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APPENDIX H APPENDICES
APRIL 2009 GASTON EAST-WEST CONNECTOR DEIS
APPENDIX H
MOBILE SOURCE AIR TOXICS (MSAT) – DISCUSSION OF
IMPACTS
APPENDIX H
APRIL 2009 GASTON EAST-WEST CONNECTOR DEIS
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APPENDIX H – MOBILE SOURCE AIR TOXICS –
DISCUSSION OF IMPACTS
Contents
H.1 MOBILE SOURCE AIR TOXICS
H.2 MOBILE SOURCE AIR TOXICS IMPACT ANALYSIS
H.1 MOBILE SOURCE AIR TOXICS
In addition to the criteria air pollutants for which there are National Ambient Air Quality
Standards (NAAQS), EPA also regulates air toxics. Most air toxics originate from human-made
sources, including on-road mobile sources, non-road mobile sources (e.g., airplanes), area sources
(e.g., dry cleaners) and stationary sources (e.g., factories or refineries).
Mobile Source Air Toxics (MSATs) are a subset of the 188 air toxics defined by the Clean Air Act.
The MSATs are compounds emitted from highway vehicles and non-road equipment. Some toxic
compounds are present in fuel and are emitted to the air when the fuel evaporates or passes
through the engine unburned. Other toxics are emitted from the incomplete combustion of fuels
or as secondary combustion products. Metal air toxics also result from engine wear or from
impurities in oil or gasoline.
The EPA is the lead federal agency for administering the Clean Air Act and has certain
responsibilities regarding the health effects of MSATs. The EPA issued a Final Rule on
Controlling Emissions of Hazardous Air Pollutants from Mobile Sources (66 CFR 17229) (March
29, 2001). This rule was issued under the authority in Section 202 of the Clean Air Act. In its
rule, EPA examined the impacts of existing and newly promulgated mobile source control
programs, including its reformulated gasoline (RFG) program, national low emission vehicle
(NLEV) standards, Tier 2 motor vehicle emissions standards and gasoline sulfur control
requirements, and its proposed heavy duty engine and vehicle standards and on-highway diesel
fuel sulfur control requirements. Between 2000 and 2020, FHWA projects that even with a 64
percent increase in VMT, these programs will reduce on-highway emissions of benzene,
formaldehyde, 1,3-butadiene, and acetaldehyde by 57 percent to 65 percent, and will reduce on-
highway diesel PM emissions by 87 percent, as shown in Exhibit H-1.
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Exhibit H-1. Vehicle Miles Traveled (VMT) vs. Mobile Source Air Toxics Emissions, 2000–2020
Source: FHWA Web site, www.fhwa.gov/environment/airtoxic/vmtmsat2020.htm
Notes: For on-road mobile sources. Emissions factors were generated using MOBILE 6.2. MTBE proportion of market for
oxygenates is held constant, at 50 percent. Gasoline RVP and oxygenate content are held constant. VMT: Highway Statistics
2000, Table VM-2 for 2000, analysis assumes annual growth rate of 2.5 percent. "DPM + DEOG" is based on MOBILE 6.2-
generated factors for elemental carbon, organic carbon, and SO4 from diesel-powered vehicles, with the particle size cutoff set
at 10.0 microns. 1 short ton = 907,200,000 mg.
On February 9, 2007, and under authority of CAA Section 202(l), EPA signed a final rule, Control
of Hazardous Air Pollutants from Mobile Sources, which sets standards to control MSATs from
motor vehicles. Under this rule, EPA is setting standards on fuel composition, vehicle exhaust
emissions, and evaporative losses from portable containers. The new standards are estimated to
reduce total emissions of MSATs by 330,000 tons in 2030, including 61,000 tons of benzene.
Concurrently, total emissions of volatile organic compounds (VOC) will be reduced by over
1.1 million tons in 2030 as a result of adopting these standards.
H.2 MOBILE SOURCE AIR TOXICS IMPACT ANALYSIS
Unavailable Information for Project Specific MSAT Impact Analysis. This EIS includes
a basic analysis of the likely MSAT emission impacts of this project. However, available
technical tools do not enable us to predict the project-specific health impacts of the emission
changes associated with the alternatives in this EIS. Due to these limitations, the following
discussion is included in accordance with CEQ regulations (40 CFR 1502.22(b)) regarding
incomplete or unavailable information.
