January 31, 2011

EPA Proposes to Retain National Air Quality Standards for Carbon Monoxide

Air monitoring revisions would ensure people are protected

WASHINGTON – After a careful review of the best available science, the U.S. Environmental Protection Agency (EPA) is proposing to keep the current national air quality standards for carbon monoxide (CO), while taking steps to gather additional data through more focused monitoring. The science shows that the current standards will protect people, especially those susceptible to health problems associated with breathing CO from the outdoor air. CO can cause harmful health effects by reducing oxygen delivery to the body’s organs (like the heart and brain) and tissues. At extremely high levels, CO can cause death.

The current health standards are 9 parts per million (ppm) measured over 8 hours, and 35 ppm measured over 1 hour. To ensure people are protected from high concentrations of CO and to develop better information about CO and its health impacts, EPA is proposing to revise the air monitoring requirements.  The proposed changes would require a more focused monitoring network with CO monitors placed near highly trafficked roads in urban areas with populations of 1 million or more. The data from these sites would be available for scientific studies that could help inform future reviews of the standard.

EPA estimates that the proposal would require approximately 77 CO monitors in 53 urban areas. EPA expects that states would not need to purchase new monitoring equipment. They could relocate some of their existing CO monitors to the near-road monitoring stations already required in connection with the revised nitrogen dioxide standards issued in January 2010. CO monitors at the new locations would be required to be operational by January 1, 2013.

The proposed rule only addresses the primary CO standards and is consistent with the advice and recommendations from the agency’s independent science advisors, the Clean Air Act Scientific Advisory Committee.

CO is a colorless, odorless gas emitted from combustion processes. Nationally and, particularly in urban areas, the majority of CO emissions come from motor vehicles.

EPA will accept comments for 60 days after the proposed rule is published in the Federal Register. If requested, the agency will hold a public hearing on the proposed rule on Feb. 18, 2011. EPA will take final action by Aug. 12, 2011.

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