50-10-2: [Testing atmosphere in sewer line; time and frequency.]

The requirements of Section 1 [50-10-1 NMSA 1978] shall be followed at the beginning of every workday, and also at the resumption of work following each meal period and also at the beginning of each shift in the event more than one shift per day is used; provided that such requirements need not be followed more often than once each four hours.