Microbial analyses of airborne dust collected from dormitory rooms predict the sex of occupants.

We have long known that human occupants are a major source of microbes in the built environment, thus raising the question: How much can we learn about the occupants of a building by analyzing the microbial communities found in indoor air? We investigated bacterial and fungal diversity found in airborne dust collected onto heating, ventilation, and air-conditioning (HVAC) air filters and settling plates from 91 rooms within a university dormitory. The sex of the room occupants had the most significant effect on the bacterial communities, while the room occupants had no significant effect on fungal communities. By examining the abundances of bacterial genera, we could predict the sex of room occupants with 79% accuracy, a finding that demonstrates the potential forensic applications of studying indoor air microbiology. We also identified which bacterial taxa were indicators of female and male rooms, and found that those taxa often identified as members of the vaginal microbiome were more common in female-occupied rooms while taxa associated with human skin or the male urogenital microbiota were more common in male-occupied rooms.

Role of mechanical ventilation in the airborne transmission of infectious agents in buildings.

Infectious disease outbreaks and epidemics such as those due to SARS, influenza, measles, tuberculosis, and Middle East respiratory syndrome coronavirus have raised concern about the airborne transmission of pathogens in indoor environments. Significant gaps in knowledge still exist regarding the role of mechanical ventilation in airborne pathogen transmission. This review, prepared by a multidisciplinary group of researchers, focuses on summarizing the strengths and limitations of epidemiologic studies that specifically addressed the association of at least one heating, ventilating and/or air-conditioning (HVAC) system-related parameter with airborne disease transmission in buildings. The purpose of this literature review was to assess the quality and quantity of available data and to identify research needs. This review suggests that there is a need for well-designed observational and intervention studies in buildings with better HVAC system characterization and measurements of both airborne exposures and disease outcomes. Studies should also be designed so that they may be used in future quantitative meta-analyses.

Contribution of human-related sources to indoor volatile organic compounds in a university classroom.

Although significant progress has been made in understanding the sources and chemistry of indoor volatile organic compounds (VOCs) during the past decades, much is unknown about the role of humans in indoor air chemistry. In the spring of 2014, we conducted continuous measurements of VOCs using a proton transfer reaction mass spectrometer (PTR-MS) in a university classroom. Positive matrix factorization (PMF) of the measured VOCs revealed a 'human influence' component, which likely represented VOCs produced from human breath and ozonolysis of human skin lipids. The concentration of the human influence component increased with the number of occupants and decreased with ventilation rate in a similar way to CO2 , with an average contribution of 40% to the measured daytime VOC concentration. In addition, the human skin lipid ozonolysis products were observed to correlate with CO2 and anticorrelate with O3 , suggesting that reactions on human surfaces may be important sources of indoor VOCs and sinks for indoor O3 . Our study suggests that humans can substantially affect VOC composition and oxidative capacity in indoor environments.