Reformulated Gasoline

The reformulated gasoline program was mandated by Congress in the 1990 Clean Air Act amendments. The CAA intended that RFG would be blended to burn more cleanly than conventional gasoline and would reduce emissions of smog-forming and toxic pollutants. The first phase of the RFG program began in 1995 and the second (current) phase began in 2000.

RFG is required in cities with high smog levels and is optional elsewhere. RFG is currently used in 17 states and the District of Columbia. About 25 percent of gasoline sold in the U.S. is reformulated. In addition, the sale of California Phase 3 RFG is required throughout the entire State of California.

The air quality benefits RFG has achieved since 1995 represent a significant part of the country's smog reduction strategy. The RFG program, combined with other industrial and transportation controls aimed at smog reduction, has contributed to the long-term downward trend in U.S. smog levels. About 75 million people breathe cleaner air now compared to 1995 in part because of RFG. Building on the success of the RFG program, EPA has harmonized requirements that apply to both conventional gasoline (the typical gasoline used in non-RFG areas) and RFG. For example, CG and RFG must both comply with same standards for benzene and sulfur content. This ensures that both CG and RFG provide similar substantial reductions in emissions of toxic pollutants and emissions of nitrogen oxides, which react in the atmosphere to form smog. In addition, RFG continues to provide reductions in emissions of volatile organic compounds from onroad and nonroad sources during the summer due to its lower vapor pressure, which is a measure of how easily gasoline evaporates. VOC emissions also contribute to the formation of smog.

In light of this harmonization between CG and RFG, EPA simplified the RFG summer VOC standards by converting them to a singular 7.4 psi Reid vapor pressure standard as part of its Fuels Regulatory Streamlining rule, which was finalized on December 4, 2020 (see 85 FR 78412). More information is available on the Fuels Regulatory Streamlining page.

Phase II Reformulated Gasoline: The Next Major Step Toward Cleaner Air (pdf) (124 KB, November 1999, EPA420-F-99-042)

Learn more about RFG federal standards.

The tables below list the RFG covered areas including the counties and independent cities in each area and descriptions of any partial counties in the RFG area.

• Table 1: Nine RFG covered areas required by 42 U.S.C. 7545(k)(10)(D) to implement RFG
• Table 2: RFG covered areas based on being reclassified as Severe ozone nonattainment areas under 42 U.S.C. 7511(b)
• Table 3: RFG covered areas based on being classified ozone nonattainment areas at the time that the state requested to opt into RFG under 42 U.S.C. 7545(k)(6)(A)(i)
• Table 4: RFG covered areas located in the ozone transport region established by 42 U.S.C. 7511c(a) that a state requested to opt into RFG under 42 U.S.C. 7545(k)(6)(B)(i)(I)
• A note about federal RFG requirements in California
• Table 5: Areas where EPA has approved a state’s request to “opt-out” of RFG

¹ That portion of San Bernardino County, CA that lies south of latitude 35 degrees, 10 minutes north and west of longitude 115 degrees, 45 minutes west. 

² That portion of Riverside County, CA that lies to the west of a line described as follows: beginning at the northeast corner of Section 4, Township 2 South, Range 5 East, a point on the boundary line common to Riverside and San Bernardino Counties; then southerly along section lines to the centerline of the Colorado River Aqueduct; then southeasterly along the centerline of said Colorado River Aqueduct to the southerly line of Section 36, Township 3 South, Range 7 East; then easterly along the township line to the northeast corner of Section 6, Township 4 South, Range 9 East; then southerly along the easterly line of Section 6 to the southeast corner thereof; then easterly along section lines to the northeast corner of Section 10, Township 4 South, Range 9 East; then southerly along section lines to the southeast corner of Section 15, Township 4 South, Range 9 East; then easterly along the section lines to the northeast corner of Section 21, Township 4 South, Range 10 East; then southerly along the easterly line of Section 21 to the southeast corner thereof; then easterly along the northerly line of Section 27 to the northeast corner thereof; then southerly along section lines to the southeast corner of Section 34, Township 4 South, Range 10 East; then easterly along the township line to the northeast corner of Section 2, Township 5 South, Range 10 East; then southerly along the easterly line of Section 2, to the southeast corner thereof; then easterly along the northerly line of Section 12 to the northeast corner thereof; then southerly along the range line to the southwest corner of Section 18, Township 5 South, Range 11 East; then easterly along section lines to the northeast corner of Section 24, Township 5 South, Range 11 East; and then southerly along the range line to the southeast corner of Section 36, Township 8 South, Range 11 East, a point on the boundary line common to Riverside and San Diego Counties.

