Me. Rev. Stat. tit. 22, § 1583

It is unlawful for any supplier of compressed air to fill or supply any breathing apparatus with life supporting gases in the State of Maine unless licensed to do so by the department. The initial license fee and the annual renewal license fee shall be $10, except that fire departments shall be exempt from the licensing requirements of this chapter, so long as the use of the apparatus is restricted to departmental use.