Recent Developments in Air Quality Modeling Techniques for studying Air Toxics in the Houston-Galveston Area Prof. Daewon W. Byun Dr. Soontae Kim, Ms. Violeta Coarfa Dr. Peter Percell University of Houston Institute for Multidimensional Air Quality Studies Dr Graciela Lubertino, Houston Galveston Area Council Jason Ching, U.S. EPA Workshop for Air Toxics and Health Effects October 17-18, 2005 University of Houston

Why modeling air toxics? To better understand their impacts on human health and air quality To better understand their impacts on human health and air quality To protect public health by limiting their emissions from man- made sources To protect public health by limiting their emissions from man- made sources To help communities prepare to better respond in case of chemical spills of such substances To help communities prepare to better respond in case of chemical spills of such substances Air toxics assessment activities include - assessment of emissions: monitoring and modeling of air quality - programs for reducing exposure and emissions of pollutants; - development and implementation of control strategies of emissions; - emergency response in case of serious events. Fate-Transport Modeling Based on First Principles ”

Linking Air Quality and Exposure Modeling Estimate emissions Obtain concentrations of chemical in the medium at distance of interest Determine exposure of the population of interest Calculate the risk of injury associated with that exposure Ching, 2005 presentation

For neighborhood scale modeling: Method 1: Combine CMAQ with ASPEN (following EPA’s Philadelphia Study) Method 2: Apply trajectory adaptive grid (TAG) method Air toxics modeling Follows Ozone & PM approach Where we are now…. What we need to work on… Ching, 2005 presentation Meteorology Air Quality US Continent Regional/State HG area Neighborhood scale HAPEM

Key Issue: How to improve Air Toxics Emissions Inventories Air toxics Emissions Processing Method Air toxics Emissions Processing Method Separate processing: of toxics species that do not get involved in the main chemistry (i.e. CMAQ/HAPS) Separate processing: of toxics species that do not get involved in the main chemistry (i.e. CMAQ/HAPS) Combined processing of toxics with other photochemical (O3) and PM model species with full interaction (i.e. extended SAPRC) CMAQ/Air-Toxics Combined processing of toxics with other photochemical (O3) and PM model species with full interaction (i.e. extended SAPRC) CMAQ/Air-Toxics Which Emissions Inventory? Which Emissions Inventory? Which Model Species? Which Model Species? How to process?? How to process??

Toxic Emissions Inventories NEI Criteria VOC emissions NEI Criteria VOC emissions Needs proper speciation profiles Needs proper speciation profiles NEI HAP emissions NEI HAP emissions One-to-one mapping One-to-one mapping Texas Criteria VOC emissions Texas Criteria VOC emissions Needs proper speciation profiles Needs proper speciation profiles Texas PSDB Texas PSDB Speciated: One-to-one mapping Speciated: One-to-one mapping MOBILE6.2 Toxic emissions from HGAC MOBILE6.2 Toxic emissions from HGAC Additional Efforts Required EPA air toxics Inventories available What we did What we are working on now

Preliminary CMAQ/AT Results Preliminary studies have been done using three different inventories Preliminary studies have been done using three different inventories Emissions Data Emissions Data 1. EPA’s National Emissions Inventory NEI99 : 1. EPA’s National Emissions Inventory NEI99 : Criteria (CAPs) + Hazardous (HAPs) Criteria (CAPs) + Hazardous (HAPs) Tools: SMOKE ; CMAQ/Air-Toxics ; PAVE Tools: SMOKE ; CMAQ/Air-Toxics ; PAVE Domain: 4km_83x65 Domain: 4km_83x65 Period: Aug, 22 – Aug, 31, 2000 Period: Aug, 22 – Aug, 31, 2000 Simulation results were compared with the observations Simulation results were compared with the observations

Emissions for toluene and ethylbenzene Air Toxics Emissions August 25, :00 CDT PointAreaNon-road On-road All Sources PointArea Non-road On-road NEI99 with SMOKE2.1Result

CMAQ/AT 4.4 results for aromatics August 25, 1 pm GMT and 9 pm GMT Air Concentrations August 25, :00 CDT August 25, :00 CDT

