census of hospitals to analyse caesarean delivery use in Ethiopia. The Global Moran’s I and the Getis-Ord Gi* statistics need to be carried out for identifying hot spots of maternal health service use in ArcGIS software. In addition to this, since the two datasets contain hierarchical data, a multilevel analysis was carried out to identify key determinants of maternal health service use in Ethiopia.ResultsAdministrative boundary link gave more types of health facilities and more maternal health services as compared to the Euclidean buffer link. Administrative boundary link is the method of choice in case of sampled health facilities. However, for a census of health facilities, the Euclidean buffer link is the appropriate choice as this provides cluster level service environment estimates, which the administrative boundary link does not. Applying a False Discovery Rate correction enables the identification of true spatial clusters of maternal health service use.ConclusionsA service environment link minimizes the methodological issues associated with geographic data linkage. A False Discovery Rate correction needs to be used to account for multiple and dependent testing while carrying out local spatial statistics. Examining maternal health service use both spatially and hierarchically has tremendous importance for identifying geographic areas that need special emphasis and for intervention purposes.

Type and density of independent takeaway outlets: a geographical mapping study in a low socioeconomic ward, Manchester

ObjectivesThe socioeconomic disparity in childhood and early adult obesity prevalence has been well characterised. Takeaway outlets may cluster in lower socioeconomic areas and their proximity to schools is of concern....

Associations of Unhealthy Food Environment With the Development of Coronary Artery Calcification: The CARDIA Study.

BackgroundWhile prior studies have linked the neighborhood environment and development of subclinical atherosclerosis, it is unknown whether living in neighborhoods with greater availability of “unhealthy” food outlets (fast‐food chain restaurants and convenience stores) is associated with risk of developing coronary artery calcification (CAC).Methods and ResultsWe included 2706 CARDIA study (Coronary Artery Risk Development in Young Adults) participants who underwent CAC measurement during follow‐up years 15 (2000–2001), 20 (2005–2006), and 25 (2010–2011). Neighborhood features examined included percentage of all food outlets that were convenience stores and fast‐food chain restaurants within a 3‐km Euclidean buffer distance from each participant's residence. Econometric fixed effects models, which by design control for all time‐invariant covariates, were used to model the longitudinal association between simultaneous within‐person change in percentage food outlet and change in CAC. At baseline (year 15), 9.7% of participants had prevalent CAC. During 10 years of follow‐up, 21.1% of participants developed CAC. Each 1‐SD increase in percentage of convenience stores was associated with a 1.34 higher odds of developing CAC (95% CI: 1.04, 1.72) after adjusting for individual‐ and neighborhood‐level covariates; however, there was no significant association between increased percentage of fast‐food chain restaurants and developing CAC (odds ratio=1.15; 95% CI: 0.96, 1.38). There were no significant associations between increases in either food outlet percentage and progression of CAC.ConclusionsOur findings suggest that increases in the relative availability of convenience stores in participants' neighborhoods is related to the development of CAC over time.

The Moderating Role of Self-Control and Financial Strain in the Relation between Exposure to the Food Environment and Obesity: The GLOBE Study.

Low self-control and financial strain may limit individuals’ capacity to resist temptations in the local food environment. We investigated the moderating role of self-control and financial strain in the relation between the food environment and higher body weight. We used data from 2812 Dutch adults who participated in the population-based GLOBE study in 2014. Participants’ home addresses and the location of food retailers in 2013 were mapped using GIS. The density of fast food retailers and the totality of food retailers in Euclidean buffers of 250, 400 and 800 m around the home were linked to body mass index and overweight status. A higher density of fast food outlets (B (95% confidence interval (CI)) = −0.04 (−0.07; −0.01)) and the totality of food outlets (B (95% CI) = −0.01 (−0.01; −0.00)) were associated with a lower body mass index. Stratification showed that associations were strongest for those experiencing low self-control or great financial strain. For example, every additional fast food outlet was associated with a 0.17 point lower BMI in those with great financial strain, while not significantly associated with BMI in those with no financial strain. In conclusion, we did find support for a moderating role of self-control and financial strain, but associations between the food environment and weight status were not in the expected direction.

Local Retail Food Environment and Consumption of Fruit and Vegetable among Adults in Hong Kong.

