Green areas around homes reduce atopic sensitization in children

American children today spend 90% less time playing outdoors than their parents did

Western lifestyle is associated with high prevalence of allergy, asthma and other chronic inflammatory disorders. ‘Biodiversity hypothesis’ suggests that reduced contact of children with environmental biodiversity, including environmental microbiota in natural habitats, has adverse consequences on the assembly of human commensal microbiota and its contribution to immune tolerance.

This study analysed 4 cohorts from Finland and Estonia with 1,000 children and adolescents aged 0.5–20 yrs. The prevalence of atopic sensitization was assessed by measuring serum IgE specific to inhalant allergens. WProportion of 5 land-use types—forest, agricultural land, built areas, wetlands, and water bodies—in the landscape around the homes was calculated using the CORINE2006 classification.

The cover of forest and agricultural land within 2–5 km from the home was inversely associated with atopic sensitization. This relationship was observed for children 6 years of age and older.

Land-use pattern explained 20% of the variation in the relative abundance of Proteobacteria on the skin of healthy individuals, supporting the hypothesis of a strong environmental effect on the commensal microbiota.

The amount of green environment (forest and agricultural land) around home was inversely associated with the risk of atopic sensitization in children. Early life exposure to green environments is especially important. The environmental effect may be mediated via the effect of environmental microbiota on the commensal microbiota influencing immunotolerance.


Green areas around homes reduce atopic sensitization in children. Lasse Ruokolainen et al. Allergy, 2014, DOI: 10.1111/all.12545.

Nature deficit disorder refers to a hypothesis by Richard Louv in his 2005 book Last Child in the Woods that human beings, especially children, are spending less time outdoors resulting in a wide range of behavioral problems.

Image source: A conifer forest in the Swiss Alps (National Park), Hansueli Krapf, Wikipedia, GNU Free Documentation License.

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