OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.

ARA for Technical Support
Regional Administrator

Directorate of Technical Operations

Directorate of Technical Support
Office of Occupational Medicine
SUBJECT: Interpretation of 1910.1043(h)(ii)(c)

1. Medical surveillance as required in paragraph (h)(3)(i) of the standard, shall be provided every 6 months for all employees with FEV1 values of less than 80 percent of the predicted value (h)(ii)(c). However, if the FEV1 is greater than 80 percent BUT there is a FEV1 decrement of 5 percent (or greater) that is 200 ml (or more) on the first working day (that is the difference between the first test conducted on entering the workplace after an absence of at least 35 hours, and the second test conducted between 4 and 10 hours after beginning the work shift), that will require a re-test in 6 months.

In addition to the above, (h)(ii)(c) mandates that if the physician finds a significant change in the responses to the questionnaire which the worker completes as part of the medical history, or in any aspect of the pulmonary function test (PFT) results or other diagnostic tests he/she will provide another PFT in 6 months.

Because "significant change" depends on findings which are too numerous and varied to list and on the physician's interpretation of those findings based on his/her experience and training, the "significant change" is not defined. The standard relies on the physician's opinion.

2. FEV1/FVC ratios are referred to in Appendix D of the standard as part of NIOSH guidelines. A drop below 0.75 of the FEV1/FVC ratio is suggested as an indicator for a repeat evaluation within 1 month. However, it must be noted these are recommendations, not mandated requirements. The FEV1/FVC ratios do change with age but the test is a relatively reliable indicator of obstructive lung disease.