Act means the Clean Air Act as amended (42 U.S.C. 7401 et seq.).

Administrator, Deputy Administrator, Assistant Administrator, General Counsel, Associate General Counsel, Deputy Assistant Administrator, Regional Administrator, Headquarters, Staff Office, Operational Office, and Regional Office are described in part 1 of this title.

Mechanism means an administrative procedure, guideline, manual, or written statement.

Program directive means any formal written statement by the Administrator, the Deputy Administrator, the Assistant Administrator, a Staff Office Director, the General Counsel, a Deputy Assistant Administrator, an Associate General Counsel, or a division Director of an Operational Office that is intended to guide or direct Regional Offices in the implementation or enforcement of the provisions of the act.

Responsible official means the EPA Administrator or any EPA employee who is accountable to the Administrator for carrying out a power or duty delegated under section 301(a)(1) of the act, or is accountable in accordance with EPA's formal organization for a particular program or function as described in part 1 of this title.