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estimated exposure. Each of these steps is encumbered by technical shortcomings or uncertain
science that prevents a more complete determination of the MSAT health impacts of this project.
• Emissions. The EPA tools to estimate MSAT emissions from motor vehicles are not
sensitive to key variables determining emissions of MSATs within the context of highway
projects. While MOBILE 6.2 is used to predict emissions at a regional level, it has
limited applicability at the project level. MOBILE 6.2 is a trip-based model—emission
factors are projected based upon a typical trip of 7.5 miles, and on average speeds for this
typical trip. This means that MOBILE 6.2 does not have the ability to predict emission
factors for a specific vehicle operating condition at a specific location at a specific time.
Because of this limitation, MOBILE 6.2 can only approximate the operating speeds and
levels of congestion likely to be present on the largest-scale projects, and cannot
adequately capture the emissions effects of smaller projects. For particulate matter, the
model results are not sensitive to average trip speed, although the other MSAT emission
rates do change with changes in trip speed. Also, the emissions rates used in MOBILE
6.2 for both particulate matter and MSATs are based upon a limited number of tests of
mostly older-technology vehicles. Lastly, in its discussions of PM under the conformity
rule, EPA has identified problems with MOBILE 6.2 as an obstacle to quantitative
analysis.
These deficiencies compromise the capability of MOBILE 6.2 to estimate MSAT
emissions. MOBILE 6.2 is an adequate tool for projecting emissions trends and
performing relative analyses between alternatives for very large projects, but it is not
sensitive enough to capture the effects of travel changes tied to smaller projects or to
predict emissions near specific roadside locations.
• Dispersion. The tools to predict how MSATs disperse are also limited. The EPA’s
current regulatory models, CALINE3 and CAL3QHC, were developed and validated more
than a decade ago for the purpose of predicting episodic concentrations of carbon
monoxide to determine compliance with the NAAQS. The performance of dispersion
models is more accurate for predicting maximum concentrations that can occur at some
time at some location within a geographic area. This limitation makes it difficult to
predict accurate exposure patterns at certain times at specific highway project locations
across an urban area in order to assess potential health risk. The National Cooperative
Highway Research Program (NCHRP) is conducting research on best practices in
applying models and other technical methods in the analysis of MSATs. This work also
will focus on identifying appropriate methods of documenting and communicating MSAT
impacts in the NEPA process and to the general public. Along with these general
limitations of dispersion models, FHWA is also faced with a lack of monitoring data in
most areas for use in establishing project-specific MSAT background concentrations.
• Exposure Levels and Health Effects. Finally, even if emission levels and
concentrations of MSATs could be accurately predicted, shortcomings in current
techniques for exposure assessment and risk analysis preclude us from reaching
meaningful conclusions about project-specific health impacts. Exposure assessments are
difficult because it is difficult to accurately calculate annual concentrations of MSATs
near roadways and to determine the portion of a year during which people are actually
exposed to those concentrations at a specific location. These difficulties are magnified for
70-year cancer assessments, particularly because unsupportable assumptions would have
to be made regarding changes in travel patterns and vehicle technology (which affects
emissions rates) over a 70-year period. There are also considerable uncertainties
APPENDIX H
APRIL 2009 GASTON EAST-WEST CONNECTOR DEIS
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associated with the existing estimates of toxicity of the various MSATs, because of
factors such as low-dose extrapolation and translation of occupational exposure data to
the general population. Because of these shortcomings, any calculated difference in
health impacts between alternatives is likely to be much smaller than the uncertainties
associated with calculating the impacts. Consequently, the results of such assessments
would not be useful to decision makers, who would need to weigh this information
against other project impacts that are better suited for quantitative analysis.
Summary of Existing Credible Scientific Evidence Relevant to Evaluating the Impacts
of MSATs. Research into the health impacts of MSATs is ongoing. For different emission types,
there are a variety of studies that show that some either are statistically associated with adverse
health outcomes through epidemiological studies (frequently based upon emissions levels found
in occupational settings) or that animals demonstrate adverse health outcomes when exposed to
large doses.
