Abstract
Background: Information regarding the exposure characteristics of ultrafine particles generated by working activities in the steelmaking industry is very limited. This study aimed to investigate the exposure characteristics of ultrafine particles from the blast furnace process in a steelmaking industry. Methods: The morphology of particles, their elemental compositions, temporal variations in particle concentrations (e.g., total number concentration (NC), total respirable mass concentration (MC), surface area concentration (SAC)), personal exposure level, and the size distributions by number were measured. The relationships among total NC, total respirable MC, and SAC were determined by analyzing the concentration ratios (CR), correlation coefficients (CC), and the consistency of temporal variations in particle concentrations. Results: The particles collected from the blast furnace process presented as irregular agglomerates, and the predominant elements were O, Al, and Si. The total NC, total respirable MC, and SAC increased after working activity started and decreased gradually to background levels after the operation stopped. The median, mean, geometric mean, and modal sizes of particles remained relatively stable during working activities, ranging from 20 to 50 nm. Size distribution by number showed that the sizes of particles released from the slag releasing location were mainly gathered at 10.4 and 40 nm. The highest numbers appeared at 10.4 nm and 40 nm, which reached 3 × 106 pt/cm3. Particles ranging 100–469 nm were less than 8 × 105 pt/cm3, while particles with sizes larger than 374 nm were less than 2 × 104 pt/cm3. There was a good correlation between the total NC, SAC, and respirable MC. The order of CC for these three parameters was R total NC and SAC (r = 0.681) > R SAC and respirable MC (0.456) > R total NC and respirable MC (0.424).Conclusions: These findings indicate that working activities generated high levels of ultrafine particles. The ultrafine particle concentrations exhibited activity-related and periodic variations. The total NC and SAC were more appropriate metrics for characterizing ultrafine particles at the slag releasing location than total respirable MC. This study provides baseline data on the exposure characteristics of ultrafine particles during the blast furnace process.
Exposure characterization and risk assessment of ultrafine particles from the blast furnace process in a steelmaking plant
