General National Ambient Air Quality Standards (NAAQS) Issues

1. Dom Ruggeri, P.E. Air Permits Division Texas Commission on Environmental Quality Advanced Air Permitting Seminar 2011 General National Ambient Air Quality Standards (NAAQS) Issues

2. Presentation Objectives • Review NAAQS basic elements • Discuss NAAQS review schedule • Update on NAAQS implementation

3. NAAQS Basic Elements • Indicator • Chemical species or mixture to be measured in ambient air • Averaging Time • The relevant period of exposure to the indicator • Level • Standard in parts per million or billion, or micrograms per cubic meter

4. NAAQS Basic Elements • Form • The air quality statistic compared to the level of the standard • Example • 1-hour NO2 NAAQS = 100 ppb • Compliance based on the 3-year average of the 98th percentile of the daily maximum 1-hour concentrations

5. NAAQS Review Schedule - Ozone • No change until at least 2013 • Continue to demonstrate compliance with current standard • EPA considering Ozone de minimis and single-source modeling rules

6. NAAQS Review Schedule - Lead and PM • Primary and secondary reviews • Lead proposal expected 2013 • PM10 and PM2.5 proposals expected late 2011 • Protection from visibility-related effects

7. NAAQS Review Schedule - Secondary NO2 and SO2 • Keep current standards; add new 1-hour standards • But, EPA decided current standards are not ecologically relevant • Must consider deposition-related effects • Proposed 5-year study to develop multi-pollutant, multimedia approach

8. Implementation Challenges • Lack of implementation rules • Required for major source permitting • Have not been issued concurrently with new standards

9. Implementation Challenges • Limited modeling guidance • Still no settled PM2.5, NO2, SO2 approach • Techniques may be too conservative • EPA trying to use old guidance but NAAQS changes make this difficult • Update plan for Appendix W delayed • Rule challenges

10. Key Implementation Changes - PM10 and PM2.5 • Jan 1, 2011 – must include condensable emissions (PM10 and 2.5) • Oct 20, 2011 – PM2.5 increment minor source baseline trigger date • Waiting for more PM2.5 guidance

11. Key Implementation Changes - NO2 and SO2 • Mar 2011 – new guidance, issues • Intermittent and production emissions • Averaging for SIL • Background temporal pairing • Screening ratios NO2/NOX • Ambient ratio 0.8; in-stack ratio 0.5

12. Key Implementation Changes - SO2 • Continue to evaluate 24-hour and annual NAAQS until 1-hour designations made • Continue to evaluate 3-hour, 24-hour, and annual increment

13. Major vs. Minor NSR • EPA wants to include precursor emissions and secondary effects for major NSR • Currently only Ozone review triggered by precursors (NOx or VOC) • PM2.5 precursors (NOx and SO2) included indirectly

14. Major vs. Minor NSR • EPA wants to move to multi-pollutant model such as CMAQ • Considering AERMOD update to include photochemical capability

15. Major vs. Minor NSR • Federal Clean Air Act requires a minor program • Should implement minor program consistent with major program • EPA desires unclear since each state minor program is different

16. Major vs. Minor NSR • Texas Clean Air Act requires controls and impacts review for all pollutants • TCEQ evaluating approaches to comply with state and federal requirements

17. Take-Home Points • Several changes to NAAQS have occurred and more are coming • New technical issues create challenges for both the regulated community and TCEQ

18. Contact Information • Dom Ruggeri • (512) 239-1508 • dom.ruggeri@tceq.texas.gov • Daniel Menendez • Team Leader - Air Dispersion Modeling Team • (512) 239-1537 • daniel.menendez@tceq.texas.gov