Having a better understanding of air pollutants in railway systems is crucial to ensure a clean public transport. This study measured, for the first time in Brazil, nanoparticles (NPs) and black carbon (BC) on two ground-level platforms and inside trains of the Metropolitan Area of Porto Alegre (MAPA). An intense sampling campaign during thirteen consecutive months was carried out and the chemical composition of NPs was examined by advanced microscopy techniques. The results showed that highest concentrations of the pollutants occur in colder seasons and influenced by variables such as frequency of the trains and passenger densities. Also, internal and external sources of pollution at the stations were identified. The predominance of NPs enriched with metals that increase oxidative stress like Cd, Fe, Pb, Cr, Zn, Ni, V, Hg, Sn, and Ba both on the platforms and inside trains, including Fe-minerals as hematite and magnetite, represents a critical risk to the health of passengers and employees of the system. This interdisciplinary and multi-analytical study aims to provide an improved understanding of reported adverse health effects induced by railway system aerosols.

更好地了解铁路系统中的空气污染物对于确保清洁的公共交通至关重要。这项研究首次在巴西的阿雷格里港大都会区（MAPA）的两个地面平台和火车内部测量了纳米颗粒（NPs）和黑碳（BC）。在连续的13个月中进行了一次密集的采样活动，并通过先进的显微镜技术检查了NP的化学成分。结果表明，污染物的最高浓度出现在较冷的季节，并受火车频率和乘客密度等变量的影响。此外，还确定了车站的内部和外部污染源。富含NP的金属NP会增加氧化应激，例如Cd，Fe，Pb，Cr，Zn，Ni，V，Hg，Sn，平台和火车内部的Ba和Ba（包括铁矿物质，如赤铁矿和磁铁矿）均对系统的乘客和员工的健康构成重大威胁。这项跨学科，多分析的研究旨在更好地了解由铁路系统气溶胶引起的不良健康影响。