icfi.com april 30, 2009 icfi.com © 2006 icf international. all rights reserved. air toxics in...

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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3

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

US

45

US

45

US

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US

45

US

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US

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US

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US

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US

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US

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US

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US

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US

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US

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US

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US

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US

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US

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Hw

y 217

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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