Exposure characteristics of ferric oxide nanoparticles released during activities for manufacturing ferric oxide nanomaterials.

The exposure characteristics of Fe2O3 nanoparticles (NPs) released in a factory were investigated, as exposure data on this type of NP is absent. The nature of the particles was identified in terms of their concentrations [i.e. number concentration (NC(20-1000 nm)), mass concentration (MC(100-1000 nm)), surface area concentration (SAC(10-1000 nm))], size distribution, morphology and elemental composition. The relationships between different exposure metrics were determined through analyses of exposure ranking (ER), concentration ratios (CR), correlation coefficients and shapes of the particle concentration curves. Work activities such as powder screening, material feeding and packaging generated higher levels of NPs as compared to those of background particles (p < 0.01). The airborne Fe2O3 NPs exhibited a unimodal size distribution and a spindle-like morphology and consisted predominantly of the elements O and Fe. Periodic and activity-related characteristics were noticed in the temporal variations in NC(20-1000 nm) and SAC(10-1000 nm). The modal size of the Fe2O3 NPs remained relatively constant (ranging from 10 to 15 nm) during the working periods. The ER, CR values and the shapes of NC(20-1000 nm) and SAC(10-1000 nm) curves were similar; however, these were significantly different from those for MC(100-1000 nm). There was a high correlation between NC(20-1000 nm) and SAC(10-1000 nm), and relatively lower correlations between the two and MC(100-1000 nm). These findings suggest that the work activities during the manufacturing processes generated high levels of primary Fe2O3 NPs. The particle concentrations exhibited periodicity and were activity dependent. The number and SACs were found to be much more relevant metrics for characterizing NPs than was the mass concentration.

Characteristics and risk assessment of occupational exposure to ultrafine particles generated from cooking in the Chinese restaurant.

Ultrafine particles have been increasingly linked to adverse health effects in restaurant workers. This study aimed to clarify the exposure characteristics and risks of ultrafine particles during the cooking process, and to provide a reasonable standard for protecting the workers in the Chinese restaurant. The temporal variations in particle concentrations (number concentration (NC), mass concentration (MC), surface area concentration (SAC), and personal NC), and size distributions by number were measured by real-time system. The hazard, exposure, and risk levels of ultrafine particles were analyzed using the control banding tools. The NC, MC, and SAC increased during the cooking period and decreased gradually to background levels post-operation. The concentration ratios of MC, total NC, SAC, and personal NC ranged from 3.82 to 9.35. The ultrafine particles were mainly gathered at 10.4 and 100 nm during cooking. The exposure, hazard and risk levels of the ultrafine particles were high. These findings indicated that the workers during cooking were at high risk due to exposure to high levels of ultrafine particles associated with working activity and with a bimodal size distribution. The existing control strategies, including engineering control, management control, and personal protection equipment need to be improved to reduce the risk.

Exposure characterization and risk assessment of ultrafine particles from the blast furnace process in a steelmaking plant.

OBJECTIVES: This study aimed to clarify the exposure characteristics and risks of ultrafine particles from the blast furnace process and to provide a reasonable control strategy for protecting the health of workers. METHODS: The blast furnace location of a steelmaking plant was selected as a typical investigation site. A membrane-based sampling system was used to collect ultrafine particles to analyze their morphology and elemental compositions. A real-time system was used to monitor the total number concentration (NC), total respirable mass concentration (MC), surface area concentration (SAC), and size distribution by number. The risk level of ultrafine particles was analyzed using the Stoffenmanager-Nano model. RESULTS: The total NC, total MC, and SAC increased significantly relative to background concentrations after slag releasing started and decreased gradually after the activity stopped. The three highest total concentrations during slag releasing were 3-10 times higher than those of the background or non-activity period. The ultrafine particles were mainly gathered at 10.4 or 40 nm, and presented as lump-like agglomerates. The metal elements (Al and Pt) in the ultrafine particles originated from slag and iron ore. The risk level of the ultrafine particles was high, indicating the existing control measures were insufficient. CONCLUSIONS: The blast furnace workers are at high risk due to exposure to high levels of ultrafine particles associated with working activity and with a bimodal size distribution. The existing control strategies, including engineering control, management control, and personal protection equipment need to be improved.

Qualitative and quantitative differences between common control banding tools for nanomaterials in workplaces.

A number of control banding (CB) tools have been developed specifically for managing the risk of exposure to engineered nanomaterials. However, data on the methodological differences between common CB tools for nanomaterials in workplaces are rare. A comparative study with different CB tools, such as Nanosafer, Stoffenmanager-Nano, Nanotool, Precautionary Matrix, ECguidance, IVAM Guidance, ISO, and ANSES, was performed to investigate their qualitative and quantitative differences in real exposure scenarios. These tools were developed for different purposes, with different application domains, methodological principles, and criteria. Multi-criteria analysis showed that there was a diverse distribution of these eight CB tools across different evaluation indicators. The total evaluation scores for Nanotool, Stoffenmanager-Nano, and Nanosafer were higher than the other tools. Quantitative comparisons demonstrated that ANSES, ECguidance, and IVAM Guidance tools were better in terms of information availability. Nanotool, Stoffenmanager-Nano, and ECguidance were better in terms of the sensitivity of outputs to changes in exposure parameters. The Nanotool, ANSES, and ECguidance tools were better in terms of accuracy of hazard outcomes evaluated with toxicological data. The Stoffenmanager-Nano, Nanotool, and Nanosafer tools' exposure scores for seven scenarios had a good correlation with measurement data. The Nanotool and Stoffenmanager-Nano tools had much higher comprehensive advantages based on quantitative and qualitative assessment. More comparative studies evaluating different tools are required, using more types of nanomaterials in real exposure scenarios.