1. strum.madeleine@epa.gov 1 Integration of Criteria and Toxic Pollutants in SMOKE Madeleine Strum, OAQPS Collaborators: Marc Houyoux, MCNC/EMC Ron Ryan & Greg Stella, OAQPS Bill Benjey & Gerald Gipson, ORD Rich Cook, OTAQ For the Models 3 User’s Workshop October 22, 2002

2. strum.madeleine@epa.gov 2 EPA’s Toxics and Criteria Modeling Systems Separate b Photochemical vs Gaussian b SMOKE vs EMS-HAP b Criteria vs NTI Issues: Sound Science Consistency Efficiency EPA is moving towards one-atmosphere modeling to address these issues Grid

3. strum.madeleine@epa.gov 3 One-Atmosphere Approach National Emissions Inventory SMOKE CMAQ Modify to process multipollutant inventories Add capabilities for toxics Still two separate inventories for 1999: toxics (HAPs) & criteria COMMENTS:

4. strum.madeleine@epa.gov 4 Main Issue for SMOKE is to Address Overlap in Pollutants b No double-counting b Use of toxics inventory pollutants, where possible b Conservation of VOC mass, where possible Note: even though we’re not looking at particulates, addressing the VOC – HAP overlap will impact PM modeling

5. strum.madeleine@epa.gov 5 Steps in Determining Changes Needed to SMOKE b Examine criteria and toxics inventories; select when to use toxics in cases of overlap Mobile sources: EPA-generated nonroad and MOBILE6 onroad inventories for toxics and critera are consistentMobile sources: EPA-generated nonroad and MOBILE6 onroad inventories for toxics and critera are consistent Stationary source: Generally not consistentStationary source: Generally not consistent b Examine potential modeling applications Modeling ozone/PM using emission estimates for toxics from the toxics inventory in place of the criteria inventoryModeling ozone/PM using emission estimates for toxics from the toxics inventory in place of the criteria inventory Modeling toxics using emission estimates for toxics from the toxics inventoryModeling toxics using emission estimates for toxics from the toxics inventory

6. strum.madeleine@epa.gov 6 Steps in Determining Changes Needed to SMOKE (continued) b Determine how CMAQ could be modified for the applications No modifications needed for modeling ozone/PMNo modifications needed for modeling ozone/PM Develop new mechanisms and solvers to handle toxicsDevelop new mechanisms and solvers to handle toxics –Modify CB-IV to treat key toxics explicitly (e.g., formaldehyde and acetaldyde) –Add capability to approximate chemical loss of other toxics outside chemical mechanism via pseudo-first order reaction rates b Determine model species needed and how SMOKE will produce them – see next slide for details

7. strum.madeleine@epa.gov 7 For Ozone/PM Modeling Mobile sources: integration - toxic pollutants (gaseous organic HAP) from toxics inventory - non toxics (nonHAP VOC) from criteria inventory Stationary sources: speciate criteria How SMOKE Will Produce Model Species For Toxics Modeling Mobile sources: integration (same as above) Stationary sources: - speciate criteria for mechanism species that are not toxics - use toxics inventory for mechanism species that are explicit toxics (e.g., formaldehyde) - use toxics inventory for toxics modeled outside of mechanism

8. strum.madeleine@epa.gov 8 VOC or TOG (criteria) emissions Gaseous HAP emissions Create NONHAPTOG or NONHAPVOC: = VOC – sum(gaseous toxics species) Speciation Model species New SMOKE function Existing SMOKE function: but new speciation profiles are needed Integration Approach for Mobile Sources

9. strum.madeleine@epa.gov 9 Practical Considerations for Integration b The emission sources must be exactly the same for the toxics and the VOC/TOG b The methodology to estimate emissions should be consistent between the two inventories Both of these hold true for EPA-generated nonroad emissions and MOBILE6 generated emissions Generally, these don’t hold true for stationary sources

10. strum.madeleine@epa.gov 10 Integration for Onroad Mobile Sources b SMOKE runs MOBILE6.2 to generate TOG and 26 gaseous HAPs such as benzene, acetaldehdye, PAHs b For each emission source, SMOKE creates a nonHAPTOG pollutant by subtracting the toxics from the TOG b SMOKE applies speciation profiles for nonHAPTOG and individual HAPs to generate emissions of model species. b For a toxic modeled outside the mechanism, SMOKE maps the toxic to itself and its mechanism species EXAMPLE SPECIATION PROFILES FOR ONROAD SOURCES 1313A NONHAPTOG OLE 0.00127373705 1 0.0357011 1313A NONHAPTOG PAR 0.03439269933 1 0.491116 0000 BENZENE BENZENE 1.00 78.11 1.0 0000 BENZENE PAR 1.00 78.11 0.1666667 0000 BENZENE NR 5.00 78.11 0.8333333

11. strum.madeleine@epa.gov 11 Integration for Nonroad Mobile Sources Similar to Onroad b SMOKE imports toxic and criteria nonroad emission sources to be integrated- user assures consistency in sources b SMOKE creates a nonHAPVOC pollutant by subtraction b SMOKE applies speciation profiles

12. strum.madeleine@epa.gov 12 Approach For Stationary Sources is Replacement, not Integration Approach For Stationary Sources is Replacement, not Integration b SMOKE imports both criteria and toxic inventories b SMOKE speciates criteria inventory using speciation profiles that zero out the explicit toxics model species (e.g., formaldehyde) b SMOKE maps the toxics inventory pollutants to the CB-IV explicit toxics model species b For a toxic modeled outside the mechanism, SMOKE maps the toxic to itself, but not its mechanism species EXAMPLE SPECIATION PROFILES FOR STATIONARY SOURCES 0307 TOG OLE 0.00126649899 1 0.03553 0307 TOG PAR 0.03791738749 1 0.5397267 0000 FORM FORM 0.00126649899 1 0.03553 0000 BENZENE_ST BENZENE 1.00 30.03 1

13. strum.madeleine@epa.gov 13 Summary b We have explored one-atmosphere modeling using toxics and criteria inventories in the SMOKE/CMAQ modeling system, focusing on gaseous HAPS b Benefits to ozone/PM modeling: better estimates of a subset of the pollutants (gaseous TOG) than current VOC speciation approach b Benefits to Toxics modeling: allows for use of photochemical grid models with toxics inventory b Wider integration will be possible when inventories become more consistent