Data from: Thirdhand smoke uptake to aerosol particles in the indoor environment

Aerosol composition measurements made in an indoor classroom indicate the uptake of thirdhand smoke (THS) species to indoor particles, a novel exposure route for THS to humans indoors. Chemical speciation of the organic aerosol fraction using mass spectrometric data and factor analysis identified a reduced nitrogen component, predominantly found in the indoor environment, contributing 29% of the indoor submicron aerosol mass. We identify this factor as THS compounds partitioning from interior surfaces to gas phase and then aerosol phase. Partitioning of THS vapors to aerosols requires an aqueous phase for reactive uptake of the reduced nitrogen species (RdNS), leading to seasonal differences in THS concentration indoors. RdNS protonate under the acidic conditions expected for indoor aerosols of outdoor origin. Controlled laboratory measurements performed using cigarette smoke deposited into a Pyrex vessel showed a similar partitioning behavior to aerosol of outdoor origin and mass spectral features comparable to the measured indoor THS factor after 1 week of residence time in the closed vessel. This study reports a new, potentially large THS exposure route from partitioning of surface volatile organic compounds into the aerosol phase and subsequent dispersion in a mechanically ventilated building.

本研究针对一间室内教室开展气溶胶组成测量，结果发现三手烟（thirdhand smoke, THS）组分可附着于室内颗粒物，这是三手烟在室内环境中暴露于人体的全新途径。研究借助质谱数据与因子分析对有机气溶胶组分开展化学形态解析，识别出一类主要存在于室内环境的还原态氮组分，该组分占室内亚微米气溶胶总质量的29%。我们将该因子认定为从室内表面分配至气相、随后进一步进入气溶胶相的三手烟类化合物。三手烟蒸气向气溶胶的分配过程，需要依托水相环境以实现还原态氮物种（reduced nitrogen species, RdNS）的反应性摄取，这一机制也导致室内三手烟浓度存在季节差异。还原态氮物种在源自室外的室内气溶胶的预期酸性环境中会发生质子化反应。使用沉积有卷烟烟气的派热克斯（Pyrex）玻璃容器开展的控制实验室实验显示，其向源自室外的气溶胶展现出相似的分配行为；且在封闭容器中静置1周后，其质谱特征与实测得到的室内三手烟因子特征具有可比性。本研究揭示了一条全新且潜在影响范围广泛的三手烟暴露途径：室内表面的挥发性有机化合物先分配进入气溶胶相，随后在机械通风建筑中进一步扩散。