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

Nonattainment in Georgia

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.

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

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

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)

12-km CMAQ Modeling Domain

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

100% NOx Reduction in Georgia

Hourly Model Performance for OC Yorkville – July 2002

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.

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) 2015 + 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%

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

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

30% NOx Reduction in Georgia

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

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

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.

Contact Information Jim Boylan, Ph.D. Georgia Dept. of Natural Resources 4244 International Parkway, Suite 120 Atlanta, GA 30354 James.Boylan@dnr.state.ga.us 404-362-4851