Outside of western countries, the study of the local food environment and evidence for its association with dietary behavior is limited. The aim of this paper was to examine the association between the local retail food environment and consumption of fruit and vegetables (FV) among adults in Hong Kong. Local retail food environment was measured by density of different types of retail food outlets (grocery stores, convenience stores, and fast food restaurants) within a 1000 m Euclidean buffer around individual’s homes using a geographic information system (GIS). The Retail Food Environment Index (RFEI) was calculated based on the relative density of fast-food restaurants and convenience stores to grocery stores. Logistic regressions were performed to examine associations using cross-sectional data of 1977 adults (18 years or older). Overall, people living in an area with the highest RFEI (Q4, >5.76) had significantly greater odds of infrequent FV consumption (<7 days/week) after covariates adjustment (infrequent fruit consumption: OR = 1.36, 95% CI 1.04–1.78; infrequent vegetable consumption: OR = 1.72, 95% CI 1.11–2.68) in comparison to the lowest RFEI (Q1, <2.25). Highest density of fast food restaurants (Q4, >53) was also significantly associated with greater odds of infrequent fruit consumption (<7 days/week) (unadjusted model: OR = 1.34, 95% CI 1.04–1.73), relative to lowest density of fast food restaurants (Q1, <13). No significant association of density of grocery stores or convenience stores was observed with infrequent FV consumption regardless of the covariates included in the model. Our results suggest that the ratio of fast-food restaurants and convenience stores to grocery stores near people’s home is an important environmental factor in meeting fruit and vegetable consumption guidelines. “Food swamps” (areas with an abundance of unhealthy foods) rather than “food deserts” (areas where there is limited access to healthy foods) seems to be more of a problem in Hong Kong’s urban areas. We advanced international literature by providing evidence in a non-western setting.

Kids in space: Measuring children's residential neighborhoods and other destinations using activity space GPS and wearable camera data

IntroductionDefining the boundary of children's ‘neighborhoods’ has important implications for understanding the contextual influences on child health. Additionally, insight into activities that occur outside people's neighborhoods may indicate exposures that place-based studies cannot detect. This study aimed to 1) extend current neighborhood research, using data from wearable cameras and GPS devices that were worn over several days in an urban setting; 2) define the boundary of children's neighborhoods by using leisure time activity space data; and 3) determine the destinations visited by children in their leisure time, outside their neighborhoods. MethodOne hundred and fourteen children (mean age 12y) from Wellington, New Zealand wore wearable cameras and GPS recorders. Residential Euclidean buffers at incremental distances were paired with GPS data (thereby identifying time spent in different places) to explore alternative definitions of neighborhood boundaries. Children's neighborhood boundary was at 500 m. A newly developed software application was used to identify ‘destinations’ visited outside the neighborhood by specifying space-time parameters. Image data from wearable cameras were used to determine the type of destination. ResultsChildren spent over half of their leisure time within 500 m of their homes. Children left their neighborhood predominantly to visit school (for leisure purposes), other residential locations (e.g. to visit friends) and food retail outlets (e.g. convenience stores, fast food outlets). Children spent more time at food retail outlets than at structured sport and in outdoor recreation locations combined. ConclusionPerson-centered neighborhood definitions may serve to better represent children's everyday experiences and neighborhood exposures than previous methods based on place-based measures. As schools and other residential locations (friends and family) are important destinations outside the neighborhood, such destinations should be taken into account. The combination of image data and activity space GPS data provides a more robust approach to understanding children's neighborhoods and activity spaces.

Does exposure to the food environment differ by socioeconomic position? Comparing area-based and person-centred metrics in the Fenland Study, UK

