Are school-based measures of walkability and greenness associated with modes of commuting to school? Findings from a student survey in Ontario, Canada.

Objectives: In Canada, students are increasingly reliant on motorized vehicles to commute to school, and few meet the recommended overall physical activity guidelines. Infrastructure and built environments around schools may promote active commuting to and from school, thereby increasing physical activity. To date, few Canadian studies have examined this research question.
Methods: This study is a cross-sectional analysis of 11,006 students, aged 11-20, who participated in the 2016/2017 Ontario Student Drug Use and Health Survey. The remote sensing-derived Normalized Difference Vegetation Index (NDVI), at a buffer of 500 m from the schools' locations, was used to characterize greenness, while the 2016 Canadian Active Living Environments (Can-ALE) measure was used for walkability. Students were asked about their mode of regular commuting to school, and to provide information on several socio-demographic variables. Multivariable logistic regression models were used to quantify associations between active commuting and greenness and the Can-ALE. The resulting odds ratios, and their 95% confidence intervals, were adjusted for a series of risk factors that were collected from the survey.
Results: Overall, 21% of students reported active commuting (biking or walking) to school, and this prevalence decreased with increasing age. Students whose schools had higher Can-ALE scores were more likely to be active commuters. Specifically, the adjusted odds ratio (OR) of being an active commuter for schools in the highest quartile of the Can-ALE was 2.11 (95% CI = 1.64, 2.72) when compared with those in the lowest. For children, aged 11-14 years, who attended schools in high dwelling density areas, a higher odds of active commuting was observed among those in the upper quartile of greenness relative to the lowest (OR = 1.41; 95% CI = 0.92, 2.15). In contrast, for lower dwelling density areas, greenness was inversely associated with active commuting across all ages.
Conclusion: Our findings suggest that students attending schools with higher Can-ALE scores are more likely to actively commute to school, and that positive impacts of greenness on active commuting are evident only in younger children in more densely populated areas. Future studies should collect more detailed data on residential measures of the built environment, safety, distance between home and school, and mixed modes of commuting behaviours.