Home gardens and distances to nature associated with behavior problems in alpine schoolchildren: Role of secondhand smoke exposure and biomarkers

Background: Behavior problems in children are shaped by a complex intertwining of environmental, social, and biological factors. This study investigated whether more nature exposure was associated with less behavior problems and whether these associations were mediated by differences in secondhand smoke in the home, sleep problems, adiposity, and inflammation.
Methods: We used cross-sectional data collected from 1251 schoolchildren (8-12 years old) in the Tyrol region of Austria and Italy. Information on sociodemographics, lifestyle, perinatal data, and housing conditions was obtained by questionnaire. Behavior problems in the past school year were rated by teachers using the Needleman questionnaire for classroom performance. We estimated nature exposure using a comprehensive naturalness index called "distance to nature" (D2N). This was calculated in several buffer sizes around the child's home and school. Presence of a home garden was assessed by self-report. Data on potential mediators including parental smoking in the home, child's urinary cotinine concentrations, sleep problems, body mass index, and urinary neopterin concentrations were also collected. Structural equation modeling was used to examine the multiple pathways between nature exposure and behavior problems.
Results: Children who lived in a home with a garden and those whose school was closer to nature exhibited less school behavior problems. The effect of proximity to nature from the school was directly associated with less behavior problems, and the effect of a home garden on behavior problems acted indirectly through a lower likelihood of secondhand smoke exposure. Associations were in unexpected directions between behavior problems and residential proximity to nature and depended on the outcome and context.
Conclusions: Natural environments in school and home surroundings might be beneficial for school conduct and performance. Lower secondhand smoke exposure at home might be a pathway between home gardens and children's behavioral problems. Associations with residential proximity to nature in this study were in unexpected directions and warrant further investigation. These findings serve as a point of departure for investigating how proximal nature might activate health supportive pathways in children and simultaneously confer childhood health benefits via positive behavioral changes in their parents.