[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: 30CFR33.32]

[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. 33.32  Determination of dust concentration.

    (a) Concentrations of airborne dust in the test space shall be 
determined by sampling with a midget impinger apparatus, and a light-
field microscopic technique shall be employed in determining 
concentrations of dust in terms of millions of particles (5 microns or 
less in diameter) per cubic foot of air sampled.
    (b) Before a drilling test is started the surfaces of the test space 
shall be wetted; the test space shall be cleared of air-borne dust 
insofar as practicable by mechanical ventilation or other means; and an 
atmospheric sample, designated as a control sample, shall be collected 
during a 5-minute period to determine residual airborne dust in the test 
space.
    (c) A sample of airborne dust, designated as a test sample, shall be 
collected in the breathing zone of the drill operators during the 
drilling of each test hole. Time consumed in changing drill steel shall 
not be considered as drilling time and sampling shall be discontinued 
during such periods.

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