AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
The Floor Dust-Indoor Air Continuum: A Microbial Community Perspective
DENINA HOSPODSKY, William Nazaroff, Jordan Peccia, Yale University
Abstract Number: 728 Working Group: The Indoor Microbiome
Abstract Humans spend approximately 90% of their time indoors, where inhalation of microbial constituents is a significant exposure route. Through combining indoor air modeling efforts with molecular biology-based microbial population assessments, previous research has suggested that human occupancy shapes the indoor air microbiome, mostly through resuspension of bacteria contained in floor dust. The goal of this study is to examine how independent parameters including human activity, air exchange rate, floor dust load, and relative humidity, influence the contribution of floor dust bacteria to the bacterial species found in indoor air.
Floor dust and indoor aerosols were sampled in six classrooms in the US (1), Europe (3), and China (2) during times of occupancy. Phylogenetic libraries based on the 16S universal bacterial gene were produced for floor dust and air samples using 454 pyrosequencing technology. Retrieved sequences were assigned to phylotypes and the differences between floor dust and air populations were quantified via their weighted UniFrac distance metric. A low (near zero) distance metric indicates that the floor dust and air populations are identical (i.e., demonstrating a strong floor dust source contribution). We investigated linear correlations between this UniFrac distance metric and independent parallel measured variables including air exchange rate [h-1], relative humidity [%], floor bacterial load [genomes m-2], and the intensity of occupants’ activities [W m-2 h-1].
Results demonstrate that an increase in floor dust contribution (lower UniFrac distance) was strongly correlated with increased human activity (Pearson correlation, r = -0.67) and bacterial floor dust load (r = -0.57), and moderately correlated to increased relative humidity (r = -0.39). Decreased source strengths of the floor dust were moderately correlated with increasing air-exchange rate (r = 0.43). Multivariate statistics analysis will be presented to identify the combination of building parameters that most confidently predicts the resuspension of microbial communities from the floor to the air.