This part 90 establishes the option of miners who are employed at coal mines and who have evidence of the development of pneumoconiosis to work in an area of a mine where the average concentration of respirable dust in the mine atmosphere during each shift is continuously maintained at or below the applicable standard as specified in §90.100. The rule sets forth procedures for miners to exercise this option, and establishes the right of miners to retain their regular rate of pay and receive wage increases. The rule also sets forth the operator's obligations, including respirable dust sampling for part 90 miners. This part 90 is promulgated pursuant to section 101 of the Act and supersedes section 203(b) of the Federal Mine Safety and Health Act of 1977, as amended.