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Newsroom

July 16, 2007

New EPA Ambient Ozone Standard Proposal

On June 20, 2007, EPA proposed a new ambient ozone standard, as required by provisions of the Clean Air Act that call for revisions of air quality standards when there is evidence of deleterious effects at those established standards. This specific proposal was triggered by an evaluation of the health effects of ground-level ozone (smog). Ozone is formed via the reaction of NOx and certain organic compounds in the presence of sunlight.

The current ozone standard is .08 ppm, averaged over 8 hours. The proposed new standard ranges from .07 to .075 ppm, averaged over 8 hours, and EPA is seeking comment on which value (.07 or .075) to apply. At present, 104 counties do not meet the current .08 standard. If the new standard is approved, the number of areas that fail the ozone threshold will increase to potentially 533 counties. The EPA proposal would implement the new .07 or .075 ppm standard in 2013, allowing States that time interval to conduct modeling, evaluate NOx and reactive organic compound inventories & sources, and develop specific State Implementation Plans to achieve the new levels.

Additional NOx controls will certainly be a focal point of these future State-level rules. With the proposed rulemaking just underway there is not yet any indication which specific NOx sources will be affected. However, EPA Rulemaking is confirmation of the long-term trend that is at the core of the CPS-1 Legacy Engine Emissions Control program – the inexorable downward ratcheting of allowable NOx emissions and the potential these NOx control programs will include pipeline compressor engines, which in many states are collectively the second largest stationary source of NOx emissions after electric power plants. The pressure to reduce NOx from the installed base of pipeline engines will continue to create significant economic exposures for many pipelines, for which the CPS-1 program is developing a set of cost-effective retrofit options to achieve the very low NOx levels that States may require.

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