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Ozone National Air Quality Standard Review. WESTAR Fall Business Meeting Boise, Idaho September 2006. Ozone NAAQS Review - History. Current review process started in 2005 Comprehensive assessment of the latest scientific and technical information Criteria Document published in August 2005
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Ozone National Air Quality Standard Review WESTAR Fall Business Meeting Boise, Idaho September 2006
Ozone NAAQS Review - History • Current review process started in 2005 • Comprehensive assessment of the latest scientific and technical information • Criteria Document published in August 2005 • EPA staff assessment in November 2005 – 1st Draft Staff Paper • Clean Air Scientific Advisory Committee (CASAC) reviewed • EPA released Final Criteria Document March 2006
EPA released 2nd Draft Staff Paper July 18, 2006 • Comments received until September 18, 2006 • EPA expects to issue Final Staff Paper sometime this fall (perhaps October)
EPA Administrator will consider: • Final Staff Paper • CASAC Comments • Public Comments • Final Decision to revise or retain the ozone standard is expected by March 28, 2007 • Final Action is expected by Dec. 19, 2007
Clean Air Scientific Advisory Committee • Met August 24 – 25, 2006 and recommended lowering the standard • Current 8 hour O3 standard = 0.08 parts per million (ppm) • CASAC, no more than 0.070 ppm • Should consider 0.055 or 0.060
Clean Air Science Advisory Committee • The current standard is not protective • EPA should eliminate the rounding convention • The upper end should be 0.070 ppm • The risk assessment should include all ozone, man made and natural
Are the WRAP CMAQ model results a useful guide for rural ozone analysis? • Is the model providing good estimates of hourly ozone production and depletion? • Compare observed ozone at the 6 monitors in the domain with model estimates • Statistical metrics • Mean normalized bias • Mean normalized error • Time series charts • Tools used • GIS • Perl programming • Additional scripts from the RMC • HYSPLIT
Evaluation Metrics • Mean Normalized Bias (MNB):A value of zero would indicate that the model over predictions and model under predictions exactly cancel each other out. • Mean Normalized Gross Error (MNGE):A value of zero would indicate that the model exactly matches the observed values at all points in space/time. • Previous guidance in the modeling community set a goal of: MNB <= 15% and MNGE of <= 25%. This was based on the experience of actual model performance over the years.
