PART XIX GENERAL BLASTING — Employer's responsibility

to provide adequate direction and instruction of workers and to assign work only to those workers who are qualified;

to ensure that measurement of air volume is taken at the end of the ventilation duct near the working face underground and that records are maintained of all air-volume measurements; and

to ensure that a worker does not return to the scene of a blasting operation until the air contaminants have been reduced to concentrations below their respective threshold limit values and the concentration of oxygen is at a respirable level.