Indoor dust microbiota and residential surrounding greenness

Abstract

Background: Green spaces are associated with better health. Among others, the environmental microbiome may be a mechanism explaining these associations. However, the impact of outdoor green spaces in shaping the indoor microbial communities has scarcely been investigated. We investigate residential greenness as a potential determinant of the indoor microbiota. Methods: Settled dust was collected from 174 homes from the Belgian ENVIRONAGE birth cohort and bacterial and fungal measures (Chao1 richness, Shannon and Simpson diversity indices) were calculated from Illumina MiSeq sequencing data. The greenness indicators were defined using high-resolution land-cover data with multiple residential buffers(50m,100m,500m and 1000m). Total surrounding greenness was stratified in low (height<3m) and high greenness (height>3m) and land use data was used to calculate the total surrounding nature. We run linear regression models adjusting for the number of sampling days, average temperature and black carbon concentrations during the sampling period, pet ownership and use of passive ventilation. Results are expressed as units change for an interquartile range (IQR) increase in surrounding greenness and their 95% confidence intervals (CI). Results: After adjustment, we observed significant associations of the diversity indices with surrounding greenness within 50m and 100m around the home. For bacteria, Shannon was positively associated with surrounding nature (e.g. 0.07 units increase (CI:0.02,0.13) per IQR increase in nature within a 50m buffer). Fungal diversity was positively associated with high surrounding greenness and inversely with low greenness. For example, an IQR increase in high greenness within a 50m buffer was associated with increases in 0.16 (CI:0.04,0.3) and 0.02 (CI:0.01,0.04) units in the Shannon and Simpson indices, respectively. No statistically significant results were observed for richness and larger buffers. Conclusions: In this urban cohort, the close surrounding environment impacts indoor microbial diversity. Further research is needed to investigate how green spaces determine the specific characteristics of these microbial communities.