show Abstracthide AbstractThis study was conducted to get knowledge of the size-related properties of bacterial community composition, diversity, and abundance in outdoor aerosol samples and their potential influence on human health. We used 16S rRNA gene-targeted quantitative PCR and amplicon sequencing with Illumina MiSeq. Air samples were collected by eight-stage Andersen samplers between August and October 2016, at a suburban site in Toyama City and an urban site in Yokohama City, Japan.