&EPA
United Sates
Environmental Plutadiuii
Agency
National Air Toxics Program:
The Second Integrated Urban Air Toxics Report to Congress
8/21/2014
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EPA-456/R-14-001
August 21, 2014
National Air Toxics Program:
The Second Integrated Urban Air Toxics
Report to Congress
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Outreach and Information Division
Research Triangle Park, North Carolina
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Acknowledgements
Lead Authors
Office of Air and Radiation
Yvonne W. Johnson, project lead
Regina Chappell, project lead
Rich Cook
Jeneva Craig
Barbara Driscoll
Marc Houyoux
Ted Palma
Kelly Rimer
Nate Topham
Margaret Zawacki
Office of Research and Development
Janet Burke
Sarah Mazur
Contributing Authors
Office of Air and Radiation
Mike Jones
Laura McKelvey
Sharon Nizich
Chris Stoneman
Office of Enforcement and Compliance
Scott Throwe
Office of Policy
William Nickerson
Office of Research and Development
Richard Baldauf
Philip Bushnell
Michael Hays
Danielle Lobdell
Yolanda Sanchez
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John Stanek
Tim Watkins
Larke Williams
Additional Contributions to the Report
The U.S. EPA Office of Children's Health
The U.S. EPA Office of Environmental Justice
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Table of Contents
National Air Toxics Program: iii
U.S. Environmental Protection Agency iii
Acronyms and Abbreviations ix
Executive Summary xii
Chapter 1: Introduction and Background 1-1
1.1. What are Air Toxics? 1-1
1.2. Relevant CAA Air Toxics Requirements 1-1
1.3. The Integrated Urban Air Toxics Strategy 1-2
1.3.1. List of 30 Urban Hazardous Air Pollutants 1-3
1.3.2. Area Source Categories 1-4
1.4. First Report to Congress 1-5
1.5. Second Report to Congress Overview 1-6
Chapter 2: Standard-Setting Activities 2-1
2.1. Introduction 2-1
2.2. Air Toxics Standard Setting for Area and major Sources 2-2
2.2.1. Emission Standards for Area Sources 2-3
2.2.2. Emission Standards for Major Sources 2-4
2.3. Air Toxic Standard Setting for Mobile Sources 2-6
2.3.1. Urban HAPs Emitted from Mobile Sources 2-6
2.3.2. Mobile Source Emission Control Programs 2-6
2.3.3. Recent and Upcoming Mobile Source Rulemaking Activities 2-7
2.3.4. Near-Roadway Pollution 2-8
2.4. Continued Efforts 2-9
Chapter 3: Identifying Air Toxics Risks in Urban Areas 3-1
3.1. Introduction 3-1
3.1.1. Data Gaps and Limitations 3-2
3.2. National Emissions Reduced Significantly Since 1990 3-3
3.3. National Air Toxics Monitoring: Key Pollutants Declining 3-5
3.4. Pollutant-Specific Emissions and Monitoring Trends 3-8
3.4.1. Benzene Levels Decline by 66 Percent from 1994 to 2009 3-8
3.4.2. U.S. Mercury Emissions 3-9
3.4.3. Dioxin Levels Are Down 3-11
3.4.4. Lead Emissions and Blood Lead Levels Have Been Significantly Reduced 3-12
3.4.5. Diesel Emissions Have Been Significantly Reduced 3-14
3.5. Evaluating Air Toxics Risks 3-15
3.5.1. Summary of 2005 NATA Risk Results 3-17
3.5.2. Urban Areas with the Highest Cancer Risk 3-19
3.6. Overall Findings In This Chapter and Continued Efforts 3-24
Chapter4: National, Regional and Community-Based Initiatives 4-1
4.1. Introduction 4-1
4.2. Area-wide Activities 4-2
4.3. State, Tribal and Local Government Initiatives and Programs 4-2
4.4. Community-Based Initiatives 4-4
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4.4.1. Community Air Risk Reduction Initiative (CARRI) 4-4
4.4.2. Community Action for a Renewed Environment (CARE) 4-4
4.5. Sustainable Skylines Initiative (SSI) 4-6
4.6. Community-Scale Air Toxics Ambient Monitoring Grants 4-7
4.7. National Initiatives 4-7
4.7.1. Wood Smoke Reduction Initiative 4-7
4.7.2. Collision Repair Campaign 4-9
4.7.3. School Air Toxics Monitoring Project Study 4-10
4.8. Mobile Source Initiatives 4-11
4.8.1. National Clean Diesel Campaign 4-11
4.8.2. SmartWay 4-12
4.8.3. Clean School Bus USA 4-12
4.9. National Enforcement-Based Initiatives 4-13
4.10. Continued Efforts 4-13
Chapter 5: Education and Outreach 5-1
5.1. Introduction 5-1
5.2. State, Tribal and Local Partnerships 5-1
5.3. Training and Outreach 5-2
5.4. Implementation Assistance Tools 5-3
5.5. Information Management and Public Awareness 5-3
5.6. Continued Efforts 5-5
Chapter 6: Research to Address Knowledge Gaps 6-1
6.1. Introduction 6-1
6.2. Exposure Assessment 6-3
6.2.1. Characterization of Need 6-3
6.2.2. Progress Thus Far 6-4
6.3. Health Effects - Hazard Identification and Dose-Response Assessment 6-10
6.3.1. Characterization of Need 6-10
6.3.2. Progress Thus Far 6-10
6.4. Risk Assessment And Risk Characterization 6-14
6.4.1. Characterization of Need 6-14
6.4.2. Progress Thus Far 6-14
6.5. Risk Management 6-16
6.5.1. Characterization of Need 6-16
6.5.2. Progress Thus Far 6-16
6.6. Research For The 21ST Century 6-17
Chapter 7: Conclusions and Looking Ahead 7-1
Appendix A. Standard-Setting Activities 1
A.I. Source Categories Subject to Standards under Sections 112 and 129 1
A.2. Risk and Technology Review (RTR) Program 6
Appendix B. Air Toxics Assessments 1
B.I. National Air Toxics Trends Station (NATTS) Network Sites 1
B.2. Urban HAP Trend Analysis 2
Appendix C. Urban Air Toxics Studies 1
C.I. Overview 1
C.2. Summaries of Studies 2
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Appendix D. Integrated Risk Information System (IRIS) Status 1
D.I. Status of Progress of Updates to IRIS assessments 1
References Cited 1
VIM
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Acronyms and Abbreviations
ACE
AMS
APEX
APTI
AQMP
AQS
BMDS
CAA
CalEPA
CARE
CARRI
CAS
CBSA
CDC
CFR
CHAD
CISWI
CMAQ
CMAQ-MP
CNS
CO
CRTS
DEARS
DEQ
DERA
DHHS
DOE
DOT
DPM
EGU
EIS
EPM
FACA
FDA
FR
FSIS
GACT
GIS
GPS
HAD
HAP
HAPEM
HC
HEATS
HEI
HERO
HHRA
HI
Air, Climate and Energy
Air Management Services
Air Pollutant Exposure
Air Pollution Training Institute
Air Quality Management Plan
Air Quality System
Benchmark Dose Software
Clean Air Act
California Environmental Protection Agency
Community Action for Renewed Environment
Community Air Risk Reduction Initiative
Chemical Abstract Service
Core Based Statistical Areas
Centers for Disease Control and Prevention
Code of Federal Regulations
Consolidated Human Activity Database
Commercial and Industrial Solid Waste Incinerators
Community Multi-Scale Air Quality
CMAQ Multipollutant Model
Central Nervous System
Carbon Monoxide
Community Risk and Technical Support
Detroit Exposure and Aerosol Research Study
Department of Environmental Quality
Diesel Emissions Reduction Provisions of the Energy Policy Act
U.S. Department of Health and Human Services
U.S. Department of Energy
U.S. Department of Transportation
Diesel Particulate Matter
Electric Generating Unit
Emissions Inventory System
Environmental Program Management
Federal Advisory Committee Act
U.S. Food and Drug Administration
Federal Register
Food Safety and Inspection Service
Generally Achievable Control Technology
Geographic Information System
Global Positioning System
Health Assessment Document
Hazardous Air Pollutant
Hazardous Air Pollutant Exposure Model
Hydrocarbon
Houston Exposure to Air Toxics Study
Health Effects Institute
Health and Environmental Research Online
Human Health Risk Assessment
Hazard Index
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HMIWI
I/M
IARC
IRIS
ISA
ITEP
LAX
LCA
IMS
MACT
MAP
MATES
MATS
MSATs
MWC
MYP
NAAQS
NACAA
NATA
NATTS
NEG/ECP
NEI
NEJAC
NESCAUM
NESHAP
NexGen
NEXUS
NHANES
NIEHS
NIOSH
NRC
NTAA
NTEC
NTI
OAQPS
OAR
OECA
OIG
ORD
OSWI
P2
PAH
PATA
PBT
PCBs
PEMS
PM
POM
PPRTV
RARE
REACH
RfC
Hospital/Medical/lnfectious Waste Incinerators
Inspection and Maintenance
International Agency for Research on Cancer
Integrated Risk Information System
Integrated Science Assessments
Institute for Tribal Environmental Professionals
Los Angeles International Airport
Life-Cycle Analysis
Learning Management System
Maximum Achievable Control Technology
Mercury Action Plan
Multiple Air Toxics Exposure Study
Mercury and Air Toxics Standards
Mobile Source Air Toxics
Municipal Waste Combustors
Multi-Year Plan
National Ambient Air Quality Standards
National Association of Clean Air Agencies
National Air Toxics Assessment
National Air Toxics Trends Station
New England Governors and Eastern Canadian Premiers
National Emissions Inventory
National Environmental Justice Advisory Council
Northeast States for Coordinated Air Use Management
National Emission Standards for Hazardous Air Pollutants
Advancing the Next Generation of Risk Assessment
Near-Road Exposures and Effects from Urban Air Pollutants Study
National Health and Nutrition Examination Survey
National Institutes of Environmental Health Sciences
National Institute for Occupational Safety and Health
National Research Council
National Tribal Air Association
National Tribal Environmental Council
National Toxics Inventory
Office of Air Quality Planning and Standards
Office of Air and Radiation
Office of Enforcement and Compliance Assurance
Office of Inspector General
Office of Research and Development
Other Solid Waste Incinerators
Pollution Prevention
Polycyclic Aromatic Hydrocarbons
Portland Air Toxics Assessment
Persistent Bioaccumulative Toxics
Polychlorinated Biphenyls
Portable Emission Measurement Systems
Particulate Matter
Polycyclic Organic Matter
Provisional Peer Reviewed Toxicity Values
Regional Applied Research Effort
Registration, Evaluation Authorization and Restriction of Chemicals
Reference Concentration
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RfD
RFS
RICE
RSD
RTR
SAB
SGI
SHC
SHEDS
SSI
STAG
STAR
SVOCs
TEF
TEQ
TRY
TRIM
TRIM.FaTE
VOC
WHO
Reference Dose
Renewable Fuel Standards
Reciprocating Internal Combustion Engines
Remote Sensing Device
Risk and Technology Review
Science Advisory Board
Seventh Generation Initiative
Sustainable and Healthy Communities
Stochastic Human Exposure and Dose Simulation
Sustainable Skylines Initiative
State and Tribal Assistance Grants
Science To Achieve Results
Semivolatile Organic Compounds
Toxic Equivalency Factors
Toxic Equivalents
Tons Per Year
Total Risk Integrated Model
The Environmental Fate, Transport and Ecological Exposure Module
Volatile Organic Compound
World Health Organization
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Executive Summary
The 1990 Clean Air Act Amendments (CAA) required the EPA to take specific actions to reduce
emissions and risks from air toxics. Air toxics (also known as hazardous air pollutants or HAPs) are
pollutants known to cause or suspected of causing cancer as well as respiratory, neurological,
reproductive and other serious health effects. Air toxics are emitted by mobile sources (e.g., cars,
trucks and construction equipment); large or major sources (e.g., factories and power plants);
smaller, or area, sources (e.g., gas stations and dry cleaners); and background sources (e.g., long-
range transport of pollution and natural emissions sources such as wildfires). Examples of air toxics
include benzene, found in gasoline; perchloroethylene, emitted from some dry cleaning facilities;
and methylene chloride, used as a solvent by several industries.
Congress expressed under CAA section 112(k) that emissions of air toxics, individually or in the
aggregate, may present significant risks to public health in urban areas and directed the U.S.
Environmental Protection Agency (EPA) to develop a strategy to reduce these risks. Considering
the large number of persons exposed and the risks of carcinogenic and other adverse health
impacts from HAPs, the EPA believed that to reduce public health risks in urban areas, aggregated
exposures from all sources had to be addressed. Therefore, it developed the Integrated Urban Air
Toxics Strategy in 1999, using all available authorities, for reducing cumulative public health risks in
urban areas posed by the aggregated exposures from all sources, including major stationary
sources, smaller area stationary sources and mobile sources. The EPA also recognized that national
regulations alone would not be enough to address all of the issues, particularly those affecting
urban areas. The Strategy consists of four key components:
Source-specific and sector-based standards, which include regulatory activities designed
to address air toxics on a national level;
National, regional and community-based initiatives focusing on multimedia and
cumulative risks to address and resolve issues at the local level through partnerships with
state, tribal and local governments and community stakeholders;
National-level air toxics assessments using analytical tools such as emissions inventories,
monitoring networks and analytical assessments to identify risks, track progress and help
prioritize efforts; and
Education and outreach consisting of activities involving state, tribal and local agencies,
cities, communities and other groups and organizations that help the EPA implement its
program to reduce air toxics emissions.
The CAA also required the EPA to submit two reports to Congress describing actions the EPA has
taken to reduce public health risks from urban air toxics. The EPA issued the first Urban Air Toxics
Report to Congress in 2000.l This report fulfills the requirement for the second report to Congress.
This report to Congress discusses the EPA's regulatory actions to address major, area and mobile
1National Air Toxics Program: The Integrated Urban Strategy Report to Congress. July 2000.
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sources of air toxics; provides background information on emissions and monitoring data;
discusses areas of the country that continue to experience elevated risks to public health as a
result of emissions of air toxics; describes national, regional and community-based initiatives to
address air toxics; provides detail on the EPA's education and outreach efforts; and identifies the
data gaps and limitations that affect our understanding of the air toxics program.
