Chamber Bioaerosol Study: Outdoor Air and Human Occupants as Sources of Indoor Airborne Microbes

Abstract

Human occupants are an important source of microbes in indoor environments. In this study, we used DNA sequencing of filter samples to assess the fungal and bacterial composition of air in an environmental chamber under different levels of occupancy, activity, and exposed or covered carpeting. In this office-like, mechanically ventilated environment, results showed a strong influence of outdoor-derived particles, with the indoor microbial composition tracking that of outdoor air for the 2-hour sampling periods. The number of occupants and their activity played a significant but smaller role influencing the composition of indoor bioaerosols. Human-associated taxa were observed but were not particularly abundant, except in the case of one fungus that appeared to be transported into the chamber on the clothing of a study participant. Overall, this study revealed a smaller signature of human body-associated taxa than had been expected based on recent studies of indoor microbiomes, suggesting that occupants may not exert a strong influence on bioaerosol microbial composition in a space that, like many offices, is well ventilated with air that is moderately filtered and moderately occupied.

Spacio-Temporal Distribution and Tourist Impact on Airborne Bacteria in a Cave (Škocjan Caves, Slovenia)

“…For long-distance transport, microbes and other minute particles use one of three modes of dispersion: air (anemochoric), water (hydrochloric), or biological vectors (biochoric), the latter via either animal or human vectors [2]. When airborne, microbes can travel reasonably great distances and can have a global impact on ecosystems [3].…”

Time-Dependent Size-Resolved Bacterial and Fungal Aerosols in Beijing Subway

“…As an indispensable means of public transportation for urban metropolises, subway system around the globe is carrying the largest commuter traffic daily. Humans themselves are shown to be an important source of bioaerosol emission, especially for indoor environment via coughing, breathing and shedding of human skin (Xu et al, 2011;Hospodsky et al, 2012;Noti et al, 2012;Ghosh et al, 2013;Adams et al, 2015). In addition, human activities such as walking could also resuspend the particles (some of them could be the settled biological materials) into the air from the floor (Qian et al, 2014).…”

Humans differ in their personal microbial cloud.

“…Research on bioaerosols to date has rarely focused on the direct emission of bioaerosols from human sources, because it is difficult to disentangle direct emission from resuspension of dust observationally (Meadow et al, 2013;Qian et al, 2012;Qian, Peccia & Ferro, 2014;Nazaroff, 2014;Hospodsky et al, 2014;Bhangar et al, 2015;Adams et al, 2015). Previous attempts to account for dust resuspension in indoor bioaerosols indicate that active human emission, as opposed to resuspended particulate matter, is an underestimated part of the total indoor airborne bacterial pool in buildings (Qian, Peccia & Ferro, 2014).…”