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GIS Applications for Air Quality Management. Robert Wu 吳震球 South Coast Air Quality Management District SCCAEPA April 26, 2008. Geographic Information System A Definition of GIS.
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GIS Applications forAir Quality Management Robert Wu 吳震球 South Coast Air Quality Management District SCCAEPA April 26, 2008
Geographic Information SystemA Definition of GIS GIS is a system of computer software, hardware, data, and personnel to help manipulate, analyze and present information that is tied to a spatial location
GIS Applications for Air Quality Management • Providing Air Quality Information • Health Risk Assessment Tool • Compliance/Enforcement Tool • Environmental Impact Analysis • Planning/Analytical Tool
GIS Applications for Air Quality Management (cont’d) • Exposure Studies • Identify Hot Spot Areas • Rule Development • Identification of Sources • Proximity Analysis
South Coast Air Quality Management DistrictSource/Receptor Areas
South Coast Air Quality Management DistrictAir Monitoring Stations
AERMOD Regulatory Status and Applicability • AERMOD is now an EPA Guideline Model, replacing ISCST3 • Published in Federal Register 9 Nov 2005 • Became Effective 9 Dec 2005 • First major short-range model promulgation in 25 years • Applicable for distances up to 50 km • 1-Year grace period for ISCST3
Implications for Departure of ISCST3 • This is a big deal - ISCST3 used around the world • In California, ISCST3 can still be used for State-only programs, BUT • ARB is moving the HARP model and air toxic program to AERMOD • Future ISCST3 modeling will be subject to criticism of not reflecting “best science” • Most District rules require permit modeling to follow EPA’s Guideline on Air Quality Models
AERMOD Overcomes Many ISCST3 Deficiencies • Meteorology treatment • Dispersion treatment • Building wake treatment • Terrain treatment
AERMOD Modeling System Structure AERMAP (Terrain) AERMOD(Dispersion) AERMET(Meteorology) AERSURFACE(Boundary Layer) AERSCREEN(Screening) Development In Progress
Comparison of Dispersion Model Features: Complex Terrain Modeling • ISCST3: • Elevation of each receptor point input • Predictions are very conservative in complex terrain • AERMOD: • Controlling hill elevation and point elevation at each receptor are input • Predictions are nearly unbiased in complex terrain
Overall Summary of Model Formulation • AERMOD is based on a newer understanding of atmospheric turbulence and dispersion • AERMOD solves many identified problems with ISCST3 • The issue of over-predictions in complex terrain is eliminated
Implementation of AERMOD in Southern CaliforniaAir Resources Board • HARP incorporates ISCST3 as an internal module • ARB will upgrade HARP to AERMOD • Definitive plans not yet made • Implementation highly unlikely by Dec 2006 • Critical decision: internal module vs external file • ARB staff have begun to run AERMOD • No current plans to hold AERMOD training courses for District staff • Not Discussed: Where is the funding coming from? 2/1/06
Reasons to Begin the Switch to AERMOD • ISCST3 will be allowed only until 9 Dec 2006 • ARB is implementing AERMOD in HARP • Restrictive ISCST3 modeling results may be relaxed with AERMOD • Facilities with complex terrain and building downwash issues expect the largest benefit • AERMOD is a complex model with a long learning curve
Expect to Buy a Faster Computer Real World ENSR Permit Modeling AERMOD Run • 3.0 GHz Intel XEON Workstation • 317 Sources: • 72 point sources (60 w/ downwash) • 236 volume sources • 9 area sources • 3,563 Receptors • 1.13 Million Source-Receptor Pairs • 215 source-receptors / min • 87.6 hours elapsed run time
Difficulties Ahead with Implementation • Meteorological data acquisition • Specific data requirements for AERMOD • EPA requiring 3-5 years of data • Quality upper air data critical • Funding • Where will ARB get funding for HARP development? • Where will Districts get training budgets? • Where will Districts get funding to upgrade their meteorological monitoring networks if needed?
Impact Analysis of Emissions • Gridded emission inventory • Temporal emission analysis • Show relationships between emissions and health effects data • Siting of new schools or facilities • Impact on sensitive receptors (schools, day-care centers, hospitals, etc)
AB 2588 • Emission Inventory • Prioritization • Risk Assessment • Public Notice • Risk Reduction California program under the Air Toxics Hot Spots Information and Assessment Act of 1987, Health and Safety Code Section 44300
Hotspots Analysis and Reporting ProgramHARP • Effective in 7/1/2005, required in Tier IV • Emission Inventory - CEIDARS • Dispersion Modeling – ISCST • Mapping – GIS • Analysis - HRA
Toxics Emission Inventory • Assembly Bill 2588 • SCAQMD MATES Project • Community Health Air Pollution Information System (CHAPIS) • California Emission Inventory Development and Reporting System (CEIDARS 2.5)
California Emission Inventory Development and Reporting System (CEIDARS 2.5)
Rule 1401New Source Review for Air Toxics • Adopted in June 1, 1990 • Initially specified limits for maximum individual cancer risk (MICR) and excess cancer cases for new, related, or modified sources which emit carcinogenic air contaminants • Amended several times to include non- carcinogenic compounds and to update the list of toxic compounds and the corresponding risk values
Rule 1401New Source Review for Air Toxics • Risk-based Regulation • 4-Tier Health Risk Assessment (HRA) • Tier I – Screening Emission Levels • Tier II – Screening Risk Assessment • Tier III – Screening Dispersion Modeling • Tier IV – Detailed Risk Assessment • Standards • Cancer Risk > 10-6 without T-BACT • Maximum Risks for each permit unit: • Cancer Risk = 10-5 • Cancer Burden = 0.5 • Hazard Index = 1.0