BackgroundRetail food environments (foodscapes) are a recognised determinant of eating behaviours and may contribute to inequalities in diet. However, findings from studies measuring socioeconomic inequality in the foodscape have been mixed, which may be due to methodological differences. The aim of this cross-sectional study was to compare exposure to the foodscape by socioeconomic position using different measures, to test whether the presence, direction or amplitude of differences was sensitive to the choice of foodscape metric or socioeconomic indicator.MethodsA sample of 10,429 adults aged 30–64 years with valid home address data were obtained from the Fenland Study, UK. Of this sample, 7270 participants also had valid work location data. The sample was linked to data on food outlets obtained from local government records. Foodscape metrics included count, density and proximity of takeaway outlets and supermarkets, and the percentage of takeaway outlets relative to all food outlets. Exposure metrics were area-based (lower super output areas), and person-centred (proximity to nearest; Euclidean and Network buffers at 800 m, 1 km, and 1 mile). Person-centred buffers were constructed using home and work locations. Socioeconomic status was measured at the area-level (2010 Index of Multiple Deprivation) and the individual-level (highest educational attainment; equivalised household income). Participants were classified into socioeconomic groups and average exposures estimated. Results were analysed using the statistical and percent differences between the highest and lowest socioeconomic groups.ResultsIn area-based measures, the most deprived areas contained higher takeaway outlet densities (p < 0.001). However, in person-centred metrics lower socioeconomic status was associated with lower exposure to takeaway outlets and supermarkets (all home-based exposures p < 0.001) and socioeconomic differences were greatest at the smallest buffer sizes. Socioeconomic differences in exposure was similar for home and combined home and work measures. Measuring takeaway exposure as a percentage of all outlets reversed the socioeconomic differences; the lowest socioeconomic groups had a higher percentage of takeaway outlets compared to the middle and highest groups (p < 0.001).ConclusionsWe compared approaches to measuring socioeconomic variation in the foodscape and found that the association was sensitive to the metric used. In particular, the direction of association varied between area- and person-centred measures and between absolute and relative outlet measures. Studies need to consider the most appropriate measure for the research question, and may need to consider multiple measures as a single measure may be context dependent.

Effect Of Neighborhood-unit Definition On The Relationship Between Physical Activity And The Built Environment

PURPOSE: Substantial evidence demonstrates that built environment features, like density, connectivity, land-use, pedestrian/transit infrastructure, and recreational facilities, can influence physical activity. However, inconsistent findings remain in terms of significance, direction and strength. The purpose of this paper was to determine if the lack of a standardized definition for a neighborhood unit contributes towards these inconsistencies. METHODS: Published literature (PUBMED & SCOPUS) was abstracted to identify studies examining the relation between physical activity and Geographic Information Systems (GIS)-based built environment measures. Data were abstracted to determine the various definitions of neighborhood units used for GIS built environment measures. Each tested association was coded per the presence or absence of a significant finding. Logistic regression was used to estimate the odds of reporting a significant association (p<0.05) between GIS built environment measures and physical activity outcomes, by neighborhood unit definition. Models adjusted for study sample size. RESULTS: Among 165 articles (published articles since Jan 2013), 26.8% used Euclidean buffers of varying radii (400-3000m) to define neighborhoods, 28.4% used network buffers, and 44.8% used administrative units of different shapes and sizes (e.g., census tracts). Relative to studies using large administrative units to represent a neighborhood, those using buffers of 400-500m (OR: 3.2, 95% CI: 1.4, 5.8), and 800-1000m (OR: 2.9, CI: 1.3, 7.1), had greater odds of reporting a significant association between GIS built environment measures and physical activity outcomes. Among those using buffers, no significant differences were found between Euclidean vs. network buffers (OR: 1.07, 95% CI: 0.46, 4.29). CONCLUSIONS: Researchers aiming to accurately estimate the effect of the neighborhood built environment on physical activity should consider using 400-1000m buffer-based GIS indicators. Using network vs. Euclidean buffers may not be essential for characterizing the neighborhood environment for physical activity research. Future analyses should examine differences by physical activity measures (objective vs. subjective) and by built environment constructs. Supported by NIH R01DK101593

Interplay of takeaway food outlet exposure and income on diet and obesity: a cross-sectional study in UK Biobank

BackgroundThe proliferation of takeaway food outlets has been called a public health problem by Public Health England and the Chief Medical Officer for England. Evidence indicates that the density of takeaway outlets in neighbourhoods can promote unhealthy eating and obesity. But takeaway outlets tend to cluster in deprived areas, and vulnerability to unhealthy food environments might vary across social groups. This study examined the interplay between exposure to takeaway outlets and individual-level socioeconomic position in relation to diet and obesity. MethodsThis cross-sectional study included UK Biobank participants based in Greater London (n=51 361) aged 38–72 years with valid height and weight data, food frequency data, and food environment exposures. Food environment exposures were estimated using geographic information systems and food outlet data from UKMap, as counts of outlets by type, within one-mile radius Euclidean (circular) buffers centred on each participant's home address. Our primary exposure was the number of takeaway outlets as a proportion of all food outlets. Participants were jointly classified on the basis of household income (four groups) and quartile of neighbourhood takeaway outlet proportion to create 16 exposure groups. Regression models estimated the odds of frequent processed meat consumption and obesity. We calculated relative excess risk due to interaction (RERI), relative to a single reference group. Participant data were collected during 2005–13 and analysed in 2016. FindingsBoth income and takeaway exposure were systematically associated with frequent consumption of processed meat and obesity. In mutually adjusted models, lowest-income participants were more likely than highest-income participants to be obese (odds ratio 1·53, 95% CI 1·38–1·69); and relative to those least exposed, highest takeaway exposure was also associated with obesity (1·76, 1·61–1·91). In additive models, the combination of lowest income and highest takeaway exposure was associated with substantially increased odds of obesity (2·75, 2·33–3·24), with the RERI indicating significant interaction. Results were similar in diet analyses. InterpretationWe have confirmed the findings of earlier work showing independent associations between income, neighbourhood takeaway outlet exposure, and diet and adiposity. Moreover, we provide evidence of the double burden of low income and an unhealthy neighbourhood food environment, resulting in higher rates of unhealthy diet and obesity. FundingBritish Heart Foundation, Cancer Research UK, Economic and Social Research Council, Medical Research Council, National Institute for Health Research, and the Wellcome Trust, under the auspices of the UK Clinical Research Collaboration.

