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

2019年，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年全国青少年烟草调查，33.8%的美国中学生和高中生报告说，他们在室内空间接触过二手ENDS气溶胶。尽管对直接由ENDS吹口产生的气溶胶进行了广泛的研究，但二手ENDS气溶胶的特性还没有得到充分的了解，因为这些气溶胶需要由人类受试者使用ENDS设备产生。人类受试者的使用非常有限，由于无法控制的其他变量（例如，现有疾病、肺功能和吸烟习惯），引入了不确定性，并引起了伦理问题。由于缺乏数据而造成的知识差距导致室内环境中ENDS使用监管的混乱和潜在延迟。这项研究旨在研究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。这个项目的成功完成将通过开发新的知识来了解二手挥发性废气气溶胶对环境和健康的影响，从而造福社会。通过对学生的教育、培训和公众宣传，进一步造福社会。通过将研究成果融入课程模块、研究人员参与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，STEM培训将得到加强。由于二手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气溶胶的典型尺寸分布是什么，以及它们在受控环境因素下如何演变？2)实际室内环境中二手ENDS气溶胶是否会引起氧化应激和细胞毒性？3)金属和香料在决定二手ENDS气溶胶的大小分布和毒性效应中的作用是什么？这个项目提出通过在一个步入式环境室和一个实验室内进行实验来回答这些问题，将测量与现实世界的室内环境联系起来。本研究将采用一系列在线和离线测量和建模技术，以检查现实室内环境中二手ENDS气溶胶的物理、化学和毒理学特性。收集到的数据将用于建立气溶胶动力学模型，以预测二手ENDS气溶胶在蒸发、凝固、壁面沉积和通风影响下的演变。这项工作有可能对室内二手ENDS气溶胶的行为和控制产生革命性的理解。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，以便分离二手ENDS气溶胶动力学的潜在原因。该奖项反映了美国国家科学基金会的法定使命，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.