APPENDIX F
INSTRUCTIONS FOR CALCULATING INCIDENCE RATES

Occupational injury and illness incidence rates can be calculated easily using the following information:

A. The number of injuries and illnesses.
Count the number of recordable cases from the Log and Summary of Occupational Injuries and Illnesses (form OSHA No. 200) or refer to the Totals line for the yearly total on the Log. The Log and Summary also provides the yearly total for fatalities, injuries and illnesses with lost workdays, and injuries and illnesses without lost workdays.

B. The number of hours all employees actually worked.
Hours worked can be obtained from payroll or other time records. Employee hours worked should not include any non-work time, even though paid, such as vacation, sick leave, holidays, etc. (If actual hours worked are not available, hours worked may be estimated on the basis of scheduled hours or 8 hours per workday.)

An incidence rate of occupational injuries and illnesses may be computed using the following formula:

(Number of injuries and illnesses X 200,000)/Employee hours worked

Note: The 200,000 in the formula represents the equivalent of 100 employees working 40 hours per week for 50 weeks per year, and provides the standard base for incidence rates. The same formula can be used to compute incidence rates for:

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