In this study, we examine the oxidative potential of airborne particulate matter (PM) in Beirut, Lebanon, as influenced by dust events originating in the Sahara and Arabian deserts. Segregated fine (< 2.5 μm) and coarse (2.5-10 μm) PM samples collected during dust events, as well as during non-dust periods, were analyzed for chemical composition, and the in vitro alveolar macrophage (AM) assay was utilized to determine the oxidative potential of both types of samples. We performed Spearman rank-order correlation analysis between individual chemical components and the oxidative potential of PM to examine the impact of the changes in PM chemical composition due to the occurrence of dust events on overall PM oxidative potential. Our findings revealed that the oxidative potential of Beirut's urban PM during non-dust periods was much higher than during dust episodes for fine PM. Our findings also indicated that tracers of tailpipe emissions (i.e., elemental (EC) and organic carbon (OC)), non-tailpipe emissions (i.e., heavy metals including Cu, Zn, As, Cd, and Pb), and secondary organic aerosols (SOA) (i.e., water-soluble organic carbon, WSOC) were significantly associated with the oxidative potential of PM during dust days and non-dust periods. However, the contribution of desert dust aerosols to Beirut's indigenous PM composition did not exacerbate its oxidative potential, as indicated by the negative correlations between the oxidative potential of PM and the concentrations of crustal elements that were enriched during the dust days. This suggests that aerosols generated during Saharan and Arabian dust events pose no additional health risk to the population due to PM-triggered reactive oxygen species formation. These results significantly contribute to our understanding of the effects of desert dust aerosols on the composition and oxidative potential of PM in several countries throughout the entire Middle East region that are impacted by dust events in the Sahara and Arabian deserts.

中文翻译：

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撒哈拉和阿拉伯沙尘事件期间贝鲁特环境颗粒物的氧化潜力

在这项研究中，我们研究了黎巴嫩贝鲁特空气中颗粒物 (PM) 的氧化潜力，因为它受到源自撒哈拉沙漠和阿拉伯沙漠的灰尘事件的影响。在粉尘事件期间以及非粉尘期间收集的分离的细 (< 2.5 μm) 和粗 (2.5-10 μm) PM 样品的化学成分被分析，并利用体外肺泡巨噬细胞 (AM) 测定确定两种类型样品的氧化电位。我们在单个化学成分与 PM 氧化电位之间进行了 Spearman 等级顺序相关分析，以检查由于粉尘事件的发生而导致 PM 化学成分变化对整体 PM 氧化电位的影响。我们的研究结果表明，贝鲁特的氧化潜力 s 非沙尘期的城市 PM 远高于沙尘期的细颗粒物。我们的研究结果还表明，尾气排放（即元素 (EC) 和有机碳 (OC)）、非尾气排放（即重金属，包括铜、锌、砷、镉和铅）和二次有机气溶胶的示踪剂(SOA)（即水溶性有机碳，WSOC）与粉尘日和非粉尘期 PM 的氧化潜力显着相关。然而，沙漠尘埃气溶胶对贝鲁特本土 PM 成分的贡献并没有加剧其氧化潜能，正如 PM 的氧化潜能与沙尘期间富集的地壳元素浓度之间的负相关性所表明的那样。这表明在撒哈拉和阿拉伯尘埃事件期间产生的气溶胶不会由于 PM 触发的活性氧物质的形成而对人群造成额外的健康风险。这些结果极大地有助于我们了解沙漠尘埃气溶胶对整个中东地区几个国家的 PM 组成和氧化潜力的影响，这些国家受撒哈拉沙漠和阿拉伯沙漠的尘埃事件影响。