Clean Air Act Ozone Design Value Study
Clean Air Act Ozone Design Value Study: Final Report, A Report to Congress
Under Section 183 of the Clean Air Act, EPA was directed to conduct a study of the methodology currently in use for calculating design values to determine if the calculated design value "provides a reasonable indicator of the ozone air quality of ozone nonattainment areas." The focus of the study was on technical and statistical issues relating to the methodology contained in existing rules and guidance. Issues concerning the current form of the National Ambient Air Quality Standard (NAAQS) for ozone were not dealt with in the study.
The study found that the EPA ozone design value method does indeed provide a reasonable estimate of the "true" air quality design value for ozone nonattainment areas and of peak ozone levels within those nonattainment areas for the initial 3-year compliance period. However, the design value cannot describe the spatial variability in ozone concentrations across the area. More robust indicators based on specific monitoring sites also have large spatial variability. Ozone design values calculated with the EPA design value method are highly correlated with other more robust indicators. However, due to the spatial variability observed across urban areas one cannot expect a single numerical value to adequately describe complex concentration gradients across large metropolitan areas.
Note: The original report is not available in electronic format and was therefore scanned and its image files were converted to text to allow for searches. The conversion process does not result in a perfect transfer, some of the text may be misspelled and charts and graphs may not align.
We have posted, below, the Table of Contents and the Executive Summary. If you are interested in obtaining the full report, please contact Alice Chow for a CD-ROM of the scanned report. A copy of the original report is available for review at the EPA Region III library, 1650 Arch Street, Philadelphia, PA 19103-2029.
- Table of Contents [this is a 7.3 MB Portable Document Format (PDF) file which requires Adobe's free Acrobat Reader to view. See Adobe's web site for more information and to download Acrobat Reader].
- Executive Summary [this is a 16.5 MB Portable Document Format (PDF) file which requires Adobe's free Acrobat Reader to view. See Adobe's web site for more information and to download Acrobat Reader].