13 research outputs found
Navajo Coal Combustion and Respiratory Health Near Shiprock, New Mexico
Indoor air pollution has been identified as a major risk factor for acute and chronic respiratory diseases throughout the world. In the sovereign Navajo Nation, an American Indian reservation located in the Four Corners area of the USA, people burn coal in their homes for heat. To explore whether/how indoor coal combustion might contribute to poor respiratory health of residents, this study examined respiratory health data, identified household risk factors such as fuel and stove type and use, analyzed samples of locally used coal, and measured and characterized fine particulate airborne matter inside selected homes. In twenty-five percent of homes surveyed coal was burned in stoves not designed for that fuel, and indoor air quality was frequently found to be of a level to raise concerns. The average winter 24-hour PM(2.5) concentration in 20 homes was 36.0 μg/m(3). This is the first time that PM(2.5) has been quantified and characterized inside Navajo reservation residents' homes
The Effect of Topical Clonidine on Intraocular Pressure
• Topical 0.125% and 0.25% clonidine hydrochloride were compared with 2% pilocarpine hydrochloride and a placebo in a double-masked crossover study. Both strengths of clonidine had an ocular hypotensive effect similar in magnitude and duration to pilocarpine. Clonidine in both concentrations also significantly lowered systemic blood pressure. Further studies will be needed to establish the value and safety of clonidine in the treatment of glaucoma
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Toxic substances from coal combustion -- Forms of occurrence analyses. Technical progress report, April 30--November 1, 1996
The overall objective of this project is to provide analytical support for the Physical Sciences, Inc. (PSI) effort being performed under a DOE Contract. The Pittsburgh, Elkhorn/Hazard, and Illinois No. 6 program coals have been examined to determine the mode of occurrence of selected trace elements using scanning electron microscopy, microprobe analysis, and experimental leaching procedures. Preliminary microprobe data indicates that the arsenic content of pyrite grains in the Illinois No. 6 (0.0--0.027 ppm As) and Pittsburgh (0.0--0.080 ppm As) coals is similar. Pyrite grains observed in the Elkhorn/Hazard coal generally have arsenic concentrations (0.0--0.272 wt.% As) that are slightly higher than those of the Pittsburgh or Illinois No. 6 coals. One pyrite grain observed in the Elkhorn/Hazard coal contained much higher levels of arsenic (approximately 2 wt.% As). Preliminary microprobe analyses and data from leaching experiments indicate the association of arsenic with pyrite in the Pittsburgh and Illinois No. 6 coals. Leaching data for arsenic in the Elkhorn/Hazard coal, in contrast, is inconclusive and additional data are needed before a definite determination can be made
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Toxic substances from coal combustion - forms of occurrence analyses. Progress report, April 30, 1996 - November 1, 1996
The Pittsburgh, Elkhorn/Hazard, and Illinois No. 6 program coals have been examined to determine the mode of occurrence of selected trace elements using scanning electron microscopy, microprobe analysis, and experimental leaching procedures. Preliminary microprobe data indicates that the arsenic content of pyrite grains in the Illinois No. 6 and Pittsburgh coals is similar. Pyrite grains observed in the Elkhorn/Hazard coal generally have arsenic concentrations that are slightly higher than those of the Pittsburgh or Illinois No. 6 coals. One pyrite grain observed in the Elkhorn.Hazard coal contained much higher levels of arsenic. Preliminary microprobe analysis and data from leaching experiments indicate the association of arsenic with pyrite in the Pittsburgh and Illinois No. 6 coals. Leaching data fore arsenic in the Elkhorn/Hazard coal, in contrast, is inconclusive and additional data are needed before a definite determination can be made
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Toxic Substances from Coal Combustion - Forms of Occurrence Analyses
In a cooperative agreement with DOE (Contract No. DE- AC22- 95101), the USGS has participated with Physical Sciences, Inc. (PSI) in a project entitled "Toxic Substances From Coal Combustion -A Comprehensive Assessment". Samples from the Pittsburgh, Elkhorn/ Hazard, Illinois No. 6, and Wyodak program coals were examined to determine the mode of occurrence of selected trace elements (As, Se, Cr, Hg, and Ni) using selective leaching, scanning electron microscopy, electron microprobe analysis, and X- ray diffraction techniques. Among other findings, our results indicate that the bulk of the arsenic in the Pittsburgh and Illinois No. 6 coals is in pyrite. High percentages (60- 80%) of arsenic were leached by nitric acid, and microprobe data confirm the presence of arsenic in pyrite in each of these coals (concentrations ranging from <0.01 to 0.09 wt.% of the pyrite grains). In the Elkhorn/ Hazard coal, arsenic may have several modes of occurrences. About 30 percent of the arsenic in the Elkhorn/ Hazard coal was leached by hydrochloric acid, possibly indicating the presence of arsenates that were formed by the oxidation of pyrite. About 25 percent of the arsenic in the Elkhorn/ Hazard coal was leached by nitric acid, suggesting an association with pyrite. Only sixty percent of the total arsenic in the Elkhorn/ Hazard coal was leached. The low percentage of leachable arsenic may be accounted for by unleached pyrite grains, which were detected in solid residues from the nitric acid leach. In the Wyodak coal, arsenic probably occurs in iron oxides or carbonates (35 % arsenic leached by HCl) and clays (15% arsenic leached by HF). Arsenic in the Wyodak coal may also have an organic association, as indicated by low totals for leaching (50% unleached arsenic). In the four program coals 20 to 45 percent of the chromium was leached by hydrofluoric acid, suggesting an association with silicates (probably illite). Microprobe analysis of the Pittsburgh, Elkhorn/ Hazard, and Illinois No. 6 coals confirmed the presence of chromium in illite and possibly in other clays, at concentrations that are near the detection limits. Results related to the forms of occurrence of the other trace elements (Se, Hg, and Ni) are varied; further work in Phase II is planned to determine their mode of occurrence