Mineral dust

Estimates of emissions of mineral dust into the atmosphere presently lie around 1,500-2,000 Tg per annum [145] making mineral dust an important component of the coarse fraction of atmospheric aerosol and explaining its significant impact on 

The photolysis of nitrate on surfaces is especially important as it could lead to the renoxification of the atmosphere, whereby nitrate (or nitric acid) becomes a source of NO c and thus mineral dust would not be a permanent sink for gaseous nitrogen oxides, uptake of several gases, i.e., NO2 [ 126,172,173], O3 [174], and HCHO [175], while [176] presented similar conclusion for the surface photooxidation of SO2. 

The striking features in all cases are that under illuminatimi (1) the uptake of these gases is enhanced by more than one order of magnitude as compared to data obtained in the dark and (2) the reaction is sustained as long as light is available (while in the dark most surfaces are passivated in short time scales). 

The photocatalytic action of Ti02 (and other semicOTiductors) is initiated by the photo-production of excess electrons in the conducticni band (e cb) and holes in the valence band (h%b). The electron reduces the oxygen or the nitrogen dioxide while the hole oxidizes water vapor. The associated reactions mechanism could be [5] 

It is well known that nitrate anions are formed as a consequence of the photocatalytic oxidation of NO2 on UV-illuminated Ti02 surfaces [181-186]. 

TABLE 2.20 Global Emission Estimates for Major Aerosol Classes 

Organic aerosol from biogenic VOC 11.2 Chung and Seinfeld (2002) 

Industrial dust (except black carbon) 100 Kiehl and Rodhe (1995) 

Mineral dust is emitted from both natural and anthropogenic activities. Natural emissions arise by wind acting on undisturbed source regions. Anthropogenic emissions result from human activity, including (1) land-use changes that modify soil surface conditions and (2) climate modifications that, in turn, alter dust emissions. Such modifications include changes in windspeeds, clouds and precipitation, and the amounts of airborne soluble material, such as sulfate, that may become attached to mineral dust particles and render them more susceptible to wet removal. 

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Minelbite Mineral dusts Mineral feed Mineral fibers Mineral fillers Mineralization Mineralizers... 

Coal-Mine Dusting. A steady market for pulverized limestone is ia dusting coal mines with a noncombustible mineral dust as a federally mandated mine safety requirement. Of aU mineral dusts, limestone is by far the most commonly used (60—75% 0.074 mm (200 mesh)). Consumption ia 1991 was... 

Recommended Health-Tased Eimits in Occupational Exposure to Selected Mineral Dusts Silica, Coal), Wodd Health Organization Technical Report Series 734, Geneva, Switzedand, 1986. 

The industries which produce and handle various stone products emit considerable amounts of particulate matter at every stage of the operation. These particulates may include fine mineral dusts of a size to cause damage to the lungs. The threshold values for such dusts have been set quite low to prevent disabling diseases for the worker. 

Dry aerosols, or particulate matter, differ so much from the carrying gas stream that their removal should present no major difficulties. The aerosol is different physically, chemically, and electrically. It has vastly different inertial properties than the carrying gas stream and can be subjected to an electric charge. It may be soluble in a specific liquid. With such a variety of removal mechanisms that can be applied, it is not surprising that particulate matter, such as mineral dust, can be removed by a filter, wet scrubber, or electrostatic precipitator with equally satisfactory results. 

Outdoor inhalation exposure is mainly due to traffic, energy production, heating, and natural factors such as pollen and mineral dusts. These outdoor sources of pollution also affect indoor air quality. The indoor concentration is typically 20-70% of the corresponding outdoor concentration. Occasionally the indoor concentrations of an external pollutant (especially radon) may even exceed the concentrations outdoors. ... 

Autoimmune nephrotic syndromes Bronchopulmonary dysplasia Mineral dust pneumoconiosis... 

While by common perception, mineral dusts may appear as particularly inert materials, inorganic particles can participate in a variety of chemical and cellular reactions, some of which are mediated by free radicals. 

