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Development of a Ventilated Artificial Lung Model for Characterizing the Physicochemical Properties of Inhaled E-cigarette Aerosols
LIQIAO LI, Haoxuan Chen, Airi Harui, Michael D. Roth, Yifang Zhu, University of California, Los Angeles
Abstract Number: 273
Working Group: Aerosol Exposure
Abstract
E-cigarettes (e-cigs), such as JUUL, are increasingly popular among adolescents and young adults even though emerging data raise concerns about their health effects. To better understand lung exposure and toxicity, we developed a ventilated artificial lung exposure model in which temperature, humidity, puff volume, puff frequency, and breathing pattern can be independently controlled. The effects of breathing, temperature, and humidity on the fate of inhaled e-cig aerosols were investigated by measuring the particle number concentration (PNC), particulate matter (PM) mass concentration, and size distribution during a 4-puff vaping cycle (33 ml puff every 60s). Samples were collected in real time from the 6L lung chamber. In the absence of breathing, the peak PNC and PM reached 6.9 × 106 #/cm3 and 111 mg/m3, respectively. In comparison, the peak PNC and PM were reduced by 23% and 44%, respectively, at 10 breaths/min [38% relative humidity (RH); 25°C]. Five min after the last puff, the PNC and PM were washed out by > 97% in the presence of ventilation, while those only decreased by 60% in the static model. Compared to the 38% RH, 25°C condition, a dry environment (1% RH, 25°C) accelerated the decay process by facilitating evaporation. In a simulated lung environment (85% RH, 37°C), the particle size grew due to the hygroscopic effect, where fewer submicron particles with smaller size were identified while particle levels at 3 µm increased over time. Vaping topography, breath pattern, and airway distribution are also being studied. This work provides novel insight as to the physiochemical transformation that occurs when e-cig aerosols are inhaled and an estimation of organ-specific exposure (and exposure pattern) that is not evident from conventional chamber analysis.