Are Measures Derived From Land Use and Transport Policies Associated With Walking for Transport?

BACKGROUND: There is growing urgency for higher quality evidence to inform policy. This study developed geographic information system spatial measures based on land use and transport policies currently used in selected Australian states to assess which, if any, of these measures were associated with walking for transport. METHODS: Overall, 6901 participants from 570 neighborhoods in Brisbane, Australia, were included. Participants reported their minutes of walking for transport in the previous week. After a review of state-level land use and transport policies relevant to walking for transport across Australia, 7 geographic information system measures were developed and tested based on 9 relevant policies. Data were analyzed using multilevel multinomial logistic regression. RESULTS: Greater levels of walking for transport were associated with more highly connected street networks, the presence of public transport stops, and having at least 2 public transport services per hour. Conversely, neighborhoods with shorter cul-de-sac lengths had lower levels of walking for transport. There was no evidence of associations between walking for transport and street block lengths less than 240 m or traffic volumes. CONCLUSIONS: These findings highlight the need for urban design and transport policies developed by governments to be assessed for their impact on transport-related physical activity.

Intersection of neighborhood dynamics and socioeconomic status in small-area walkability: the Heart Healthy Hoods project.

BACKGROUND: Previous studies found a complex relationship between area-level socioeconomic status (SES) and walkability. These studies did not include neighborhood dynamics. Our aim was to study the association between area-level SES and walkability in the city of Madrid (Spain) evaluating the potential effect modification of neighborhood dynamics. METHODS: All census sections of the city of Madrid (n = 2415) were included. Area-level SES was measured using a composite index of 7 indicators in 4 domains (education, wealth, occupation and living conditions). Two neighborhood dynamics factors were computed: gentrification, proxied by change in education levels in the previous 10 years, and neighborhood age, proxied by median year of construction of housing units in the area. Walkability was measured using a composite index of 4 indicators (Residential Density, Population Density, Retail Destinations and Street Connectivity). We modeled the association using linear mixed models with random intercepts. RESULTS: Area-level SES and walkability were inversely and significantly associated. Areas with lower SES showed the highest walkability. This pattern did not hold for areas with an increase in education level, where the association was flat (no decrease in walkability with higher SES). Moreover, the association was attenuated in newly built areas: the association was stronger in areas built before 1975, weaker in areas built between 1975 and 1990 and flat in areas built from 1990 on. CONCLUSION: Areas with higher neighborhood socioeconomic status had lower walkability in Madrid. This disadvantage in walkability was not present in recently built or gentrified areas.

Children's Out-of-School Independently Mobile Trips, Active Travel, and Physical Activity: A Cross-Sectional Examination from the Kids in the City Study.

BACKGROUND: The study aim was to determine the association between children's objectively assessed moderate-to-vigorous physical activity (MVPA) and active trips (AT) and independently mobile trips (IM) during out-of-school hours. METHODS: Children aged 9 to 13 years (n = 254) were recruited from 9 schools in Auckland, New Zealand between 2011 and 2012. Children completed travel diaries and wore accelerometers for 7 days. Parents provided demographic information. Geographic information systems-derived distance to school was calculated. Accelerometer data were extracted for out of school hours only. Percentage of time spent in MVPA (%MVPA), AT, and IM were calculated. Generalized estimating equations were used to determine the relationship between daily %MVPA and AT and between daily %MVPA and IM, accounting for age, sex, ethnicity, distance to school, day of the week, and numeric day of data collection. RESULTS: A significant positive relationship was observed between %MVPA and both AT and IM. For every unit increase in the daily percentage of trips made that were AT or IM, we found an average increase of 1.28% (95% CI 0.87%, 1.70%) and 1.15% (95% CI 0.71%, 1.59%) time in MVPA, respectively. CONCLUSION: Children's AT and IM are associated with increased MVPA during out-of-school hours.

Assessing Walking and Cycling Environments in the Streets of Madrid: Comparing On-Field and Virtual Audits.