Note: On October 7, 2022 (87 FR 60926) EPA reclassified the following areas as Severe for the 2008 ozone NAAQS:

New York-N. New Jersey-Long Island, NY-NJ-CT (New York);
Houston-Galveston-Brazoria, TX (Houston);
Dallas-Fort Worth, TX (Dallas);
Denver-Boulder-Greeley-Ft. Collins-Loveland, CO (Denver); and
Morongo Band of Mission Indians, CA

These reclassifications were effective on November 7, 2022. CAA section 211(k)(10)(D) requires that the sale of CG be prohibited in any ozone nonattainment area that is reclassified as Severe beginning one year after the effective date of the reclassification. The sale of RFG is already required in the New York, Houston, and Morongo Band of Mission Indians areas because they are among the original nine areas required to implement RFG as shown above and the sale of RFG continues in these areas. The Morongo Band of Mission Indians area is within the Los Angeles-Anaheim-Riverside RFG area listed in Table 1.

RFG was already required in four counties in the Dallas area because EPA approved a request from Texas to opt those counties into the RFG program. RFG was required to be sold throughout the 10-county Dallas nonattainment area for the 2008 ozone NAAQS beginning on November 7, 2023. The gasoline sold in 10-county Dallas area is required to comply with the RFG summer RVP standard of 7.4 psi beginning on June 1, 2024, for wholesale purchaser-consumers, and for all other parties beginning on May 1, 2024.

RFG has not previously been required in the Denver area. RFG was required to be sold throughout the Denver nonattainment area for the 2008 ozone NAAQS beginning on November 7, 2023. The gasoline sold in the Denver area is required to comply with the RFG summer RVP standard of 7.4 psi beginning on June 1, 2024, for wholesale purchaser-consumers, and for all other parties beginning on May 1, 2024.

¹ All portions of Placer County except that portion of the County within the drainage area naturally tributary to Lake Tahoe including said Lake, plus that area in the vicinity of the head of the Truckee River described as follows: commencing at the point common to the aforementioned drainage area crestline and the line common to Townships 15 North and 16 North, Mount Diablo Base and Meridian (M.D.B.& M.), and following that line in a westerly direction to the northwest corner of Section 3, Township 15 North, Range 16 East, M.D.B.& M., thence south along the west line of Sections 3 and 10, Township 15 North, Range 16 East, M.D.B.& M., to the intersection with the said drainage area crestline, thence following the said drainage area boundary in a southeasterly, then northeasterly direction to and along the Lake Tahoe Dam, thence following the said drainage area crestline in a northeasterly, then northwesterly direction to the point of beginning.

² That portion of Solano County that lies north and east of a line described as follows: beginning at the intersection of the westerly boundary of Solano County and the 1/4 section line running east and west through the center of Section 34; T. 6 N., R. 2 W., M.D.B.& M.; thence east along said 1/4 section line to the east boundary of Section 36, T. 6 N., R. 2 W.; thence south 1/2 mile and east 2.0 miles, more or less, along the west and south boundary of Los Putos Rancho to the northwest corner of Section 4, T. 5 N., R. 1 W.; thence east along a line common to T. 5 N. and T. 6 N. to the northeast corner of Section 3, T. 5 N., R. 1 E.; thence south along section lines to the southeast corner of Section 10, T. 3 N., R. 1 E.; thence east along section lines to the south 1/4 corner of Section 8, T. 3 N., R. 2 E.; thence east to the boundary between Solano and Sacramento Counties.