Because mobile sources are being included in this second report, as in the first report to Congress,
we address both the pollutants listed in Section 112(b) and pollutants that are mobile source air
toxics (that is, compounds that are emitted by mobile sources and have the potential for serious
adverse health effects). As a result, this report includes discussion of diesel exhaust (diesel
particulate matter and diesel exhaust organic gases). The EPA has identified diesel exhaust as a
mobile source air toxic of particular concern in its 2000 and 2007 mobile source air toxics rules and
its National Air Toxics Assessments (U. S. EPA, 2000; U. S. EPA, 2007).
Major findings of this report:
Overall air toxics emissions (from major, area and mobile sources) have significantly
declined since 1990. For stationary sources, it is estimated that over 1.5 million tons per
year of HAPs have been removed from the air due to standards promulgated, or made into
law, by the EPA. In addition, the EPA also estimates that about three million tons per year
of co-benefit criteria pollutant reductions have been achieved as a result of these
promulgated standards.
Mobile source emissions have been reduced by approximately 50 percent, about
1.5 million tons of HAPs, since 1990. With additional fleet turnover, we expect these
reductions to grow to 80 percent by the year 2030.
These reductions have been achieved through the following:
The EPA has issued emission standards for 68 area source categories, representing
90 percent of the emissions of the 30 urban HAPs.2 These include standards for
drycleaners, hazardous waste combustors, medical waste incinerators, iron and steel
foundries and paint-stripping operations.
Since 1990, the EPA has issued 97 maximum achievable control technology (MACT)
standards covering 174 major source categories. Some of these sources include gasoline
distribution facilities, chemical plants, petroleum refineries and steel mills. Most
recently, the EPA promulgated the 2012 Mercury and Air Toxics Standards for utilities.
The EPA has issued emissions standards to assure that sources accounting for not less
than 90 percent of the aggregate emissions of each of the seven persistent and
bioaccumulative pollutants listed in the CAA are addressed. These pollutants are
20n March 21, 2011, EPA completed its requirement under the Clean Air Act to assure that area sources accounting for 90
percent of the aggregate area source emissions of each of the 30 urban HAPs are subject to regulation. Simultaneously, EPA
issued a notice that the Agency had completed its requirement under the Clean Air Act to assure that sources accounting for
not less than 90 percent of the aggregate emissions of each of the seven HAP enumerated under Section 112(c)(6) are subject
to standards. Topham to Docket, Emission Standards for Meeting the 90 Percent Requirement Under
Section 112(c)(6) of the Clean Air Act (found in Docket ID EPA-HQ-OAR-2004-0505).
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alkylated lead compounds, polycyclie organic matter (POM), mercury,
hexachlorobenzene, polychlorinated biphenyls (PCB), 2,3,7,8-tetrachlorodibenzofurans
(TCDF) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).
For mobile sources, the EPA issued a rule in 2007 to reduce air toxics from gasoline-
fueled passenger vehicles, gasoline fuel and portable fuel containers. In addition, the
EPA has issued many rules to reduce volatile organic compounds, including gaseous air
toxics, and diesel particulate matter (PM) from a range of on- and off-road gasoline and
diesel vehicles and equipment.3 Exhaust from diesel engines contains many urban air
toxics, such as acetaldehyde, acrolein, benzene, 1,3-butadiene, formaldehyde and
polycyclic aromatic hydrocarbons.
The EPA has also issued numerous regulations that either have directly (using PM as a
surrogate for toxic metals), or indirectly as a co-benefit, reduced PM as a result of the
control equipment we anticipate will be installed.4 For example, PM emissions from the
integrated iron and steel industry estimate to be reduced by 5,800 tons per year5, and
PM emissions from power plants to be reduced by 52,000 tons per year.6
Emission reductions have also been achieved through non-regulatory efforts such as the
National Clean Diesel Campaign, administered by the EPA through the Diesel Emissions
Reduction provisions of the Energy Policy Act of 2005 (DERA). The EPA has provided
funding to national and state programs to support the implementation of diesel
emission reduction technologies. Over their lifetime, these projects are estimated to
reduce at least 12,500 tons of diesel PM, in addition to large reductions in emissions of
other pollutants.
In addition to developing regulatory air toxics programs, many state, tribal and local
agencies have moved forward with voluntary programs, which have been effective in
achieving air toxics emission reductions. Certain industries have been proactive in
participating in these programs.
Monitors show reduced levels of key air toxics in outdoor air. Ambient concentrations of
many air toxics (especially those that drive national cancer risk) show notable decreases
nationally. Benzene and lead are two air toxics that have been monitored for many years.
Since 1994, ambient levels of benzene have declined 66 percent. Across the country,
ambient levels of lead decreased 84 percent between 1990 and 2010. For this report, the
EPA completed an analysis of HAP emissions trends in urban areas based on recent
monitoring data. All pollutants, except for two, show a decrease in average concentrations
across selected metropolitan areas between 2003 and 2010. The greatest reductions
occurred for arsenic, benzene, 1,3-butadiene, lead, nickel and tetrachloroethylene.
Chloroform and dichloromethane show a slight increase in national trends primarily due to
a few sites located near industry using these solvents or roadways. Thus, even though the
trend for a given pollutant nationwide could be down, this does not mean that
372 FR 8427. February 26, 2007.
4Particulate matter is not an air toxic, however, it is a surrogate for some air toxics.
568 FR 27646. May 20, 2003.
6Mercury Air Toxics Standard. 77 FR 9304. February 16, 2012.
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concentrations are necessarily decreasing in every place with a monitor.
Some areas around the country have elevated levels of risks from air toxics. The EPA's
2005 National Air Toxics Assessment (NATA)7 estimated that based on 2005 conditions, the
national average cancer risk was about 50 in a million due to emissions of air toxics from all
outdoor sources (i.e., all stationary sources and mobile sources as well as background and
secondary formation). NATA also estimated that based on 2005 conditions, more than 13.8
million people mainly in urban locations were exposed to cancer risks greater than 100 in a
million due to these emissions of air toxics. While emissions from three pollutants, namely
formaldehyde, benzene and acetaldehyde, contributed to about two-thirds of the total
risks at a national level; each urban area had a unique set of sources and pollutants that
drive the risk.
The EPA is partnering with state, tribal and local governments and communities to
reduce risks from air toxics. Since 2001, the EPA has provided just under $20 million in
grant funding to communities to assess air toxics impacts and find local solutions to reduce
releases of HAPs, first under the Community Air Risk Reduction Initiative (CARRI) and then
the Community Action for a Renewed Environment (CARE) program. Most of the recipients
of these grants are from low income, minority or tribal communities. Since 2008, the EPA
has also provided over $500 million in funding to reduce emissions from diesel engines,
many of which are located in urban areas, under the National Clean Diesel Campaign.
The EPA focused compliance and enforcement efforts on communities that are known to
be affected by significant air toxic emissions and has identified previously unknown
emissions of air toxics. Since 2004, federal enforcement cases have resulted in
approximately 5,000 tons of HAP reductions. In addition, the Federal Air Toxics
Enforcement Initiative has resulted in facilities installing an estimated $42 million in
pollution controls.
The EPA continues to address air toxics research needs. The EPA is conducting research to
make further progress in understanding and reducing potential for human health and
environmental effects related to air toxics. The quality and quantity of data supporting
EPA's air toxics program have improved since 1990, with better emissions information,
health benchmark data, models and monitoring data. The EPA also has more effective
analytical tools, including models that account more fully for exposure and transformation
of pollutants over time; however, there remain areas where additional information is
needed. This report includes a summary of research needs and knowledge gaps identified
in the first report to Congress. For example, to improve the EPA's exposure assessments
and our ability to track progress, this report identified the need for measurement data and
human activity patterns to better model exposure microenvironments, such as urban areas
or indoor environments. This report also highlights current or recent air toxics research
7The 2005 National Air Toxic Assessment technical report and results can be found on the EPA website at:
http://www.epa.gov/ttn/atw/nata2005/index.html. It should be noted that the 2005 NATA represents a snap-shot of
conditions in 2005 and, as such, does not reflect current conditions. Since 2005, the EPA, states, and communities have
implemented a number of programs to reduce air toxics emissions. The EPA is in the process of updating its NATA using more
recent data.
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activities and describes ways to improve or bolster existing efforts, with the goal of
reducing the public health impacts of air toxics emissions in the future.
Conclusion:
Through the EPA's efforts and those of our partners, emissions and concentrations of toxic air
pollution in the outdoor air are decreasing in both urban and rural communities across the United
States. However, despite the significant strides in the air toxics program, many areas around the
country remain with elevated risks from air toxics compared to areas of the country with very few
or no sources of air toxics emissions. These risks occur mostly in urban areas where emission
sources can be more concentrated, in communities near facilities emitting toxic air pollution and
near roadways. One of the ways the EPA will continue to address urban air toxics on numerous
fronts, including joint efforts with state, tribal and local governments, is through regulations called
for under the CAA. In addition, the EPA will continue to address data gaps and other research
needs, improve emissions data reporting systems and better integrate pollution prevention and
voluntary programs in regulatory and non-regulatory efforts to ensure protection of public health
and to better manage air quality.
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Chapter 1: Introduction and Background
1.1. WHAT ARE AIR TOXICS?
Air toxics are pollutants known to cause or suspected of causing cancer or other serious health
effects (e.g., birth defects, reproductive effects).8 Most air toxics originate from on-road mobile
sources (e.g., cars, trucks); off-road mobile sources (e.g., construction equipment and lawn
mowers); major stationary sources (e.g., factories, refineries, power plants); smaller area sources
(e.g., hospital sterilizers and small publicly owned treatment works); and indoor sources (e.g.,
some building materials and cleaning solvents). The long-range transport of pollution and natural
emissions sources such as wildfires and volcanoes can also contribute to the "background" levels
of toxics in the air. Examples of toxic air pollutants include benzene, found in gasoline;
tetrachloroethylene (i.e., perchloroethylene), emitted from some dry cleaning facilities; and
dichloromethane (i.e., methylene chloride), used as a solvent by several industries. Exhaust from
diesel engines contains many urban air toxics, such as acetaldehyde, acrolein, benzene, 1,3-
butadiene, formaldehyde and polycyclic aromatic hydrocarbons, and diesel exhaust itself is a likely
human carcinogen and may cause other serious effects (U.S. EPA, 2002a).
More than half of the 187 HAPs listed by Congress in the CAA are known or suspected to cause
cancer. In addition, many HAPs can cause noncancer health effects, such as damage to the
immune, respiratory, neurological, reproductive and developmental systems. Health concerns can
result from both short-term and long-term exposure. HAPs can disperse locally, regionally,
nationally or globally and after deposition can persist in the environment for long periods of time,
bioaccumulate in the food chain, or both.
The health risks from exposure to air toxics are greater in urban areas due to the concentration of
air pollution sources, including mobile and stationary sources, and population density. Health
effects from exposure to HAPs might be more severe to more susceptible or sensitive populations
such as children or individuals with compromised health status, or members of disproportionately
impacted communities.
1.2. RELEVANT CAA AIR TOXICS REQUIREMENTS
The air toxics provisions of the CAA were substantially amended in 1990. Section 112(d) requires
the EPA to issue emissions standards for certain stationary sources of HAPs. Section 112(k) focuses
on HAP emissions from smaller stationary sources or area sources in urban areas that could
individually, or in the aggregate, present significant risks to public health.9 Section 112(k)(3) directs
the EPA to develop a comprehensive national strategy to control emissions of air toxics from area
8The use of the terms "air toxics" or "toxic air pollutants" in this report refers specifically to those pollutants that are listed
under section 112(b) of the CAA as "hazardous air pollutants" or HAPs.
9Area sources are those stationary sources that emit, or have the potential to emit, less than 10 tons per year of any one HAP
and less than 25 tons per year of a combination of HAPs.
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sources in urban areas. This section also requires the EPA to identify at least 30 HAPs emitted from
area sources that present the greatest threat to public health in the largest number of urban areas
and the source categories emitting such pollutants. After identifying the source categories, section
112(k) requires the EPA to ensure that 90 percent or more of the aggregate emissions of each of
the 30 identified air toxics are subject to standards. Section 112(k)(5) requires the EPA to submit
two reports to Congress on actions taken under section 112(k) to reduce the risk to public health
posed by the release of HAPs from area sources.
In addition to section 112, section 202(1) requires the EPA to issue a study of the need for, and
feasibility of, controlling emissions of toxic air pollutants which are unregulated under the Act and
associated with motor vehicles and motor vehicle fuels, and the need for and feasibility of,
controlling such emissions and the means and measures for such controls. The Act required the
EPA, based on the study, to issue regulations containing reasonable requirements to control air
toxics from motor vehicles and motor vehicle fuels. This study was completed in 1993 (U.S. EPA,
1993) and EPA issued regulations addressing mobile source air toxics in 2000 and 2007 (U.S. EPA,
2000, 2007).
1.3. THE INTEGRATED URBAN AIR TOXICS STRATEGY
As noted above, section 112(k)(3) instructs the EPA to develop a comprehensive strategy to control
emissions of HAPs from area sources in urban areas. Considering the large number of persons
exposed and the risks of carcinogenic and other adverse health effects from HAPs, the EPA
believed that to reduce public health risks in urban areas, aggregated exposures from all sources
had to be addressed. The EPA also recognized that national regulations alone would not be enough
to address all of the issues, particularly those affecting urban areas. Therefore, the Integrated
Urban Air Toxics Strategy10 (Strategy) was developed in 1999, using all available authorities, for
reducing cumulative public health risks in urban areas posed by the aggregated exposures from all
sources, including major stationary sources, smaller area stationary sources and mobile sources.
The Strategy, relying on the requirements of sections 112(c), 112(k) and 202(1), consists of four key
components:
Source-specific and sector-based standards which include regulatory activities designed
to address air toxics on a national level;
National, regional and community-based initiatives focusing on multimedia and
cumulative risks to address and resolve issues at the local level through partnerships with
state, tribal and local governments and community stakeholders;
National-level air toxics assessments using analytical tools such as emissions inventories,
monitoring networks and analytical assessments to identify risks, track progress and help
prioritize efforts; and
Education and outreach consisting of activities involving state, tribal and local agencies,
cities, communities and other groups and organizations that help the EPA implement its
10The National Air Toxics Program: The Integrated Urban Strategy. July 19,1999. 64 FR 38706.