Audit tools are useful for exploring the urban environment and its association with physical activity. Virtual auditing options are becoming increasingly available potentially reducing the resources needed to conduct these assessments. Only a few studies have explored the use of virtual audit tools. Our objective is to test if the Madrid Systematic Pedestrian and Cycling Environment Scan (M-SPACES) discriminates between areas with different urban forms and to validate virtual street auditing using M-SPACES. Three areas (N = 500 street segments) were selected for variation in population density. M-SPACES was used to audit street segments physically and virtually (Google Street View) by two researchers in 2013-2014. For both physical and virtual audits, all analyzed features score significantly different by area (p < 0.05). Most of the features showed substantial (ICC = 0.6-0.8) or almost perfect (ICC ≥ 0.8) agreement between virtual and physical audits, especially neighborhood permeability walking infrastructure, traffic safety, streetscape aesthetics, and destinations. Intra-rater agreement was generally acceptable (ICC > 0.6). Inter-rater agreement was generally poor (ICC < 0.4). Virtual auditing provides a valid and feasible way of measuring residential urban environments. Comprehensive auditor training may be needed to guarantee good inter-rater agreement.

Socio-demographic factors and neighbourhood social cohesion influence adults' willingness to grant children greater independent mobility: A cross-sectional study.

BACKGROUND: In developed countries, children's independent mobility levels are low. Built environmental factors and parental safety concerns are well-known to predict the level of independent mobility adults grant to children. In contrast, the influence of adults' socio-demographic characteristics and neighbourhood social cohesion on children's independent mobility is largely unexplored. This study investigated the influence of adults' socio-demographic factors and neighbourhood social cohesion on distances they would permit children for independent travel and outdoor play. METHODS: In 2013, a random sample of 1293 Australian adults (mean age: 56.1 years, 52 % male, 81 % parents) participated in the Queensland Social Survey (QSS) via computer-assisted telephone interview. Socio-demographic factors measured included age, sex, parental status, education and area-level socio-economic disadvantage. Perceived neighbourhood social cohesion was assessed using a standardised scale. Adults reported the distances children aged 8-12 years should be allowed to walk/cycle to places, and play outdoors without adults. Responses were categorised into 'within sight', < 0.5 kilometres (km) , 0.5-1 km and >1 km. Ordinal logistic regression was used to assess associations of socio-demographic factors and neighbourhood social cohesion with distances adults would permit for children's independent travel and outdoor play. RESULTS: Parents and adults with lower education were less likely to permit greater distances for children's independent travel (OR 0.57 and OR = 0.59, respectively). Women, parents and adults with lower education were less likely to grant children greater distances for independent outdoor play (OR = 0.61, OR = 0.50 and OR = 0.60, respectively). In contrast, adults with higher perceptions of neighbourhood social cohesion were more likely to permit children greater distances for independent travel (OR = 1.05)and outdoor play (OR = 1.05). Adult age and area-level socio-economic disadvantage were not associated with distances adults would permit for independent travel and outdoor play. CONCLUSIONS: Women, parents (particularly those of younger children), adults with lower education and those who perceived neighbourhood social cohesion as being lower were less willing to let children independently travel further away from home. Interventions to increase children's independent mobility may be more effective if targeted to these groups. In addition, increasing neighbourhood social cohesion may help increase adults' willingness to grant children greater independent mobility.

A longitudinal analysis of the influence of the neighborhood built environment on walking for transportation: the RESIDE study.

The purpose of the present analysis was to use longitudinal data collected over 7 years (from 4 surveys) in the Residential Environments (RESIDE) Study (Perth, Australia, 2003-2012) to more carefully examine the relationship of neighborhood walkability and destination accessibility with walking for transportation that has been seen in many cross-sectional studies. We compared effect estimates from 3 types of logistic regression models: 2 that utilize all available data (a population marginal model and a subject-level mixed model) and a third subject-level conditional model that exclusively uses within-person longitudinal evidence. The results support the evidence that neighborhood walkability (especially land-use mix and street connectivity), local access to public transit stops, and variety in the types of local destinations are important determinants of walking for transportation. The similarity of subject-level effect estimates from logistic mixed models and those from conditional logistic models indicates that there is little or no bias from uncontrolled time-constant residential preference (self-selection) factors; however, confounding by uncontrolled time-varying factors, such as health status, remains a possibility. These findings provide policy makers and urban planners with further evidence that certain features of the built environment may be important in the design of neighborhoods to increase walking for transportation and meet the health needs of residents.

Do low-income neighbourhoods have the least green space? A cross-sectional study of Australia's most populous cities.