Exposure to toxics has been a focus of a number of EPA efforts. Most notably, the EPA
conducted the last National Air Toxics Assessment (NATA) in 1996 to evaluate modeled
estimates of human exposure applicable to the county level. While not intended for use as a
measure of or benchmark for local exposure, the modeled estimates in the NATA database best
illustrate the levels of various toxics when aggregated to a national or state level.
The EPA is in the process of assessing the risks of various kinds of exposures to these pollutants.
The EPA Integrated Risk Information System (IRIS) is a database of human health effects that
may result from exposure to various substances found in the environment. The IRIS database is
located at www.epa.gov/iris. The following toxicity information for the six prioritized MSATs
was taken from the IRIS database Weight of Evidence Characterization summaries. This
information is taken verbatim from EPA’s IRIS database and represents the agency’s most
current evaluations of the potential hazards and toxicology of these chemicals or mixtures.
• Benzene is characterized as a known human carcinogen.
• The potential carcinogenicity of acrolein cannot be determined because the existing data
are inadequate for an assessment of human carcinogenic potential for either the oral or
inhalation route of exposure.
• Formaldehyde is a probable human carcinogen, based upon limited evidence in humans
and sufficient evidence in animals.
• 1,3-butadiene is characterized as carcinogenic to humans by inhalation.
• Acetaldehyde is a probable human carcinogen based upon increased incidence of nasal
tumors in male and female rats and laryngeal tumors in male and female hamsters after
inhalation exposure.
• Diesel exhaust (DE) is likely to be carcinogenic to humans by inhalation from
environmental exposures. Diesel exhaust as reviewed in this document is the
combination of diesel particulate matter and diesel exhaust organic gases.
• Diesel exhaust also represents chronic respiratory effects, possibly the primary non-
cancer hazard from MSATs. Prolonged exposures may impair pulmonary function and
could produce symptoms, such as cough, phlegm, and chronic bronchitis. Exposure
relationships have not been developed from these studies.
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There have been other studies that address MSAT health impacts in proximity to roadways. The
Health Effects Institute, a non-profit organization funded by EPA, FHWA, and industry, has
undertaken a major series of studies to research near-roadway MSAT hot spots, the health
implications of the entire mix of mobile source pollutants, and other topics. The final summary
of the series is not expected for several years.
Some recent studies have reported that proximity to roadways is related to adverse health
outcomes, particularly respiratory problems1,2. Much of this research is not specific to MSATs,
instead surveying the full spectrum of both criteria and other pollutants. The FHWA cannot
evaluate the validity of these studies, but more importantly, these studies do not provide
information that would be useful in alleviating the uncertainties listed above and enable us to
perform a more comprehensive evaluation of the health impacts specific to this project.
Relevance of Unavailable or Incomplete Information to Evaluating Reasonably
Foreseeable Significant Adverse Impacts on the Environment, and Evaluation of
Impacts Based upon Theoretical Approaches or Research Methods Generally Accepted
in the Scientific Community. Because of the uncertainties outlined above, a quantitative
assessment of the effects of air toxic emissions impacts on human health cannot be made at the
project level. While available tools do allow us to reasonably predict relative emissions changes
between alternatives for larger projects, the amount of MSAT emissions from each of the project
alternatives and MSAT concentrations or exposures created by each of the project alternatives
cannot be predicted with enough accuracy to be useful in estimating health impacts. (As noted
above, the current emissions model is not capable of serving as a meaningful emissions analysis
tool for smaller projects.) Therefore, the relevance of the unavailable or incomplete information
is that it is not possible to make a determination of whether any of the alternatives would have
“significant adverse impacts on the human environment.”
Qualitative Impact Assessment for Mobile Source Air Toxics. In this DEIS, FHWA has
provided a qualitative analysis of MSAT emissions relative to the various alternatives, and has
acknowledged that all project alternatives may result in increased exposure to MSAT emissions
in certain locations, although the concentrations and duration of exposures are uncertain, and
because of this uncertainty, the health effects from these emissions cannot be estimated.
The FHWA has developed a tiered approach for analyzing MSATs in NEPA documents.
