Determination of airborne metal-containing nanoparticles in a historic mining area using single particle ICP-MS

Given limited information on airborne metal-containing NPs-a highly bioaccessible fraction of metals relevant to human exposure-in the upper Meža Valley, a historic mining area in Slovenia, this study aimed to assess their presence in PM₁₀ air filters from the region using the spICP-MS method. The extraction procedure, refined using a certified reference material of PM₁₀-like fine dust deposited on filters, achieved an extraction efficiency of 9.1% for Zn- and 14.0% for Pb-containing NPs after two hours of ultrasonication in 10 mM sodium pyrophosphate. The method proved effective for detecting metal-containing NPs in PM₁₀ from mining and smelting areas, as demonstrated by a case study from the upper Meža Valley. SpICP-MS analyses identified both Zn- and Pb-containing NPs in PM₁₀ samples, with 0.6-3.8% of Zn and 0.3-1.7% of Pb extracted as NPs. Additionally, SEM-EDS analysis confirmed the presence of Zn- and Pb-containing (nano)particles of different chemical compositions. This study is the first to report the occurrence of metal-containing NPs in PM₁₀ from this region. Although they represent only a small fraction of total Zn and Pb in the samples, NPs are more bioaccessible and thus more relevant for assessing local population's exposure to these particles.