Comparison with hourly observations at Clinton site

TEIb4a+NEI99 gives a better agreement between the simulation results and Clinton observational data for benzene Some success & some failures: But modeling advances are very promising if and only if we can improve emissions inventories… 2. TEI00 + NEI99:  TEIb4a + HAPs  TEIb4a + HAPs 3.NEI99 + TRI00:  CAPs + ( HAPs + TRI00)  CAPs + ( HAPs + TRI00) Comparison with observations at Clinton site

MOBILE 6.2 emissions Estimation NEI MOBILE MOBILE6 County-basedLink-based Spatial allocation Use surrogatesDefined by location Temporal allocation Use x-ref & profilesHourly emissions Species HAPsMSATs Example species: BENZ, MTBE, BUTA, FORM, ACETA, ACROL, NAPTHALENE, ETHYLBENZE, N-HEXENE, STYRENE, TOLUENE, XYLENE, LEAD What we are working on now  Link-based MSATS = mobile source air toxics species

How mobile emissions are estimated? VMT factors, Capacity factors, Speed model parameters Transportation Network Data Set TRANSVMT Mobile6 input POLFACRATEADJ IMPSUM VMT mix Hourly emissions

MOBILE6: Input/Ouput Registration distribution- TTI Registration distribution- TTI Gasoline content – TCEQ Gasoline content – TCEQ Control programs – TCEQ Control programs – TCEQ Trip data – H-GAC Trip data – H-GAC Temperature, humidity – SIP Temperature, humidity – SIP Diesel sales fractions – TTI Diesel sales fractions – TTI Calendar year Calendar year Emission factors (g/mile) for different air chemical species INPUTOUTPUT

Mobile Source Air Toxics (MSAT) Compounds By default: Benzene, 1,3-Butadiene, Formaldehyde, Acetaldehyde, Acrolein, MTBE By default: Benzene, 1,3-Butadiene, Formaldehyde, Acetaldehyde, Acrolein, MTBE Extended: Extended: Arsenic compounds, Chromium compounds, Dioxin/Furans, Ethylbenzene, n-Hexane, Lead compounds, Manganese compounds, Mercury compounds, Naphthalene, Nickel compounds, Polycyclic Organic Matter, Styrene, Toluene, Xylene, Diesel, Particulate Matter

Additional Parameters needed for Air Toxic Calculations GAS AROMATIC%: aromatic content of gasoline on a percentage of total volume basis GAS AROMATIC%: aromatic content of gasoline on a percentage of total volume basis GAS OLEFIN%: olefin content of gasoline on a percentage of total volume basis GAS OLEFIN%: olefin content of gasoline on a percentage of total volume basis GAS BENZENE%: benzene content of gasoline on a percentage of total volume basis GAS BENZENE%: benzene content of gasoline on a percentage of total volume basis E200: Percentage of vapor a given gasoline produces at 200°F E200: Percentage of vapor a given gasoline produces at 200°F E300: percentage of vapor a given gasoline produces at 300°F E300: percentage of vapor a given gasoline produces at 300°F OXYGENATE: oxygenate type and content of gasoline on a percentage of total volume basis. There are four oxygenate types in the model: MTBE, ETBE, ETOH, TAME OXYGENATE: oxygenate type and content of gasoline on a percentage of total volume basis. There are four oxygenate types in the model: MTBE, ETBE, ETOH, TAME

Houston Road Network What are required to estimate mobile source air toxics emissions?

Road Network, Nodes & Links

Processing is not always easy – the link data can be messed up

Link Nodes inside HGB 8 Counties

Link Nodes inside Harris County

Example of MOBILE6 outputs

Example Output File Anode Bnode Roadtype Pollutant EmissionType grams emissions by vehicle type BENZ COMPOSITE E BENZ COMPOSITE E BENZ EXH_RUNNING E E BENZ EXH_RUNNING E E BENZ START E E BENZ START E E BENZ HOT_SOAK E E BENZ HOT_SOAK E E BENZ REST_LOSS E E BENZ REST_LOSS E E BENZ RUN_LOSS E E BENZ RUN_LOSS E E MTBE COMPOSITE E MTBE COMPOSITE E MTBE EXH_RUNNING E E MTBE EXH_RUNNING E E MTBE START E E MTBE START E E MTBE HOT_SOAK E E MTBE HOT_SOAK E E MTBE REST_LOSS E MTBE REST_LOSS E MTBE RUN_LOSS E E MTBE RUN_LOSS E E BUTA COMPOSITE E E BUTA COMPOSITE E E BUTA EXH_RUNNING E E BUTA EXH_RUNNING E E BUTA START E E BUTA START E E FORM COMPOSITE E E FORM COMPOSITE E E-2

