Comparative Assessment of Bioaerosol Propagation Through an Air Curtain Using Microbiological Methods and Particulate Matter Sensors

Abstract

An important route of transmission for potentially harmful bacteria is the spread of bioaerosols in indoor environments. In a chamber specially developed for particle dispersion tests, we created a defined bioaerosol to study the performance of two methods commonly used in biology and engineering studies: airborne bacterial detection and particulate matter (PM) analysis. A total of five ventilation cases were investigated in which an air curtain, operated at Reynolds numbers Re < 11, 000, shielded the particles in one half of the test chamber from the other half. In two of these five cases, a HEPA filter was also installed to specifically reduce the particle concentration in the test chamber. In addition to active and passive air sampling measurements of bacteria, we took PM measurements in front of, beneath, and behind the air curtain under constant air temperature and relative humidity conditions. The bioaerosol contained nine bacterial species, evenly distributed in artificial saliva. Two species in the bioaerosol, Staphylococcus capitis DSM 111179 and Burkholderia lata DSM 23089^T, were selected for evaluation due to their antibiotic resistance, which makes them distinguishable from other species. The results show a similar trend in the concentrations of the detected particles and bacteria. The survival rates of the evaluated bacterial species differed; S. capitis exhibited a greater agreement with the PM measurements than B. lata did, which emphasizes the importance of using a various model organism in such experimental setups. We evaluated the effectiveness of the air curtain in reducing particle and bacterial spread, with values reaching up to 66% for both measurement approaches. This study highlights the key differences between the two detection methods and confirms the reproducibility and suitability of the standardized bioaerosol for future research applications. Both methods have demonstrated their potential for use in more realistic scenarios.