Solving the Mystery of Humidity's Effect on Viability of Airborne Microorganisms

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

1438103 Marr Solving the Mystery of Humidity's Effect on Viability of Airborne Microorganisms This project will benefit society by enhancing the understanding of transmission of infectious disease via the airborne route. Results could be used to improve prediction of the spread of infectious disease and may help explain the seasonality of some diseases. Application of the results could lead to interventions such as manipulating liquid-phase chemistry to reduce the viability of pathogens in aerosols generated from the liquid. If humidity is proven to play a controlling role in airborne pathogen viability, then recommendations about indoor humidity levels could be developed. The project will build interdisciplinary ties between atmospheric science and microbiology, which are needed for progress in understanding infectious disease transmission. By developing new educational material on airborne microorganisms for students ranging from the preschool to undergraduate level, we will improve scientific literacy and will hopefully help prevent at least one case of infectious disease. The goal of the proposed research is to develop new, fundamental knowledge about how ambient humidity and aerosol chemistry interact to affect the survival of airborne microorganisms. This project is based upon the hypothesis that evaporation-induced changes in the chemical composition of an aerosol, such as increases in salt and protein concentrations, shifts in pH, crystallization of solutes, and phase separation, affect the viability of microorganisms contained in the aerosol. By applying environmental engineering tools to this problem, we are poised to make potentially transformative advances in understanding and potentially controlling the dynamics of microorganisms in the atmosphere Recent studies employing high-throughput sequencing have found a surprisingly diverse, complex, and dynamic microbiome in the natural and built environments. There are many opportunities for aerosolization of microorganisms, such as from wastewater treatment plants, animal feeding operations, land application of biosolids, toilets, showers, and humidifiers. Environmental engineers have made large gains in understanding how environmental conditions affect microorganisms in water, but a parallel understanding for microorganisms in air does not yet exist. An interdisciplinary approach is critical to progress in this area. This project unites environmental engineering, aerosol science, and microbiology to develop a new interdisciplinary understanding of the dynamics of microorganisms in the atmosphere. Specific objectives are to (1) characterize evaporation-induced changes in aerosol composition in terms of solute concentrations, pH, crystallization, and phase separation; (2) determine the relationship between microorganism viability and solute concentrations, pH, crystallization, and phase separation in aerosols; (3) describe the partitioning of microorganisms in aerosols and examine structural changes in them as a function of aerosol chemistry; and (4) broaden the scientific literacy of students and the general public regarding airborne microorganisms and infectious disease transmission. The research team will produce droplets and aerosols of varying initial chemical composition (inorganic salts, organic material, pH) and size, expose the them to varying relative humidity in an environmental chamber, determine their final chemical composition after equilibration, measure the inactivation rate of microorganisms contained in the droplets and aerosols, and visualize the microorganisms using electron microscopy.