Scanning electron micrographs demonstrate the presence of microcrystalline structures on the surface of coal-derived fly ash samples taken from electrostatic precipitator hoppers. Cenospheres (hollow spheres) were found to be packed with smaller cenospheres, which were also packed with spheres. Microspheres, apparently formed by uneven heating, are encapsulated in the parent sphere. Chemical analyses provide a basis for the postulation of a mechanism of formation for plerospheres (hollow spheres packed with spheres) and microcrystals.

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This review evaluates the available information on the effects of mainstream and environmental tobacco smoke on the immune system in animals and humans. The primary emphasis is on mainstream smoke since little information is available on the effects of environmental smoke. The effects of mainstream tobacco smoke on the immune system in humans and animals are similar. Animals exposed to mainstream tobacco smoke for periods of a few weeks generally exhibit a slight immunostimulation. However, subchronic and chronic exposure studies indicate that immunosuppressive changes develop. Lymphocyte proliferation in response to the mitogens PHA and LPS is decreased, suggesting compromise of cell function. Antibody production can be suppressed. Smoke-exposed animals that are challenged with metastasizing tumors or viruses have been shown to exhibit a higher incidence of tumorigenic and infectious diseases, respectively. Localized immunological changes in the lung can include reduction of bronchus-associated lymphoid tissue and immunoglobulin levels. Smoking-related changes in the peripheral immune system of humans have included elevated WBC counts, increased cytotoxic/suppressor and decreased inducer/helper T-cell numbers, slightly suppressed T-lymphocyte activity, significantly decreased natural killer cell activity, lowered circulating immunoglobin titers, except for IgE which is elevated, and increased susceptibility to infection. The effects of environmental tobacco smoke on the immune system, in contrast to mainstream tobacco smoke, have just begun to be investigated and information available in the literature, to date, is limited. Immunoreactive substances are known to be present in environmental tobacco smoke, but to date, environmental tobacco smoke has been more closely associated with irritation than sensitization. A few studies have indicated a potential for environmental smoke-induced hypersensitivity and suppression of immunoregulatory substances. In contrast, other investigators have failed to detect immunological or other biological changes associated with environmental smoke. Clearly, more research is needed to resolve these differences.

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Methods are developed for determining quantitative relative concentrations of elements in the aluminosilicate matrix and in nonmatrix or surface material of coal fly ash. The dependence of total element concentration on particle size and the solubility of elements in solutions of HC1 and HF are discussed. The results indicate greater than 70% of the Ti, Na, K, Mg, Hf, Th, and Fe is associated with the aluminosilicate matrix. More than 70% of the Ca, Sc, Sr, La, the rare earth elements, and probably Ni appears to be associated with an acid-soluble phase, which has the same particle size distribution as the aluminosilicate phases. More than 70% of the As, Se, Mo, Zn, Cd, W, V, U, and Sb are associated with surface material on the ash particles. The elements Mn,