Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh, NC, USA.
J Air Waste Manag Assoc. 2012 Mar;62(3):322-35. doi: 10.1080/10473289.2011.650316.
The tapered element oscillating microbalance (TEOM) is one type of continuous ambient particulate matter (PM) monitor. Adsorption and desorption of moisture and semivolatile species may cause positive or negative artifacts in TEOM PM mass measurement. The objective of this field study was to investigate possible uncertainties associated with TEOM measurements in the poultry operation environment. For comparisons of TEOM with filter-based gravimetric method, four instruments (TEOM-PM10, low-volume PM10 sampler TEOM-PM2.5, and PM2.5 speciation sampler) were collocated and tested inside a poultry house for PM2.5 and PM10 (PM with aerodynamic equivalent diameter < or =2.5 and < or =10 microm, respectively) measurements. Fifteen sets of 24-hr PM10 concentrations and 13 sets of 24-hr PM2.5 measurements were obtained. Results indicate that compared with filter-based gravimetric method, TEOM gave significantly lower values of both PM10 and PM2.5 mass concentrations. For PM10, the average ratio of TEOM to the gravimetric method was 0.936. For PM2.5, the average ratio of TEOM to the gravimetric method was 0.738. Particulate matter in the poultry houses possibly contains semivolatile compounds and moisture due to high levels of relative humidity (RH) and gas pollutants. The internal heating mechanism of the TEOM may cause losses in mass through volatilization. To investigate the effects of TEOM settings on concentration measurements, the heaters of two identical TEOMs were set at 50 degrees C, 30 degrees C, or no heating at all. They were collocated and tested for total suspended particle (TSP), PM10, and PM25 measurements in layer house for 6 weeks. For all TSR PM10, and PM2.5 measurements, the internal TEOM temperature setting had a significant effect (P < 0.05). Significantly higher PM mass concentrations were measured at lower temperature settings. The effects of environmental (i.e., temperature, RH, NH3 and CO2 concentrations) and instrumental (i.e., filter loading and noise) parameters on PM measurements were also assessed using regression analysis.
锥形元件振荡微天平（TEOM）是一种连续环境颗粒物（PM）监测仪。水分和半挥发性物质的吸附和解吸可能会导致 TEOM PM 质量测量出现正或负的人为偏差。本现场研究的目的是调查与家禽作业环境中 TEOM 测量相关的可能存在的不确定性。为了将 TEOM 与基于过滤器的重量法进行比较，将四台仪器（TEOM-PM10、低容量 PM10 采样器 TEOM-PM2.5 和 PM2.5 分级采样器）放置在禽舍内进行 PM2.5 和 PM10（分别表示空气动力学等效直径<或=2.5 和<或=10 微米的颗粒物）测量。共获得了 15 组 24 小时 PM10 浓度和 13 组 24 小时 PM2.5 测量值。结果表明，与基于过滤器的重量法相比，TEOM 对 PM10 和 PM2.5 质量浓度的测量值均显著较低。对于 PM10，TEOM 与重量法的平均比值为 0.936。对于 PM2.5，TEOM 与重量法的平均比值为 0.738。由于相对湿度（RH）和气体污染物水平较高，禽舍中的颗粒物可能含有半挥发性化合物和水分。TEOM 的内部加热机制可能会导致通过蒸发而造成质量损失。为了研究 TEOM 设置对浓度测量的影响，将两台相同的 TEOM 的加热器设置为 50°C、30°C 或完全不加热。它们被放置在一起并在鸡舍中进行总悬浮颗粒物（TSP）、PM10 和 PM2.5 测量，持续了 6 周。对于所有 TSP、PM10 和 PM2.5 测量，TEOM 内部温度设置具有显著影响（P<0.05）。在较低的温度设置下，测量到的 PM 质量浓度明显更高。还使用回归分析评估了环境（即温度、RH、NH3 和 CO2 浓度）和仪器（即过滤器负载和噪声）参数对 PM 测量的影响。
