[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: 30CFR33.33]

[Page 157]
 
                       TITLE 30--MINERAL RESOURCES
 
  CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR
 
PART 33--DUST COLLECTORS FOR USE IN CONNECTION WITH ROCK DRILLING IN COAL MINES--Table of Contents
 
                      Subpart C--Test Requirements
 
Sec. 33.33  Allowable limits of dust concentration.

    (a) The concentration of dust determined by the control sample shall 
be subtracted from the average concentration of dust determined by the 
test samples collected at each drill operator's position, and the 
difference shall be designated as the net concentration of airborne 
dust. Calculations of the average concentration of dust determined from 
the test samples shall be based upon the results of not less than 80 
percent of each set of test samples.
    (b) Under each prescribed test condition, the net concentration of 
airborne dust at each drill operator's position shall not exceed 10 
million particles (5 microns or less in diameter) per cubic foot of air 
when determined in accordance with the method given in Sec. 33.32(a).

[Sched. 25B, 25 FR 6473, July 9, 1960, as amended at 26 FR 2599, Mar. 
28, 1961]