This part 50 implements sections 103(e) and 111 of the Federal Coal Mine Health and Safety Act of 1969, 30 U.S.C. 801 et seq., and sections 4 and 13 of the Federal Metal and Nonmetallic Mine Safety Act, 30 U.S.C. 721 et seq., and applies to operators of coal, metal, and nonmetallic mines. It requires operators to immediately notify the Mine Safety and Health Administration (MSHA) of accidents, requires operators to investigate accidents, and restricts disturbance of accident related areas. This part also requires operators to file reports pertaining to accidents, occupational injuries and occupational illnesses, as well as employment and coal production data, with MSHA, and requires operators to maintain copies of reports at relevant mine offices. The purpose of this part is to implement MSHA's authority to investigate, and to obtain and utilize information pertaining to, accidents, injuries, and illnesses occurring or originating in mines. In utilizing information received under part 50, MSHA will develop rates of injury occurrence (incident rates or IR), on the basis of 200,000 hours of employee exposure (equivalent to 100 employees working 2,000 hours per year). The incidence rate for a particular injury category will be based on the formula:

IR = (number of cases × 200,000) divided by hours of employee exposure.

MSHA will develop data respecting injury severity using days away from work or days of restricted work activity and the 200,000 hour base as criteria. The severity measure (SM) for a particular injury category will be based on the formula:

SM = (sum of days × 200,000) divided by hours of employee exposure.

[42 FR 65535, Dec. 30, 1977; 43 FR 1617, Jan. 11, 1978, as amended at 43 FR 12318, Mar. 24, 1978; 71 FR 16666, Apr. 3, 2006]