According to a study by the US EPA,

According to a study by the US EPA, “Travel and Environmental Implications of School Siting,” students are more likely to walk or bike to their school if it’s nearby and if the environment is pedestrian-friendly. By increasing the number of students walking or biking to school, a community can eliminate some of the pollution that would otherwise be generated by motor vehicles. EPA says this study is the first empirical examination of the relationship between school locations, the built environment around schools, how children get to school, and the impact on air emissions. Find the study online in the publications section at www.epa.gov/smartgrowth.