NATA Overview

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NATA Overview

• Maine Air Toxic Initiative
• Ted Palma, USEPA, OAQPS
• August 3, 2004

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Outline

• What was NATA (a quick review)?
• Why did we do it
• What did the assessment consist of
• What were the results of the 1996 Assessment
• What are we up to now?
• What changes are in the 1999 NATA
• What are the results looking like
• When can I expect to see more

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Goals of the National-Scale Assessment

• Tool for EPA and States/Locals/tribes
• Identify air toxics of greatest concern
• Characterize contributions of different emission
  sources to exposure and risk
• Prioritize collection of new data
• Provide a baseline (with ambient data) to track
  trends and measure progress against goals
• By itself, the assessment is NOT being used as
  the basis for specific regulatory decisions

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1996 National Scale Assessment Chronology

• Initial draft of 1996 assessment Summer 2000
• SAB Review March 2001
• SAB Report December 2001
• Update Assessment based on SAB short-term
  recommendations January 2002
• Previewed by S/L/T January - March 2002
• Website opened to public May 31, 2002

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Features of the 1996 National-Scale Assessment

• Inhalation exposure only
• Chronic exposures only
• 1996 emissions data
• 48 states, VI, PR
• Sources of indoor origin excluded
• 50-km range
• Focuses on average/median exposures, not
  individual extremes
• Census tract-level calculations county-level and
  higher presentations
• 32 urban HAPs diesel PM

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Components of the Initial National-Scale
Assessment

Comparison
with
Ambient
Concentration
Monitoring
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Initial National-Scale AssessmentRisk
Characterization

• Cancer
• National drivers1
• Benzene
• Chromium
• Formaldehyde
• Regional drivers2
• Arsenic
• 1,3-Butadiene
• Coke oven emissions
• POM

• Non-Cancer
• National drivers3
• Acrolein
• Regional drivers4
• Acetaldehyde
• Arsenic
• 1,3-Butadiene
• Formaldehyde
• Manganese

1 Risk gt 10 in 1 million to 25 million people 2
Risk gt 10 in 1 million to 1 million people OR
Risk gt 100 in 1 million to 10,000 people
3 HQ gt 1.0 to 25 million people 4 HQ gt 1.0 to
10,000 people
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Initial National-Scale AssessmentRisk
Characterization

• Cancer
• National contributors1
• Acetaldehyde
• Carbon tetrachloride
• Chloroform
• Ethylene dibromide
• Ethylene dichloride
• Nickel
• Perchloroethylene

• Cancer
• Regional contributors2
• Acrylonitrile
• Beryllium
• Cadmium
• Ethylene oxide
• 1,3-Dichloropropene
• Hydrazine
• Trichloroethylene
• Quinoline
• 1,1,2,2-Tetrachloroethane

1 Risk gt 1 in 1 million to 25 million people 2
Risk gt 1 in 1 million to 1 million people
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Initial National-Scale AssessmentRisk
Characterization

• Not found to be drivers or contributors
• Hexachlorobenzene
• Lead compounds
• Mercury compounds
• Methylene chloride
• PCBs
• Propylene dichloride
• Vinyl chloride
• But this assessment cannot exonerate HAPs
  because
• It includes inhalation exposure only - some air
  pollutants (e.g., PCBs, mercury, lead) may pose
  significant risks by ingestion
• It has low resolution may not capture hot spots
• Limited comparisons show substantial
  underprediction of ambient levels, especially for
  metals
• It does not estimate individual extremes only
  typical exposures

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Diesel Exhaust

• Diesel Health Assessment Document
• CASAC reached closure on document
• Have a RfC no (EPA) potency slope
• Diesel exhaust likely human carcinogen
• Presently unable to assign a carcinogenic potency
• Possible range of upper-bound risk 10-3 to 10-5
• Also, diesel PM contributes to PM-2.5 non-cancer
  concerns

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Differences between 1999 NATA and 1996 NATA
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Emission Inventory

• Enhanced to 99 NEI for HAPs
• Quality control automated, improved
• Included more categories in point sources
• Increased number of facilities in point source
  inventory from 40K to 70K
• Included new non-point categories
• Included new mobile source models
• Improved speciation profiles by category-specific
  for
• Chromium (6)
• POM into unit risk classes

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Dispersion Modeling

• Addition of new HAPs (150 total)
• Selected all HAPs where we have health data
  (except Dioxin)
• Addition of Alaska and Hawaii
• U/R flag slightly differently to account for
  areas with industrial/commercial land but low
  population
• Accuracy improved by
• Updated spatial surrogates (new national database
  of land use data and updated census data)
• Improved region-specific background levels from
  monitoring data
• Analysis includes
• Updated meteorology (1999)
• Updated tract centroids (2000)
• Updated model-to-monitor comparison

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Exposure Assessment

• Characterization of variability improved by
• Use of ME factor distributions for some HAPs
• Revised grouping of activity patterns
• Use of 2000 Census
• Characterization of uncertainty improved by
• Presenting exposure ranges at tract level
• Incorporating results of case study
• Comparison of exposure estimates with personal
  monitoring data

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Dose Response/Risk Characterization

• Accuracy improved by use of most current values
  from IRIS and other sources
• Will not include Diesel PM in cancer risk
  calculations
• May not include Formaldehyde in cancer risk
  calculations (URE under review by OAQPS)
• Attached charts/maps do NOT include these HAPs
• Evaluate risk using both ambient (ASPEN) and
  exposure (HAPEM5) concentrations

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NATA 1999 efforts

• Draft 1999 NEI (Fall 2002)
• ASPEN modeling performed using draft NEI, 32 NATA
  1996 pollutants (Spring 2003)
• Air quality modeling results shared with State
  local agencies (Spring 2003)
• NEI corrections received in March 2003
• Revised final NEI in July 2003
• Air Quality Modeling using ASPEN (December 2003)
• Exposure Modeling using HAPEM5 (May 2004)
• Final Risk Characterization (using HAPEM5) (June
  2004)
• Internal Reviews (August 2004)
• Regional Office S/L/T Previews (Late August
  2004)
• Final NATA 1999 Public Release (Late September
  2004)

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1999 NEI Summary
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1999 NATADRAFT ASPEN Preview
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1996 NATA County Ambient Concentrations
Benzene County Medians Ug/m3
Median (Ug/m3)
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1999 NATA County Ambient Concentrations
Benzene County Medians Ug/m3
Median (Ug/m3)
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1999 NATADRAFT Risk Estimates Preview(Based on
HAPEM5 exposures)
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DRAFT
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DRAFT
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DRAFT