[Code of Federal Regulations]
[Title 30, Volume 1]
[Revised as of July 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 30CFR70.101]

[Page 421]
 
                       TITLE 30--MINERAL RESOURCES
 
  CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR
 
PART 70--MANDATORY HEALTH STANDARDS--UNDERGROUND COAL MINES--Table of Contents
 
                        Subpart B--Dust Standards
 
Sec. 70.101  Respirable dust standard when quartz is present.

    When the respirable dust in the mine atmosphere of the active 
workings 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 each miner in the active 
workings is exposed at or below a concentration of respirable dust, 
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 Sec. 70.206 (Approved sampling devices; 
equivalent concentrations), computed by dividing the percent of quartz 
into the number 10.

    Example: The respirable dust associated with a mechanized mining 
unit or a designated area in a mine contains quartz in the amount of 
20%. Therefore, the average concentration of respirable dust in the mine 
atmosphere associated with that mechanized mining unit or designated 
area shall be continuously maintained at or below 0.5 milligrams of 
respirable dust per cubic meter of air (10/20=0.5 mg/m\3\ ).

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