Models are increasingly used to estimate and pre-emptively calculate the occupational exposure of airborne released particulate matter. Typical two-box models assume instant and fully mixed air volumes, which can potentially cause issues in cases with fast processes, slow air mixing, and/or large volumes. In this study, we present an aerosol dispersion model and validate it by comparing the modelled concentrations with concentrations measured during chamber experiments. We investigated whether a better estimation of concentrations was possible by using different geometrical layouts rather than a typical two-box layout. A one-box, two-box, and two three-box layouts were used. The one box model was found to underestimate the concentrations close to the source, while overestimating the concentrations in the far field. The two-box model layout performed well based on comparisons from the chamber study in systems with a steady source concentration for both slow and fast mixing. The three-box layout was found to better estimate the concentrations and the timing of the peaks for fluctuating concentrations than the one-box or two-box layouts under relatively slow mixing conditions. This finding suggests that industry-relevant scaled volumes should be tested in practice to gain more knowledge about when to use the two-box or the three-box layout schemes for multi-box models.

Data on the potential impact on human health of engineered nanomaterials are still scarce, with an evident lack of knowledge on the exposure levels at all stages of the life cycle. By prioritizing the responsible handling of engineered nanomaterials (ENMs), companies can promote sustainability by minimizing the risks of occupational exposure, protecting employee well-being, reducing liability, and avoiding costly environmental remediation efforts. This research aims to evaluate the risk in real scenarios involving the use of carbon-based nanomaterials in research laboratories, pilot-scale facilities, and industrial settings. Several online and offline instruments have been employed to characterize the particulate matter present in these environments, including particles in the nanometer range and relevant fractions for risk assessment purposes. Samples collected on polycarbonate filters were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Exposure estimation has been performed by applying a decision based on tier 2 from the nanoGEM methodology, with the weighing and transferring of reduced graphene oxide (RGO) in a pilot plant being the most liberating processes, which are the activities with the highest risk of exposure. In addition, high levels of particle concentration, with peaks up to 1.7 × 10⁵ and 4.7 × 10⁵ part/cm³, have been found for the dispersion of carbon nanotubes (CNTs) and incorporation of carbonaceous nanoparticles into resins, respectively.

The air quality in a hospital’s underground car park is a concern because diesel fumes from cars impact upon vulnerable people attending medical consultations. This research aims to quantify the potential health risk associated with a particular hospital car park. Particulate matter was evaluated in the area with direct reading devices for particle numbers and mass concentrations (CPC 3007, EEPS 3090, Trolex Air XD, Nanozen, and Grimm 1109). Elemental and total carbon concentrations were measured following the NIOSH 5040 method, while volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs) were measured through laboratory analysis and Scanning Electron Microscopy and Energy Dispersive using X-Ray Analysis SEM-EDX microscopy. The nanoparticle levels reached over 80,000 nanoparticles/cm³ (double the German Institut für Arbeitsschutz (IFA) benchmark levels). Diesel particulate matter levels measured as elemental carbon were around 35% of the occupational limit, and from the 49 VOCs analyzed only 13 were detected in quantities below the 0.1% of the occupational limit, while levels of the 13 PAHs analyzed, were below the laboratory limit of quantification. The study concludes that particulate matter in the underground car park can easily exceed nanoparticles benchmark levels and could be harmful, mainly to vulnerable people. It is therefore recommended that they use the outdoor car park or minimize their time in the underground one.