Time spent by Brazilian students in different modes of transport going to school : changes over a decade ( 2001-2011 )

To examine changes in the time spent in each mode of transportation used for going to school by gender and age among adolescents from Santa Catarina State, Brazil. Two school-based surveys were performed in 2001 (N = 5,028) and 2011 (N = 6,529) in high school students (15-19 years old). The mode of transportation (on foot; by bicycle; by bus; car/motorcycle) and the time spent for commuting to school were assessed. Active commuting increased for short trips in both genders (male: 25.1% to 36.7%; female: 18.8% to 29.2%) and in all ages (15-16 years: 21% to 32.7%; 17-19 years: 21.9% to 32.4%), and declined for longer trips in males (30.5% to 21.9%) and in 15-16 years old students (25.7% to 34.7%). Car/motorcycle use has doubled for short trips in males (38.1% to 65.9%) and in 17-19 years old students (37.7% to 62.7%), while the use of buses remained stable in both genders. Our findings contribute to discussions on public policy focusing on the design of safe environments to promote active commuting to schools, particularly to decrease the use of motorized transport for short trips. Pendular Migration; Motor Activity; Students Resumo Identificar mudanças no tempo gasto em cada modo de transporte para ir à escola por sexo e idade, em adolescentes de Santa Catarina, Brasil. Dois levantamentos de base escolar foram realizados, em 2001 (N = 5.028) e 2011 (N = 6.529), com estudantes de 15-19 anos de idade. O modo de transporte (a pé, de bicicleta, de ônibus, carro/moto) e o tempo gasto para ir à escola foram analisados. O deslocamento ativo aumentou para viagens curtas em rapazes (25,1% para 36,7%) e moças (18,8% para 29,2%) e em todas as idades (15-16 anos: 21% para 32,7%; 17-19 anos: 21,9% para 32,4%); e diminuiu para viagens longas nos rapazes (30,5% para 21,9%) e adolescentes de 15-16 anos (25,7% para 34,7%). O uso de carro/ moto dobrou para viagens curtas em rapazes (38,1% para 65,9%) e em estudantes de 17-19 anos (37,7% para 62,7%). Nossos resultados contribuem em discussões com foco em políticas públicas sobre ambiente seguro para promover deslocamento ativo à escola, especialmente para diminuir o uso de transporte motorizado em curtas distâncias. Migração Pendular; Atividade Motora; Estudantes 2471 COMUNICAÇÃO BREVE BRIEF COMMUNICATION http://dx.doi.org/10.1590/0102-311X00161913 Silva KS et al. 2472 Cad. Saúde Pública, Rio de Janeiro, 30(11):2471-2476, nov, 2014 Introduction Active commuting to school is an alternative way to promote an active and healthy lifestyle among children and adolescents 1; however it has decreased over time 2. Among the factors that have affected the journey to school in the last seven decades, researchers have highlighted the change in the availability of transportation technologies and an expectation to travel greater distances in a shorter time 3. Identification of changes in the proportion of time spent in each type of transportation for commuting to school is important for clarifying some issues like the contribution of time spent in commuting to school for physical activity level proposed in the guidelines 4 or evaluated in intervention 5. Nevertheless, there are limited data examining changes in time spent in different types of transportation used for going to school. The rationale of this study is to answer some questions, such as how many students used walking/ bike or car/motorcycle or bus to school for short, middle and long distance trips? Overall, it is expected that people choose motorized transport for long trips, and active commuting as a strategy for short trips. This study analyses changes in the time spent in each mode of transportation to school in two surveys conducted with high school students living in Santa Catarina, Brazil. We also evaluated whether the trend between 2001 and 2011 differed according to gender and age.


Abstract
To examine changes in the time spent in each mode of transportation used for going to school by gender and age among adolescents from Santa Catarina State, Brazil.Two school-based surveys were performed in 2001 (N = 5,028) and 2011 (N = 6,529) in high school students (15-19 years old).The mode of transportation (on foot; by bicycle; by bus; car/motorcycle) and the time spent for commuting to school were assessed.Active commuting increased for short trips in both genders (male: 25.1% to 36.7%; female: 18.8% to 29.2%) and in all ages (15-16 years: 21% to 32.7%; 17-19 years: 21.9% to 32.4%), and declined for longer trips in males (30.5% to 21.9%) and in 15-16 years old students (25.7% to 34.7%).Car/motorcycle use has doubled for short trips in males (38.1% to 65.9%) and in 17-19 years old students (37.7% to 62.7%), while the use of buses remained stable in both genders.Our findings contribute to discussions on public policy focusing on the design of safe environments to promote active commuting to schools, particularly to decrease the use of motorized transport for short trips.

Introduction
Active commuting to school is an alternative way to promote an active and healthy lifestyle among children and adolescents 1 ; however it has decreased over time 2 .Among the factors that have affected the journey to school in the last seven decades, researchers have highlighted the change in the availability of transportation technologies and an expectation to travel greater distances in a shorter time 3 .
Identification of changes in the proportion of time spent in each type of transportation for commuting to school is important for clarifying some issues like the contribution of time spent in commuting to school for physical activity level proposed in the guidelines 4 or evaluated in intervention 5 .Nevertheless, there are limited data examining changes in time spent in different types of transportation used for going to school.The rationale of this study is to answer some questions, such as how many students used walking/ bike or car/motorcycle or bus to school for short, middle and long distance trips?Overall, it is expected that people choose motorized transport for long trips, and active commuting as a strategy for short trips.This study analyses changes in the time spent in each mode of transportation to school in two surveys conducted with high school students living in Santa Catarina, Brazil.We also evaluated whether the trend between 2001 and 2011 differed according to gender and age.

