The Piston Effect Scientists and engineers around the world are becoming aware that the United States 8-hour ozone standard may present a problem that is called "unattainability." In November 1998, the topic was discussed at an international meeting in Beijing, China. The unattainability issue has been raised by A.S.L. & Associates and others. In the coming years, policymakers will find that the 8-hour ozone standard will be difficult to attain and control strategies will not work as planned. Mid-range hourly average concentrations decline slower than the higher hourly average concentrations and make it difficult to attain the standard. Independent analyses have confirmed the "piston" effect. Watch a slide presentation of the "piston" effect. Home Page | News | Corporation | Maps | Publications | Table of Contents | Multimedia Center Copyright © 1995-2008 A.S.L. & Associates. All rights reserved.