The systematic review revealed overall positive effects of outdoor time  on physical activity , sedentary behaviour , and cardiorespiratory fitness , although causality could not be assumed due to a lack of RCTs .
Motor skill development was unrelated to outdoor time ; however , this relationship was only examined in a single study of preschool children .
No studies were found that examined associations between outdoor time and musculoskeletal fitness
The objective of this systematic review was to examine the relationship between outdoor time and : ( 1 ) physical activity , ( 2 ) cardiorespiratory fitness , ( 3 ) musculoskeletal fitness , ( 4 ) sedentary behaviour ; or ( 5 ) motor skill development in children aged 3 - 12 years .
Traffic-Related Air Pollution and Asthma Onset in Children: A Prospective Cohort Study with Individual Exposure Measurement
Background The question of whether air pollution contributes to asthma onset remains unresolved . Objectives In this study , we assessed the association between  asthma onset in children and traffic-related air pollution . Methods We selected a sample of 217 children from participants in the Southern California Children ’s Health Study , a prospect i ve cohort design ed to investigate associations between air pollution and respiratory health in children 10–18 years of age . Individual covariates and new asthma incidence ( 30 cases ) were reported annually through question naires during 8 years of follow-up . Children had nitrogen dioxide monitors placed outside their home for 2 weeks in the summer and 2 weeks in the fall – winter season as a marker of traffic-related air pollution . We used multilevel Cox models to test the associations between asthma and air pollution . Results In models controlling for confounders , incident asthma was positively associated with traffic pollution , with a hazard ratio ( HR ) of 1.29 [ 95 % confidence interval ( CI ) , 1.07–1.56 ] across the average within-community interquartile range of 6.2 ppb in annual residential NO2 . Using the total interquartile range for all measurements of 28.9 ppb increased the HR to 3.25 ( 95 % CI , 1.35–7.85 ) . Conclusions In this cohort , markers of traffic-related air pollution were associated with the onset of asthma . The risks observed suggest that air pollution exposure contributes to new-onset asthma
The systematic review revealed overall positive effects of outdoor time  on physical activity , sedentary behaviour , and cardiorespiratory fitness , although causality could not be assumed due to a lack of RCTs .
Motor skill development was unrelated to outdoor time ; however , this relationship was only examined in a single study of preschool children .
No studies were found that examined associations between outdoor time and musculoskeletal fitness
The objective of this systematic review was to examine the relationship between outdoor time and : ( 1 ) physical activity , ( 2 ) cardiorespiratory fitness , ( 3 ) musculoskeletal fitness , ( 4 ) sedentary behaviour ; or ( 5 ) motor skill development in children aged 3 - 12 years .