As a consequence of the inhalation of mineral dusts, infiltration into the lung of inflammatory phagocytic cells, namely PMN and macrophages, occurs (Rola-Pleszczynski et al., 1984). Analysis of the cell populations of the rat pleural cavities after injection with asbestos and silica dust also showed both degranulation and reduction of the mast cell population (Edwards etal., 1984), and it is of interest to note that histamine augments the particle-stimulated generation of macrophage superoxide production (Diaz et al., 1979). 

Mineral dust-induced ROMs contributes to pulmonary fibrosis, malignancy, hypersensitivity and emphysema (Doelman etctl., 1990 Kamp etui., 1992). The involvement of ROMs in pulmonary fibrotic reactions is indicated by the participation of PMN oxidants in the autoactivation of latent coUagenase (Weiss et al., 1985). Prolyl hydroxylase, a key enzyme in collagen fibril formation, has been shown to be dependent on the reaction of superoxide with prolyl residues (Myllyla et al., 1979). 

Doelman, C.J.A., Leurs, R., Ooestrom, W.C. and Bast, A. (1990). Mineral dust exposure and free radical-mediated lung damage. Exp. Lung Res. 16, 41-55. 

Mossman, B.T. and Marsh, J.P. (1985). Mechanisms of cell toxic injury by asbestos fibres role of oxygen free radicals. In In vitro Effects of Mineral Dusts (eds. E.G. Beck and J. Bignon) pp. 66-81. Springer Verlag, Berlin. 

Nadeau, D., Lane, D.A., Paradis, D. and Fouquette, L. (1989). Effects of nicotinamide on the cytotoxicity of mineral dusts towards pulmonary alveolar macrophages. In Effects of Mineral Dusts on Cells (eds. B.T. Mossman and R.O. Begin) pp. 115-122. Springert Verlag, Berlin. 

Figure 3.13. Examples of the positive ion and negative ion spectrum acquired from a single mineral dust particle (of aerodynamic particle diameter 1 pm). (Trimborn et al. 2000.)...

Case-control M (176, 630) Mineral dust —job/exposure history OR 1.9 (0.8, 2.5) p < 0.05 for trend with duration no association seen in females (339 cases, 627 controls) Olsson38... 

The aerial parts of grasses in Savanna ecosystems exhibit a high ash content from 6 to 10%. This is partly due to the presence of minute particles of mineral dust, which are discernible under a microscope or, occasionally, even with the naked eye. The exposure to mineral dust accounts for 2-3% of the weight of dry mass of grass aerial parts. We can consider that this dust is responsible for the elevated concentrations of some minerals, like Ga, which has a low Cb value. This element contains in windblown finely dispersed clay particles. Nevertheless, even with allowance made for the silicate dust content, the total sum of ash elements in grasses of savanna ecosystems is twice as much as that of the grasses from Alpine Meadow ecosystems. 

Hazardous substances include not oidy synthetic chemicals, but also some natural materials such as mineral (dust or fibres) and a range of metals. It is very difficult to estimate the production volume and distribution of these materials. 

Chamberlain, M., and R. C. Brown (1978). The cytotoxic effects of asbestos and other mineral dust in tissue culture cell lines. Br. J. Exper. Pathol. 59 183— 188. 

Davis, J. M. G. (1972). Pathological effects of mineral dusts injected into the pleural cavity of mice. Br. J. Exper. Pathol. 53 190-201. 

McNab, G., and J. S. Harrington (1967). Haemolytic activity of asbestos and other mineral dusts. Nature 214 522—523. 

These results have suggested that mineral dusts that are inert in a particulate form may have biological activity when they occur in a fibrous form. Factors affecting fiber toxicity include length, diameter, respirability resistance to chemical dissolution in biological fluids, and durability. "... 

Inhalation of silica dusts or sdicate mineral dusts can cause silicosis and other lung diseases. 

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