Characterizing the Physical, Chemical, and Toxicological Properties of Secondhand Aerosols Generated from Electronic Nicotine Delivery Systems in Indoor Environments

2019年，有1090万美国成年人使用电子尼古丁输送系统（ENDS），如电子烟、电子水烟和电子烟笔。根据2020年的全国青少年烟草调查，33.8%的美国初高中生报告他们在室内空间接触过二手ENDS气溶胶。尽管对ENDS吹口直接产生的气溶胶进行了广泛的研究，但对二手ENDS气溶胶的性质了解不够，因为这些气溶胶需要由人类受试者使用ENDS装置产生。人类受试者的使用非常有限，由于不受控制的其他变量（例如，现有的疾病，肺功能和吸烟习惯），并提出了伦理问题。由于缺乏数据而造成的知识差距导致了在室内环境中规范ENDS使用方面的混乱和潜在延误。本研究旨在检查研究小组最近开发的模拟呼吸系统产生的二手ENDS气溶胶的物理，化学和毒理学特性。该项目的成功完成将通过开发新知识来了解二手ENDS气溶胶对环境和健康的影响，从而造福社会。通过学生教育、培训和公众宣传，将进一步造福社会。将通过将研究成果纳入课程单元，研究人员参加K-12暑期科学营，以及与当地公共图书馆合作向公众传播项目成果，加强STEM培训。 由于有关二手ENDS气溶胶性质的数据有限，几个基本问题仍然没有得到回答：1）二手ENDS气溶胶的典型粒径分布是什么，以及它们在受控环境因素下如何演变？2)在实际的室内环境中，二手ENDS气溶胶是否会引起氧化应激和细胞毒性？3)金属和调味料在决定二手ENDS气溶胶的粒径分布和毒性作用方面有什么作用？该项目建议通过在步入式环境室和实验室中进行实验来回答这些问题，以将测量结果与真实的室内环境联系起来。一系列的在线和离线测量和建模技术将部署在这项研究中，以检查物理，化学和毒理学性质的二手ENDS气溶胶在现实的室内环境。收集到的数据将被用来建立一个气溶胶动力学模型，预测二手ENDS气溶胶的蒸发，凝结，壁沉积和通风的影响下的演变。这项工作有可能对室内二手ENDS气溶胶的行为和控制产生变革性的理解。此外，它消除了对人类受试者研究的需要，并创造了一个有效控制其他潜在变量的环境，以隔离二手ENDS气溶胶动力学的根本原因。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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. The successful completion of this project will benefit society through the development of new knowledge in understanding the environmental and health impact of secondhand ENDS aerosols. Further benefits to society will be achieved through student education, training, and public outreach. STEM training will be enhanced through integration of research findings into course modules, participation of researchers in K-12 summer science camps, and a partnership with local public library to disseminate the project findings to the public. Due to the limited data on the properties of secondhand ENDS aerosols, several fundamental questions are still not answered: 1) What are the typical size distributions of secondhand ENDS aerosols, and how do they evolve under controlled environmental factors? 2) Will secondhand ENDS aerosols in actual indoor environments induce oxidative stress and cytotoxicity? 3) What are the roles of metals and flavorings in determining the size distribution and toxic effect of secondhand ENDS aerosols? This project proposes to answer these questions by conducting 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. Furthermore, it eliminates the need for human subject studies and creates an environment that effectively controls other potential variables in order to isolate underlying causes of secondhand ENDS aerosol dynamics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.