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Summary of Anchorage Carbon Monoxide (CO) Maintenance Plan and Second 10-Year Limited Maintenance Plan


Anchorage, Alaska, was first declared a nonattainment area for carbon monoxide (CO) and classified as moderate on January 27, 1978.

The Municipality of Anchorage (MOA) prepared a plan to attain the National Ambient Air Quality Standards (NAAQS) by December 31, 1987. However, Anchorage failed to achieve attainment by December 31, 1987.

The Clean Air Act was amended in November 1990, and EPA designated Anchorage as a moderate nonattainment area for CO and required submission of a revised air quality plan to bring Anchorage into attainment by December 31, 1995. EPA approved the plan in 1995. However, two violations of the NAAQS in 1996 resulted in EPA reclassifying Anchorage to serious nonattainment on July 13, 1998 with an attainment date of December 31, 2000.

The MOA submitted a new attainment plan on January 4, 2002, and EPA proposed approval of the plan  (67 FR 38218 (PDF)(5 pp, 145 K, About PDF)). On June 3, 2002, EPA approved the Anchorage CO attainment plan (67 FR 58711 (PDF)(2 pp, 132 K)). The MOA submitted a maintenance plan on February 18, 2004. 

On February 18, 2004, the State of Alaska submitted a carbon monoxide (CO) maintenance plan for the Anchorage CO nonattainment area to EPA for approval. EPA proposed approval of the Anchorage CO maintenance plan (69 FR 25869 (PDF)(5 pp, 159 K)) on May 10, 2004, and approved the plan on June 23, 2004 (69 FR 34935 (PDF)(3 pp, 147 K)).

The State of Alaska submitted revisions to the Alaska SIP relating to the motor vehicle inspection program in Anchorage. The revisions were approved by EPA in two separate actions: 

  1. A March 29, 2002, SIP revision that contained minor revisions to the statewide I/M program, and a December 11, 2006, submittal contained more substantial revisions to the statewide I/M program. EPA proposed to approve the revisions on September 15, 2009 (74 FR 47154 (PDF)(6 pp, 158 K)) and took final action on March 22, 2010 (75 FR 13436 (PDF)(6 pp, 159 K)). 
  2. A September 29, 2010, SIP revision that discontinued the I/M program in Anchorage as an active control measure in the SIP and shifted it to a contingency measure. EPA proposed to approve the revision on September 7, 2011 (76 FR 55325 (PDF)(5 pp, 161 K)) and took final action on January 10, 2012 (77 FR 1414 (PDF)(4 pp, 156 K)). 

On September 20, 2011, Alaska submitted a SIP revision to update Anchorage's CO motor vehicle emissions budget in the Anchorage area using the EPA's Motor Vehicle Emission Simulator (MOVES) model. 

On April 22, 2012, the State submitted a Second 10-Year Limited Maintenance Plan (LMP) for CO for the Anchorage area. The area qualified for an LMP since the second highest 8-hour CO concentration for the Anchorage area during the most recent 8 quarters (2011-2012) was 5.5 ppm, which is below the LMP Option requirement of 7.65 ppm. The EPA approved these SIP revisions on March 3, 2014 (79 FR 11707 (PDF)(5 pp, 228 K)).


The maintenance focuses on the Federal Motor Vehicle Emission Control Program, expanded wintertime transit service and promotion of engine preheaters. 


  • 40 CFR Part 86, Federal Motor Vehicle Emission Control Program.
  • Share-A-Ride Program.
  • Promotion of engine preheaters.
  • Free winter transit service.
  • Expanded transit service through 2006.

Contingency Measures

  • 18 AAC 52, Emissions Inspection and Maintenance (I/M) requirements for Motor Vehicles.
  • Rule 18 AAC 53.010, Control periods and control areas.
  • Rule 28 AAC 53.190(b), Suspension and reestablishment of control period (Reinstatement of ethanol-blended gasoline program).
  • Best Available Control Technology will be replaced with requirement to install Lowest Achievable Emission Rate technology.

Attainment Date

December 31, 2000

Redesignation EPA Effective Date

July 23, 2004

Second 10-Year LMP Effective Date

May 2, 2014