NAC512.178. Exposure to mercury.

     1. An operator shall provide training to each worker who will or may come into contact with mercury before the worker is assigned production work, including, without limitation, training related to:

     (a) The health hazards of mercury;

     (b) The routes of entry of mercury into a person;

     (c) Personal protective equipment;

     (d) The effective measures to control mercury; and

     (e) The appropriate response to the cleanup of spills of mercury.

     2. In mercury extraction areas or other areas within the mine where the health and safety of a worker may be at risk from exposure to mercury:

     (a) Hoeing tables must be completely enclosed except for the frontal opening and provided with mechanical exhaust ventilation providing a minimum hood face velocity of 100 cubic feet per minute of ventilation continuously during each shift.

     (b) Bottling operations must be as automatic as possible to reduce unnecessary exposure to a worker. A pan containing a layer of water must be placed under each mercury flask during the filling of the mercury flask to catch any spilled mercury.

     (c) A polysulfide mercury depressant must be applied at least once a month to surface areas where mercury may accumulate and immediately after all mercury spills.

     3. At each mill for refining mercury and each mercury extraction area:

     (a) The operator shall provide nonabsorbent, smooth and impenetrable floors and sidewalls to a height of at least 6 inches under kilns, cooling towers, hoeing tables, retorts, bottling operations and in any other area where mercury may be spilled or otherwise accumulate on floors.

     (b) General dilution ventilation is required in all areas where other methods are not adequate to maintain the mercury in air concentrations below the recommended threshold limit value recommended by the American Conference of Governmental Industrial Hygienists.

     (c) While performing operations where exposure to mercury vapors in air concentrations may exceed the recommended limit, workers shall wear devices approved for respiratory protection by the National Institute for Occupational Safety and Health or the Mine Safety and Health Administration.

     4. “No Smoking” signs must be posted in mercury extraction areas and other areas where mercury vapors may be present, and workers are prohibited from smoking or eating except in designated areas.

     5. A shower and change room must be provided for workers who work in mercury extraction areas, along with adequate locker space for storage of off-duty clothing.

     6. The operator shall collect urine samples monthly from workers who work in mercury extraction areas and where mercury-bearing ore is processed. The operator shall submit the urine samples monthly to a medical laboratory for determination of levels of mercury. Workers with a confirmed Biological Exposure Index value of 35 ug/gCRT or more or a single sample confirming mercury levels above 45 ug/gCRT must be removed from further exposure until their levels of mercury return to a normal level of 25 ug/gCRT or less. The operator shall notify the Enforcement Section and take appropriate action if a worker’s creatinine-corrected level of mercury is found to be more than 25 ug/gCRT.

     7. The operator shall provide annual physical examinations to any worker for whom a urine sample collected pursuant to subsection 6 demonstrates that the worker’s level of mercury exceeds 25 ug/gCRT to determine any effects of exposure to mercury vapor.

     8. As used in this section:

     (a) “Biological Exposure Index” means the concentration of mercury found in the body of a worker, including, without limitation, in the urine, blood or exhaled air of the worker, that corresponds to inhalation exposure at a specific air concentration.

     (b) “Medical laboratory” has the meaning ascribed to it in NRS 652.060.

     [Inspector of Mines, Part 1 No. 5 subsec. g, eff. 8-13-75]—(NAC A by Div. of Mine Inspection, 8-26-83; A by Div. of Industrial Relations by R125-08, 5-30-2012)