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Summary of Spokane Carbon Monoxide (CO) Maintenance Plan


 The Spokane, Washington, urbanized area was designated nonattainment for carbon monoxide (CO) and classified as moderate upon enactment of the Clean Air Act Amendments in 1990. Spokane was unable to attain the standard by December 31, 1995, and was redesignated to serious on April 13, 1998. 

Washington submitted Spokane CO attainment plan revisions on September 20, 2001, and November 22, 2004. The EPA announced its proposed approval of the Spokane CO plan revisions on March 8, 2005 (70 FR 11179 (PDF)(6 pp, 163 K, About PDF)).

On May 12, 2005, the EPA approved the Spokane CO attainment plan (70 FR 24991 (PDF)(2 pp, 143 K)) which was effective June 13, 2005.

On June 29, 2005, the EPA approved the Spokane CO first 10-year maintenance plan effective August 29, 2005 (70 FR 37269 (PDF)(5 pp, 159 K)).

On July 14, 2016, the EPA approved the second 10-year maintenance plan effective August 15, 2016 (81 FR 45417 (PDF)(3 pp, 223 K)).


The plan relies on control strategies needed to assure attainment of the National Ambient Air Quality Standard (NAAQS) for CO. The strategy focuses on the Federal Motor Vehicle Emission Control Program, an approved basic vehicle Inspection and Maintenance program, and transportation control measures.


  • 40 CFR Part 86, Federal Motor Vehicle Emission Control Program 
  • WAC 173-422-031, Vehicle Emission Inspection Schedule
  • WAC 173-422-170, Exemptions
  • WAC 173-492, Motor Fuel Specifications for Oxygenated Gasoline

Contingency Measures

Oxygenated fuel program is changed from a control measure to a contingency measure.

EPA Effective Date

August 15, 2016