Department of Civil, Architectural, and Environmental Engineering, Drexel University, Philadelphia, PA, USA.
Environ Sci Process Impacts. 2019 Aug 14;21(8):1301-1312. doi: 10.1039/c9em00097f.
Humans impact indoor air quality directly via emissions from skin, breath, or personal care products, and indirectly via reactions of oxidants with skin constituents, or with skin that has been shed. However, separating the influence of the many emissions and their oxidation products from the influence of outdoor-originated aerosols has been a challenge. Indoor and outdoor aerosols were alternatively sampled at 4 minute time resolution with a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) in a classroom with student occupants at regular intervals per university class schedule. Mass spectral analysis showed aerosol enhancements of oxidized and unoxidized hydrocarbon ion families during occupied periods, especially at ion fragments larger than m/z 100 and double bond equivalents consistent with squalene (C30H50) and its oxidized products from reaction with ozone, indicative of the secondary nature of the aerosol mass. Individual hydrocarbon mass fragments consistent with squalene fragmentation, including C5H9+, and C6H9+ were especially enhanced with room occupancy. Emissions of individual organic fragment ions were estimated using a model accounting for outdoor aerosols and air exchange. This showed occupancy related emissions at smaller fragments (C3H5+, C4H9+) that despite reflecting mostly outdoor-originated aerosols transported indoors, also show enhancements from occupant emissions indoors. Total emission of all fragments was 17.6 μg β-1 h-1 above unoccupied levels, translating to approximately 25% increase in organic aerosol mass concentration in the classroom during an occupied hour with a median occupied ozone loss (β). Human occupants, therefore, represent an additional mass burden of organic aerosol, especially in poorly ventilated or highly occupied indoor spaces.
人类通过皮肤、呼吸或个人护理产品的排放直接影响室内空气质量，通过氧化剂与皮肤成分或已脱落的皮肤的反应间接影响室内空气质量。然而，将许多排放物及其氧化产物的影响与源自室外的气溶胶的影响分开一直是一个挑战。在有学生居住的教室中，使用高分辨率飞行时间气溶胶质谱仪（HR-ToF-AMS）以 4 分钟的时间分辨率交替采集室内和室外气溶胶，按照大学课程时间表定期进行。质谱分析显示，在有人居住期间，氧化和未氧化的碳氢化合物离子族的气溶胶浓度增加，尤其是在大于 m/z 100 的离子碎片和双键当量处，与角鲨烯（C30H50）及其与臭氧反应的氧化产物一致，表明气溶胶质量的二次性质。与角鲨烯碎片一致的单个碳氢化合物质量碎片，包括 C5H9+和 C6H9+，尤其是在有人居住时增强。使用考虑到室外气溶胶和空气交换的模型估算单个有机碎片离子的排放。这表明在较小的碎片（C3H5+、C4H9+）处与占用相关的排放，尽管主要反映了运入室内的源自室外的气溶胶，但也显示出室内人员排放的增强。所有碎片的总排放量比无人居住时高出 17.6 μg β-1 h-1，这意味着在有人占用的一个小时内，教室中有机气溶胶质量浓度增加了约 25%，中位数占用臭氧损失（β）。因此，人类居住者代表着有机气溶胶的额外质量负担，尤其是在通风不良或高度占用的室内空间。
