1. Ozone Reactivity of Air Pollutant Emission Inventories Zachariah Adelman University of North Carolina William Carter University of California at Riverside Gail Tonnesen US EPA 12 th Annual CMAS ConferenceOctober 28-30, 2013

2. 3-State Air Quality Study (3SAQS) Colorado Utah Wyoming Cooperative agreement between UNC and National Park Service Broad modeling and data warehousing project to support oil and gas NEPA modeling 12 th Annual CMAS ConferenceOctober 28-30, 2013

8. VOC Reactivity Volatile organic compounds (VOCs) react at different rates and via different mechanisms to form ozone Reactivity: change in ozone with change in VOC emissions –f(Chemistry): reaction rate and mechanism –f(Ambient conditions): physical and chemical –f(Emissions change): magnitude and sign 12 th Annual CMAS ConferenceOctober 28-30, 2013

9. VOC Reactivity Reactivity may be calculated from chamber experiments or photochemical modeling Incremental reactivity: dO 3 /dVOC –Greatest under high NOx conditions Max Incremental Reactivity (MIR) – NOx conditions that yield highest VOC reactivity Max Ozone Incremental Reactivity (MOIR) - NOx conditions that yield highest peak [O 3 ] 12 th Annual CMAS ConferenceOctober 28-30, 2013

10. Reactivity Applications Conventional –Development of O 3 mitigation strategies that replace high with low reactive VOCs –Photochemical grid modeling calculations of lumped VOC reactivity This work –Reactivity-based perspective of emissions inventories 12 th Annual CMAS ConferenceOctober 28-30, 2013

11. VOC Chemical Speciation Speciation profiles: chemical composition of emission sources –Derived from source testing and lab studies –Mass fractions of organic compounds –Convert inventory VOC to photochemical mechanism species SPECIATE database –1000+ emission source profiles 12 th Annual CMAS ConferenceOctober 28-30, 2013

12. VOC Emissions Reactivity Profile Total MIR –Profile 7: Natural Gas Turbine –70% methane, MIR CH4 = 0.014 gO 3 /gCH 4 –30% formaldehyde, MIR FORM = 9.46 gO 3 /gH 2 CO –Total MIR = 0.7MIR CH4 + 0.3MIR FORM = 2.85 gO 3 /gVOC SPECIATE database reactivity now completed –Carter estimated MIR, MOIR, EBIR, for all 1700+ compounds in the database, including complex mixtures 12 th Annual CMAS ConferenceOctober 28-30, 2013

13. VOC Emissions Reactivity RTOG = TOG * Profile Total MIR RTOG/TOG = Relative emission reactivity 12 th Annual CMAS ConferenceOctober 28-30, 2013

14. VOC Emissions Reactivity RTOG = TOG * Profile Total MIR RTOG/TOG = Relative emission reactivity 12 th Annual CMAS ConferenceOctober 28-30, 2013

16. Conclusions Reactivity-based analysis of inventories focuses on sources with greatest ozone formation potential The validity of the analysis is dependent on the quality of emissions speciation data Reactivity metrics are based on “typical” urban conditions: extensibility problem 12 th Annual CMAS ConferenceOctober 28-30, 2013

17. Future Work Use RTOG results to explore inventory and speciation trends Look at the results from alternative reactivity metrics (MOIR and EBIR) Can this same concept be applied to VOC toxicity or other health effects endpoints? 12 th Annual CMAS ConferenceOctober 28-30, 2013

18. Acknowledgements 3SAQS Team UNC WRAP ENVIRON Colorado State University UC Riverside 3SAQS Cooperators National Park Service National Forest Service Bureau of Land Management States of CO, UT, WY EPA Region 8 12 th Annual CMAS ConferenceOctober 28-30, 2013