School of Energy and Environment, Southeast University , Nanjing, Jiangsu 210096, China.
Department of Building Science, Tsinghua University , Beijing 100084, China.
Environ Sci Technol. 2017 Jun 6;51(11):6220-6228. doi: 10.1021/acs.est.6b05864. Epub 2017 May 10.
Inhaled semivolatile organic compounds (SVOCs) are simultaneously present in gas and particle phases. Particles desorb a fraction of their SVOCs moving through the human respiratory tract (RT). Quantifying such desorption is challenging but important since gas- and particle-phase SVOCs deposit in different locations in the RT, encountering different cell populations with varying health consequences. This paper presents a mass transfer model to quantify this desorption process in the head, tracheobronchial, and alveolar regions of the RT. The desorption of SVOCs from inhaled particles can be gauged using the ratio of particle residence time to the time required to achieve particle/gas equilibrium. Results indicate that the larger this ratio is, the more likely particles desorb the SVOCs they carry. For particles smaller than 0.5 μm diameter and SVOCs with a particle/gas partition coefficient (unitless) of 10, accounting for desorption reduces the estimated particle-phase SVOC concentrations in the alveolar region by more than 35%; the reduction is almost 700% for 0.05 μm diameter particles. In hypothetical scenarios representing common indoor and outdoor situations, neglecting desorption significantly overestimates the concentration of ultrafine particle associated SVOCs in the alveolar region. This model is a preliminary step toward more nuanced estimates of exposure to inhaled SVOCs.
吸入性半挥发性有机化合物 (SVOCs) 同时存在于气体相和颗粒相中。颗粒在穿过人体呼吸道 (RT) 的过程中会解吸一部分 SVOCs。定量描述这种解吸过程具有挑战性，但非常重要，因为气体相和颗粒相的 SVOCs 在 RT 的不同部位沉积，遇到具有不同健康后果的不同细胞群体。本文提出了一个传质模型，用于量化 RT 的头部、气管支气管和肺泡区域中的这种解吸过程。可以通过比较颗粒停留时间与达到颗粒/气体平衡所需的时间来衡量 SVOCs 从吸入颗粒中的解吸。结果表明，该比值越大，颗粒越有可能解吸其所携带的 SVOCs。对于直径小于 0.5μm 的颗粒和具有 10 的颗粒/气体分配系数（无量纲）的 SVOCs，考虑解吸会使肺泡区域中估计的颗粒相 SVOC 浓度降低超过 35%；对于 0.05μm 直径的颗粒，降低幅度接近 700%。在代表常见室内和室外情况的假设情景中，忽略解吸会大大高估肺泡区域中与超细颗粒相关的 SVOC 浓度。该模型是对吸入性 SVOCs 暴露进行更细致估计的初步步骤。
