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Air samples were collected by personal sampling with five stage Sioutas cascade impactors and respirable cyclones in parallel among tappers and crane operators in two manganese (Mn) alloy smelters in Norway to investigate PM fractions. The mass concentrations of PM collected by using the impactors and the respirable cyclones were critically evaluated by comparing the results of the parallel measurements. The geometric mean (GM) mass concentrations of the respirable fraction and the ＜10 μm PM fraction were 0.18 and 0.39 mg m−3, respectively. Particle size distributions were determined using the impactor data in the range from 0 to 10 μm and by stationary measurements by using a scanning mobility particle sizer in the range from 10 to 487 nm. On average 50% of the particulate mass in the Mn alloy smelters was in the range from 2.5 to 10 μm, while the rest was distributed between the lower stages of the impactors. On average 15% of the particulate mass was found in the ＜0.25 μm PM fraction. The comparisons of the different PM fraction mass concentrations related to different work tasks or different workplaces, showed in many cases statistically significant differences, however, the particle size distribution of PM in the fraction ＜10 μm dae was independent of the plant, furnace or work task. [ABSTRACT FROM AUTHOR]

The hygroscopic behaviour of individual aerosol particles from workplaces in a primary aluminium smelter was investigated by environmental scanning electron microscopy. At a high relative humidity, comparable with the human respiratory tract, most particles encountered in the Søderberg and Prebake potrooms either undergo partial deliquescence (leading to a water droplet with an insoluble core) or form thin water films at the surface. As gaseous HF and SO(2) are highly soluble in water, the aerosol particles may act as carrier for these two gases into the alveolar region of the lower respiratory tract. Based on a one-dimensional mass balance model, it is estimated that under peak exposure conditions (particle surface area concentration of 10(-4) cm(2) cm(-3)) approximately 10% of the initial gaseous HF may be transferred to the particle phase. For SO(2), this fraction is much lower (approximately 1%). These results indicate that at least HF may penetrate deeper into the lung in the presence of soluble particles or particles that form surface water films compared to HF alone.

Workers in the Mn alloy producing industry are exposed to aerosols containing a variety of Mn compounds (MnO, MnO,, Mn2O3, Mn3O4, FeMn and SiMn). This paper reports a novel four-step chemical speciation/ fractionation procedure developed for characterisation of workroom aerosols collected in Mn alloy producing plants. The following components of the aerosol have been quantified: "water soluble" Mn dissolved in 0.01 M ammonium acetate: Mn0 and Mn2+ dissolved in 25% acetic acid; Mn3+ and Mn4+ dissolved in 0.5%) hydroxylamine hydrochloride in 25%) acetic acid; and "insoluble" Mn digested in aqua regia and hydrofluoric acid. Dissolution of pure Mn compounds with well-defined stoichiometries were essentially complete in the respective leaching steps with detectable amounts of < 1% in others. Recoveries of a mixed quality control sample were also acceptable in the range 92-97% for the different oxidation states. The levels measured in the inhalable and respirable fractions in three Mn alloy producing plants were approximately 300 and 35 microg m(-3) of total Mn, respectively. The most obvious feature of the speciation results is that none of the work areas is characterised by a single Mn contaminant. The predominant oxidation states in the inhalable aerosol fraction are Mn0 and Mn2+ independent of job functions/departments. The occurrence of insoluble Mn compounds in both the inhalable and respirable aerosol fractions is significantly higher during production of SiMn.