Estimation of Direct Human Contribution to the Aerobiome Composition of Indoor Environments

AUSTIN MARSHALL, Suresh Dhaniyala, Shantanu Sur, Clarkson University

     Abstract Number: 454
     Working Group: Aerosol Science of Infectious Diseases: What We Have Learned and Still Need to Know about Transmission, Prevention, and the One Health Concept

Abstract
Bioaerosols of the built environment can be substantially influenced by anthropogenic factors with estimations that 5 - 40% of the microbial DNA from indoor bioaerosols are attributed to human sources. However, much less information is available on the impact of human occupancy to microbial composition in the air. Airborne transmission of pathogens stemming from the recent pandemic has generated a strong interest toward better understanding the microbial release in the air from humans. Apart from occupant numbers, several other factors such as human activities (e.g., speaking, singing), practices (e.g., wearing mask), and air exchange rates can potentially influence the human contribution to the microbial composition in air. To assess the impact of these factors, we captured bioaerosols from indoor spaces using a low-power, low-flow rate, portable electrostatic sampler and performed downstream analysis by real-time PCR and long-read nanopore sequencing. First, we developed an optimized workflow for sample processing and 16S ribosomal RNA gene sequencing that allowed us to reliably measure bacterial abundance and diversity in air from a very low biomass bioaerosol sample. To assess the human contribution to the bacterial load, human RNase P gene and bacterial 16S genes were targeted and quantified in tandem using real-time PCR. The absolute number of RNase P and 16S rRNA gene copies were used to measure the extent of direct human contribution within each sampling location. We have collected and analyzed bioaerosol samples from Clarkson University, focusing on the classroom environment in an attempt to observe abundance and diversity variations due to masked and unmasked students. We compared these samples on the basis of their microbial composition and assessed the human contribution to the differences observed. The knowledge gained from this study could help in deciding context-specific actionable measures to prevent airborne transmission of disease.