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program to reduce air toxics emissions.
In addition, the Strategy includes three goals, two mandated by section 112(k) and the third being
an overall programmatic goal to address populations and areas disproportionately impacted by air
toxics. The goals of the Strategy are as follows:
Attain a 75 percent reduction in incidence of cancer attributable to exposure to HAPs
emitted by stationary sources;
Attain a substantial reduction in public health risks (such as birth defects and
reproduction effects) posed by HAP emissions from area sources; and
Address disproportionate impacts of air toxics hazards across urban areas.
1.3.1. List of 30 Urban Hazardous Air Pollutants
The Strategy also addresses the requirements of CAA section 112(c)(3) and (k)(3)(B). First,
consistent with sections 112(c)(3) and 112(k)(3)(B), the agency must identify at least 30 HAPs,
"which, as the result of emissions from area sources, present the greatest threat to public health in
the largest number of urban areas." The EPA met this requirement in 1999 in the Integrated Urban
Air Toxics Strategy. Specifically, in the Strategy, the EPA identified 30 HAPs that pose the greatest
potential health threat in urban areas, and these HAPs are referred to as the "30 urban HAPs." In
the Strategy, the EPA also identified an additional three HAPs, but these HAPs were not generally
emitted by area sources and as such were not included as part of the 30 urban HAPs. The three
additional HAPs are coke oven emissions, 1,2-dibromoethane and carbon tetrachloride. Exhibit 1-1
includes the list of the 30 urban HAPs.
Exhibit 1-1. List of the 30 Urban HAPs
Acetaldehyde
Acrolein
Acrylonitrile
Arsenic compounds
Benzene
Beryllium compounds
1,3-butadiene
Cadmium compounds
Chloroform
Chromium compounds
Dioxin
Propylene dichloride
1,3-dichloropropene
Ethylene dichloride (1,2-
dichloroethane)
Ethylene oxide
Formaldehyde
Hexachlorobenzene
Hydrazine
Lead compounds
Manganese compounds
Mercury compounds
Methylene chloride
(dichloromethane)
Nickel compounds
Polychlorinated biphenyls (PCBs)
Polycyclic organic matter (POM)
Quinoline
1,1,2,2-tetrachloroethane
Tetrachloroethylene
(perchloroethylene)
Trichloroethylene
Vinyl chloride
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1.3.2. Area Source Categories
Second, sections 112(c)(3) and 112(k)(3)(B) require the EPA
to list sufficient categories or subcategories of area sources
to ensure that area sources representing 90 percent of the
emissions of the 30 urban HAPs are subject to regulation.
Through the Strategy and multiple separate listings (see
side box), the EPA identified 68 area source categories
representing 90 percent of the aggregate emissions of the
30 urban HAPs.
Area Source Category Listings
July 19,1999 (64 FR 38705)
Feb. 12, 2002 (67 FR 6521)
June 26, 2002 (67 FR 43112)
Nov. 8, 2002 (67 FR 68124)
Nov. 22, 2002 (67 FR 70427)
Finally, sections 112(c)(3) and 112(k)(3)(B) require that, by November 15, 2000, the EPA
promulgate emission standards to assure that area sources accounting for 90 percent of the
aggregate area source emissions of each of the 30 urban HAPs are subject to regulation. The EPA
has issued sufficient regulations to meet this requirement. Exhibit 1-2 presents the list of source
categories for which the Agency has issued emission standards pursuant to section 112(c)(3) and
Exhibit 1-2. List of Sixty-Eight Area Source Categories to Meet 90-Percent Requirement under
Clean Air Act Sections 112(c)(3) and 112(k)(3)(B)
Chromic Acid Anodizing
Commercial Sterilization Facilities
Decorative Chromium Electroplating
Dry Cleaning Facilities
Halogenated Solvent Cleaners
Hard Chromium Electroplating
Hazardous Waste Incineration
Medical Waste Incinerators
Mercury Cell Chlor-Alkali Plants
Municipal Landfills
Municipal Waste Combustors (MWC)
Oil and Natural Gas Production
Public Owned Treatment Works
Secondary Lead Smelting
Primary Copper (not subject to MACT)
Primary Nonferrous Metals (Zn, Cd and Be)
Flexible Polyurethane Foam Fabrication Operations
Flexible Polyurethane Foam Production
Wood Preserving
Gas Distribution Stage 1
Hospital Sterilizers
Stationary Internal Combustion Engines
Autobody Refinishing Paint Shops
Clay Products Manufacturing (Clay Ceramics Manuf.)
Iron Foundries
Paint Strippers
Plastic Parts and Products (Surface Coating)
Pressed and Blown Glass and Glassware
Manufacturing
Secondary Nonferrous Metals
Stainless and Nonstainless Steel Manufacturing
Electric Arc Furnace
Steel Foundries
Electrical and Electronic Equipment- Finish
Operations
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Exhibit 1-2. List of Sixty-Eight Area Source Categories to Meet 90-Percent Requirement under
Clean Air Act Sections 112(c)(3) and 112(k)(3)(B)
Polyvinyl Chloride and Copolymers Production
Secondary Copper Smelting
Acrylic Fibers/Modacrylic Fibers Production
Carbon Black Production
Chemical Manufacturing: Chromium Compounds
Lead Acid Battery Manufacturing
Pharmaceutical Production
Synthetic Rubber Manufacturing
Nonferrous Foundries
Asphalt Processing and Asphalt Roofing Manufacturing
Chemical Preparations
Portland Cement
Industrial Boilers Fired by Coal, Wood and Oil
Plating and Polishing
Valves and Pipe Fittings
Agricultural Chemicals and Pesticides Manufacturing
Industrial Inorganic Chemical Manufacturing
Inorganic Pigments Manufacturing
Heating Equipment, Except Electric
Industrial Machinery and Equipment - Finish
Operations
Iron and Steel Forging
Fabricated Metal Products
Fabricated Plate Work
Fabricated Structural Metal Manufacturing
Plastic Materials and Resins Manufacturing
Copper Foundries
Aluminum Foundries
Paints and Allied Products Manufacturing
Prepared Feeds Materials
Sewage Sludge Incineration
Institutional/Commercial Boilers Fired by Coal, Wood
and Oil
Primary Metal Products Manufacturing
Ferroalloys Production: Ferromanganese &
Silicomanganese
Cyclic Crude and Intermediate Production
Industrial Organic Chemical Manufacturing
Miscellaneous Organic NESHAP
1.4. FIRST REPORT TO CONGRESS
Under section 112(k)(5), the CAA required that the EPA report to Congress on progress toward
meeting the goals of section 112(k) and to identify specific metropolitan areas that continue to
experience high risks to public health as the result of emissions from area sources. The first report
to Congress (Report), originally due in 1998, was published in July 2000.11 The first Report
expanded on much of the information provided in the Strategy, such as the methodology for
developing the emissions inventory used to identify the 30 urban HAPs. The Report also
summarized information on risk assessments that the EPA and several states conducted in various
urban areas over the past several years. The first Report also provided a detailed discussion of
specific research needs to address in achieving the goals of the Strategy and the EPA activities
nhttp://www.epa.gov/ttn/atw/urban/natprpt.pdf.
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aimed at addressing those needs.
1.5. SECOND REPORT TO CONGRESS OVERVIEW
This second report to Congress, as required by section 112(k)(5), discusses the EPA's actions to
date to address urban air toxics; provides background information on emissions, monitoring data
and risks; and discusses areas of the country experiencing elevated risks from air toxics. This report
is written so that:
Chapter Two is devoted to a discussion of the EPA's standard-setting activities for
stationary and mobile sources, the first component of the Strategy. The chapter presents
the list of area source categories that were identified. The chapter also describes: 1) the
statutory and regulatory requirements governing standard setting under section 112; 2)
the regulation of major sources, which are larger emitters of HAPs, and area sources, which
include those stationary sources that are not major sources, through Maximum Achievable
Control Technology (MACT) standards; 3) HAP emissions from mobile sources and the EPA
regulatory activities for addressing those sources; 4) regulatory actions taken to reduce
emissions from combustion sources; and 5) activities underway in the residual risk
program.
Chapter Three describes the range of assessment activities that the agency has undertaken
to measure progress toward meeting the requirements of section 112(k), the third
component of the Strategy. The chapter: 1) presents results regarding changes in emissions
and monitoring data; 2) describes the results from the 2005 NATA and discusses the urban
areas that continue to pose the highest lifetime cancer risks from air toxics; and 3) presents
an analysis of trends in ambient concentrations of benzene for one particular metropolitan
area with the highest risk.
Chapter Four focuses on the second component of the Strategy and provides: 1) an
overview of national, regional and community-based initiatives, including state, tribal and
local programs to reduce air toxics; and 2) approaches taken to develop partnerships
between the EPA and state, tribal and local governments and voluntary efforts to address
area-wide and community level issues.
Chapter Five provides an update on the EPA's education and outreach efforts, which is the
fourth component of the Strategy. The chapter discusses a variety of on-going EPA
activities involving state, tribal and local agencies, cities, communities and other groups
and organizations that help the agency implement its programs to reduce air toxics
emissions.
Chapter Six summarizes the research needs identified in the first report to Congress and
describes a sampling of research projects that highlight the EPA's progress toward
addressing those needs. The chapter concludes by discussing the EPA's focus on
sustainability and systems approaches and how these concepts are influencing our
research related to air toxics.
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Chapter Seven provides a summary of the findings of this report and identifies areas where
continued effort is needed to achieve additional air toxics emissions reductions.
Appendix A provides details on the EPA's standard-setting activities for stationary and
mobile sources.
Appendix B provides supplemental details on HAPs trend analysis conducted for this report
and the National Air Toxics Trends Station (NATTS) network sites.
Appendix C provides summaries of several air toxics studies. By no means a full
compendium, this appendix includes sample studies that have been conducted to examine
the impacts of air toxics in specific urban areas and provides more detailed information for
several EPA studies cited in Chapter Six.
Appendix D provides a summary of the current status of Integrated Risk Information
System (IRIS) assessments for the 33 urban HAPs.
All data in this report were developed in accordance with the EPA's data quality guidelines (U.S.
EPA, 2002b). For example, the emissions, monitoring and NATA data, which have been previously
released publicly, have been independently peer reviewed and/or follow Quality Assurance Project
Plans. Since no significant new information or technical analyses are presented, the EPA has
determined that no further independent review of this document is necessary.
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Chapter 2: Standard-Setting Activities
2.1. INTRODUCTION
The regulatory structure of the CAA provides for key regulatory activities designed to address air
toxics: 1) MACT standards that require stationary sources covered by these rules to achieve
emissions reductions at the levels of the best performing sources; 2) Generally Achievable Control
Technology (GACT) standards that put requirements in place by considering the control
technologies and management practices that are generally available to stationary sources of air
toxics; and 3) combustion standards to control emissions of certain types of solid waste facilities.
Within 8 years of issuance of a MACT standard, the EPA is required to conduct a residual risk
review and determine whether the promulgation of additional standards is required to provide an
ample margin of safety to protect public health and to prevent adverse environmental effects. The
EPA also has an obligation every 8 years to review and revise standards, "as necessary" taking into
account developments in practices, processes and control technologies. As for mobile sources, the
EPA has developed requirements for onroad and offroad vehicles (such as cars, trucks and other
mobile sources) and fuel standards. See Exhibit 2-1 for summary.
As part of its regulatory activities, the EPA also looks to analyze the impact of rules on low income,
minority and indigenous communities under Executive Order 12898, Environmental Justice for Low
Income and Minority Populations. In the past few years, the agency has developed a range of
approaches for better understanding the populations most affected by our rules. The analyses
largely look at the demographics of the communities near the sources being regulated; however,
this is an area that is evolving, and the EPA is continuously improving its methods of conducting
analyses.
This chapter describes what the EPA has accomplished with respect to the standards issued to
reduce air toxics emissions from stationary and mobile sources. The standards are a significant
accomplishment because, collectively, they have produced (or will produce) substantial reductions
in air toxics emissions that are further described in Chapter Three. Some of the standards will also
achieve co-benefit criteria pollutant emission reductions.
Exhibit 2-1. Summary of EPA Standard-Setting Activities Since 1990 for Air Toxics
Emission Source
Type
Major Stationary
Sources
Standards Set
97 standards for 174 major source categories developed
under section 112(c)(2).
Standard Types
Technology-based standards
based on MACT
Area Stationary
Sources
56 standards for 68 area source categories required to
fulfill the requirements of sections 112(c)(3) and
Technology-based standards
(MACT or GACT)
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Mobile Sources
Mobile source (on-road and off-road) standards that put
requirements in place for cars, trucks and other mobile
sources and fuel requirements.
Tailpipe standards; engine and
engine exhaust standards; and
fuels standards
Categories
46 subparts issued under section 112(c)(6) ensures that
seven specific persistent and bioaccumulative pollutants
are subject to MACT standards.
Technology-based standards
based on MACT
Technology
Review Rules
Rules developed under 112(d)(6) which calls for the EPA to
review standards every 8 years and revise them "as
necessary (taking into account developments in practices,
processes and technologies)."
Technology-based standards
Residual Risk
Rules
Rules developed under section 112(f) which requires the
EPA to determine whether MACT standards provide an
ample margin of safety to protect public health and
prevent against adverse environmental effects.
Health-based standards
Combustion
Sources
Solid waste combustion source rules developed under
section 129, which sets emission limits for new solid waste
combustion facilities and provide emissions guidelines for
existing sources.
Technology-based standards
The area source program was designed to control emissions of HAPs from smaller-emitting
sources. Area sources include facilities that have air toxics emissions below the major source
threshold as defined in CAA section 112 and thus emit less than 10 tons per year of any single toxic
air pollutant and less than 25 tons per year of multiple toxic air pollutants in any one year. Major
sources are defined as sources that emit 10 tons per year or more of any of the listed toxic air
pollutants or 25 tons per year or more of a combination of air toxics. For example, these major
sources could release air toxics from equipment leaks when materials are transferred from one
location to another or during discharge through emission stacks or vents. Area sources include
smaller facilities such as dry cleaners, gasoline stations and autobody repair shops.
