Association of residential greenness with incident allergic rhinitis among adults: A prospective analysis of UK Biobank

Limited studies have assessed the impact of residential greenness exposure on allergic rhinitis in adults, and its relationship with ambient air pollutants remains unknown. To investigate the association of residential greenness with allergic rhinitis incidence and explore the mediation effects of ambient air pollutants in adults using data from a prospective cohort study in UK Biobank. Greenness was defined as the area-weighted mean of greenness coverage based on the land used data from the Generalized Land Use Database for England (GLUD) 2005 in the UK Biobank. Multiple Cox proportional hazard models and a generalized additive model incorporating restricted cubic splines were used to model the potential nonlinear effect of residential greenness on allergic rhinitis incidence and the potential mediation effect of ambient air pollutants. Among the 281,699 subjects included in the analysis, 3260 allergic rhinitis incident cases occurred after a median follow-up of 14 years. With per 10 % increase in residential greenness at a 300 m buffer, a 2.5 % (95%CI: 1.0 %, 4.0 %) decreased risk of allergic rhinitis was observed. An L-shaped, non-linear dose-response relationship was indicated with a threshold of 54.9 % greenness above which no excess allergic rhinitis risk was seen. PM10 partially mediated the relationship between greenness and allergic rhinitis incidence with a mediation effect of 26.9 % (95%CI: 12.6 %, 41.2 %). A similar pattern of association was found at 1000 m buffer size. This study demonstrates a significant beneficial effect of residential greenness on reducing allergic rhinitis incidence. Greenness may erase air pollutants and mitigate the rhinitis risk from air pollution.