AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Measurement and Observation of the Hygroscopic Growth Properties of Biological Aerosols
SHANNA RATNESAR-SHUMATE, Elizabeth Corson, Jonathan Eshbaugh, Sean Kinahan, Joshua Santarpia, The Johns Hopkins Applied Physics Laboratory
Abstract Number: 278 Working Group: Bioaerosols: Characterization and Environmental Impact
Abstract There are many mechanisms by which primary biological aerosols may undergo chemical or physical changes in the atmosphere. Fluctuations in RH may influence aerosolized biological organism viability, facilitate chemical reactions, lead to shifts in size, and affect aerosol transport. It is important to understand the hygroscopic nature of biological aerosols including spores, vegetative bacteria, viruses and proteins. The hygroscopic growth, as indicated by changes in the aerodynamic diameter, of several biological organisms and other materials often associated with biological aerosol particles was measured at The Johns Hopkins University Applied Physics Laboratory to determine the behavior of these particles during both humidification and drying. Changes to the size distribution of biological aerosols are measured by using three Aerodynamic Particle Sizer® (APS) spectrometers separated by two Nafion® tubes in series in which the RH is controlled. Using this method, the hygroscopic properties of sodium chloride, polystyrene latex beads, and sodium nitrate aerosols were compared against those reported in previous literature in order to characterize the ability of the new method to accurately predict the deliquescence and efflorescence of aerosol particles. Hygroscopic measurements ranging from 20% to 85% RH were taken of Bacillus thuringiensis Al Hakam, Bacillus thuringiensis kurstaki, Bacillus globigii, MS2 Phage, Pseudomonas fluorescens and Pseudomonas syringae. Hygroscopic growth measurements of the supernatent material from each biological aerosol type were were also made, to isolate any hygroscopic growth due soley to the material in the supernatent. Additionally, the hygroscopic properties of several materials often found in biological aerosol particles were measured, including: phosphate buffered saline (PBS), glucose, Cab-O-Sil®, and Tween 20®. Results of the characterization process and the measured hygroscopic properties of different types of biological organisms are discussed.