EPA hasannounced the availability of a new final document titled “Policy Assessment for the Review of the Carbon Monoxide National Ambient Air Quality Standards (PA).” 75 Fed. Reg. 67,361 (11/2/10). The PA recommends that EPA consider revising one or both of the existing national ambient air quality standards (NAAQS) for carbon monoxide (CO) based on available research into the health effects of exposure to the pollutant. The PA recommends setting the hourly standard for CO in a range between 9 parts per million (ppm) and 10 ppm and the eight-hour standards at 8 ppm or 9 ppm. EPA set the current air quality standards for CO in 1971; they are 35 ppm averaged hourly and 9 ppm averaged over eight hours. EPA is expected to propose either revising or retaining the existing standards later this year with a final rule projected for May 2011.