Example of Link-based Emissions VOC emissions from Brazoria County VOC emissions from Brazoria County

Example of Link-based Emissions BenzeneToluene XyleneStyrene

Benzene

Further Processing of air toxics emissions with SMOKE for CMAQ/AT modeling Link-to-gridded emissions Input data EI Processing for AQMs Temporal profiles SMOKE Allocating each link emissions to the covering cells Preparing MOBILE6 emission / vehicle types for temporal allocation Link-based MOBILE6 output Hourly emissions Gridded MOBILE6 emissions Diurnal temporal x-ref and profile

Point Source VOC Emissions in Houston-Galeston Static Adaptive Fine- mesh Eulerian (SAFE) Grid

Point source emissions inventory differences

Differences in Benzene Emissions from Point Sources TCEQ PSDB 2000NEI99 HAP

Differences in 1,3-Butadiene emissions from Point Sources TCEQ PSDB 2000NEI99 HAP

Processing of EI for speciated air toxics modeling requires speciation profile SAPRC99 SAPRC TOG ALK TOG ALK TOG ALK TOG ALK TOG ARO TOG ARO TOG CH TOG CH TOG ETHENE TOG ETHENE TOG OLE TOG OLE SAPRC Extended SAPRC Extended 0005 TOG CH TOG CH TOG ALK TOG ALK TOG ALK TOG ALK TOG ETHE TOG ETHE TOG OLE TOG OLE TOG BENZ TOG BENZ CMAQ/AT with Extended Aromatic Chemistry Mechanism

Current Developments in Air Toxics Modeling at IMAQS, University of Houston An Extended Chemical Mechanism of the EPA’s CMAQ for Air Toxics Studies (Poster) An Extended Chemical Mechanism of the EPA’s CMAQ for Air Toxics Studies (Poster) Problem of popular chemical mechanisms: many chemical species are lumped; cannot simulated the behavior of individual compounds important in the atmospheric chemical processes and/or with serious impact on the human health and surroundings; SAPRC99/extended (CMAQ/AT) Solution: find methods to implement species of interest in the chemical mechanisms employed by the photochemical models - SAPRC99/extended (CMAQ/AT) Suitable for studying acute health effects and verifying auto GC and canister measurements Suitable for studying acute health effects and verifying auto GC and canister measurements

Current Developments in Air Toxics Modeling at IMAQS, University of Houston A Transport Model for the Air Toxics Studies (Poster) A Transport Model for the Air Toxics Studies (Poster) Long-term simulations (several months, yearly) are preferred to better analyze and understand the physical and chemical behavior of toxic pollutants Health effect studies need long-term simulations for a proper correlation between pollutant concentration and various health conditions; need a faster model than CMAQ/Air-Toxics; IMAQS developed an engineering version of CMAQ/Air-Toxics, which can simulates seasonal and annual simulations (CMAQ/HAPS)  Suitable for studying chronic health effects of air toxics New method for air quality modeling -- under development New method for air quality modeling -- under development An Eulerian-Lagrangian Hybrid Modeling Method, Trajectory Adaptive Grid (TAG) underdevelopment (CMAQ/TAG) An Eulerian-Lagrangian Hybrid Modeling Method, Trajectory Adaptive Grid (TAG) underdevelopment (CMAQ/TAG) Can handle multiscale air quality issues at reasonable computational cost with high accuracy Can handle multiscale air quality issues at reasonable computational cost with high accuracy

Lagrangian packets to represent movement of pollutants, but in Eulerian adative grid 2-D 3-D Eulerian Grid Lagrangian packets Trajectory Adaptive Grid (TAG) Algorithm (very, very preliminary results as of today) Eulerian Grid

Testing of TAG – O3 (UTC 20:00 Aug 25) Preliminary O3 simulation results Eulerian (CMAQ-PPM) TAG-Result Maximum Minimum Closest Packet Average