140 likes | 150 Views
Finding of Significant PM2.5 Precursors for SIP and Conformity Analysis Washington DC-MD-VA PM2.5 NAA. Sunil Kumar TAC, COG July 9, 2007. Washington DC-MD-VA PM2.5 NAA. Significant Precursors: Two-stage Process. Determine PM2.5 Precursors for SIP
E N D
Finding of Significant PM2.5 Precursors for SIP and Conformity AnalysisWashington DC-MD-VA PM2.5 NAA Sunil Kumar TAC, COG July 9, 2007
Significant Precursors:Two-stage Process • Determine PM2.5 Precursors for SIP • Base Year inventory must include all precursors (PM10, PM2.5, NOx, SO2, NH3, VOC) in emissions inventory • SIP: Focus on significant precursors • NEXT, Determine PM2.5 Precursors for Mobile Budgets/Conformity
PM2.5 Composition – STN DataMcMillan (Washington, DC) - 2004
PM2.5 Composition – High Level DaysMcMillan (Washington, DC) - 2001-2003 Winter Spring Summer Fall
PM2.5 Precursors for SIP Planning • PM2.5-Pri, SO2, NOx – Presumed significant by EPA • VOC & NH3 - Presumed insignificant by EPA
PM2.5 Precursors for SIP Planning • VOC – • EPA presumes insignificant. Role of VOC varies by region and is not well understood yet. • NH3 – • Limited control options • Uncertainties in inventories • NH3 reduction increases precipitation acidity (ecological & health hazard) • After SO2 reduction, PM2.5 more responsive to NOx reduction than NH3.
Detailed technical analyses needed to prove VOC & NH3 significant Need • Photochemical modeling – zero-out analysis; sensitivity analysis • Photochemical source apportionment tools (PSAT, DDM, TSSA, etc.) for estimating impact of all sources • Receptor modeling (e.g. PMF, CMB) Have • Analysis of ambient monitoring data, speciation data, and trends • Analysis of emissions inventories and trends
Recommendation PM2.5 Precursors for SIP Planning • Limited timeline to submit Annual PM2.5 SIP • Limited time/resources for modeling • Follow EPA’s recommendation – Consider PM2.5, SO2 and NOx as significant in absence of modeling
PM2.5 Precursors for Conformity Analysis • PM2.5-Pri and NOx - Mobile budgets needed (Conformity rule). • SO2 - Need to demonstrate significant contributionfrom mobile sources and also look at other criteria for setting up mobile budget. • VOC & NH3 – If found significant for PM2.5 SIP, then need to look at contributionfrom mobile sources and other criteria for setting up mobile budget.