Methods
This study is part of a school-based panel survey entitled Comportamento do Adolescente Catarinense (COMPAC Project).Data were collected in 2001 (N = 5,028) and 2011 (N = 6,529) and included 15 to 19 years old students from public schools.Detailed sampling procedures have been published elsewhere 6 .
The data collection was conducted in the classroom, and the students completed the questionnaire in a guided session by the researchers.We assessed the mode of transportation students typically used to go to school (on foot/by bicycle; by bus; car/motorcycle) and the time spent in commuting (< 10min/day: short trips; 10-19min/ day: medium trips; ≥ 20min/day: long trips).
Comparisons across surveys and variables studied (sex and age) were based on the prevalence and its 95% confidence interval (95%CI), according to procedures for studies with complex sample in Stata version 11 (Stata Corp., College Station, USA).

Results
In 2001, 5,028 students participated in the survey.Of these, 4,801 responded to the questions on type and time spent in commuting to school (response rate = 95.5%).In 2011, 6,379 adolescents provided valid data (response rate = 97.7%).In 2001 and 2011, there was a greater proportion of females (59.7%; 55.7%) and of students aged 15-16 years (51.1%;58.7%), respectively.In general, there was a significant increase in commuting by car/motorcycle over ten years (from 6.4% in 2001 to 12.6% in 2011).Active transport (from 56.3% to 51.3%) and the use of the bus (from 37.3% to 36.1%) remained stable over a decade.

Discussion
Our findings indicated changes in short versus long trips by foot/bike over a ten-year period.These changes occurred for both genders and among students aged 15-16 years.Active commuting for at least 10 minutes has been commonly recommended as a strategy by govern-ment agencies to promote physical activity and to achieve health benefits 7 .However, after a decade, we observed a decrease in the proportion of adolescents in this commuting group, which, in turn, substantially reduces the contribution of this domain to the total physical activity level.
Several correlates of active commuting to school are described in the literature, including personal and socio-demographic factors 8 , and physical environment 9 .Many factors were investigated, including traffic and neighborhood aesthetics; however, the distance from home to school remained the main determinant of active Cad.Saúde Pública, Rio de Janeiro, 30 (11):2471-2476, nov, 2014 commuting 10 .In a previous study of Brazilian adolescents, the distance, crime/safety concerns and traffic were associated with passive commuting 11 .These factors may partially explain the rise in the use of motorized transport for short trips found in our study.
Our findings may be a result of recent socioeconomic improvements in Brazil.Between 2001 and 2011, there was an increase of 78% in the number of cars and buses in Brazil.In the same period, the number of cars and buses almost doubled (95.3%) in Santa Catarina (Departamento Nacional de Trânsito.Frota de Veículos.http:// www.denatran.gov.br/frota.htm,accessed on 01/ Jun/2012).Census data indicated an increase in the proportion of households with cars in Santa Catarina from 50.3% in 2000 to 64% in 2010 12 .Regarding the number of buses, we are unsure if the increase aimed to serve more people along the same routes or if new ones were made available as an extension of services to accommodate more users in the public transport system.
Our study showed that for all types of transportation, the proportion of youth who travelled for more than 20 minutes decreased over time.An explanation for this result is the growth of 17.5% in the number of high schools over this decade, from 598 in 2001 to 725 in 2011.This probably resulted in closer distances between home and school, thus decreasing the proportion of long trips over time.In this study, no evidence for decreased time for travel to school by bus was observed for long trips, mainly because the majority of students who use this mode of transportation lived in rural areas.
In summary, our findings indicated a stable pattern of commuting by bus in the two surveys.However, there was a rise in the proportion of males who actively traveled or commuted by car/ motorcycle to school for short trips and a decrease for longer trips over a ten-year period.These findings could reflect the decrease of overall physical activity levels of young people.A systematic review on the association between active travel to school and physical activity levels in youth found that active commuters tend to be more physically active than passive commuters 13 .
The findings of the present study contribute to the discussion in public policy on the design of safe environments to promote active commuting to schools, especially to decrease the use of motorized transport for short trips.
Migración Pendular; Actividad Motora; Estudiantes Contributors K. S. Silva, R. C. R. Silva, F. F. Costa and M. A. A. Assis participated in all phases of the preparation of the manuscript.A. S. Lopes and M. V. Nahas critically revised this study with important contributions and gave their final approved of the version to be published.

Figure 1 Changes
Figure 1 Changes in the proportion of time spent in each mode of transportation used for going to school, by gender.Santa Catarina State, Brazil, 2001 and 2011.

Figure 2 Changes
Figure 2 Changes in the proportion of time spent in each mode of transportation used for going to school by age.Santa Catarina State, Brazil, 2001 and 2011.