Miller Shelly L, Facciola Nick A, Toohey Darin, Zhai John
Department of Mechanical Engineering; University of Colorado, Boulder, CO 80309, USA.
Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO 80309, USA.
Int J Environ Res Public Health. 2017 Jan 28;14(2):128. doi: 10.3390/ijerph14020128.
The objectives of this study were to measure levels of particulate matter (PM) in mechanically ventilated buildings and to improve understanding of filtration requirements to reduce exposure. With the use of an Ultra High Sensitivity Aerosol Spectrometer and an Aerodyne Mass Spectrometer, ultrafine (0.055-0.1 μm) and fine (0.1-0.7 μm) indoor and outdoor PM was measured as a function of time in an office, a university building, and two elementary schools. Indoor particle levels were highly correlated with outdoor levels. Indoor and outdoor number concentrations in Denver were higher than those in Boulder, with the highest number concentrations occurring during summer and fall. The ratio of indoor-to-outdoor (I/O) PM was weakly but positively correlated with the amount of ventilation provided to the indoor environment, did not vary much with particle size (ranged between 0.48 and 0.63 for the entire size range), and was similar for each period of the week (weekend vs. weekday, night vs. day). Regression analyses showed that ultrafine indoor PM baseline concentrations were higher at night from nighttime infiltration. A lag time was observed between outdoor and indoor measurements. Weekday days had the shortest lag time of 11 min, and weekend nighttime lags when the HVAC was not in use were 50 to 148 min. Indoor-outdoor PM concentration plots showed ultrafine PM was more correlated compared to fine, and especially when the HVAC system was on. Finally, AMS data showed that most of the PM was organic, with occasional nitrate events occurring outdoors. During nitrate events, there were less indoor particles detected, indicating a loss of particulate phase nitrate. The results from this study show that improved filtration is warranted in mechanically ventilated buildings, particularly for ultrafine particles, and that nighttime infiltration is significant depending on the building design.
本研究的目的是测量机械通风建筑中的颗粒物（PM）水平，并增进对过滤要求的理解以减少暴露。通过使用超高灵敏度气溶胶光谱仪和 Aerodyne 质谱仪，在一间办公室、一栋大学建筑和两所小学中，测量了超细（0.055 - 0.1μm）和细颗粒（0.1 - 0.7μm）室内外 PM 随时间的变化情况。室内颗粒物水平与室外水平高度相关。丹佛的室内和室外数量浓度高于博尔德，夏季和秋季的数量浓度最高。室内与室外（I/O）PM 的比值与提供给室内环境的通风量呈弱但正相关，随粒径变化不大（整个粒径范围在 0.48 至 0.63 之间），并且在一周的每个时间段（周末与工作日、夜间与白天）相似。回归分析表明，由于夜间渗透，夜间超细室内 PM 基线浓度较高。在室外和室内测量之间观察到有滞后时间。工作日的滞后时间最短，为 11 分钟，而在周末夜间且暖通空调未使用时，滞后时间为 50 至 148 分钟。室内 - 室外 PM 浓度图显示，与细颗粒相比，超细颗粒的相关性更强，尤其是在暖通空调系统开启时。最后，AMS 数据表明，大部分 PM 是有机的，室外偶尔会出现硝酸盐事件。在硝酸盐事件期间，检测到的室内颗粒较少，表明颗粒相硝酸盐有所损失。本研究结果表明，在机械通风建筑中，特别是对于超细颗粒，有必要改进过滤，并且夜间渗透根据建筑设计情况显著不同。