Depending upon the specific project circumstances, FHWA has identified three levels of analysis
(Memorandum – Interim Guidance on Air Toxic Analysis in NEPA Documents, FHWA, February
2006):
• No analysis for projects with no potential for meaningful MSAT effects;
• Qualitative analysis for projects with low potential MSAT effects; or
• Quantitative analysis to differentiate alternatives for projects with higher potential
MSAT effects.
1 South Coast Air Quality Management District, Multiple Air Toxic Exposure Study-II (2000); Highway Health
Hazards, The Sierra Club (2004) summarizing 24 studies on the relationship between health and air quality;
NEPA’s Uncertainty in the Federal Legal Scheme Controlling Air Pollution from Motor Vehicles,
Environmental Law Institute, 35 ELR 10273 (2005) with health studies cited therein.
2 Department of Preventive Medicine, University of Southern California Los Angeles, WJ Gauderman, H. Vora,
R. McConnell et al., Effect of Exposure to Traffic on Lung Development from 10 to 18 Years of Age: A Cohort
Study. The Lancet, (2007).
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APRIL 2009 GASTON EAST-WEST CONNECTOR DEIS
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Projects requiring a quantitative analysis include projects that have the potential for meaningful
differences among project alternatives. To fall into this category, projects must:
• Create or significantly alter a major intermodal freight facility that has the potential to
concentrate high levels of diesel particulate matter in a single location, or
• Create new or add significant capacity to urban highways such as interstates, urban
arterials, or urban collector-distributor routes with traffic volumes where the annual
average daily traffic (AADT) volumes are projected to be in the range of 140,000 to
150,000, or greater, by the design year; and also
• Be proposed to be located in proximity to populated areas or in rural areas, in proximity
to concentrations of vulnerable populations (i.e., schools, nursing homes, hospitals).
The proposed project falls into the qualitative analysis category due to its length and regional
importance. The project would not qualify as requiring a quantitative analysis because it would
not create or significantly alter a major intermodal facility, nor would the AADT be in the
140,000 to 150,000 range.
The AADTs for the various DSAs vary by segment and range from 10,000–12,800 AADT on the
west end of the project between I-85 and US 29-74 to 58,400-61,800 AADT on the east end of the
project across the Catawba River between NC 273 (Southpoint Road) and Dixie River Road,
based upon 2030 forecasts prepared for the project as a toll facility.
As discussed above, technical shortcomings of emissions and dispersion models and uncertain
science with respect to health effects prevent meaningful or reliable estimates of MSAT
emissions and effects of this project. However, even though reliable methods do not exist to
accurately estimate the health impacts of MSATs at the project level, it is possible to
qualitatively assess the levels of future MSAT emissions under the project. Although a
qualitative analysis cannot identify and measure health impacts from MSATs, it can provide a
basis for identifying and comparing the potential differences among MSAT emissions (if any)
from the various alternatives.
The qualitative assessment presented below is derived in part from a study conducted by the
FHWA titled A Methodology for Evaluating Mobile Source Air Toxic Emissions Among
Transportation Project Alternatives, found at:
www.fhwa.dot.gov/environment/airtoxic/msatcompare/msatemissions.htm.
For each DSA, the amount of MSATs emitted would be proportional to the vehicle miles traveled
(or VMT), assuming that other variables such as fleet mix remain the same for each alternative.
Table H-2 shows the projected 2030 VMT and vehicle hours traveled (VHT) in the Metrolina
region as a whole and also just in Gaston County (a subset of the Metrolina region), under the
No-Build Alternative and three representative DSAs: DSAs 4, 64, and 77. The other DSAs are
combinations of the segments included in these three representative DSAs and would have
similar results. The VMT and VHT for Gaston County under various alternatives are presented
in addition to the VMT and VHT for the Metrolina region as a whole because the Metrolina
region is so large (13 counties). Including information for the smaller area of Gaston County
provides another picture of the trends projected for each alternative in the county where the
majority of the project is located.