2.2. AIR TOXICS STANDARD SETTING FOR AREA AND MAJOR
SOURCES
For major sources, the EPA must establish emission standards that "require the maximum degree
of reduction in emissions of the hazardous air pollutants subject to this section" that the EPA
determines is achievable taking into account certain statutory factors. See CAA section 112(d)(2).
These standards are referred to as "maximum achievable control technology" or "MACT"
standards. The MACT standards for existing sources must be at least as stringent as the average
emission limitation achieved by the best performing 12 percent of existing sources in the category
(for which the Administrator has emissions information) or the best performing 5 sources for
source categories with less than 30 sources. See CAA section 112(d)(3)(A) and (B), respectively.
This level of minimum stringency is referred to as the "MACT floor," and the EPA cannot consider
cost in setting the floor. For new sources, MACT standards must be at least as stringent as the
control level achieved in practice by the best-controlled similar source. See CAA section 112(d)(3).
For area sources, the EPA may issue standards or requirements that provide for the use of
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generally available control technologies or management practices (GACT standards) in lieu of
promulgating MACT or health-based standards. See CAA section 112(d)(5).
To determine GACT, the EPA considers control technologies and management practices that are
generally available to the area sources in the source category. We also consider the standards
applicable to major sources in the same industrial sector to determine whether the control
technologies and management practices are transferable and generally available to area sources.
In appropriate circumstances, we may also consider technologies and practices at area and major
sources in similar categories to determine whether such technologies and practices could be
considered generally available for the area source category at issue. Finally, in determining GACT
for a particular area source category, we consider the costs and economic impacts of available
control technologies and management practices on that category.
Both MACT and GACT have yielded standards that are effective in reducing toxic emissions.
Emissions and risk reductions are discussed in more detail in Chapter Three.
2.2.1. Emission Standards for Area Sources
The EPA has completed the emission standards required by section 112(c)(3) of the CAA. Section
112(c)(3) requires that the EPA promulgate emission standards to ensure that area sources
representing 90 percent of the area source emissions of the 30 HAPs that present the greatest
threat to public health in the largest number of urban areas are subject to regulation. For the 68
area source categories, the EPA has promulgated 56 area source rules.12 Compliance under all
standards is anticipated to be no later than 2014,13 which is 2 years later than originally predicted
in the 1999 Strategy.
Appendix A presents a comprehensive list of the 56 area source standards, including targeted
pollutants.14 The following are examples of area source categories for which the EPA has issued
National Emission Standards for Hazardous Air Pollutants (NESHAP) that have or will result in
emission/risk reductions:
NESHAP for Paint Stripping and Miscellaneous Surface Coating Operations at Area
Sources: On December 14, 2007, the EPA issued final air toxics standards for area
sources in the following three industry sectors: 1) paint stripping operations that use
methylene chloride (MeCl)-containing paint stripping formulations; 2) surface coating
operations that involve spray-applied coatings that contain metal air toxic compounds
to miscellaneous parts and products made of metal, plastic or a combination of metal
and plastic; and 3) spray-applied finishing or refinishing of motor vehicles and mobile
equipment. The EPA estimated that about 1,000 facilities would take action to comply
with the final rule. The standards for paint stripping achieve an estimated annual
reduction of 1,200 tons of methylene chloride emissions, which are an inhalation irritant
12Some rules address more than one area source category; thus, the number of rules is less than the number of source
categories.
13Under the CAA, compliance with these standards is required within 3 years of promulgation.
14http://www.epa.gov/ttn/atw/area/arearules.html.
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and potential carcinogen. The surface coating standards achieve an estimated annual
reduction of about 6,900 tons of HAPs, including 11 tons of metal HAPs. The rules also
result in estimated annual reductions of 2,900 tons and 20,900 tons of particulate
matter and volatile organic compounds, respectively.
NESHAP for Source Categories: Gasoline Distribution Bulk Terminals, Bulk Plants and
Pipeline Facilities, and Gasoline Dispensing Facilities: On December 20, 2007, the EPA
issued air toxics standards for area sources that distribute and store gasoline. The final
rules limited air toxics emissions from two types of area sources: bulk gasoline
distribution facilities (such as bulk terminals and plants, pipeline facilities) and storage
tanks at gasoline dispensing facilities. We estimated the rules to result in 5,000 tons per
year of HAP reductions, including 175 tons per year of benzene. The final rules were
designed to achieve estimated annual VOC reductions of about 100,000 tons.15
NESHAP for Secondary Lead Smelting: Secondary lead smelters produce lead from scrap
and provide the primary means for recycling lead-acid automotive batteries
(approximately 95 percent of all lead-acid batteries). The EPA originally promulgated the
rule in 1995 and it established numerical emission limits for lead. The agency estimates
that the rule reduced emissions of HAPs by about 1,400 tons annually, representing a 67
percent reduction from levels prior to enactment of the standards. This rule also covers
secondary lead smelters that are major sources of HAPs.
2.2.2. Emission Standards for Major Sources
Maximui i Achievable Control Technology Standards
Since 1990, the EPA has issued 97 MACT standards covering all of the 174 major source categories
originally listed by the EPA in 1992, as required by the CAA. This report also covers the recently
issued Mercury and Air Toxics Standards (MATS) for utilities. Appendix A contains a list of the
standards and the relevant Federal Register citations. Chapter Three describes emissions
reductions from these rules collectively, which are substantial and will help reduce the health risk
from air toxics in urban and other areas.
As required under section 112(c)(6), the EPA promulgated emission standards (total of 46 subparts
under 40 CFR parts 60, 61, 62 and 63) to assure that sources accounting for not less than
90 percent of the aggregate emissions of each of the seven persistent and bioaccumulative
pollutants which includes alkylated lead compounds, polycyclic organic matter (POM), mercury,
hexachlorobenzene, polychlorinated biphenyls (PCB), 2,3,7,8-tetrachlorodibenzofurans (TCDF) and
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).
1573 FR 1916. January 10, 2008.
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Solid Waste Combustion Sources
Solid waste combustion source rules, required under section 129 of the CAA, set emission limits for
new solid waste combustion facilities and provided emissions guidelines for existing solid waste
combustion facilities. Pursuant to section 129, the EPA has issued standards for large and small
municipal waste combustors (MWC), hospital/medical/infectious waste incinerators (HMIWI),
sewage sludge incinerators (SSI), commercial and industrial solid waste incinerators (CISWI), and
"other" solid waste incinerators (OSWI). These standards set emission standards for 9 pollutants:
cadmium, carbon monoxide, dioxins/furans, hydrogen chloride, lead, mercury, oxides of nitrogen,
particulate matter and sulfur dioxide.
By the time these rules are fully implemented, we expect them to reduce mercury emissions from
these sources by about 90 percent from current levels and reduce dioxin/furan emissions by more
than 95 percent from current levels. The rules affect MWC and HMIWI, which account for
30 percent16 of the national mercury emissions to the air.
Residual Risk Program
The residual risk program, required under section 112(f), is designed to assess the risk from source
categories after MACT standards are implemented. If we find a remaining - or residual - risk, we
are required, within 8 years of the promulgation of the MACT standard, to set additional standards
if the MACT standard does not provide an "ample margin of safety to protect public health" or "to
prevent, taking into consideration costs, energy, safety and other relevant factors, an adverse
environmental effect."17 The Residual Risk Report to Congress, released March 3, 1999, describes
our approach to risk assessment for the residual risk program.18 The EPA has conducted
demographic analyses as part of the rulemakings issued to date to help us better understand the
potential impacts of the rule on low income, minority or indigenous communities.
Technology Review Program
In addition to the residual risk review, the CAA requires a technology review every 8 years under
section 112(d)(6). The EPA looks at a host of different items during the technology review,
including whether certain technologies available at the time of the initial MACT have changed to
more efficient, cost-effective methods.
The Risk and Technology Review (RTR) is a combined effort to evaluate both risk and technology as
required by the CAA after the application of MACT standards (U.S. EPA, 2009). Current information
regarding proposals and final actions can be found on the EPA's RTR website.19
16As cited in the Urban Air Toxics Strategy. 64 FR 38709.
17Clean Air Act section 112(f).
18Residual Risk Report to Congress. March 3,1999. EPA-453-/R-99-001.
19See http://www.epa.gov/ttn/atw/rrisk/rtrpg.html for more information on the status of ongoing RTR rulemakings.
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2.3. AIR TOXIC STANDARD SETTING FOR MOBILE SOURCES
This section presents an overview of the EPA's mobile source program aimed at reducing air toxics
and other pollutants. Mobile source air toxics (MSATs) are compounds, known or suspected to
cause cancer or other serious health and environmental effects, which are emitted from highway
vehicles and nonroad equipment. Mobile sources consist of onroad and nonroad vehicles, engines,
and equipment, such as aircraft, locomotives and marine vessels. This section highlights mobile
source emission control programs and outlines recent and upcoming mobile source rulemaking
activities.
2.3.1. Urban HAPs Emitted from Mobile Sources
Numerous pollutants are known to be emitted from onroad trucks and passenger cars and from
various types of nonroad equipment, several of which could have serious effects on human health
and welfare (U.S. EPA, 2000b). Many of the compounds emitted by mobile sources have been
evaluated and published in the IRIS database.20 Appendix D contains a list of compounds that have
been assessed in the IRIS program, including those emitted by mobile sources and those on the list
of 33 priority urban HAPs. Exhaust from diesel engines contains many urban air toxics, such as
acetaldehyde, acrolein, benzene, 1,3-butadiene, formaldehyde and polycyclic aromatic
hydrocarbons.
A subset of the urban HAPs compounds that are emitted by mobile sources, with the addition of
diesel particulate matter, is of particular concern. They are found in the exhaust or evaporative
emissions from passenger cars, onroad trucks and various types of nonroad equipment, were
designated as national or regional risk drivers in the 2005 NATA and are produced in significant
quantities by mobile sources (U.S. EPA, 2010c). These compounds include:
Acrolein
Acetaldehyde
Benzene
1,3-butadiene
Diesel Particulate Matter
Formaldehyde
Naphthalene
POM
2.3.2. Mobile Source Emission Control Programs
The EPA regulates mobile source emissions through a wide range of programs under the authority
of the CAA. Programs include motor vehicle provisions contained in section 202(a); the fuel
requirements in section 211; the nonroad engine and vehicle provisions in section 213; the urban
20The EPA's Integrated Risk Information System (IRIS) is a program that evaluates risk information on effects that may result
from exposure to environmental contaminants. Through IRIS, the EPA provides the highest quality science-based human health
assessments to support regulatory activities. The database contains data for more than 550 chemicals regarding human health
effects that may result from exposure to various substances in the environment. http://www.epa.gov/IRIS/.
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bus standards in section 219; and the aircraft provisions in section 231. In addition to the general
emission control provisions, the EPA has specific authority related to air toxics listed in section
202(1) of the Act. The EPA regulates toxic air pollutants from motor vehicles through vehicle
emissions and fuel quality standards.
2.3.3. Recent and Upcoming Mobile Source Rulemaking Activities
The EPA's most recent rule specifically targeted at MSATs, "Control of Hazardous Air Pollutants
from Mobile Sources," or "MSAT2," was published in 2007.21 The rule has three components:
1. A standard that lowers the benzene content of gasoline (beginning in 2011).
2. A standard that reduces exhaust emissions from passenger vehicles operating at cold
temperatures, less than 75°F (beginning in 2010).
3. A standard that reduces emissions that can evaporate from, and permeate through,
portable fuel containers (beginning in 2009).
The new fuel benzene standard and hydrocarbon standards for vehicles and gas cans are expected
to reduce total emissions of MSATs by 330,000 tons in 2030, including 61,000 tons of benzene. As
a result of this rule, new passenger vehicles will emit 45 percent less benzene, gas cans will emit
78 percent less benzene and gasoline will have 38 percent less benzene overall.22
The EPA's general authorities have been used primarily to control criteria pollutants from mobile
sources. These rules, however, have also achieved important reductions in HAPs. For example,
vehicle- and engine-based control programs reduce hydrocarbons that are produced during the
combustion process as a result of incomplete combustion. Similarly, the EPA has several programs
aimed at reducing diesel exhaust emissions from diesel engines and equipment. The EPA's
evaporative control programs are designed to reduce further emissions of volatile air toxics due to
engine design or faulty components that allow fuel vapors to escape into the atmosphere. Mobile
source fuel control programs also have resulted in significant reductions in the emissions of toxic
substances from motor vehicles. Both vehicle- and engine-based control programs and fuel control
programs have helped to address disproportionate impacts to those populations living in close
proximity to roadways, rail yards and ports. Examples of criteria pollutant-focused engine and fuel
control programs are listed below.
In 2001, the EPA finalized a rule to make heavy-duty trucks and buses run more cleanly.
The sulfur content allowed in diesel fuel was lowered to enable modern pollution-
control technology to be installed on new trucks and buses starting with the 2007 model
year. Once this action is fully implemented, the EPA estimates that diesel particulate
matter will be reduced by 110,000 tons per year.23
In May 2004, as part of the Clean Air Nonroad Diesel Rule, the EPA finalized stringent
emission standards for new non-road diesel engines beginning with model year 2008.
2172 FR 8427. February 26, 2007.
2272 FR 8427. February 26, 2007.
2366 FR 5001. January 18, 2001.
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The EPA also introduced requirements for nonroad diesel fuel that decrease the
allowable levels of sulfur in fuel by 99 percent. The rule will have significant
environmental and public health benefits by reducing diesel particulate matter from
new and existing engines.24
In March 2008, the EPA finalized a three-part program that will dramatically reduce
emissions from locomotives and marine diesel engines with displacement of less than
30 liters per cylinder. The rule will reduce diesel PM emissions from these engines by as
much as 90 percent when fully implemented.25
In 2008, the EPA adopted new exhaust emission standards for marine spark-ignition engines and
small land-based nonroad engines.26 The EPA also adopted evaporative emission standards for
equipment and vessels using these engines. The EPA estimates that, by 2030, the standards will
result in significant annual reductions of pollutant emissions from regulated engine and equipment
sources nationwide, including approximately 600,000 tons of volatile organic compound (VOC)
emissions.
