The U.S. Environmental Protection Agency is proposing to keep the current national air quality standards for carbon monoxide, while taking steps to gather additional data through more focused monitoring.

The current health standards are 9 parts per million (ppm) measured over 8 hours and 35 ppm measured over 1 hour. EPA is proposing to revise air monitoring requirements to provide a more focused monitoring network with CO monitors placed near highly trafficked roads in urban areas with populations of 1 million or more. Data from these sites would be available for scientific studies that could help inform future reviews of the standard.

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

EPA said 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.

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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