BACKGROUND: An inequitable distribution of parks and other 'green spaces' could exacerbate health inequalities if people on lower incomes, who are already at greater risk of preventable diseases, have poorer access. METHODS: The availability of green space within 1 kilometre of a Statistical Area 1 (SA1) was linked to data from the 2011 Australian census for Sydney (n = 4.6 M residents); Melbourne (n = 4.2 M); Brisbane (n = 2.2 M); Perth (n = 1.8 M); and Adelaide (n = 1.3 M). Socioeconomic circumstances were measured via the percentage population of each SA1 living on < $21,000 per annum. Negative binomial and logit regression models were used to investigate association between the availability of green space in relation to neighbourhood socioeconomic circumstances, adjusting for city and population density. RESULTS: Green space availability was substantively lower in SA1s with a higher percentage of low income residents (e.g. an incidence rate ratio of 0.82 (95% confidence interval (95% CI) 0.75, 0.89) was observed for SA1s containing ≥20% versus 0-1% low income residents). This association varied between cities (p < 0.001). Adelaide reported the least equitable distribution of green space, with approximately 20% greenery in the most affluent areas versus 12% availability in the least affluent. Although Melbourne had a smaller proportion of SA1s in the top quintile of green space availability (13.8%), the distribution of greenery was the most equitable of all the cities, with only a 0.5% difference in the availability of green space between SA1s containing 0-1% low income households versus those with ≥20%. Inequity of access, however, was reported across all cities when using logit regression to examine the availability of at least 20% (odds ratio 0.74, 95% CI 0.59, 0.93) or 40% (0.45, 0.29, 0.69) green space availability in the more disadvantaged versus affluent neighbourhoods. CONCLUSION: Affirmative action on green space planning is required to redress the socioeconomic inequity of access to this important public health resource.

Associations between children's independent mobility and physical activity.

BACKGROUND: Independent mobility describes the freedom of children to travel and play in public spaces without adult supervision. The potential benefits for children are significant such as social interactions with peers, spatial and traffic safety skills and increased physical activity. Yet, the health benefits of independent mobility, particularly on physical activity accumulation, are largely unexplored. This study aimed to investigate associations of children's independent mobility with light, moderate-to-vigorous, and total physical activity accumulation. METHODS: In 2011-2012, 375 Australian children aged 8-13 years (62% girls) were recruited into a cross-sectional study. Children's independent mobility (i.e. independent travel to school and non-school destinations, independent outdoor play) and socio-demographics were assessed through child and parent surveys. Physical activity intensity was measured objectively through an Actiheart monitor worn on four consecutive days. Associations between independent mobility and physical activity variables were analysed using generalized linear models, accounting for clustered sampling, Actiheart wear time, socio-demographics, and assessing interactions by sex. RESULTS: Independent travel (walking, cycling, public transport) to school and non-school destinations were not associated with light, moderate-to-vigorous and total physical activity. However, sub-analyses revealed a positive association between independent walking and cycling (excluding public transport) to school and total physical but only in boys (b = 36.03, p < 0.05). Frequent independent outdoor play (three or more days per week) was positively associated with light and total physical activity (b = 29.76, p < 0.01 and b = 32.43, p = 0.03, respectively). No significant associations were found between independent outdoor play and moderate-to-vigorous physical activity. When assessing differences by sex, the observed significant associations of independent outdoor play with light and total physical activity remained in girls but not in boys. All other associations showed no significant differences by sex. CONCLUSIONS: Independent outdoor play may boost children's daily physical activity levels, predominantly at light intensity. Hence, facilitating independent outdoor play could be a viable intervention strategy to enhance physical activity in children, particularly in girls. Associations between independent travel and physical activity are inconsistent overall and require further investigation.

Recruitment and retention of children in behavioral health risk factor studies: REACH strategies.