³ That portion of Sutter County south of a line connecting the northern border of Yolo Co. to the SW tip of Yuba Co. and continuing along the southern Yuba Co. border to Placer Co.

⁴ The western portion of Kern County is included in the San Joaquin Valley area. The eastern portion of Kern County is a separate ozone nonattainment area. The boundary between the Eastern Kern County area and the western portion of Kern County, which is included in the San Joaquin Valley area generally follows the ridge line of the Sierra Nevada and Tehachapi Mountain Ranges. That portion of Kern County that lies west and north of a line described as follows: beginning at the Kern-Los Angeles County boundary and running north and east along the northwest boundary of the Rancho La Liebre Land Grant to the point of intersection with the range line common to Range 16 West and Range 17 West, San Bernardino Base and Meridian; north along the range line to the point of intersection with the Rancho El Tejon Land Grant boundary; then southeast, northeast, and northwest along the boundary of the Rancho El Tejon Grant to the northwest corner of Section 3, Township 11 North, Range 17 West; then west 1.2 miles; then north to the Rancho El Tejon Land Grant boundary; then northwest along the Rancho El Tejon line to the southeast corner of Section 34, Township 32 South, Range 30 East, Mount Diablo Base and Meridian; then north to the northwest corner of Section 35, Township 31 South, Range 30 East; then northeast along the boundary of the Rancho El Tejon Land Grant to the southwest corner of Section 18, Township 31 South, Range 31 East; then east to the southeast corner of Section 13, Township 31 South, Range 31 East; then north along the range line common to Range 31 East and Range 32 East, Mount Diablo Base and Meridian, to the northwest corner of Section 6, Township 29 South, Range 32 East; then east to the southwest corner of Section 31, Township 28 South, Range 32 East; then north along the range line common to Range 31 East and Range 32 East to the northwest corner of Section 6, Township 28 South, Range 32 East; then west to the southeast corner of Section 36, Township 27 South, Range 31 East; then north along the range line common to Range 31 East and Range 32 East to the Kern-Tulare County boundary.

⁵ That portion of Larimer County that lies south of a line described as follows: Beginning at a point on Larimer County’s eastern boundary and Weld County’s western boundary intersected by 40 degrees, 42 minutes, and 47.1 seconds north latitude, proceed west to a point defined by the intersection of 40 degrees, 42 minutes, 47.1 seconds north latitude and 105 degrees, 29 minutes, and 40.0 seconds west longitude, thence proceed south on 105 degrees, 29 minutes, 40.0 seconds west longitude to the intersection with 40 degrees, 33 minutes and 17.4 seconds north latitude, thence proceed west on 40 degrees, 33 minutes, 17.4 seconds north latitude until this line intersects Larimer County’s western boundary and Grand County’s eastern boundary.

⁶ That portion of Weld County that lies south of a line described as follows: Beginning at a point on Weld County’s eastern boundary and Logan County’s western boundary intersected by 40 degrees, 42 minutes, 47.1 seconds north latitude, proceed west on 40 degrees, 42 minutes, 47.1 seconds north latitude until this line intersects Weld County’s western boundary and Larimer County’s eastern boundary.

Note: On October 7, 2022 (87 FR 60926), EPA reclassified the Dallas-Fort Worth, TX (Dallas) area as Severe for the 2008 ozone NAAQS. The reclassification was effective on November 7, 2022. CAA section 211(k)(10)(D) requires that the sale of CG be prohibited in any ozone nonattainment area that is reclassified as Severe beginning one year after the effective date of the reclassification (i.e., November 7, 2023). As such, Dallas is now listed in Table 2.

A note about federal RFG requirements in California:

All counties implement a version of the California Reformulated Gasoline Program, not just those listed here as CAA-required areas. Standards differ from EPA’s RFG requirements, and compliance periods vary by air basin. Please refer to the California Air Resources Board website for additional details: Federal Reformulated Gasoline.