(a) The power of the Secretary of Labor under section 16 of the Act to provide reasonable limitations and variations, tolerances, and exemptions to and from any or all provisions of the Act as he may find necessary and proper to avoid serious impairment of the national defense is reserved.

(b) No action by a State under a plan shall be inconsistent with action by the Secretary under this section of the Act.

(c) Where a State standard is identical to a Federal standard addressed to the same hazard, an employer or group of employers seeking a temporary or permanent variance from such standard, or portion thereof, to be applicable to employment or places of employment in more than one State, including at least one State with an approved plan, may elect to apply to the Assistant Secretary for such variance under the provisions of 29 CFR part 1905.

(d) Actions taken by the Assistant Secretary with respect to such application for a variance, such as interim orders, with respect thereto, the granting, denying, or issuing any modification or extension thereof, will be deemed prospectively an authoritative interpretation of the employer or employers' compliance obligations with regard to the State standard, or portion thereof, identical to the Federal standard, or portion thereof, affected by the action in the employment or places of employment covered by the application.

(e) Nothing herein shall affect the option of an employer or employers seeking a temporary or permanent variance with applicability to employment or places of employment in more than one State to apply for such variance either to the Assistant Secretary or the individual State agencies involved. However, the filing with, as well as granting, denial, modification, or revocation of a variance request or interim order by, either authority (Federal or State) shall preclude any further substantive consideration of such application on the same material facts for the same employment or place of employment by the other authority.

(f) Nothing herein shall affect either Federal or State authority and obligations to cite for noncompliance with standards in employment or places of employment where no interim order, variance, or modification or extension thereof, granted under State or Federal law applies, or to cite for noncompliance with such Federal or State variance action.