Characterizing the transport and evolution of indoor bioaerosols
The airborne transmission of indoor pathogens is a critical public health concern. The ongoing COVID-19 pandemic has attracted increased attention to improving indoor air quality control strategies to reduce disease transmission. The CDC and WHO currently believe that airborne transmission of SARS-CoV-2 through the airborne mode, which is by inhaling virus-containing bioaerosols smaller than 5 μm in diameter, is unlikely. However, coughing, sneezing, and speaking generate microscopic aerosols, with more than 90% of them being less than 5 μm in size. The objective of this research is to study the evolution and transport of indoor bioaerosols through controlled laboratory experiments and model simulation. Experiments conducted in a small-scale chamber and a walk-in environmental chamber will establish the size-dependent load and viability of microorganisms contained in bioaerosols. The information will be utilized to establish and validate a computational fluid dynamics (CFD) model that incorporates the transport and evolution of bioaerosols to predict the infection risk and optimize indoor ventilation design.
Understanding the physicochemical and toxicological effects of electronic cigarette aerosols
In 2019, 10.9 million American adults used Electronic Nicotine Delivery Systems (ENDS) such as e-cigarettes, e-hookahs, and vape pens. According to the National Youth Tobacco Survey in 2020, 33.8% of U.S. middle and high school students report that they have been exposed to secondhand ENDS aerosols in indoor spaces. Despite extensive studies on aerosols directly generated from the ENDS mouthpieces, the properties of secondhand ENDS aerosols are insufficiently understood because these aerosols need to be generated by human subjects using ENDS devices. The use of human subjects is very limited, introduces uncertainty due to uncontrolled other variables (e.g., existing diseases, lung functions, and smoking habits), and raises ethical concerns. The knowledge gaps caused by this lack of data lead to confusion and potential delays in regulating ENDS usage in indoor environments. This research aims to examine the physical, chemical, and toxicological properties of secondhand ENDS aerosols generated from a simulated respiratory system recently developed by the research team. We will conduct experiments in a walk-in environmental chamber and an experimental house to relate measurements to real-world indoor environments. An array of online and offline measurement and modeling techniques will be deployed in this study to examine the physical, chemical, and toxicological properties of secondhand ENDS aerosols in realistic indoor environments. The collected data will be used to establish an aerosol dynamics model to predict the evolution of secondhand ENDS aerosols under the influence of evaporation, coagulation, wall deposition, and ventilation. This work has the potential to produce a transformative understanding of the behavior and control of indoor secondhand ENDS aerosols.
