Practical Field Calibration of Portable Monitors for Mobile Measurements of Multiple Air Pollutants
Practical Field Calibration of Portable Monitors for Mobile Measurements of Multiple Air Pollutants
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DOI：
10.3390/atmos8120231
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发表时间：
2017-12-01
期刊：
影响因子：
2.9
通讯作者：
Heal, Mathew R.
中科院分区：
文献类型：
--
作者：
Lin, Chun;Masey, Nicola;Heal, Mathew R.
为了减少便携式监测器测量空气污染物的不准确性，有必要建立与各自参考分析仪的定量校准关系。这通常是在受控的实验室条件下进行的，或在现场与参考分析仪一起进行一次性静态共置，这两种方法都不能充分代表便携式监测器在暴露评估研究中的广泛使用。为了解决这个问题，我们研究了如何建立和评估便携式显示器校准关系，从重复的间歇性部署周期在一个较长的时间内，涉及固定部署在一个参考网站，移动的监测，并完全关闭。我们评估了四种类型的便携式监护仪：Aeroqual Ltd.（奥克兰，新西兰）S500 O-3金属氧化物和S500 NO2电化学; RTI（Berkeley，CA，USA）MicroPEM PM2.5;和AethLabs（San弗朗西斯科，CA，USA）AE 51炭黑（BC）。我们研究中的创新包括：（i）将便携式监视器与其参考分析仪的单独共定位或所有共定位周期组合成单个数据集的校准进行比较;以及（ii）在瞬态测量期间，便携式监视器在固定共定位校准周期的不同时间靠近其参考分析仪，对校准的监视器估计值进行评估。在7个月的研究期间，O-3、PM2.5和BC监测器的组合校准关系平均与参考测量值的一致性高于时间上最接近瞬时部署期的共址部署的单独校准关系。个别的校准关系有时基本上不能代表组合的关系。PM2.5监测仪现场校准关系的定量一致性降低可能是由于本研究中遇到的PM2.5浓度普遍较低。Aeroqual NO2监测仪对NO2和O-3以及未解决的偏差都很敏感。然而，总的来说，我们观察到，使用组合的“方法”，指示性的测量精度（O-3 +/- 30%，BC和PM2.5 +/- 50%），1小时的时间平均值可以保持在7个月的时间内，这里评估的监测器。
To reduce inaccuracies in the measurement of air pollutants by portable monitors it is necessary to establish quantitative calibration relationships against their respective reference analyser. This is usually done under controlled laboratory conditions or one-off static co-location alongside a reference analyser in the field, neither of which may adequately represent the extended use of portable monitors in exposure assessment research. To address this, we investigated ways of establishing and evaluating portable monitor calibration relationships from repeated intermittent deployment cycles over an extended period involving stationary deployment at a reference site, mobile monitoring, and completely switched off. We evaluated four types of portable monitors: Aeroqual Ltd. (Auckland, New Zealand) S500 O-3 metal oxide and S500 NO2 electrochemical; RTI (Berkeley, CA, USA) MicroPEM PM2.5; and, AethLabs (San Francisco, CA, USA) AE51 black carbon (BC). Innovations in our study included: (i) comparison of calibrations derived from the individual co-locations of a portable monitor against its reference analyser or from all the co-location periods combined into a single dataset; and, (ii) evaluation of calibrated monitor estimates during transient measurements with the portable monitor close to its reference analyser at separate times from the stationary co-location calibration periods. Within the 7 month duration of the study, combined' calibration relationships for O-3, PM2.5, and BC monitors from all co-locations agreed more closely on average with reference measurements than individual' calibration relationships from co-location deployment nearest in time to transient deployment periods. Individual' calibrations relationships were sometimes substantially unrepresentative of the combined' relationships. Reduced quantitative consistency in field calibration relationships for the PM2.5 monitors may have resulted from generally low PM2.5 concentrations that were encountered in this study. Aeroqual NO2 monitors were sensitive to both NO2 and O-3 and unresolved biases. Overall, however, we observed that with the combined' approach, indicative' measurement accuracy (+/- 30% for O-3, and +/- 50% for BC and PM2.5) for 1 h time averaging could be maintained over the 7-month period for the monitors evaluated here.