Bimonthly sampling.

(a) Each operator shall take one valid respirable dust sample for each part 90 miner during each bimonthly period beginning with the bimonthly period of February 1, 1981. The bimonthly periods are:

February 1-March 31
April 1-May 31
June 1-July 31
August 1-September 30
October 1-November 30
December 1-January 31.

(b) When the respirable dust standard is changed in accordance with §90.101 (Respirable dust standard when quartz is present), respirable dust sampling of part 90 miners shall begin on the first shift on which the miner is performing normal work duties during the next bimonthly period following notification of such change from MSHA.

(c) Upon issuance of a citation for a violation of §90.100 (Respirable dust standard) or §90.101 (Respirable dust standard when quartz is present), paragraphs (a) and (b) of this section shall not apply to that part 90 miner until the violation is abated in accordance with §90.201(d) (Sampling; general requirements).