Air Sampling Detects Asbestos and Sources of Fumes

Read the U.S. Department of Labor (DOL) and the Mine Safety and Health Administration (MSHA) report about the sources of fumes to which miners are exposed. Miners are routinely exposed to carcinogenic dusts, including asbestos.

The two most frequently encountered sources of fumes will be welding operations and furnaces which produce molten materials during or as a result of the process. Other fume sources, such as the small furnaces in assay labs, may also be encountered.

The welding rod, the material being welded, the coating material on the surface to be welded, and the welding flux will all contribute to the amount and composition of the welding fume and gases generated.

Although sampling techniques will be similar in both cases, specific variations may occur in the placement of cassettes and the need for short-term samples in addition to full-shift measurements.

Any welding operation should be checked for hazardous concentrations of contaminants. The base material in most cases will be iron or steel, resulting in airborne concentrations of iron oxide (Fe2O3), nickel compounds (Ni), and chromic oxide (Cr2O3).

Hard facing on stainless steel can result in hazardous concentrations of manganese (Mn) and other highly toxic compounds. Welding of nonferrous metals, such as brass and copper alloys, may produce copper oxide fume (CuO), zinc oxide fume (ZnO), lead fume (Pb), or tin oxide fume (SnO2). Aluminum welding can produce an aluminum oxide fume (Al2O3).

Coatings on base metals will be vaporized. Galvanized metal, when welded, will release cadmium fume (Cd) or zinc oxide fume (ZnO). Metals with lead based paint will release lead fume (Pb) when welded.

Some latex paints contain mercury that will be vaporized when heated. It is also possible that the base metal being welded has surface deposits of the ore being mined or milled or has residue of cleaning solvents or other chemicals that could become a toxic air contaminant.

This would be true, for example, if the ore contains lead, arsenic, beryllium, barium, cadmium, mercury, platinum, selenium, or other metal compounds.

During arc-welding, part of the welding rod will be vaporized and will release metal fumes into the atmosphere. Fluorides will be produced in gaseous or particulate forms from welding rods containing fluorides. The filler material on most welding rod coatings is a silica or calcium compound, and, therefore, silicon dioxide (SiO2) or calcium oxide (CaO) can also be expected as air contaminants. These contaminants should be counted as part of the total dust concentration.

Consult the welding rod manufacturer's literature or a local supplier to determine the major components of the rods in use at the site to be sampled. Any of the components could be released by vaporization and many could become a health hazard.

Courtesy of http://www.msha.gov/S&HINFO/OPRSAMP/OPRSAMP.HTM

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