APPENDIX H
APRIL 2009 GASTON EAST-WEST CONNECTOR DEIS
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TABLE H-2: Vehicle Miles and Vehicle Hours Traveled Under Various Scenarios
2030 Vehicle Miles
Traveled (VMT)
in 1000s
2030 Vehicle Hours
Traveled (VHT)
in 1000s Scenario Region
Daily AM
Peak
PM
Peak Daily AM
Peak
PM
Peak
Gaston County Only 8,512 2,058 2,308 234.9 70.3 78.6
No‐Build Alternative
Entire Metrolina
Region 92,634 21,970 24,679 2,579.6 710.4 855.6
Gaston County Only 9,510 2,308 2,577 258.7 74.9 87.2 Detailed Study Alternative 4 –
Toll Facility Entire Metrolina
Region 93,339 22,290 24,880 2580.0 711.9 861.2
Gaston County Only 9,473 2,294 2,569 255.8 75.2 84.5 Detailed Study Alternative 64 –
Toll Facility Entire Metrolina
Region 93,226 22,245 24,867 2602.7 720.0 868.8
Gaston County Only 9,492 2,308 2,566 259.7 77.0 87.0 Detailed Study Alternative 77 –
Toll Facility Entire Metrolina
Region 93,216 22,267 24,843 2,607.7 723.4 872.2
Source: Gaston East-West Connector Traffic Forecasts for Toll Alternatives, Martin/Alexiou/Bryson, August 2008.
The VMT in Gaston County estimated for each of the DSAs is slightly higher than that for the
No Build Alternative (about 12 percent increase in Gaston County and <1 percent increase in the
Metrolina region as a whole) because the DSAs would provide a new facility over the Catawba
River and South Fork Catawba River where there are few to no crossings.
This increase in VMT means MSATs under the DSAs would probably be slightly higher than the
No-Build Alternative in the study area. In addition, because the estimated VMT under each of
the DSAs are nearly the same, varying by less than 1 percent, it is expected that there would be
no appreciable difference in overall MSAT emissions among the various DSAs.
Also, regardless of the alternative chosen, emissions will likely be lower than present levels in
the design year as a result of EPA’s national control programs that are projected to reduce MSAT
emissions by 57 to 87 percent from 2000 to 2020. Local conditions may differ from these national
projections in terms of fleet mix and turnover, VMT growth rates, and local control measures.
However, the magnitude of the EPA-projected reductions is so great, even after accounting for
VMT growth, (12 percent VMT growth in Gaston County) that MSAT emissions in the study area
are likely to be lower in the future in virtually all locations.
Because of the specific characteristics of the DSAs (i.e. new connector roadway), there may be
localized areas where VMT would increase, and other areas where VMT would decrease.
Therefore, it is possible that localized increases and decreases in MSAT emissions may occur.
The localized increases in MSAT emissions would likely be most pronounced along the new
roadway sections that would be built where there are few major roadways and little industry,
such as the area west of US 321 and south of Linwood Road, and the area west of Daniel Stowe
Botanical Garden under any of the DSAs. However, even if these increases do occur, they too
will be substantially reduced in the future as the implementation of EPA’s vehicle and fuel
regulations improves the region’s fleet of motor vehicles.
APPENDIX H
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As discussed in Section 2.3.1.4 of this Draft EIS, schools, hospitals, and community facilities
were mapped and avoided where possible in the development of the DSAs. There are four public
schools (and no private schools) located within or near the boundaries of the DSA corridors, as
shown in Figure 3-7a-b. These are Sadler Elementary School, Forest Heights Elementary
School, and Forestview High School/WA Bess Elementary School (located next to each other).
Minor amounts of right of way would be required from Sadler Elementary School and Forestview
High School for cross-street improvements (Section 3.2.6.1). There are no hospitals or nursing
homes within or near the DSA corridors.
In summary, under all DSAs in the design year, it is expected that there would be higher MSAT
emissions in the immediate project area, relative to the No-Build Alternative, due to increased
VMT. In comparing the DSAs, MSAT levels could be slightly higher in some locations than
others, but current tools and science are not adequate to quantify them or the risks to human
health. However, on a regional basis, EPA's vehicle and fuel regulations, coupled with fleet
turnover, will over time cause substantial reductions that, in almost all cases, will cause region-
wide MSAT levels to be significantly lower than today.