In 2009, the EPA adopted more stringent exhaust emission standards for large marine
diesel engines as part of a coordinated strategy to address emissions from all ships that
affect U.S. air quality. By 2030, this coordinated strategy is expected to reduce annual
diesel particulate matter emissions by about 143,000 tons.27
The EPA continues to make progress in controlling HAP emissions from mobile sources.
Ongoing mobile source rulemaking activities can achieve additional reductions of
health risks from air toxics beyond those just discussed. In May 2010, the President
directed the EPA to review the adequacy of current non-greenhouse gas emissions
regulations for new motor vehicles, new motor vehicle engines and motor vehicle fuels,
including tailpipe emissions standards for air toxics (The White House, 2010). As a
result of the President's direction, the EPA recently finalized vehicle and fuel standards
that would further reduce MSATs and other pollutants
(http://www.epa.gov/otaq/tier3.htm).
2.3.4. Near-Roadway Pollution
Locations in close proximity to major roadways generally have elevated concentrations of air
pollutants emitted from motor vehicles (Karner et al. 2010; HEI 2010). Many studies have been
published in peer-reviewed journals, concluding that concentrations of benzene, aldehydes, PM and
many other compounds are elevated in ambient air within approximately 300-600 meters (about
1,000-2,000 feet) of major roadways. Highest concentrations of most pollutants emitted directly by
motor vehicles are found at locations within 50 meters (about 165 feet) of the edge of a roadway's
traffic lanes.28 Over twenty million U.S. homes are near large roads, railroads and airports (with the
2469FR 38957. June 29, 2004.
2573FR 37095. June 30, 2008.
2673 FR 59034. October 8, 2008.
2775 FR 22895. April 30, 2010.
2S75 FR 6474. February 9, 2010.
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majority of these homes near large roads).29 30 Populations in close proximity to major roads are
higher in minority and low-income composition.31 In some locations, other sources of air pollution
can also contribute significantly to the pollution found near major roads (e.g., industrial sources,
freight terminals).
2.4. CONTINUED EFFORTS
Areas where continued source-specific and sector-based strategies will achieve additional air toxics
emissions reductions include:
Setting risk and technology standards for industrial sources that pose the highest risks,
focusing especially where emissions can be controlled cost-effectively.
Looking for cost-effective opportunities for multipollutant reductions across sectors.
Expanding efforts to integrate pollution prevention and less-polluting substitutes into
regulatory and non-regulatory efforts.
Considering environmental justice (EJ) as we issue rules and permitting guidance.
Establishing additional vehicle and fuel standards to achieve further reductions in emissions
from mobile sources.
Evaluating the impacts of renewable and alternative fuels and determining whether
additional fuel standards are needed (as directed by the Energy Independence and Security
Act (EISA)).
Focusing efforts on communication and assessment of near-roadway exposures, including
mitigation options for local communities.
Developing compliance tools to help industries meet standards and focus enforcement
efforts, as necessary, to reduce air toxics in communities.
29U.S. Census Bureau. American Housing Survey for 2009. Table 1-6.
30About 300 feet to a highway with four or more lanes, a railroad or an airport.
3172 FR 8434. February 26, 2007.
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Chapter 3: Identifying Air Toxics Risks
in Urban Areas
3.1. INTRODUCTION
The EPA, along with state, tribal and local governments and industry partners, has made
substantial progress on air toxics,32 reducing millions of tons of these pollutants over the last 2
decades. Despite these significant strides in the air toxics program, there remain many areas
around the country with elevated levels of risks from air toxics. These risks are often found in
urban areas where emission sources can be more concentrated and in communities near industrial
facilities or near large roadways or transportation facilities. This chapter also discusses the urban
areas that continue to experience elevated risks to public health from air toxic emissions.
The health risks from exposure to air toxics are greater in urban areas due to the concentration of
air pollution sources, including mobile and stationary sources, and population density. Health
effects from exposure to HAPs might be more severe to more susceptible or sensitive populations
such as children or individuals with compromised health status and disproportionately impacted
communities.
In the last few years, the EPA has made significant strides in conducting environmental justice (EJ)
analyses so we can better understand if there are disproportionately impacted communities.33 For
instance, from 1995 to 2010, the EPA conducted EJ analysis on 20 rules, as contrasted with the 53
rules for which it has conducted such analysis between 2010 and early 2012. The Office of Air and
Radiation has been responsible for most of those analyses. The agency-wide analyses included
qualitative assessments, proximity analysis, ambient concentration impacts and risk-based
assessments. Through these efforts, the agency continues to learn and improve our ability to
conduct these analyses and identify areas where consistency in analytical approaches is needed. As
a result, the agency is improving analytical tools to help in these efforts. Two tools in particular
include EJSCREEN, a web application-screening tool that provides the EPA with a nationally
consistent approach to screening for potential areas of concern, and the Community-Focused
Exposure and Risk Screening Tool (C-FERST) which provides environmental exposure and health-
related information.
To estimate risks in urban areas, the EPA considers both the nature of the problem and the tools
and data available. Air toxics emissions, ambient air concentrations and risk can be widespread or
localized. The 187 HAPs in the CAA pose, individually and in combination, a variety of health and
environmental impacts, including cancer and respiratory, cardiovascular, neurological and
32The use of the terms "air toxics" or "toxic air pollutants" in this report refers specifically to those pollutants that are listed
under section 112(b) of the CAA as "hazardous air pollutants" or HAPs.
33EPA defines "environmental justice" as the fair treatment and meaningful involvement of all people regardless of race, color,
national origin, or income with respect to the development, implementation, and enforcement of environmental laws,
regulations, and policies. U.S. Environmental Protection Agency, Interim Guidance on Considering Environmental Justice During the
Development of an Action, http://www.epa.gov/compliance/ej/resources/policy/considering-ej-in-rulemaking-guide-07-2010.pdf..
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developmental effects. For this report, the EPA used a variety of methods to analyze different
aspects of the air toxics program and describes the following findings in this chapter:
Emissions reductions have occurred for all HAPs, including the priority urban air toxics in
urban areas, since 1990 due to promulgated standards;
Monitored levels of several key pollutants in the urban ambient air have gone down
over time;
Emissions inventories and exposure markers for key air toxics pollutants, including
mercury, dioxin, lead and diesel particulate matter, show progress in lower emissions
and exposure levels; and
Modeling tools, such as the 2005 NATA, identify certain areas of the country that may
experience elevated levels of air toxics risks.
3.1.1. Data Gaps and Limitations
While the EPA has multiple analytical tools to describe the air toxics program, there remain
significant data gaps and limitations in our understanding of air toxics, including:
Incomplete emissions data. Only some regulated industrial sources are required to submit
air toxics inventory information, and states are not required to submit data to the agency
on their air toxics emissions, making the quality and completeness of those data vary
significantly by region and source.
Limited monitoring data. Implementation of the 27 National Air Toxics Trends Station
monitoring network, which began in 2003, is only now allowing us to make comparable
analysis of ambient toxic trends over time.
Uncertainty in toxicity data for many toxics. Characterizing the health effects of air toxics at
ambient levels can be subject to a high level of uncertainty. For example, a large majority
of air toxics have toxicity information from the EPA's Integrated Risk Information System
(IRIS) and other sources based on animal studies, with substantial uncertainty in how to
interpret those data for human exposure. A relatively smaller number of air toxics have
epidemiological data based on relatively high occupational exposures (e.g., for benzene),
with some uncertainty for how to interpret that information at lower ambient levels.
Limitations in modeling air toxics exposures and risks. NATA estimates ambient
concentrations of air toxics and then estimates inhalation exposures at the census block
level, taking into account ambient exposures in various microenvironments. NATA uses
these exposure modeling results to estimate lifetime inhalation risks for both cancer and
non-cancer effects from outdoor exposure to air toxics. Although results are reported at
the census-tract level, average risk estimates are far more uncertain at this level of spatial
resolution than at the county or state level and are not appropriate for identifying
suspected "hotspots" of air toxics. In addition to inherent limitations in modeling, NATA
only estimates risks associated with inhalation of an air toxic, it does not estimate risks
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from other pathways such as air toxics being deposited in the soil and water bodies.
Information about these pathways is important for predicting risks from certain air toxics
that are prevalent in the food chain (like eating fish contaminated with mercury). Further
NATA does not include the emissions from indoor sources, accidental releases, natural
disasters or transport of some pollution from countries outside the United States.
Given the varied nature of air toxics and these and other limitations and uncertainties, this chapter
provides our best understanding of the impacts of the air toxics program using national, urban-
specific and pollutant-specific analyses. Chapter Six provides more detail on the gaps in our
knowledge about air toxics and the EPA's research plans to address those issues.
3.2. NATIONAL EMISSIONS REDUCED SIGNIFICANTLY SINCE 1990
The EPA estimates that, since 1990, CAA programs have reduced millions of tons of air toxics
emissions from stationary (major and area) and mobile sources. For stationary sources, it is
estimated that over 1.5 million tons of HAPs have been removed from the air on an annual basis
due to standards promulgated under sections 112 and 129. In addition, the EPA also estimates
about 3 million tons per year of non-HAP co-benefit reductions have been achieved because of
these promulgated standards. These reductions were projected by looking at the estimated
emissions before and after implementation of the section 112 and 129 standards promulgated for
major and area source categories. See Appendix A for a listing of these standards. Exhibit 3-1
shows a graphical representation of the cumulative HAPs reductions achieved from stationary
source standards promulgated since 1990.
Exhibit 3-1. Cumulative HAPs Reductions for Stationary Sources
Cumulative Reductions in HAP
Emissions from Stationary Source Rules
1990 1995 2000 2005 2010
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You will notice that there are significant reductions beginning around 1999. This is primarily due to
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compliance with several very significant standards:
NESHAP for Aerospace Manufacturing and Rework Facilities: Promulgated in 1995, the final
rule projected emission reductions of over 123,000 tons per year of HAPs after full
implementation of the standards. The projected decrease in HAP emissions amounts to a
reduction of nearly 60 percent from pre-MACT levels. Most of the control requirements
outlined in the final rule were based on pollution prevention options instead of end of pipe
controls.
NESHAP for Synthetic Organic Chemical Manufacturing, also known as the Hazardous
Organic NESHAP (HON): Promulgated in 1994, the HON regulated a number of processes at
chemical manufacturing facilities, including storage vessels, process vents, process
wastewater, transfer operations and equipment leaks. The HON projected emission
reductions of over 500,000 tons per year of HAPs after full implementation of the
standards and about one million tons per year of VOC reductions as a co-benefit of HAPs
controls. These projected emission reductions amount to a decrease in HAP and VOC
emissions of 88 percent and 79 percent, respectively.
NESHAP for the Pulp and Paper Industry: Promulgated in 1998, these rules were developed
as a "cluster rule" that combined requirements for air and water. The final rule projected
air emission reductions of HAPs by over 160,000 tons per year after full implementation of
the standards, a decrease of nearly 60 percent from pre-MACT levels. The final rule also
projected 450,000 tons per year of VOC reductions as a co-benefit achieved through
control of HAP emissions.
Mobile source reductions are realized over time as the vehicle fleet turns over. As depicted in
Exhibit 3-2 in 1990, mobile source emissions were estimated at about 3 million tons; however by
2008, mobile source emissions were estimated to have decreased by 1.5 million tons due to
regulations already in place.34 It is expected that mobile source emissions will continue to decrease
due to fleet turnover and by 2030 will be approximately 80 percent lower than 1990 levels.
34Reductions in diesel PM are not included in these totals.
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Exhibit 3-2. Mobile Source Air Toxics Emission Reductions
Mobile Source Air Toxics Emissions
(does not include diesel PM)
1990
2008
2030
3.3. NATIONAL AIR TOXICS MONITORING: KEY POLLUTANTS
DECLINING
Starting in 2003, the EPA worked with state and local partners to develop the NATTS program to
monitor several air toxics.35 The principal objective of the NATTS network is to provide long-term
monitoring data across representative areas of the country for priority pollutants, including
benzene, formaldehyde, 1,3-butadiene, hexavalent chromium and polycyclic aromatic
hydrocarbons (PAHs) such as naphthalene, in order to establish overall trends. Currently, data are
collected at 27 NATTS sites consisting of 20 urban and 7 rural sites. A listing of these sites can be
found in Appendix B.
The EPA regularly analyzes nationwide trends in air quality indicators, including trends from
ambient air monitoring, as part of the National Air Quality Trends Reports.36 The trends analyses
for these reports indicate that most of the NATTS monitoring sites in the United States show
decreases in ambient air concentrations of many monitored air toxics. While these trends show
that the air around the monitors has lower levels of air toxics, the results do not necessarily
represent trends beyond the particular locations monitored.
Specifically for this report, the EPA completed an analysis of air toxics in urban areas based on
available monitoring data for 2003 to 2010. The data, from sites located in areas with populations
greater than 250,000, represent pollutants measured at a minimum of 30 different monitoring
sites with at least 35 percent of the data measured at levels above monitor detection limits. As
shown in Exhibit 3-3, all pollutants except for two show a decrease in concentrations from 2003 to
2010, as measured by the median percent change per year. Ambient monitoring data show that
35http://www.epa.gov/ttn/amtic/natts. htm I.
36http://www. epa.gov/airt rends.
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some of the air toxics of greatest concern to public health (such as benzene, 1,3-butadiene,
formaldehyde and several metals) are declining at most sites. Of the metals, nickel and arsenic
both have the largest declining trends with manganese levels tending to be decreasing but also
showing some increases depending on monitoring location. Lead continues to decline at most sites
with the exception of some sites concentrated in industrial areas. There are two chlorinated VOCs
that appear to have increased slightly: dichloromethane (methylene chloride) and chloroform.
It is important to note that, while nationally on average we are seeing a downward trend in
ambient concentrations for the majority of measured air toxics, some pollutants at some sites may
be higher due to local conditions, as well as the number and types of local sources. Thus, even
though the trend for a given pollutant is down, locally values may be higher due to sources in the
area.
