What is the fair argument standard of review for a statutory exemption?

Appellants rely on footnote 24 in Gentry v. City of Murrieta (1995) 36 Cal.App.4th 1359, 1407, in which the court stated, "We have held that a substantial evidence standard of review applies to an agency's factual finding that a statutory exemption applies. [Citations.] Most statutory exemptions, however, operate regardless of whether the project will have effects on the environment. [Citations.] Thus, '[w]hen reviewing a statutory exemption, the nature and extent of the project's environmental impacts are ordinarily irrelevant.' [Citation.] Therefore, we have at least suggested that where a statutory exemption does depend on whether the project will have significant environmental effects . . . , the fair argument standard should govern review of an agency determination that the statutory exemption applies."