1. Impact of NOx Emissions in Georgia on Annual PM2.5
Jim Boylan, Byeong-Uk Kim, Michelle Bergin, Jim Kelly
Georgia Department of Natural Resources
9th Annual CMAS Conference
October 12, 2010

2. Nonattainment in Georgia

3. 1997 Annual PM2.5 NAAQS Design value of < 15.0 mg/m3
Average of 2007, 2008, and 2009 observations
State Implementation Plans
GA EPD has submitted annual PM2.5 SIPs for Atlanta, Macon, Rome/Floyd, and Chattanooga
Fine PM Implementation Rule (72 FR 20586)
“The final rule retains provisions for the State or EPA to conduct a technical demonstration to reverse the presumptive inclusion of NOx” as a PM2.5 attainment plan precursor.

4. 2002 Design Values for Georgia
SANDWICH technique has been applied to 5-year weighted FRM measurements

5. CMAQ Modeling Scenarios
2009 base case with all emissions included
100% state-wide NOx reduction (all sources)
50% state-wide NOx reduction (all sources)
30% state-wide NOx reduction (all sources)
NOx emission sources include:
Point, Area, On-road, Non-road, Fires, Biogenic

6. Evaluation Approach
Monitor specific impacts were determined by taking the difference between the 2009 future design value (with all emissions included) and the sensitivity run design value.
The modeling results were processed in accordance with EPA’s modeling guidance
SMAT, SANDWICH, and RRFs
Impacts compared against PSD Significant Impact Levels (SILs) for PM2.5 emissions from a single stationary source
Annual SILs  0.3 mg/m3 (which is 2% of the NAAQS)

7. 12-km CMAQ Modeling Domain

8. 100% NOx Reduction in Georgia
- - EPA’s Annual NSR Significant Impact Level (SIL)

9. 100% NOx Reduction in Georgia

10. Hourly Model Performance for OC Yorkville – July 2002

11. OC Model Performance
The CMAQ model shows poor hourly model performance with unrealistically high OC predictions in the early morning hours when the mixing height is low.
It is during these same hours that the model shows large OC sensitivities to NOx reductions.
OC modeling is still developing and does not include many import pathways.
Smog chamber studies at Caltech have shown that reducing NOx emissions can lead to higher SOA production from isoprene, monoterpenes, and aromatic VOC. None of these pathways are currently included in the model.

12. 30% and 50% NOx Scenario Source Sector 2009 NOx Inventory
Control Evaluation
2014 Potential
NOx Inventory
2030 Potential
EGU Point
97,168.0
Rule (sss) Remaining SCR + NG Conversion
35,950.8
Non EGU Point
51,681.7
AirControlNET
27,621.0
On Road Mobile
209,349.2
Fleet turnover
142,353.5
62,804.8
Non Road Mobile
85,732.9
Held Constant
Area
Fire
37,688.9
14,236.6
36,071.5
Total Inventory
495,857.3
341,966.3
262,417.6
Total Reduction
153,891.0
233,439.7
% Reduction
31.0%
47.1%

13. 50% NOx Reduction in Georgia
- - EPA’s Annual NSR Significant Impact Level (SIL)

14. 30% NOx Reduction in Georgia
- - EPA’s Annual NSR Significant Impact Level (SIL)

15. 30% NOx Reduction in Georgia

16. EPA’s PSAT Modeling
- - EPA’s Annual NSR Significant Impact Level (SIL)

17. 100% NOx Scenario
The 100% NOx reduction modeling scenario has a number of issues:
This scenario models unrealistic emission reduction that are far greater than can be realistically achieved
Most of the modeling response (75% - 85%) is due to reductions in secondary organic carbon
SOA pathways are highly uncertain and the model does a poor job of simulating hourly OC temporal variations

18. Conclusions
GA EPD feels it is inappropriate to evaluate the impacts from a brute force 100% statewide NOx sensitivity
GA EPD feels that a 30% statewide NOx sensitivity, a 50% statewide NOx sensitivity, or a 100% PSAT source apportionment run would be more appropriate to evaluate NOx impacts.
30% statewide NOx  0.11 mg/m3 (max. impact)
50% statewide NOx  0.22 mg/m3 (max. impact)
100% statewide PSAT NOx  0.12 mg/m3 (max. impact)
The above modeling scenarios show impacts below the annual PSD SIL and indicate that NOx is “insignificant” as a precursor to PM2.5 in the Georgia nonattainment areas.

19. Contact Information
Jim Boylan, Ph.D. Georgia Dept. of Natural Resources 4244 International Parkway, Suite 120 Atlanta, GA