icfi.com april 30, 2009 icfi.com © 2006 icf international. all rights reserved. air toxics in...
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icfi.com
April 30, 2009
icfi.com© 2006 ICF International. All rights reserved.
AIR TOXICS IN MOBILE COUNTY, ALABAMA:A MONITORING AND MODELING STUDY
WEBINAR:USEPA Office of Air Quality Planning and Standards
Arlene Rosenbaum, Ed Carr, Yi Hua Wei, Jonathan Cohen
ICF International
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Mobile County Air Quality Study
• Sponsored by local consortium – South Alabama Regional Planning Council– Mobile AL Chamber of Commerce– Mobile Bay Watch– Local industrial group– Alabama Department of Environmental
Management– US EPA Region 4
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Mobile County Air Quality Study
• Air toxics monitoring
• Modeling– Air quality– Population exposure– Health risk
• Community-based expectations process
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Air Toxics Monitoring
• 5 monitoring sites
• 45 HAPs– Fine and coarse fractions for 11 metals
• Meteorological data
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100 5
Miles
MobileBay
MOBILE CO.MOBILE CO.MOBILE CO.MOBILE CO.MOBILE CO.MOBILE CO.MOBILE CO.MOBILE CO.MOBILE CO.
BALDWIN CO.BALDWIN CO.BALDWIN CO.BALDWIN CO.BALDWIN CO.BALDWIN CO.BALDWIN CO.BALDWIN CO.BALDWIN CO.
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Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188Hwy 188
US 90US 90US 90US 90US 90US 90US 90US 90US 90
Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98Hwy 98
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Hw
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I-10I-10I-10I-10I-10I-10I-10I-10I-10
I-65I-65I-65I-65I-65I-65I-65I-65I-65
ChickasawChickasawChickasawChickasawChickasawChickasawChickasawChickasawChickasaw
SatsumaSatsumaSatsumaSatsumaSatsumaSatsumaSatsumaSatsumaSatsuma
SaralandSaralandSaralandSaralandSaralandSaralandSaralandSaralandSaraland
TheodoreTheodoreTheodoreTheodoreTheodoreTheodoreTheodoreTheodoreTheodore
Dauphin IslandDauphin IslandDauphin IslandDauphin IslandDauphin IslandDauphin IslandDauphin IslandDauphin IslandDauphin Island
Bayou La BatreBayou La BatreBayou La BatreBayou La BatreBayou La BatreBayou La BatreBayou La BatreBayou La BatreBayou La Batre
Grand BayGrand BayGrand BayGrand BayGrand BayGrand BayGrand BayGrand BayGrand Bay
CreolaCreolaCreolaCreolaCreolaCreolaCreolaCreolaCreola
MobileMobileMobileMobileMobileMobileMobileMobileMobile
Tillmans CornerTillmans CornerTillmans CornerTillmans CornerTillmans CornerTillmans CornerTillmans CornerTillmans CornerTillmans Corner
PrichardPrichardPrichardPrichardPrichardPrichardPrichardPrichardPrichard
WilmerWilmerWilmerWilmerWilmerWilmerWilmerWilmerWilmer
Mount VernonMount VernonMount VernonMount VernonMount VernonMount VernonMount VernonMount VernonMount VernonCitronelleCitronelleCitronelleCitronelleCitronelleCitronelleCitronelleCitronelleCitronelle
Population Density(persons/km2)
1 to 200 (28)200 to 600 (21)600 to 1,200 (34)
1,200 to 2,000 (29)2,000 to 2,970 (11)
Air Toxics Monitoring
• Locations – Industrial area 1– High population area– High traffic area– Industrial area 2– Rural background area
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Modeling Tools
• Air dispersion: Assessment System for Population Exposure Nationwide (ASPEN)
• Exposure: Hazardous Air Pollutant Exposure Model (HAPEM6a)
• Health Risk: IRIS, ATSDR, OEHHA
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ASPEN Modeling:Refinements from NATA
• Spatial resolution – 783 populated grid squares (2 km x 2 km)– NATA:114 Census tracts
• Temporal resolution– 3 seasons, according to local weather
patterns– NATA: annual
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Emissions• 130 HAPs• From NEI, with some corrections by local experts• 113 individual point sources• Non-point sources:
– manufacturing – non-manufacturing
• Non-road mobile: – aircraft– railroad– marine vehicles– other
• Onroad vehicles: – gasoline – diesel
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Onroad Vehicle Emissions:Refinements from NATA
• NEI county totals
• Spatial allocation to grid squares:
Local TDM link activity– primary highway with limited access – primary highway without limited access
– secondary and connecting roads
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Meteorological Inputs:Refinements from NATA
