Discussion

This is the first population-based cohort study to assess longitudinally the effects of exposure to green spaces on the development of allergic rhinitis up to 27 years of age. Unlike previous studies, we applied individual-level exposure based on information on prenatal and life-time residential addresses. Our results based on a strong study design provide novel evidence that early-life cumulative exposure to green spaces, measured as mean NDVI, during the spring increases the risk of developing allergic rhinitis up to young adulthood, whereas green space exposure in the summer decreases this risk. In addition, the results suggest that air pollution levels may modify the associations between green space and allergic rhinitis, so that the beneficial effects of green space are stronger at high levels of air pollution.