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Exhibit 3-3. Median Changes in Ambient Concentrations in Urban Areas for Urban HAPs, 2003-
2010 (percent change in annual average concentrations)
(<> Median Urban Trends 2003-201 oj
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There are some persistent chemicals that, even though they are no longer emitted, are still in the
air today. An example of such a chemical is carbon tetrachloride. Carbon tetrachloride is found
globally as a result of its significant past uses in refrigerants and propellants for aerosol cans. It is
chemically persistent in the atmosphere. Virtually all uses have been discontinued; however, it is
still measured throughout the world as a result of its slow rate of degradation in the environment
and global distribution in the atmosphere and the value remains fairly constant.
There are also pollutants of concern and of potential concern that scientists cannot accurately
monitor in the ambient air. Acrolein is one such pollutant. During the recent EPA School Air Toxics
Program study, the EPA and states determined there were issues with the consistency and
reliability of acrolein monitoring and the method for analysis. Many state and local air pollution
control agencies believed the results from their own acrolein monitoring were questionable, so
most of the acrolein measurements have been classified as "non-verified" in the EPA datasets. The
EPA is, therefore, not providing any analysis in this report for acrolein and will continue research to
improve acrolein monitoring and analysis methods to measure this pollutant more accurately. As
noted in Chapter Six, the EPA has research plans to develop and evaluate ambient monitoring
methods for key air toxics, such as acrolein.
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3.4. POLLUTANT-SPECIFIC EMISSIONS AND MONITORING TRENDS
This section provides more in-depth information, including emission and monitoring trends, for
several key pollutants.
3.4.1. Benzene Levels Decline by 66 percent from 1994 to 2009
For several years, the EPA has been reporting on the ambient concentrations of benzene as part of
the EPA's Report on the Environment. Benzene is one of the most widely monitored air toxics and
is emitted from mobile sources (on-road and off-road), major stationary sources (e.g., petroleum
refineries) and area sources (e.g., gasoline stations). Urban areas generally have higher ambient air
concentrations of benzene than other areas. Exhibit 3-4 depicts the most recent benzene trend
analysis from the 2009 Report on the Environment.37 The trend is averaged over 22 urban
monitoring sites that have a complete data record from 1994 to 2009. The exhibit shows that the
average benzene concentration across these monitoring sites has declined 66 percent from 1994
to 2009. Also shown are the 90th and 10th percentiles based on the distributions of annual average
concentrations at the 22 monitoring sites. The shaded area in the exhibit displays the
concentration range where 80 percent of measured values occurred for each year.38
37http://www.epa.gov/roe/.
3Shttp://cfpub.epa.gov/eroe/index.cfm?fuseaction=detail.viewlnd&ch=46&subtop=341&lv=list.listByChapter&r=188186.
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Exhibit 3-4. Ambient Benzene Concentrations in the U.S., 1994-2009 (Source: U.S. EPA (2010d))
CO
CD
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90% of sites have concentrations
below this line
v
o
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'96
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Coverage: 22 monitoring sites nationwide (out of a total of 339
sites measuring benzene in 2009) that have sufficient data to
assess benzene trends since 1994.
3.4.2. U.S. Mercury Emissions
As shown in Exhibit 3-5, emissions of mercury to the air from anthropogenic (human-caused)
sources have fallen by more than 58 percent to date since passage of the CAA. In 1990, more than
two-thirds of U.S. anthropogenic mercury emissions came from three source categories: coal-fired
power plants, municipal waste combustors (MWC) and medical waste incinerators. The EPA issued
regulations in the 1990s that required more than a 90 percent reduction in mercury emissions
from MWC and medical waste incinerators. In addition, actions to limit the use of mercury, most
notably Congressional action to limit the use of mercury in batteries and the EPA regulatory limits
on the use of mercury in paint, contributed to the reduction of mercury emissions from waste
combustion during the 1990s by reducing the mercury content of waste.
The EPA has developed a regulation, the Mercury and Air Toxics Standards or MATS Rule, to limit
mercury emissions from coal- and oil-fired power plants (also known as electric-generating units,
or EGUs) that will further reduce emissions of mercury over the next several years. As a result of
the December 2011 MATS, the first national standard to control power plant emissions of mercury
(as well as other toxics such as arsenic, acid gas, nickel, selenium and cyanide), mercury emissions
from these sources are expected to be reduced from 27 tons to 7 tons in 2016 (approximately a 74
percent reduction). Overall, the MATS rule will improve public health by lowering mercury
exposure, especially for children and the elderly living with low income and minority populations
that rely on subsistence fishing from inland waterways downwind from power plants.
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Exhibit 3-5. Trends in U.S. Mercury Emissions by Source (tons/year)
Trends in U.S. Mercury Emissions by
Source (tons/year)
250
200
ISO
100
50
1990
2005
2008
Utility Coal Boilers
Medical Waste
Incineration
Municipal Waste
Incineration
i! Boilers and Process
Heaters
n Chlorine Production
Electric Arc Furnaces
Portland Cement
Hazardous Waste
Incineration
Gold Mining
Sewage Sludge
Incineration
Individual states have also taken action to reduce mercury emissions. In a 2011 report, the
Northeast States for Coordinated Air Use Management (NESCAUM) estimated the total mercury air
emissions from sources in Massachusetts in 2008 have been reduced by more than 90 percent
since 1996 (NESCAUM, 2011).
In addition, according to a 2011 report on the Great Lakes, mercury levels in the environment of
the Great Lakes region have declined over the last 4 decades, concurrent with decreased air
emissions from regional and U.S. sources. After initial declines, however, concentrations of
mercury in some fishes and birds from certain locations have increased in recent yearsrevealing
how trajectories of mercury recovery can be complex (Evers et al., 2011). While the timing and
magnitude of the response will vary, further controls on mercury emission sources are expected to
lower mercury concentrations in the food web yielding multiple benefits to fish, wildlife and
people in the Great Lakes region. It is anticipated that improvements will be greatest for inland
lakes and will be roughly proportional to declines in mercury deposition, which most closely track
trends in regional and U.S. air emissions. See Chapter Six for a discussion of mercury research.
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3.4.3. Dioxin Levels Are Down
The term "dioxin" is commonly used to refer to a family of toxic chemicals that share a similar
chemical structure and induce harm through a similar mechanism. There are a total of 29 of these
"dioxin-like" toxic compounds, including seven dioxins, ten furans and 12 dioxin-like
polychlorinated biphenyls (PCBs).39 The EPA uses the Toxicity Equivalency Factor (TEF) approach to
evaluate the human health risks from exposures to environmental media containing dioxin-like
compounds (DLCs).40The total toxicity of these compounds in a mixture (in air, in an emission
stream, etc.) can be calculated as the sum of the products of the concentrations of individual
compounds (often termed "congeners") and their TEFs. This total concentration from this
calculation is referred to as the Toxic Equivalent, or TEQ, concentration (Van den Berg et al., 2006).
Dioxins have been characterized by the EPA as likely human carcinogens and are anticipated to
increase the risk of cancer at background levels of exposure. In the Strategy, the EPA included
dioxins as one of the priority pollutants that pose the greatest threat to public health in the largest
number of urban areas. Toxics such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), PCBs and POM
are all emitted as unintentional by-products of incomplete combustion from, for example,
industrial processes, wildfires and backyard burning of waste.
Dioxin levels in the United States environment have been declining for the last 30 years due to
reductions in man-made sources. An Inventory of Sources and Environmental Releases of Dioxin-
Like Compounds in the United States for the Years 1987, 1995, and 2000 is a peer-reviewed report
representing the EPA's assessment of dioxin sources and their emissions to the environment.41 The
report presented an evaluation of sources and emissions of dioxins (CDDs), dibenzofurans (CDFs)
and coplanar PCBs to the air, land and water of the U.S. The inventory suggested that there has
been a significant reduction in environmental releases of dioxin-like compounds from regulated
industrial sources between the years 1987 and 2000, and that the open burning of residential
refuse in backyard burn barrels is the largest source in 2000 that could be reliably quantified.
In 1987 and 1995, the leading source of dioxin emissions was MWC. MWCs are estimated to have
emitted collectively nearly 8.9 kg of dioxin toxic equivalents (TEQs) in 1987, but under the EPA
regulations, they are now estimated to emit less than 0.01 kg TEQs per year. Similarly, medical
waste incinerators emitted about 2.6 kg of dioxin TEQs in 1987, but under the EPA regulations,
they now will be limited to about 0.007 kg annual emissions of TEQs. The EPA has implemented
similarly strict standards for other dioxin sources. As a result of the efforts of the EPA, state
governments and industry, known and quantifiable industrial emissions of dioxin in the United
States have been reduced by more than 95 percent from 1987 levels, from 12.8 kg TEQs in 1987 to
0.07 kg TEQs in 2000 (U.S. EPA, 2006). However, dioxins break down so slowly that some of the
dioxins from past releases will still be in the environment many years from now. Dioxins that
remain in the environment from past releases are sometimes called "reservoir sources" of dioxins.
In addition, natural processes, primarily forest fires, generate dioxins (U.S. EPA, 2006a). For these
reasons, dioxin levels will never go to zero.
39http://www.epa.gov/wastes/hazard/tsd/pcbs/about. htm.
40For more information on the TEF Approach, visit www.epa.gov/raf/hhtefguidance.
41EPA/600/P-03/002F. November 2006.
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3.4.4. Lead Emissions and Blood Lead Levels Have Been Significantly
Reduced
Most ambient concentrations of lead once came from the tailpipes of cars. The EPA phased out
lead in gasoline from 1973 through 1995, and almost all lead emissions now originate from major
stationary sources (e.g., lead smelters) and aircraft with piston engines that operate on leaded
gasoline, which are generally used for personal transportation, instructional flying and business.
Lead is a criteria pollutant and lead compounds are listed HAPs. Therefore, lead has a national
ambient air quality standard and a separate monitoring network.42 As shown in Exhibit 3-6,
between 1980 and 2010, maximum annual 3-month average concentrations of lead were reduced
by 89 percent.43
Exhibit 3-6. Lead Air Quality, 1980-201044
Lead Air Quality, 1980 - 2010
(Based on Annual Maximum 3-Month Average)
National Trend based on 31 Sites
o.o
i i i i i i i
i i i i i i r
1111111111111111111122222222222
9999999999999999999900000000000
3S8SS8888S999999999900000000001
012345678901 2345678901 234567890
1980 to 2010 : 89% decrease in National Average
Lead exposure can result in a variety of health effects, including lowering the IQ of children. To
assess changes in total lead exposure of children, the EPA reviews data on lead levels in blood for
children 5 years old and younger. From 1980 to 2005, national average lead concentrations in
children were down 96 percent. See Exhibit 3-7. The median concentration of lead in the blood of
children 5 years old and under dropped from 15 micrograms per deciliter (u.g/dL) in 1976-1980 to
1.4 u.g/dL in 2007-2008, a decline of 91 percent. The concentration of lead in blood at the 90th
percentile in children 5 years old and under dropped from 25 u.g/dL in 1976-1980 to 3.2 u.g/dL in
42National Ambient Air Quality Standards, http://www.epa.gov/ttn/naaqs/.
432010 Trends Report, http://www.epa.gov/airtrends/lead.html.
44Source: National Trends Report.
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2007-2008. In 1978, about 88 percent of children ages 1 to 5 (about 13.5 million children) had
blood lead levels at or greater than 10 u.g/dL (a level emphasized in the past for purposes of
identifying children with lead poisoning). By 2008, this number had declined to about one percent
(about 250,000 children).
It should be noted that in Exhibit 3-7, the period before CDC's elevated blood lead (EBL) threshold
for children was 10 u.g/dL. However, the childhood blood lead level CDC has defined as elevated,
for which intervention is recommended, has declined from 30 u.g/dL in 1975, to 25 in 1985, 10 in
1991and5in2012.454647
This decline in blood lead levels is generally attributed to the significant reductions that have been
made in children's lead exposures including those associated with the phasing out of lead in
gasoline used in automobiles and the reduction in the number of homes with lead-based paint
from 64 million in 1990 to 37 million in 2006.48 It is also a result of the EPA regulations reducing
lead levels in drinking water, as well as legislation restricting the content of lead in solder, faucets,
pipes, and plumbing. Lead also has been eliminated or reduced in food and beverage containers
and ceramic ware and in consumer products such as toys, mini-blinds and playground equipment.
45CDC 1985. Preventing Lead Poisoning in Young Children, www.cdc.gov/nceh/lead/publications/plpycl985.pdf.
46CDC 1991. Preventing Lead Poisoning in Young Children. www.cdc.gov/nceh/lead/Publications/books/plpyc/.
47CDC 2012. Response to Advisory Committee on Childhood Lead Poisoning Prevention Recommendations in "Low Level Lead
Exposure Harms Children: A Renewed Call of Primary Prevention."
www.cdc.gov/nceh/lead/ACCLPP/CDC_Response_Lead_Exposu re_Recs.pdf.
4SDepartment of Housing and Urban Development. American Healthy Homes Survey. Lead and Arsenic Findings. 2012.
http://www.hud.gov/offices/lead/.
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Exhibit 3-7. Measure Bl: Concentrations of Lead in Blood of Children 5 and Under
Measure B1
Concentrations of lead in blood of children ages 5 and under
90th percentile
(10 percent of children have
this blood lead level or greater)
Median value^
(50 percent of
children have this
blood lead level
or greater)
1976-
1980
1988-
1991
1999-
2000
2003-
2004
SOURCE: U.S. EPA. America's Children and the Environment.
www.epa.gov/envirohealth/children
DATA: Centers for Disease Control and Prevention, National Center for Health
Statistics, National Health and Nutrition Examination Survey
* 10 ng/dl_ of blood lead has been identified by CDC as elevated, which indicates
need for intervention. There is no demonstrated safe concentration of lead in
blood. Adverse effects may occur at lower concentrations.
3.4.5. Diesel Emissions Have Been Significantly Reduced
Exhaust from diesel engines contains many urban air toxics, such as acetaldehyde, acrolein,
benzene, 1,3-butadiene, formaldehyde and polycyclic aromatic hydrocarbons. Diesel exhaust is
emitted from a broad range of engines: the onroad engines of trucks, buses and cars and the
nonroad engines that include locomotives, marine vessels and heavy-duty equipment.