BACKGROUND: Children are a common target group in behavioral health research. Yet their recruitment into community setting studies poses challenges to researchers and little guidance exists on recruitment and retention methods. PURPOSE: This study aims to present successful strategies for the recruitment and retention of children into behavioral health risk factor studies. METHOD: Firstly, a literature search in various databases was undertaken for papers published 1990-2012, focusing on recruitment and retention methods used in community-based studies with children aged 3-18 years. Secondly, a Delphi study was conducted in 2012 with 27 international experts in the fields of child-related behavioral health risk factors to gather expertise and consensus on successful recruitment and retention strategies applicable in children. RESULTS: The literature review and Delphi study yielded a set of successful child recruitment and retention strategies, and examples for implementation. These are presented as strategies to Recruit, Engage and retAin Children in behavioral Health risk factor studies (REACH). Recognized strategies for successful recruitment and retention included building trustful relationships between researchers and study partners, parents, and children; having project champions; optimizing consent and follow-up procedures; offering incentives to study partners, children, and parents; minimizing participant burden; and designing feasible studies with cohesive research teams. CONCLUSION: Using multiple REACH strategies is most promising for maximizing response rates and minimizing attrition of children in cross-sectional, longitudinal, and behavioral intervention studies in community settings such as schools, child care centers, and other youth-related organizations. Researchers can select the most suitable strategies based on their specific study design and requirements.

Utility of passive photography to objectively audit built environment features of active transport journeys: an observational study.

BACKGROUND: Active transport can contribute to physical activity accumulation and improved health in adults. The built environment is an established associate of active transport behaviours; however, assessment of environmental features encountered during journeys remains challenging. The purpose of this study was to examine the utility of wearable cameras to objectively audit and quantify environmental features along work-related walking and cycling routes. METHODS: A convenience sample of employed adults was recruited in New Zealand, in June 2011. Participants wore a SenseCam for all journeys over three weekdays and completed travel diaries and demographic questionnaires. SenseCam images for work-related active transport journeys were coded for presence of environmental features hypothesised to be related to active transport. Differences in presence of features by transport mode and in participant-reported and SenseCam-derived journey duration were determined using two-sample tests of proportion and an independent samples t-test, respectively. RESULTS: Fifteen adults participated in the study, yielding 1749 SenseCam images from 30 work-related active transport journeys for coding. Significant differences in presence of features were found between walking and cycling journeys. Almost a quarter of images were uncodeable due to being too dark to determine features. There was a non-significant tendency for respondents to under-report their journey duration. CONCLUSION: This study provides proof of concept for the use of the SenseCam to capture built environment data in real time that may be related to active transportation. Further work is required to test and refine coding methodologies across a range of settings, travel behaviours, and demographic groups.

Using the SenseCam to improve classifications of sedentary behavior in free-living settings.

BACKGROUND: Studies have shown relationships between important health outcomes and sedentary behavior, independent of physical activity. There are known errors in tools employed to assess sedentary behavior. Studies of accelerometers have been limited to laboratory environments. PURPOSE: To assess a broad range of sedentary behaviors in free-living adults using accelerometers and a Microsoft SenseCam that can provide an objective observation of sedentary behaviors through first person-view images. METHODS: Participants were 40 university employees who wore a SenseCam and Actigraph accelerometer for 3-5 days. Images were coded for sitting and standing posture and 12 activity types. Data were merged and aggregated to a 60-second epoch. Accelerometer counts per minute (cpm) of <100 were compared with coded behaviors. Sensitivity and specificity analyses were performed. Data were collected in June and July 2011 and analyzed in April 2012. RESULTS: TV viewing, other screen use, and administrative activities were correctly classified by the 100-cpm cutpoint. However, standing behaviors also fell under this threshold, and driving behaviors exceeded it. Multiple behaviors occurred simultaneously. A nearly 30-minute per day difference was found in sedentary behavior estimates based on the accelerometer versus the SenseCam. CONCLUSIONS: Researchers should be aware of the strengths and weaknesses of the 100-cpm accelerometer cutpoint for identifying sedentary behavior. The SenseCam may be a useful tool in free-living conditions to better understand health behaviors such as sitting.

Portable global positioning system receivers: static validity and environmental conditions.