• Stability Array (STAR) sets: joint frequency distributions of wind speed, wind direction, stability class
• Measurements from 11 surface stations
• CALMET used to create STAR sets, by season, for each grid square– Capture variations in patterns at land-sea
boundary
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Background Concentration:Refinements from NATA
• Background = [Measured – modeled] at rural site• Benzene: -1.7 ug/m3 to 0.4 ug/m3
• Annual average = -0.60 ug/m3
• Rural site concentrations also overestimated for– Xylene– Toluene– Ethylbenzene– Hexane
• NATA: 0.35 ug/m3 (small urban)• 1,3–Butadiene: 0.04 ug/m3 to 0.06 ug/m3
• Annual average = 0.05 ug/m3 • 1.5 per million cancer risk• NATA: 0.03 ug/m3 (small urban)
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Comparison of MCAQS and NATA
• Similarities– Annual emission totals from NEI– ASPEN air dispersion model for onroad emissions– HAPEM6 population exposure model– Health risk factors from IRIS, ATSDR, OEHHA
• MCAQS Refinements– Finer spatial resolution– Seasonal temporal resolution– Spatial allocation of onroad emissions from TDM– Finely resolved local meteorology– Background concentrations from local measurements
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BenzeneModel to Monitor Comparison
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BenzenePopulation-Weighted Average
Exposure Concentration Contributionsby Source Type
Point
Gas Vehicle
Diesel Vehicle
Other Nonroad Sources
CMV Aircraft
Area
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BenzeneCarcinogenic Risk Distribution:
Comparison to NATA 2002
0
10
20
30
40
50
60
70
80
90
100
0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05
Carcinogenic Risk
Per
cen
tile
MCAQS
NATA 2002
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BenzeneCarcinogenic Risk Spatial Distribution
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1,3-ButadieneModel to Monitor Comparison
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1,3-ButadienePopulation-Weighted Average
Exposure Concentration Contributionsby Source Type
Gas Vehicle
Diesel Vehicle
Background
Other Nonroad Sources
Aircraft
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1,3-ButadieneCarcinogenic Risk Distribution:
Comparison to NATA 2002
0
10
20
30
40
50
60
70
80
90
100
0.E+00 2.E-06 4.E-06 6.E-06 8.E-06 1.E-05
Carcinogenic Risk
Per
cen
tile
MCAQSNATA 2002
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1,3-ButadieneCarcinogenic Risk Spatial Distribution
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AcroleinPopulation-Weighted Average
Exposure Concentration Contributionsby Source Type
Point
Gas Vehic le
Diesel Vehic le
Other Nonroad
Sources
Railroad CMV
Aircraft
Area
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AcroleinHazard Quotient Distribution:
Comparison to NATA 2002
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 1 2 3 4 5 6 7 8 9 10
Hazard Quotient
Ex
po
se
d P
op
ula
tio
n (
Pe
rce
nti
le) MCAQS
NATA 2002
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AcroleinHazard Quotient Spatial Distribution
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Diesel Particulate Matter: Exposure Concentration Distribution
0
10
20
30
40
50
60
70
80
90
100
1.E-01 1.E+00 1.E+01 1.E+02
Exposure Concentration (ug/m3)
Per
cen
tile
MCAQS
NATA 2002
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Diesel Particulate Matter: Population-Weighted Average
Exposure Concentration Contributionsby Source Type
Diesel Vehic le
Railroad
CMV
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Cancer Risk Summary
Population With Cancer Risk
above 10 in 1,000,000
0
50
,00
0
10
0,0
00
15
0,0
00
20
0,0
00
25
0,0
00
30
0,0
00
35
0,0
00
40
0,0
00
Naphthalene, gas
Acetaldehyde
Chromium VI Compounds
1,3-Butadiene
Benzene
Ethylene dibromide (Dibromoethane)
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Non-Cancer Risk Summary
Population with a Hazard Quotient
Above 1.0
0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 400,000
Methylene diphenyl
Formaldehyde
Chlorine
Acrolein
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Conclusions
• MCAQS: an approach to refining NATA methodology for regional modeling domains
• Relatively easy to apply using NATA modeling tools and data bases
• Refined model predictions show increased risk variability
• Model to monitor comparisons suggest that onroad mobile emissions for Mobile County are overestimated in the NEI