Mobile Source Air Toxics

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Mobile Source Air Toxics

• AMPO meeting
• July 20, 2004

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Overview

• What are they?
• Role of mobile sources
• Toxics rulemakings
• Estimating emissions
• Urban area analyses
• Project-level impacts

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Health Effects of Air Toxics

• Serious and often irreversible health effects
• Cancer
• Birth defects
• Reproductive effects
• Respiratory effects
• Neurological effects
• Immune system effects

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Mobile Source Air Toxics of Greatest Concern

• Benzene
• Formaldehyde
• Acetaldehyde
• Acrolein
• 1,3-butadiene
• Diesel exhaust (PM and organic gases)

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Clean Air Act Authority

• Section 202(l) specifically addresses mobile
  source-related air toxics
• Requires vehicle and/or fuel standards
• Achieve greatest emission reductions available
  considering cost and technology
• EPA issued 202(l) rule in March 2001

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March 2001 MSAT Rule

• Identified 21 mobile source air toxics
• Toxic emissions performance standard for gasoline
• Anti-backsliding
• Applies to refiners
• Identified data gaps
• Technical analysis plan for future research
• Committed to future rule (2004)
• Reassess need for and feasibility of additional
  controls

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New Toxics Rule

• Currently analyzing options
• Fuels
• Vehicles
• Nonroad
• Gas cans
• Bond rule to address small gasoline equipment
• Locomotive/marine diesel rule

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Estimating Emissions

• MOBILE6.2 estimates motor vehicle emissions of
• benzene (exhaust and evap)
• formaldehyde
• acetaldehyde
• 1,3-butadiene
• acrolein
• MTBE (exhaust and evap)

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MOBILE6.2

• MOBILE6 inputs plus some fuel parameters
• Benzene
• Aromatics
• Olefins
• Oxygenate content

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Estimating Emissions

• Capable of estimating other toxics, too
• User-supplied data
• Many toxics are estimated as a fraction of total
  organic gases (VOC)

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National Mobile Inventory Model

• NMIM to be publicly released soon
• Creates national, county-level emission
  inventories
• Highway vehicles and nonroad sources
• Components of system
• MOBILE6.2
• NONROAD
• County Level Database
• temperatures
• fuel properties
• vehicle registration distributions
• IM programs
• toxics inputs (toxic to VOC ratios, toxic to PM
  ratios, or toxic emission factors)

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Urban Area Analyses

• Much toxics information is based on
  national-scale modeling
• National Air Toxics Assessment for 1996
• Uses county-level VMT, average speeds, etc.
• Urban area analyses use more refined info
• Link-level inventories based on MPO data
• Air quality model with better resolution
• Houston, Portland, Philadelphia

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Houston Results

• More detailed analysis provides more realistic
  patterns of concentrations
• Better agreement with monitoring data
• Found hot spots that were not detected in
  national-scale analysis

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Project-level Impacts

• Growing evidence of near-roadway impacts
• Concentrations, exposure, health effects
• FHWA currently considering how/if toxics should
  be considered as part of NEPA
• Analytic tools are available
• MOBILE6.2
• Dispersion models

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Voluntary Programs

• Diesel retrofits
• Trucks, construction equipment, buses
• Anti-idling programs
• Ordinances, education, truck stop electrification
• VMT reduction (e.g., TCMs)
• Low emission gas cans
• Lawnmower and gas can buybacks