Association of Greenness Exposure with Asthma, Allergic rhinitis: A Systematic Review and Meta-analysis

Abstract Peer-reviewed literature was systematically searched before 23 December 2021 to summarize existed evidence on the relationship between greenness exposure (residential greenery/greenery around schools) and some allergic respiratory diseases, including asthma and allergic rhinitis (AR). A systematic review was conducted, together with a meta-analysis. Pooled odds ratio (OR) with 95% confidence interval (CI) was used to estimate the effect of Normalized Difference Vegetation Index (NDVI) on asthma and AR. Cochran's Q chi-square test and I2 statistics were used to assess heterogeneity and sensitivity analysis was performed for high heterogeneity. Publication bias was assessed by Egger's tests. This study finally included 26 articles with positive, negative or no correlation between greenness exposure and asthma and AR. Eight of these studies underwent finite meta-analysis in different groups. The results showed no relationship between NDVI and asthma or AR. Two articles with high heterogeneity were identified by sensitivity analysis. There was no publication bias. This study protocol was registered with PROSPERO, number CRD42022299861.