The Secretary may provide such reasonable limitations and may make such rules and regulations allowing reasonable variation, tolerances, and exemptions to and from any or all provisions of this chapter (other than section
358 of this title), but only in special circumstances where he determines that such limitation, variation, tolerance, or exemption is necessary and proper in the public interest or to avoid the serious impairment of government business, and is in accord with the remedial purpose of this chapter to protect prevailing labor standards.