title: Risks and benefits of green spaces for children: a cross-sectional study of associations with sedentary behavior, obesity, asthma, and allergy.
abstract: BACKGROUND
  Green spaces have been associated with both health benefits and risks in children; however, available evidence simultaneously investigating these conflicting influences, especially in association with different types of greenness, is scarce.
  
  
  OBJECTIVE
  We aimed to simultaneously evaluate health benefits and risks associated with different types of greenness in children, in terms of sedentary behavior (represented by excessive screen time), obesity, current asthma, and allergic rhinoconjunctivitis.
  
  
  METHODS
  We conducted a cross-sectional study of a population-based sample of 3,178 schoolchildren (9-12 years old) in Sabadell, Spain, in 2006. Information on outcomes and covariates was obtained by questionnaire. We measured residential surrounding greenness as the average of satellite-derived Normalized Difference Vegetation Index (NDVI) in buffers of 100 m, 250 m, 500 m, and 1,000 m around each home address. Residential proximity to green spaces was defined as living within 300 m of a forest or a park, as separate variables. We used logistic regression models to estimate associations separately for each exposure-outcome pair, adjusted for relevant covariates.
  
  
  RESULTS
  An interquartile range increase in residential surrounding greenness was associated with 11-19% lower relative prevalence of overweight/obesity and excessive screen time, but was not associated with current asthma and allergic rhinoconjunctivitis. Similarly, residential proximity to forests was associated with 39% and 25% lower relative prevalence of excessive screen time and overweight/obesity, respectively, but was not associated with current asthma. In contrast, living close to parks was associated with a 60% higher relative prevalence of current asthma, but had only weak negative associations with obesity/overweight or excessive screen time.
  
  
  CONCLUSIONS
  We observed two separable patterns of estimated health benefits and risks associated with different types of greenness.
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain.
authors.forename: Payam
authors.initials: P
authors.lastname: Dadvand
authors.forename: Cristina M
authors.initials: CM
authors.lastname: Villanueva
authors.forename: Laia
authors.initials: L
authors.lastname: Font-Ribera
authors.forename: David
authors.initials: D
authors.lastname: Martinez
authors.forename: Xavier
authors.initials: X
authors.lastname: Basagaña
authors.forename: Jordina
authors.initials: J
authors.lastname: Belmonte
authors.forename: Martine
authors.initials: M
authors.lastname: Vrijheid
authors.forename: Regina
authors.initials: R
authors.lastname: Gražulevičienė
authors.forename: Manolis
authors.initials: M
authors.lastname: Kogevinas
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Nieuwenhuijsen
mesh_terms: D001249:Asthma / Q000150:complications / Q000453:epidemiology*; D002648:Child; D002662:Child Health Services; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000150:complications / Q000453:epidemiology*; D010944:Plants; D011998:Recreation; D018570:Risk Assessment; D057185:Sedentary Behavior; D013030:Spain / Q000453:epidemiology; D011795:Surveys and Questionnaires