EPA is expected to release its proposed new standard for ground level ozone by June 20, 2007. The deadline had been May 30, 2007, but the parties involved in the legal actions that have forced this required new standard (including the American Lung Association, Environmental Defense, the Natural Resources Defense Council, and the Sierra Club) have agreed to this additional delay. The new deadline for the final rule is March 12, 2008.
Any tightening of the existing 8-hour standard of .08 parts per million will put many more cities and counties out of compliance (information on those already out of compliance ).
Current science and EPA staff recommendations are leading to recommendations ranging from .06 to .074 ppm, and EPA staff acknowledge that concentrations as low as .04 ppm can be harmful to some people. But politics, including strong opposition by some state and local officials to any tightening, is still shaping the final proposal, says Clean Air Watch's Frank O'Donnell,  202-302-2065.
Find extensive information on the staff recommendations, litigation, and other issues and processes tied to the new standard here. 
See a brief history of the jockeying over the ozone standard  since 1971.