CFR 30-90.101-2014 Mineral Resources. Part90:Mandatory health standards—coal miners who have evidence of the development of pneumoconiosis. Section90.101:Respirable dust standard when quartz is present.
When the respirable dust in the mine atmosphere of the active workings to which a Part 90 miner is exposed contains more than 5 percent quartz, the operator shall continuously maintain the average concentration of respirable dust in the mine atmosphere during each shift to which a Part 90 miner is exposed at or below a concentration of respirable dust computed by dividing the percent of quartz into the number 10. The application of the formula shall not result in a respirable dust standard in excess of 1.0 milligrams per cubic meter of air. Concentrations shall be expressed in milligrams per cubic meter of air as measured with an approved sampling device and in terms of an equivalent concentration determined in accordance with § 90.206 (Approved sampling devices; equivalent concentrations).
CFR 30-90.101-2014 history
2014CFR 30-90.101-2014 Mineral Resources. Part90:Mandatory health standards—coal miners who have evidence of the development of pneumoconiosis. Section90.101:Respirable dust standard when quartz is present.