First Measurements of Ambient PM2.5 in Kinshasa, Democratic Republic of Congo and Brazzaville, Republic of Congo Using Field-calibrated Low-cost Sensors
First Measurements of Ambient PM2.5 in Kinshasa, Democratic Republic of Congo and Brazzaville, Republic of Congo Using Field-calibrated Low-cost Sensors
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DOI：
10.4209/aaqr.200619
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发表时间：
2021-07-01
影响因子：
4
通讯作者：
Westervelt, Daniel M.
中科院分区：
文献类型：
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作者：
McFarlane, Celeste;Isevulambire, Paulson Kasereka;Westervelt, Daniel M.
由于缺乏对细颗粒物（PM2.5）的地面观测，对撒哈拉以南非洲地区空气污染死亡率的估计受到限制。刚果民主共和国（DRC）的金沙萨（Kinshasa）和刚果共和国（ROC）的布拉柴维尔（Brazzaville）分别拥有1430万和240万人口，尽管这两个城市都是大都市，但在撰写本文时，它们没有使用参考空气污染监测仪。然而，最近在撒哈拉以南非洲的其他地区部署了一些参考监测仪，包括美国驻乌干达坎帕拉大使馆的Met One Beta衰减监测仪（bam1020），以及2019年8月在其旁边安装的低成本PM2.5监测仪PurpleAir。PurpleAir从2019年9月到2020年2月的原始数据与bam1020的测量结果密切相关（R-2 = 0.88），但平均绝对误差（MAE）约为14 μ μ m（-3）。采用多元线性回归和随机森林两种校正模型，将MAE降低至3.4 μ g m(-3)，将R-2提高至0.96。考虑到气候和排放的相似性，我们将坎帕拉的现场校正因子应用于2018年4月部署在金沙萨和邻近的布拉柴维尔的四个PurpleAir机组。我们估计，2019年金沙萨的年均PM2.5浓度为43.5 μ g(-3)，比世界卫生组织（WHO）的中期目标1 （10 μ g(-3)）高出4倍。最后，2020年新冠肺炎封城期间，地表PM2.5水平和气溶胶光学深度比2019年同期下降了约40%，这不能仅仅归因于气象或野火排放的变化。因此，我们的研究结果强调了在刚果实施清洁空气解决方案的必要性。
Estimates of air pollution mortality in sub-Saharan Africa are limited by a lack of surface observations of fine particulate matter (PM2.5). Despite being large metropolises, Kinshasa, Democratic Republic of the Congo (DRC), and Brazzaville, Republic of the Congo (ROC), which possess populations of 14.3 million and 2.4 million, respectively, use no reference air pollution monitors at the time of writing. However, a few reference monitors have recently been deployed in other parts of sub-Saharan Africa, including a Met One Beta Attenuation Monitor (BAM-1020) at the U.S. Embassy in Kampala, Uganda, next to which a low-cost PM2.5 monitor, the PurpleAir, was collocated in August 2019. The raw PurpleAir data from September 2019 through February 2020 strongly correlated with the BAM-1020 measurements (R-2 = 0.88) but also exhibited a mean absolute error (MAE) of approximately 14 mu g m(-3). Employing two calibration models, namely, multiple linear regression and random forests, decreased the MAE to 3.4 mu g m(-3) and increased R-2 to 0.96. Given the similarity in climate and emissions, we applied the collocated field correction factors for Kampala to four PurpleAir units in Kinshasa and one in neighboring Brazzaville, which were deployed in April 2018. We estimated an average annual PM2.5 concentration of 43.5 mu g m(-3) in Kinshasa for 2019, which exceeds the World Health Organization (WHO)'s Interim Target 1 (10 mu g m(-3)) by 4 times. Finally, the surface PM2.5 level and the aerosol optical depth were about 40% lower during the COVID-19 lockdown in 2020 than the corresponding period in 2019, which cannot be attributed solely to changes in meteorology or wildfire emission. Hence, our results highlight the need to implement clean air solutions in the Congo.