Diesel exhaust causes health effects from both short-term or acute exposures and also long-term
chronic exposures. The type and severity of health effects depends upon several factors including
the intensity of exposure (e.g., concentration) and the duration of exposure. Individuals also react
differently to different levels of exposure. Acute exposure to diesel exhaust may cause irritation to
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the eyes, nose, throat and lungs, and some neurological effects such as lightheadedness. Acute
exposure may also elicit a cough or nausea as well as exacerbate asthma. Chronic exposures in
experimental animal inhalation studies have shown a range of dose dependent lung inflammation
and immunological cell changes in the lung. Based upon human and laboratory studies included in
the 2002 Diesel Health Assessment Document (HAD), long-term (i.e., chronic) inhalation exposure
to diesel engine exhaust is likely to pose a lung cancer hazard to humans, as well as damage the
lung in other ways depending on exposure. Short-term (i.e., acute) exposures can cause irritation
and inflammatory symptoms of a transient nature, these being highly variable across the
population.49
The EPA concluded in the Diesel HAD that it was not possible to calculate a cancer unit risk for
diesel exhaust due to limitations in the lung cancer epidemiology studies available at the time, such
as limited quantitative exposure histories in occupational groups investigated. Although the 2005
NATA did not quantify the cancer risk from exposure to diesel exhaust, the EPA has concluded that
diesel exhaust ranks with the other emissions that the 2005 NATA suggests pose the greatest
relative risk (U.S. EPA, 2007).
Since the publication of the Diesel HAD, there have been a number of large epidemiology and
toxicology studies published about diesel exhaust's health effects. In June 2012, based on the
studies available, the World Health Organization's International Agency for Research on Cancer
(IARC) designated diesel engine exhaust as "carcinogenic to humans." The panel concluded that
there was "sufficient evidence" of lung cancer in humans and animals and "limited evidence" of
bladder cancer in humans. EPA is evaluating the new studies and lARC's conclusions in considering
future assessments of diesel exhaust.
Diesel PM emissions from both onroad (e.g., diesel trucks) engines, nonroad engines (e.g.,
construction and agricultural equipment), locomotives and commercial marine diesels have been
reduced and will continue to decline in the future. Specifically, mobile source diesel onroad and
nonroad PM decreased by about 27 percent from 1990 to 2005 and significant additional
reductions (roughly 90 percent) are projected from 2005 to 2030 as many of the recent mobile
source rules targeting diesel engines go into effect. For additional information on mobile source
diesel particulate matter regulations and voluntary programs such as the National Clean Diesel
Campaign, see Chapter Two and Chapter Four, respectively.
3.5. EVALUATING AIR TOXICS RISKS
All air toxics do not pose the same risks at the same concentrations. The magnitude of the risk is a
function of both the level of exposure as well as the toxic potency of the pollutant. Some toxics,
like dioxins, can be harmful in relatively small amounts, whereas other toxics with large emissions
might pose smaller relative risks. For the purposes of this report to Congress, this section describes
two analyses that give a better sense of the risks posed by air toxics:
49http://cf pub. epa.gov/ncea/cfm/ record isplay.cfm?deid=29060#Download.
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A snapshot of inhalation cancer and noncancer risks in 2005 (the most recent year for
which we have modeling data); and
A description of urban areas that have the highest inhalation cancer risks.
The EPA's NATA is a comprehensive evaluation of air toxics (177 HAPs and diesel particulate
matter) in the U.S. NATA provides estimates of the risk of cancer and other serious health effects
from breathing air toxics. The EPA, state, tribal and local air agencies and others use NATA to
identify and prioritize air toxics, emission source types and locations that are of greatest potential
concern in terms of contributing to population risk. Assessments include estimates of cancer and
noncancer health effects based on chronic exposure from outdoor sources, including assessments
of noncancer health effects for diesel PM. Assessments provide a snapshot of the outdoor air
quality and the risks to human health that would result if air toxics emissions levels remained
unchanged (U.S. EPA, 2011c).
As with any modeling analysis, there are uncertainties and limitations associated with NATA. The
EPA suggests that the results of this assessment be used cautiously, as the overall quality and
uncertainties of the assessment will vary from location to location as well as from pollutant to
pollutant. It is necessary to recognize that the specific limitations of NATA are critical to proper
interpretation and utility of the results shown in this report. Specifically, these risk estimates:
Apply to broader geographic areas (such as nationwide, states, core-based statistical area
(CBSA) or counties), not specific locations.
Do not reflect exposures and risk from all pollutants. Only inhalation exposures are included
(and therefore do not include risks from mercury, dioxin and other pollutants with ingestion
or other pathways of exposure).
Reflect only compounds released into the outdoor air and their chemical transformations.
Do not fully capture variation in background ambient air concentrations.
Might systematically underestimate or overestimate ambient air concentrations for some
compounds.
Are based on default, or simplifying, assumptions where data are missing or of poor quality.
Might not accurately capture sources that have
episodic emissions.
Most importantly, the 2005 NATA represents a snap-shot
of conditions in 2005 and, as such, does not reflect
current conditions. Since 2005, the EPA, states and
communities have implemented a number of programs
to reduce air toxics emissions. The EPA is in the process
of updating its NATA using more recent data.
Further details on the NATA analysis can be found in the
2005 NATA Technical Methods Document (U.S. EPA,
2011c).
The 2005 NATA estimates that
in 2005:
All 285 million people in the
U.S. had an increased cancer
risk of at least 10 in a million
due to the inhalation of HAPs
from outdoor sources.
Urban locations generally
average cancer risks of 54 in a
million compared to 31 in a
million for rural areas.
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3.5.1. Summary of 2005 NATA Risk Results
NATA is best used at a broad geographic level, such as the county or national level. Historical data
show that approximately 1 out of every 3 Americans (or 336,000 in a million) will contract cancer
during their lifetime when all causes are taken into account. The 2005 NATA estimated that all 285
million50 people in the U.S. at the time of the assessment had an increased cancer risk of at least 10
in a million due to the inhalation of HAPs from outdoor sources. The analysis showed that
background emissions alone (background includes natural emission sources, environmentally
persistent historical emissions and long-range transport of current emissions) were responsible for
risks of more than 10 in a million risk. Examining these background risks closer, NATA also showed
that persistent historical concentrations of carbon tetrachloride alone were responsible for a
nationwide risk level of about 3 in a million. Secondary formed pollutants such as aldehydes
contributed over 20 in a million risks nationwide.
Additionally, the 2005 NATA showed that about 13.8 million peopleabout 5 percent of the total
U.S. population based on the 2000 censuswere exposed to air toxics levels that result in a
person's increased cancer risk of 100 in a million or greater. These higher risk populations occur
mainly in urban locations where a combination of sources results in elevated risks levels. NATA
2005 estimated the national average lifetime cancer risks due to breathing air toxics from outdoor
sources to be 50 in a million. Emissions from three pollutants, namely formaldehyde, benzene and
acetaldehyde, contribute to about two-thirds of the total risks at a national level. Urban locations
(as defined in the Strategy)51 generally average higher cancer risks than rural locations, and the
2005 NATA reflects this: urban areas had average risks of 54 in a million and rural areas of 31 in a
million. NATA also estimated that most individuals living in the larger urban areas have average
cancer risks that are between 80 and 100 in a million for the emissions year 2005. The next section
discusses these elevated risks in some urban areas in further detail. Additional detail on the 2005
NATA analysis can be found in the NATA Technical Methods Document52 (U.S. EPA, 2011c).
Sector Contribution to NATA Cancer Risk Results
The 2005 NATA results include 80 air toxics that are considered possible, probable or known
carcinogens and have quantitative dose-response values available for calculating cancer risks. The
group of priority urban air toxics includes 26 carcinogenic pollutants that are responsible for
roughly 90 percent of the national average cancer risk estimated by the 2005 NATA. Based on the
2005 NATA, the EPA estimates that stationary source emissions are responsible for about 49
percent of the national average cancer risk (major sources 15 percent and area sources 34
percent), while mobile source emissions are responsible for about 45 percent (29 percent onroad
mobile and 16 percent nonroad mobile). Remaining background emissions (e.g., from natural
sources and pollutants that remain in the atmosphere for an extended period of time) comprise
the remaining 6 percent of the national average cancer risk. See footnote 54 for explanation on
50The 2005 NATA used the 2000 census, which estimated the U.S. population to be 285 million.
51See the Integrated Urban Air Toxics Strategy, 64 FR 38724, which defines the use of consolidated metropolitan statistical
areas (C/MSA) boundaries as a starting point to defining urban areas.
52http://www.epa.gov/ttn/atw/nata2005/05pdf/nata_tmd.pdf.
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background. Exhibit 3-8 shows the 2005 NATA distribution of risks.
Exhibit 3-8. 2005 NATA Nationwide Cancer Risks - Sector Contributions (with background and
secondary allocated)
2005 NATA Nationwide Cancer Risks-Sector Contributions
(with background and secondary a! located)
.Point
Mobile Nonroid
MobiltOnroid
2954
Summary of 2005 NATA Noncancer Risk Results
The 2005 NATA also provides an evaluation of chronic noncancer risks. NATA uses a target organ-
specific hazard index (HI)53 approach (U.S. EPA, 2011c), which is the typical approach for assessing
53The Hazard Index (HI) is the sum of hazard quotients (HQs) for substances that affect the same target organ or organ system.
The HQ is the ratio of the potential exposure to the substance and the level at which no adverse effects are expected. Because
different pollutants can cause similar adverse health effects, it is often appropriate to combine HQs associated with different
substances. The hazard index (HI) is only an approximation of the aggregate effect on the target organ, (i.e., lungs) because
some of the substances might cause irritation by different (i.e., non-additive) mechanisms. Exposures that result in a HI value
equal to or below 1 derived using target organ specific hazard quotients likely will not result in adverse noncancer health effects
over a lifetime of exposure and would ordinarily be considered acceptable. However, an HI greater than 1 does not necessarily
suggest a likelihood of adverse effects. Because of the inherent conservatism of the reference concentration (RfC)
methodology, the acceptability of exceedances must be evaluated on a case-by-case basis, considering such factors as the
confidence level of the assessment, the uncertainties, the slope of the dose-response curve (if known), the magnitude of the
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the potential for adverse health effects from breathing noncarcinogenic pollutants. While there
are local areas identified by the 2005 NATA that exceeded an HI of 1 for target organs other than
the respiratory system, the respiratory system was the only target organ in the analysis with HI
values exceeding 1 across widespread portions of the country. As a result, we have focused our
evaluation of progress related to noncancer risks on risks to the respiratory system. The 2005
NATA estimated that the national respiratory HI was more than 2, with nearly three-fourths of the
nation exposed at an HI greater than 1, and more than 2.8 million people exposed at an HI of
greater than 10. The priority urban air toxics, which include 9 noncancer respiratory pollutants,
contributed roughly 90 percent of the nationwide average respiratory HI that is estimated by the
2005 NATA. Using NATA and apportioning background concentrations to stationary and mobile
sources, the EPA estimates that stationary sources are responsible for about 49 percent of the
national average respiratory HI, and mobile sources are responsible for about 51 percent of those
risks.54
3.5.2. Urban Areas with the Highest Cancer Risk
This section responds to the requirements in CAA section 112(k)(5) that this report identify specific
metropolitan areas that continue to experience high risks to public health as the result of
emissions from area sources. The first Urban Air Toxics Report to Congress issued in 2000 did not
identify specific metropolitan areas, because the EPA had only recently begun to implement its
Integrated Urban Air Toxics Strategy. For this second Urban Air Toxics Report to Congress, the EPA
is drawing on information from its last national-scale assessment (i.e., the 2005 NATA, which was
based on a 2005 inventory of air toxics emissions), as well as other available information.
The 2005 NATA estimated that more than 13.8 million people in many urban areas were exposed to
cancer risks greater than 100 in a million due to emissions of air toxics from all outdoor sources (i.e.,
area sources, as well as all other stationary sources, mobile sources, background and secondary
formation). A summary of results from the 2005 NATA, including a map of urban areas with cancer
risks greater than 100 in a million, is available on the EPA's website at www.epa.gov/nata2005. It is
important to note that these data represent a snapshot of the estimated risks in 2005, and the data
will be updated as part of the EPA's new (2011) NATA, which is expected to be released in 2015. As
noted elsewhere in this report (see, for example, Section 3.2), because of additional emissions
reductions due in large part to federal stationary and mobile source rules and programs since 2005,
the EPA expects the risk results for the 2011 NATA to be different for some urban areas when
compared with the 2005 NATA and in many areas may be lower.
Another important finding from the 2005 NATA, as well as several other air toxics studies in
particular urban areas (as summarized in Appendix C) is that while some general similarities are
exceedance, and the numbers or types of people exposed at various levels above the RfC. Furthermore, the HI cannot be
translated to a probability that adverse effects will occur and is not likely to be proportional to risk.
54To better understand the actual distribution of cancer and noncancer risks, the background and secondary formation risk, as
presented in the 2005 NATA, have been allocated to their appropriate source categories. The EPA allocated background risks on
a pollutant-by-pollutant basis to stationary and mobiles source categories by allocating the background risks by their respective
national emission ratios for each source group. Carbon Tetrachloride, which is no longer emitted, was not allocated. Secondary
risks were allocated in a similar fashion by allocating the risks by their respective total (rather than pollutant) national emission
ratios.
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evident in urban air toxics exposures and risks, the identity and concentration of air toxics vary
significantly from area to area depending on the particular sources present (or dominant), the
substances emitted, the local meteorology and other factors.
The 2005 NATA results showed that the highest risks generally occurred in the largest metropolitan
statistical areas (MSAs). An MSA is defined as having "at least one urbanized area of 50,000 or
more population, plus adjacent territory that has a high degree of social and economic integration
with the core as measured by communities."55 It is important to note that MSAs identified in the
2005 NATA may have as few as one census tract that is actually characterized by high risk. Indeed,
this is generally the case for many of the MSAs identified on the NATA website as having elevated
risks. Since the results of the 2005 NATA are also available at the lower census tract level, the
public is encouraged to view the full results of the 2005 NATA, and any future update to the NATA,
at the census tract level in order to accurately understand the estimate of localized risk.56
In addition, the 2005 NATA results showed that the risks in largest MSAs resulted from a
combination of multiple source emissions. As shown in Exhibit 3-9, stationary sources in one large
CBSA (similar to MSA), New York City, contributed about half of the total risk.
