The availability of low-cost monitors marketed for use in homes has increased rapidly over the past few years due to the advancement of sensing technologies, increased awareness of urban pollution, and the rise of citizen science. The user-friendly packages can make them appealing for use in research grade indoor exposure assessments, but a rigorous scientific evaluation has not been conducted for many monitors on the open market, which leads to uncertainty about the validity of the data. Furthermore, many previous sensor studies were conducted for a relatively short period of time, which may not capture the changes this type of instrument may exhibit over time (known as sensor aging). We evaluated three monitors (AirVisual Pro, Speck, and AirThinx) in an occupied, non-smoking residence over a 12-month period in order to assess the sensors, the built-in calibrations, and the need for additional data to achieve high accuracy for long deployments. Two units of each type of monitor were evaluated in order to assess the precision between units, and a personal DataRAM (pDR-1200) with a filter was placed in the home for about 20% of the sampling period (e.g., about a week each month) to evaluate the accuracy over time. The average PM2.5 mass concentration from the periods of colocation with the pDR were 5.31 μg/m3 for the gravimetric-corrected pDR (hereafter pDR-corrected), 5.11 and 5.03 μg/m3 for the AirVisual Pro units, 13.58 and 22.68 μg/m3 for the Speck units, and 7.56 and 7.57 μg/m3 for the AirThinx units. The AirVisual Pros exhibited the best accuracy compared to the filter at about 86%, which was slightly better than the nephelometric component of the pDR compared to the filter weight (84%). The accuracies of the Speck (-174 and -405%) and AirThinx (42 and 40%) monitors were much lower. When the 1-minute averaged PM2.5 mass concentrations were categorized by air quality index (AQI), the pDR-corrected matched the AirVisual Pro, Speck, and AirThinx bins about 97, 40, and 87% of the time, respectively. The Pearson correlation coefficients (R2) between the unit pairs and the pDR were 0.90/0.90, 0.50/0.27, and 0.92/0.93 for the AirVisual Pro, Speck, and AirThinx units, respectively. The R2 between units of the same type were 0.99, 0.17, and 1.00 for the AirVisual Pro, Speck, and AirThinx, respectively. All of the monitors could achieve better accuracy by adding filter corrections and post-processing to correct for known biases in addition to the manufacturer's correction routine. Monthly calibrations yielded the highest accuracies, but nearly as high of accuracies could be achieved with only one or two calibrations for the Air Visual Pro and the AirThinx for many applications. In general, this type of new low-cost monitor shows exciting potential for use in scientific research. However, only one of the three monitors exhibited high accuracy (within 20% of the true mass concentration) without any post processing or additional measurements, so an evaluation of each monitor is essential before the data can be used to confidently evaluate residential exposures.

中文翻译：

---

三款低成本 PM2.5 监测器的一年评估

由于传感技术的进步、对城市污染意识的提高以及公民科学的兴起，在过去几年中销售用于家庭的低成本监视器的可用性迅速增加。用户友好的软件包可以使它们在研究级室内暴露评估中具有吸引力，但公开市场上的许多监测器尚未进行严格的科学评估，这导致数据有效性的不确定性。此外，之前的许多传感器研究都是在相对较短的时间内进行的，可能无法捕捉到此类仪器随时间可能出现的变化（称为传感器老化）。我们在 12 个月内在一个有人居住的非吸烟住宅中评估了三台显示器（AirVisual Pro、Speck 和 AirThinx），以评估传感器，内置校准，以及需要额外数据才能实现长期部署的高精度。为了评估单元之间的精确度，对每种类型的监视器的两个单元进行了评估，并在大约 20% 的采样周期（例如，每个周期约一周）内将带有过滤器的个人 DataRAM (pDR-1200) 放置在家里月）来评估随着时间的推移的准确性。与 pDR 并置期间的平均 PM2.5 质量浓度对于重量校正的 pDR（以下简称 pDR 校正）为 5.31 μg/m3，对于 AirVisual Pro 装置为 5.11 和 5.03 μg/m3，13.58 和 22.68 μg/m3 Speck 装置为 m3，AirThinx 装置为 7.56 和 7.57 μg/m3。与过滤器相比，AirVisual Pros 的准确度最高，约为 86%，与过滤器重量 (84%) 相比，这略好于 pDR 的浊度测量组件。Speck（-174% 和 -405%）和 AirThinx（42% 和 40%）显示器的准确度要低得多。当按空气质量指数 (AQI) 对 1 分钟平均 PM2.5 质量浓度进行分类时，pDR 校正后与 AirVisual Pro、Speck 和 AirThinx 分档的匹配率分别约为 97%、40% 和 87%。AirVisual Pro、Speck 和 AirThinx 装置的单位对和 pDR 之间的 Pearson 相关系数 (R2) 分别为 0.90/0.90、0.50/0.27 和 0.92/0.93。AirVisual Pro、Speck 和 AirThinx 的相同类型单元之间的 R2 分别为 0.99、0.17 和 1.00。除了制造商的校正程序外，所有监视器都可以通过添加过滤器校正和后处理来校正已知偏差，从而获得更高的准确度。每月校准产生了最高的准确度，但对于许多应用程序，Air Visual Pro 和 AirThinx 只需一两次校准就可以获得几乎同样高的准确度。总的来说，这种新型低成本监测器在科学研究中显示出令人兴奋的潜力。然而，三个监测器中只有一个表现出高精度（真实质量浓度的 20% 以内），无需任何后处理或额外测量，因此在数据可用于自信地评估住宅暴露之前，必须对每个监测器进行评估。每月校准产生了最高的准确度，但对于许多应用程序，Air Visual Pro 和 AirThinx 只需一两次校准就可以获得几乎同样高的准确度。总的来说，这种新型低成本监测器在科学研究中显示出令人兴奋的潜力。然而，三个监测器中只有一个表现出高精度（真实质量浓度的 20% 以内），无需任何后处理或额外测量，因此在数据可用于自信地评估住宅暴露之前，必须对每个监测器进行评估。每月校准产生了最高的准确度，但对于许多应用程序，Air Visual Pro 和 AirThinx 只需一两次校准就可以获得几乎同样高的准确度。总的来说，这种新型低成本监测器在科学研究中显示出令人兴奋的潜力。然而，三个监测器中只有一个表现出高精度（真实质量浓度的 20% 以内），无需任何后处理或额外测量，因此在数据可用于自信地评估住宅暴露之前，必须对每个监测器进行评估。