BACKGROUND: GPS receivers are becoming increasingly common as an objective measure of spatiotemporal movement in free-living populations; however, research into the effects of the surrounding physical environment on the accuracy of off-the-shelf GPS receivers is limited. PURPOSE: The goal of the current study was to (1) determine the static validity of seven portable GPS receiver models under diverse environmental conditions and (2) compare the battery life and signal acquisition times among the models. METHODS: Seven GPS models (three units of each) were placed on six geodetic sites subject to a variety of environmental conditions (e.g., open sky, high-rise buildings) on three separate occasions. The observed signal acquisition time and battery life of each unit were compared to advertised specifications. Data were collected and analyzed in June 2012. RESULTS: Substantial variation in positional error was observed among the seven GPS models, ranging from 12.1 ± 19.6 m to 58.8 ± 393.2 m when averaged across the three test periods and six geodetic sites. Further, mean error varied considerably among sites: the lowest error occurred at the site under open sky (7.3 ± 27.7 m), with the highest error at the site situated between high-rise buildings (59.2 ± 99.2 m). While observed signal acquisition times were generally longer than advertised, the differences between observed and advertised battery life were less pronounced. CONCLUSIONS: Results indicate that portable GPS receivers are able to accurately monitor static spatial location in unobstructed but not obstructed conditions. It also was observed that signal acquisition times were generally underestimated in advertised specifications.

Association of neighbourhood residence and preferences with the built environment, work-related travel behaviours, and health implications for employed adults: findings from the URBAN study.

Although the neighbourhoods and health field is well established, the relationships between neighbourhood selection, neighbourhood preference, work-related travel behaviours, and transport infrastructure have not been fully explored. It is likely that understanding these complex relationships more fully will inform urban policy development, and planning for neighbourhoods that support health behaviours. Accordingly, the objective of this study was to identify associations between these variables in a sample of employed adults. Self-reported demographic, work-related transport behaviours, and neighbourhood preference data were collected from 1616 employed adults recruited from 48 neighbourhoods located across four New Zealand cities. Data were collected between April 2008 and September 2010. Neighbourhood built environment measures were generated using geographical information systems. Findings demonstrated that more people preferred to live in urban (more walkable), rather than suburban (less walkable) settings. Those living in more suburban neighbourhoods had significantly longer work commute distances and lower density of public transport stops available within the neighbourhood when compared with those who lived in more urban neighbourhoods. Those preferring a suburban style neighbourhood commuted approximately 1.5 km further to work when compared with participants preferring urban settings. Respondents who preferred a suburban style neighbourhood were less likely to take public or active transport to/from work when compared with those who preferred an urban style setting, regardless of the neighbourhood type in which they resided. Although it is unlikely that constructing more walkable environments will result in work-related travel behaviour change for all, providing additional highly walkable environments will help satisfy the demand for these settings, reinforce positive health behaviours, and support those amenable to change to engage in higher levels of work-related public and active transport.

Linking GPS and travel diary data using sequence alignment in a study of children's independent mobility.

BACKGROUND: Global positioning systems (GPS) are increasingly being used in health research to determine the location of study participants. Combining GPS data with data collected via travel/activity diaries allows researchers to assess where people travel in conjunction with data about trip purpose and accompaniment. However, linking GPS and diary data is problematic and to date the only method has been to match the two datasets manually, which is time consuming and unlikely to be practical for larger data sets. This paper assesses the feasibility of a new sequence alignment method of linking GPS and travel diary data in comparison with the manual matching method. METHODS: GPS and travel diary data obtained from a study of children's independent mobility were linked using sequence alignment algorithms to test the proof of concept. Travel diaries were assessed for quality by counting the number of errors and inconsistencies in each participant's set of diaries. The success of the sequence alignment method was compared for higher versus lower quality travel diaries, and for accompanied versus unaccompanied trips. Time taken and percentage of trips matched were compared for the sequence alignment method and the manual method. RESULTS: The sequence alignment method matched 61.9% of all trips. Higher quality travel diaries were associated with higher match rates in both the sequence alignment and manual matching methods. The sequence alignment method performed almost as well as the manual method and was an order of magnitude faster. However, the sequence alignment method was less successful at fully matching trips and at matching unaccompanied trips. CONCLUSIONS: Sequence alignment is a promising method of linking GPS and travel diary data in large population datasets, especially if limitations in the trip detection algorithm are addressed.

Kids in the city study: research design and methodology.

