On March 12, 2008, EPA strengthened the national ambient air quality standards for ground-level ozone, and changed Air Quality Index (AQI) breakpoints to reflect the new primary standard. The new 100 level of the ozone AQI is 0.075 ppm, 8-hour average, which is the level of the revised primary standard.

For more information:

• About the revised ozone standards: http://www.epa.gov/groundlevelozone/
• Memo about forecasting under the revised AQI (PDF)
• Revised Ozone AQI Breakpoints (PPT)
• Final Ozone NAAQS Fact Sheet (PDF)
• Fact sheet and chart of the new breakpoints (PDF)