Abstract A70: Is the availability of fast food restaurants and tobacco outlets near schools in 97 U.S. counties associated with school sociodemographic characteristics?

Abstract Background: Fast food and tobacco product availability near schools might influence youth diet and tobacco use, and greater availability near racially diverse or lower income schools may contribute to racial/ethnic and socioeconomic disparities in cancer risk. However, no national studies have examined the availability of both fast food restaurants and retail tobacco outlets near schools in the United States (US) in association with school sociodemographic characteristics. Methods: Fast food restaurants and tobacco outlets were counted within 800 m Euclidean buffers around public primary, middle and high schools in 97 US counties. Counties were randomly selected proportionate to county population size in 2011. Generalized linear mixed models were used to examine the association of school racial/ethnic composition and participation in free/reduced price lunch programs with fast food restaurant and tobacco outlet availability near schools. Results: Nearly 40% of schools had both a fast food restaurant and a tobacco outlet within 800 m (approximately a 10 minute walk). The odds of having both a fast food restaurant and tobacco outlet within 800 m increased by 5% for every 10% increase in the percentage of Hispanic students (OR 1.05, 95% CI 1.03, 1.07). Odds increased by 3% for every 10% increase in the percentage of students receiving free/reduced price lunch (OR 1.03, 95% CI 1.01, 1.05). High schools had nearly 1.5 times the odds of having both a fast food restaurant and a tobacco outlet within 800 m compared with primary schools. Conclusion: Low income and Hispanic students, and high school students are disproportionately exposed to both fast food restaurants and tobacco outlets near schools in this sample of 97 US counties. Restricting the location of fast food and tobacco retail outlets in school neighborhoods may help reduce access to harmful products, particularly among some vulnerable populations. Citation Format: Heather D'Angelo, Alice Ammerman, Penny Gordon-Larsen, Laura Linnan, Leslie Lytle, Kurt M. Ribisl. Is the availability of fast food restaurants and tobacco outlets near schools in 97 U.S. counties associated with school sociodemographic characteristics? [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr A70.

Exploring the opportunities for food and drink purchasing and consumption by teenagers during their journeys between home and school: a feasibility study using a novel method.

To investigate the feasibility and acceptability of using wearable cameras as a method to capture the opportunities for food and drink purchasing/consumption that young people encounter on their regular journeys to and from school. A qualitative study using multiple data-collection methods including wearable cameras, global positioning system units, individual interviews, food and drink purchase and consumption diaries completed by participants over four days, and an audit of food outlets located within an 800 m Euclidean buffer zone around each school. A community setting. Twenty-two students (fourteen girls and eight boys) aged 13-15 years recruited from four secondary schools in two counties of England. Wearable cameras offered a feasible and acceptable method for collecting food purchase and consumption data when used alongside traditional methods of data collection in a small number of teenagers. We found evidence of participants making deliberate choices about whether or not to purchase/consume food and drink on their journeys. These choices were influenced by priorities over money, friends, journey length, travel mode and ease of access to opportunities for purchase/consumption. Most food and drink items were purchased/consumed within an 800 m Euclidean buffer around school, with items commonly selected being high in energy, fat and sugar. Wearable camera images combined with interviews helped identify unreported items and misreporting errors. Wearable camera images prompt detailed discussion and generate contextually specific information which could offer new insights and understanding around eating behaviour patterns. The feasibility of scaling up the use of these methods requires further empirical work.