BACKGROUND: Physical activity is essential for optimal physical and psychological health but substantial declines in children's activity levels have occurred in New Zealand and internationally. Children's independent mobility (i.e., outdoor play and traveling to destinations unsupervised), an integral component of physical activity in childhood, has also declined radically in recent decades. Safety-conscious parenting practices, car reliance and auto-centric urban design have converged to produce children living increasingly sedentary lives. This research investigates how urban neighborhood environments can support or enable or restrict children's independent mobility, thereby influencing physical activity accumulation and participation in daily life. METHODS/DESIGN: The study is located in six Auckland, New Zealand neighborhoods, diverse in terms of urban design attributes, particularly residential density. Participants comprise 160 children aged 9-11 years and their parents/caregivers. Objective measures (global positioning systems, accelerometers, geographical information systems, observational audits) assessed children's independent mobility and physical activity, neighborhood infrastructure, and streetscape attributes. Parent and child neighborhood perceptions and experiences were assessed using qualitative research methods. DISCUSSION: This study is one of the first internationally to examine the association of specific urban design attributes with child independent mobility. Using robust, appropriate, and best practice objective measures, this study provides robust epidemiological information regarding the relationships between the built environment and health outcomes for this population.

School travel plans: preliminary evidence for changing school-related travel patterns in elementary school children.

PURPOSE: In New Zealand, the School Travel Plan (STP) program was developed to increase school-related active travel rates and decrease traffic congestion. The plan was developed through collaboration among the school, community, and local council. The STP was tailored to each school's specific needs and incorporated educational initiatives, physical infrastructural changes in the vicinity of schools, and policy development. The purpose of this study was to determine the effectiveness of the STP program in changing school travel modes in children. DESIGN: Effectiveness was assessed by determining the difference between pre-STP and follow-up travel mode data in schools. The differences were assessed using multilinear regression analysis, including decile (measure of socioeconomic status), school roll at baseline, and STP year of implementation as predictors. SETTING: Thirty-three elementary schools from the Auckland region participated in the study. School size ranged from 130 to 688 students. SUBJECTS: The final 2006 sample consisted of 13,631 students. MEASURES: On a set day (pre- and post-STP), students indicated their mode of transport to school and intended mode for returning home that day. RESULTS: Differences are reported as percentage points: there was an increase in active transport by 5.9% ± 6.8% when compared to baseline travel modes. School roll, STP year of implementation, and baseline values predicted engagement with active transport. CONCLUSION: Preliminary findings suggest that the STP program may be successful in creating mode shift changes to favor school-related active travel in elementary-school children.

Seasonality in physical activity: should this be a concern in all settings?

This study examines the relationship between weather conditions and overall and domain-specific physical activity in adults living in a city with a temperate, stable climate. Objective and self-reported physical activity levels were measured in 1754 adults participating in RESIDE, a longitudinal study undertaken in Perth, Australia. Steps per week and self-reported minutes of domain-specific physical activity were compared with date-stamped weather data. Weather conditions were relatively constant across all seasons, showing little impact on physical activity behaviour. Variation in weather conditions had modest explanatory power (<6%) for predicting overall and domain-specific physical activity engagement in this sample. Weather variations observed in this study were of insufficient magnitude to impact on physical activity levels. This has implications for study designs and exploration of other factors associated with physical activity in these settings.

Can virtual streetscape audits reliably replace physical streetscape audits?

There is increasing recognition that the neighborhood-built environment influences health outcomes, such as physical activity behaviors, and technological advancements now provide opportunities to examine the neighborhood streetscape remotely. Accordingly, the aims of this methodological study are to: (1) compare the efficiencies of physically and virtually conducting a streetscape audit within the neighborhood context, and (2) assess the level of agreement between the physical (criterion) and virtual (test) audits. Built environment attributes associated with walking and cycling were audited using the New Zealand Systematic Pedestrian and Cycling Environment Scan (NZ-SPACES) in 48 street segments drawn from four neighborhoods in Auckland, New Zealand. Audits were conducted physically (on-site) and remotely (using Google Street View) in January and February 2010. Time taken to complete the audits, travel mileage, and Internet bandwidth used were also measured. It was quicker to conduct the virtual audits when compared with the physical audits (χ = 115.3 min (virtual), χ = 148.5 min (physical)). In the majority of cases, the physical and virtual audits were within the acceptable levels of agreement (ICC ≥ 0.70) for the variables being assessed. The methodological implication of this study is that Google Street View is a potentially valuable data source for measuring the contextual features of neighborhood streets that likely impact on health outcomes. Overall, Google Street View provided a resource-efficient and reliable alternative to physically auditing the attributes of neighborhood streetscapes associated with walking and cycling. Supplementary data derived from other sources (e.g., Geographical Information Systems) could be used to assess the less reliable streetscape variables.