Exxon Mobil Corp. v. United States Environmental Protection Agency

The Petitioners challenge the final rule by the Environmental Protection Agency (“EPA”) approving oxygenated fuel standards set by the revised Nevada State Implementation Plan (“SIP”). The EPA ruling approved a SIP amendment revising a Clark County, Nevada regulation requir *1248 ing all gasoline sold in the wintertime to have an oxygen content of at least 3.5 percent. The Petitioners claim that the EPA misconstrued section 211(m) of the Clean Air Act, that the county should not have been allowed to require a minimum oxygen content of more than 2.7 percent and that the county’s regulation is preempted under section 211(c)(4) of the Clean Air Act. We affirm the EPA’s ruling.

FACTUAL BACKGROUND

Clark County, Nevada is a serious non-attainment area for carbon monoxide (“CO”). In the wintertime, weather inversions trap the CO emissions in the Las Vegas Valley and substantially worsen the region’s non-attainment for CO. In 1988, Clark County began an oxygenated fuel program in the wintertime to reduce the level of CO emissions. Initially, the county required all fuel sold to consist of 2.5 percent oxygen with a 2.6 percent level required after the first year of the program. In 1991,…