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Air Pollution from Carbon Monoxide

General information on carbon monoxide (CO) and TCEQ planning that addresses the National Ambient Air Quality Standards (NAAQS) for CO.

What is carbon monoxide?

CO is a colorless, odorless gas formed by the incomplete reaction of air with fuel. CO pollution occurs primarily from emissions produced by fossil fuel–powered engines, including motor vehicles and non-road engines and vehicles (such as construction equipment and boats). Higher levels of CO generally occur in areas with heavy traffic congestion. Other sources of CO emissions include industrial processes (such as processing of metals and chemical manufacturing), residential wood burning, and natural sources such as forest fires. Woodstoves, gas stoves, cigarette smoke, and unvented gas and kerosene space heaters are indoor sources of CO. The highest levels of CO typically occur during the colder months of the year when inversion conditions (when the air pollution becomes trapped near the ground beneath a layer of warm air) are more frequent.

CO can cause harmful health effects by reducing oxygen delivery to the body’s organs and tissues. Exposure to lower levels of CO is most serious for those who suffer from heart disease, and can cause chest pain, reduce the ability to exercise, or—with repeated exposures—may contribute to other cardiovascular effects.

Even healthy people can be affected by high levels of CO. People who breathe high levels of CO can develop vision problems, reduced ability to work or learn, reduced manual dexterity, and difficulty performing complex tasks. At very high levels, CO is poisonous and can cause death.

Latest air quality planning that addresses the CO National Ambient Air Quality Standards

Last updated: 9/5/2019

2011 Carbon Monoxide Standard

On August 12, 2011, the EPA finalized the CO NAAQS rule, which will retain the existing CO primary standards: an eight-hour standard of 9 ppm and a one-hour standard of 35 ppm. The latest near-road monitors were deployed in the Dallas–Fort Worth and Houston-Galveston-Brazoria areas in April 2015 and additional monitors were installed in Austin and San Antonio in December 2016.

Redesignation of the El Paso CO to attainment

On February 13, 2008, the TCEQ submitted a SIP revision to request redesignation of the El Paso CO nonattainment area to attainment of the CO standard. The EPA proposed approval of the plan and the associated budget for motor vehicle emissions in the Federal Register ( 73 FR 45162 ) on August 4, 2008. The action was published as a direct final rule, and the effective date for the redesignation was October 3, 2008.  For more information, see El Paso and the State Implementation Plan.

Related Webpages and Publications

Get more information on the Texas SIP and contact the TCEQ

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