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Contact EPA Pacific Southwest Air Program

Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

Air Actions, Arizona

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

Thanks to ongoing environmental stewardship clean skies may continue to blow over Saguaro cactus groves like these in the Tucson area for years to come

Carbon Monoxide in Tucson Air Planning Area

FINAL RULE: On October 14, 2009, EPA’s Acting Regional Administrator signed an action which finalizes our approval of a second 10-year carbon monoxide (CO) Limited Maintenance Plan (LMP) in the Tucson Air Planning Area (TAPA) and a related statutory provision. This final action was published in the Federal Register December 21, 2009. The proposed action was signed July 21, 2009, published August 5, 2009, and no comments were received.

PROPOSED RULE: EPA has signed an action which proposes to approve a second 10-year carbon monoxide (CO) Limited Maintenance Plan (LMP) in the Tucson Air Planning Area (TAPA) and a related statutory provision. The TAPA area has not violated the 8-hour average CO concentration since 1990. In 1997, we redesignated the area to attainment and approved the first LMP in 2000. We now are approving the second 10-year maintenance plan as the area continues to meet the qualifications for the LMP option meeting all requirements of Clean Air Act (CAA) and EPA guidance. The statutory provision submitted by the state extends the life of the Vehicle Emission Inspection (VEI) program. This program is one of the measures upon which the TAPA LMP relies to maintain the CO NAAQS.

EPA is taking this proposed action though we view it as noncontroversial and do not anticipate adverse comments.


Tucson Carbon Monoxide Redesignation Approval

On April 25, 2000, EPA gave final approval to the request from Arizona for redesignation of the Tucson Air Planning Area to "attainment" of the national health-based standard for carbon monoxide (CO). The area had previously been designated as "nonattainment" for the pollutant. EPA proposed to approve Arizona's request on July 22, 1998, and reproposed the approval on December 17, 1999, to provide additional opportunities for public comment.

In order for a nonattaiment area to be redesignated to attainment, the Clean Air Act requires that the area has attained the National Ambient Air Quality Standard for that pollutant, that the improvement in air quality is due to permanent and enforceable control measures, that the area have an approved maintenance plan, and that the area has met all other relevant requirements in the Clean Air Act.

There have been no exceedances of the standard for CO in the Tucson area from 1993 to the present. Control measures for CO in the Tucson area include the Federal Motor Vehicle Control program, a State Inspection and Maintenance program, and a state oxyfuels program. The area has submitted a maintenance plan setting forth the procedures and contingency measures that it will implement should there be a probable or actual violation of the CO standard in the area in the future.

Carbon monoxide -- a clear, odorless pollutant that is primarily emitted from automobiles -- can have serious health effects, particularly for children, the elderly and those afflicted with respiratory ailments. It enters the bloodstream and reduces the body's capacity to deliver oxygen to organs and tissues. The health threat from CO is most serious for those who suffer from cardiovascular disease. At higher levels of exposure, healthy individuals are also affected. Visual impairment, reduced work capacity, reduced manual dexterity, poor learning ability, and difficulty in peforming complex tasks are all associated with exposure to elevated CO levels.

Below are links to the redesignation proposal and reproposal as published in the Federal Register, and downloadable copies of the unofficial Notice of Final Rulemaking and the Technical Support Document for the final rule in WordPerfect format. A link to the official version of the final rule will be made available upon its publication in the Federal Register.

For further information, contact Eleanor Kaplan, EPA Region 9, Air Division (air-2), 75 Hawthorne Street, San Francisco, CA 94105-3901, telephone number (415) 947-4147, or you may email her at kaplan.eleanor@epa.gov.

Proposed Rule (July 22, 1999)

Reproposal to Approve Redesignation* (December 17, 1999)

Technical Support Document (PDF) (14 pp, 77K About PDF)

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