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Cary Gentry Sr. Environmental Specialist Forsyth County Environmental Affairs Department

Cary Gentry Sr. Environmental Specialist Forsyth County Environmental Affairs Department Winston-Salem, NC National Air Quality Conference April 8, 2008 Portland, OR. Triad Region of NC. Weather Data. * May - September. Temperature/Precip vs O3 AQI. * May - September. All. Old AQI.

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Cary Gentry Sr. Environmental Specialist Forsyth County Environmental Affairs Department

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  1. Cary Gentry Sr. Environmental Specialist Forsyth County Environmental Affairs Department Winston-Salem, NC National Air Quality Conference April 8, 2008 Portland, OR

  2. Triad Region of NC

  3. Weather Data * May - September

  4. Temperature/Precip vs O3 AQI * May - September

  5. All Old AQI New AQI Max Temp >=90 293 Ozone >100 83 28% 147 50% Ozone >50<=100 153 52% 108 37% Ozone <=50 57 19% 38 13% Temperature >=90degF

  6. No Precip Old New Max Temp >=90 142 Ozone >100 58 41% 86 61% Ozone >50<=100 67 47% 44 31% Ozone <=50 17 12% 12 8% Temperature >=90degF No Precip

  7. 2002 vs 2007 High >=90degF days Different O3 …WHY? Temperature vs O3 AQI

  8. Temperature vs Ozone • Strong correlation between >=90degF days and O3 days >100AQI before 2004 • Despite increase in >=90degF days since 2004, O3 days>100AQI remain relatively low • Something is going on besides the weather!

  9. Dry Summer and low O3 compared to previous years..WHY? Precipitation vs Ozone

  10. NOX SIP Call Beginning of 2004 One Explanation?

  11. Additional Controls • Clean Smoke Stacks: Signed in June 2002 • Requires a 77% reduction of NOX by 2009 • Inspection and Maintenance/OBD expanded to most counties in the state of NC • Better cars/fuels

  12. Slow to Adjust • Prediction of Action Days more difficult esp. in 2004 • Used to “old” pattern

  13. Example of Changes • Regression model • Adjust every year • Drop pre 2004 data • Adjust mentality • Keep up with trends

  14. Conclusions • There is no doubt weather factors contribute to ozone production or lack there of • Temperature • Precipitation • Comparisons between weather and ozone levels show interesting results • Before 2004, there was a strong correlation between >=90degF days and the # of high ozone days • Dramatic drop in ozone days 2004-2007 • Biggest influence on ozone levels appears to be industrial controls • NOX SIP call • Clean Smoke Stacks rule, etc • Adjustments must be made • Forecasting tools • Mentality • Similar results for PM2.5

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