55 There are currently 381 MSAs in the United States. See, OMB Bulletin NO. 13-01, February 28, 2013, Revised Delineations of
Metropolitan Statistical Areas, and Guidance on Uses of the Delineations of These Areas, available at:
http://www.whitehouse.gov/sites/default/files/omb/bulletins/2013/b-13-01.pdf.
56 In contrast to the 381 MSAs currently delineated in the United States, there were 74,134 census tracts in the United States,
Puerto Rico, and the Island Areas for the 2010 Census, See, http://blogs.census.gov/2013/10/25/74134-census-tracts-and-
more-geographic-area-tallies-information/
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Exhibit 3-9. 2005 NATA - Sector Contributions to Risks (New York CBSA)
2005 NATA - Sector Contributions to Risk
(New York CBSA)
.Major Stationary
10%
Mom oad Mobile
Onroad Mobile
28%
_Area Stationary
38%
The 2005 NATA also showed that formaldehyde and benzene contribute to more than half of the
estimated cancer risk in this large CBSA. This is illustrated in Exhibit 3-10.
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Exhibit 3-10. 2005 NATA - Pollutant Contribution to Risk (New York CBSA)
! ,4.
DICHLOROBEHZEME
2%
2005 NATA - Pollutant Contribution to Risk
(New York CBSA)
NICKEL PAH/POM
COMPOUNDS
OTHER
5%
CARBON TETRACHLORIDE
2%
ARSENIC COMPOUNDS
3%
ETHYLBENZENE
3%
CHROMIUM COMPOUNDS
3%
ACETALDEHYDE
4%
1,3-BUTADIENE
5%
PERCHLOROETHYLENE
6%
.FORMALDEHYDE
32%
NAPHTHALENE
11%
21%
Benzene and Formaldehyde - Driver Pollutants
Benzene is among the pollutants that contributes a significant portion of the risk in large urban
areas. Examining trends in benzene concentrations in these large areas can serve as an indicator of
longer-term exposures to benzene for high risk individuals. For example, if the monitored trends
for a particular large CBSA show a decrease in benzene concentrations over time, it can be inferred
that decreases should be lower in other large metropolitan areas as well.
Available data in New York from several monitoring locations from 1990 to 2010 (Exhibit 3-11)
show a sharp decrease at one monitoring location in the 1990s, likely related to control efforts
related to reducing ozone levels. The data also show a continuing downward trend at three other
monitoring locations in New York from 2002-2010, most likely a result of further reductions in
benzene due to reformulation of gasoline and other mobile source programs. For reference, in the
graph we have plotted the NATA 2005 predicted ambient benzene concentrations for the census
tract in which the monitor is located.
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5.0
4.5
4.0
_ 3.5
ro
3.0
to
2.0
1.5
1.0
0.5
0.0
Exhibit 3-11. Benzene Trends in New York
Benzene Trends in New York
--360850055 (1990-1998)
360850111 (2002-2010)
360850132 (2002-2010)
--360810124 (2002-2010)
NATA2005 360850111
» NATA2005 360850132
NATA2005 360810124
1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011
Year
Like benzene, formaldehyde is an urban HAP that contributes significantly to risk in large
metropolitan areas. The EPA estimates that man-made formaldehyde emissions have decreased in
a large metropolitan area such as New York by 63 percent. However, it is difficult to understand
how much the emission reductions impact the ambient concentrations of formaldehyde. This is
because formaldehyde is created from biogenic sources and other pollutants or precursors in the
air via sunlight and chemical reactions called secondary formation, in addition to being emitted
directly into the air from industrial and mobile sources.
We cannot see an ambient monitoring trend in some cities (e.g., New York) due to the impact of
secondary formation on the measured formaldehyde concentrations. The formation of
formaldehyde is complex and a function of many factors including the intensity of sunlight, the
mixing and concentration of precursor pollutants in the air and the rate of the chemical reactions.
It is also a function of geographic location, season and time of day. While federal, state, local and
tribal governments and industry have taken actions to reduce emissions of formaldehyde, the fact
that much of the formaldehyde concentrations in the air are generated in the atmosphere from
other pollutants makes it difficult to assess progress.
Since 2005, the EPA rules have continued to reduce risks in these areas through further reductions
in HAP emissions. For example in New York, the NESHAP for Miscellaneous Metal Parts and
Products (surface coating) and the NESHAP for the Reciprocating Internal Combustion Engines for
major sources have reduced emissions of HAPs organic compounds such as toluene, methylene
chloride and formaldehyde. Other rules promulgated more recently will achieve further
reductions, including the NESHAP for Reciprocating Internal Combustion Engines affecting existing
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spark ignition engines and the NESHAP for Gasoline Distribution, Gasoline Dispensing Facilities.
3.6. OVERALL FINDINGS IN THIS CHAPTER AND CONTINUED EFFORTS
Overall, air toxics emissions (from major, area and mobile sources) have significantly declined since
1990. Reductions of air toxics emissions have been achieved through the EPA's standards and
other national, regional and community-based initiatives to address the most important sources of
air toxics risks in urban areas. We have shown that due to stationary source regulations
promulgated since 1990, that over 1.5 million tons of HAPs have been removed from the air on an
annual basis. In addition, mobile source emissions have been reduced by 50 percent since 1990
and will continue to decrease as the fleet turns over. By 2030, mobile source emissions will be
approximately 80 percent lower than 1990 levels, reflecting both absolute reductions in emissions
relative to 1990 levels and offsetting of emissions increases due to economic and population
growth since 1990.
These estimates are based on the tools and data available at this time. In this chapter, we have
identified several data gaps and limitations (see section 3.1.1.) that affect our understanding of air
toxics and our ability to measure actual progress achieved. Having a clear understanding of the air
toxics program is essential for the EPA and others to prioritize actions and make progress to reduce
risks. Some important steps to that end include:
Continuing research efforts related to cumulative impacts to understand and address more
fully the implications of the public's exposure to multiple pollutants at once. Other
important, related research includes improving our understanding of health effects of air
toxics (e.g., dose-response values), exposure assessment and risk assessment methods.
Improving emissions inventories. Under the current program, sources and states are not
required to submit air toxics emissions data, so the consistency and quality of these
emissions varies significantly.
Promoting ambient monitoring through national programs as well as community-scale
grants. Improved monitoring data will make it easier to identify local air toxics problems and
develop strategies that improve public health.
With the Office of Research and Development and other partners, developing new
monitoring technologies that are less costly and can provide information that is more
transparent and accessible to communities and businesses.
Updating NATA with more recent data to track progress and trends in risks.
Applying Value of Information principles to ensure the highest value returns from
investments in programs and research.
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Chapter 4: National, Regional and
Community-Based Initiatives
4.1. INTRODUCTION
The CAA stated under section 112(k)(4) that the EPA shall encourage and support area-wide
strategies developed by state and local air pollution control agencies that are intended to reduce
risks from emissions by area sources within a particular urban area. Because of the variability of air
toxics at the urban level, the Strategy acknowledged that a partnership with state, tribal and local
governments could be very beneficial at resolving issues at the local level. These governments
have the most experience with local air pollution issues and can lend their expertise and
knowledge to address and resolve concerns unique to their specific areas. As the federal partner,
the EPA can contribute national standards and requirements using CAA authorities to develop and
implement a national regulatory program. We also have the resources and expertise to evaluate,
or to help other agencies evaluate toxic pollution problems. By integrating our strengths,
partnerships can provide a stronger, more efficient and effective program to address air pollution
in urban areas. This chapter focuses on initiatives at the national, regional and community-based
level to help reduce air toxics emissions at the localized area.
The agency has also learned that communities can be drivers for local solutions; however, far too
many communities lack the capacity to truly affect environmental conditions. As a result, many
low-income, minority and indigenous communities continue to live in the most polluted air and
face some of the most severe health impacts, both in urban and rural areas. The EPA has
implemented numerous programs to support community empowerment and provide benefits that
range from basic educational and leadership development to comprehensive approaches. These
include financial assistance programs such as Environmental Justice, CARE, Brownfields Area-Wide
Planning, Lead, and Tribal grants and community-based programs such as the EPA's Local Climate
and Energy, Childhood Asthma, Sustainable Communities and Smart Growth, Urban Waters,
Superfund and Brownfields programs.57 The EPA's ten regional offices play a leading role in
implementing these programs.
Plan EJ 2014, the EPA's roadmap for integrating environmental justice into its programs and
policies, is designed to improve the effectiveness of the EPA's community-based programs through
better information access and coordination. The EPA will build upon and leverage agency efforts to
promote greater coordination in the use of programs and tools that support community
empowerment. Through these efforts, the EPA will make the agency's resources more accessible
to underserved communities, while achieving greater internal efficiency through feedback and
better understanding of how to implement community-based programs. This approach will result
in environmental, health and economic improvements in such communities.
7Plan EJ 2014. http://www.epa.gov/compliance/ej7plan-ej7.
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All of the efforts described in this chapter are directly tied to implementing Goal 3 in the Strategy
(refer to Chapter One), which is to "address disproportionate impacts from air toxics across urban
areas, such as geographic 'hot spots,' highly exposed population groups and predominately
minority and low-income communities."
4.2. AREA-WIDE ACTIVITIES
Section 112(k)(4) mandated that the Administrator shall encourage and support area-wide
strategies developed by state or local air pollution control agencies that are intended to reduce
risks from emissions by area sources within a particular urban area. From the funds available for
grants under section 112, the EPA shall set aside not less than 10 percent to support area-wide
strategies addressing HAPs emitted by area sources and shall award such funds on a
demonstration basis to those states with innovative effective strategies.
Funds for urban air toxics area-wide strategies have never been appropriated to the agency.
Congress has appropriated funds to the agency under section 103 (typically for specialized air
studies) and section 105 (to implement programs to prevent and control air pollution and address
primary and secondary ambient air quality standards) of the CAA. The EPA has issued annual
program guidance for numerous years encouraging the use of a portion of these funds by
recipients to support air toxics reduction strategies, although there is no requirement that states
or tribes do so. Actual use of funds can vary based on individual recipient negotiations, program
emphasis from year-to-year and performance partnership grant flexibility. Between 1990 and
2011, the EPA awarded about 15 to 20 percent of the allotment of funds to air toxics programs
through the State and Tribal Assistance Grants (STAG) program. In addition to the STAG funding,
the EPA has used other avenues, such as the use of the EPA's allocated Environmental Program
Management (EPM) funding, to award grants to state, tribal and local agencies for community
assessment and risk reduction activities, which are discussed in more detail within this chapter.
4.3. STATE, TRIBAL AND LOCAL GOVERNMENT INITIATIVES AND
PROGRAMS
The 1999 Integrated Urban Air Toxics Strategy noted that local and community-based initiatives
should involve partnerships between the EPA and state, tribal and local governments. To obtain
advice on how to structure a program encompassing federal, state, tribal and local governments to
address air toxics risks collectively, the EPA developed the Integrated Air Toxics State/Local/Tribal
Program Structure Workgroup in January 2000. The workgroup was created under the CAA
Advisory Committee, which was chartered in 1990 through the Federal Advisory Committee Act
(FACA). In September 2000, the FACA workgroup finalized its report titled, "Recommended
Framework for the State/Local/Tribal Air Toxics Risk Reduction Program."58 The FACA workgroup
recommended development of a flexible framework that accommodated existing, mature state
and local air toxics programs, and state, tribal and local agencies that needed to develop entire
programs. The FACA workgroup also acknowledged that it was essential for state, tribal and local
shttp://www.epa.gov/ttn/atw/urban/facawg.pdf.
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governments to form partnerships with the EPA.
In September 2001, the EPA developed the "Workplan for the National Air Toxics Program and
Integrated Air Toxics State/Local/Tribal Program Structure," and its purpose was two-fold.59 First, it
was to provide an overview of the activities the EPA had accomplished or was planning to address
during the technology- and risk-based phases of the national air toxics program under the CAA.
Second, the workplan described the EPA's approach for exploring development of a program
encompassing federal, state, tribal and local governments to address coherent air toxics risk during
the risk-based phase of the national program as recommended in the FACA report.
The EPA worked closely with the EPA regional offices, state, tribal and local agencies to determine
what was needed to establish a risk-based air toxics program as recommended by the FACA
workgroup. The EPA subsequently determined that there would be significant complexities
associated with developing the recommended type of program because air toxics issues can vary
significantly from state-to-state and community-to-community. In addition, there were issues
regarding the EPA's legal authorities to implement a program as recommended by the FACA. As a
result, it is the EPA's intention to implement the program as required under section 112, including
section 112(f). In addition, as we issue regulations pursuant to the residual risk program, we intend
to work with state, tribal and local agencies, communities and industry to ensure any new
requirements are implemented.
Since 1990, the EPA has helped state, tribal and local agencies by encouraging and supporting their
area-wide air toxics strategies. The EPA has developed technical support materials to provide
guidance and recommendations for conducting risk assessments that can inform development of
such strategies. For example, the EPA developed the Air Toxics Risk Assessment Reference
Library,60 a three-volume compendium of techniques for conducting all types of risk assessment
for sources of HAPs. In addition, a hands-on train-the-trainer course was developed and delivered
to each of the ten EPA regional offices during 2004 and 2005. The purpose of this training was for
the EPA regions to train the states and the states to train local communities on how to identify and
assess issues of concern for their specific areas. The premise behind this type of training was to
involve personnel who were knowledgeable about the issues in their regional and local areas. As a
result of these technical support and outreach activities, state, tribal and local air pollution
agencies are better equipped to use state-of-the-art risk assessment methodologies and to
develop their own risk-based air pollution control strategies.
For example, the state of Oregon developed a statewide air toxics programs that required more
stringent requirements in areas of concern. Louisville, Kentucky, developed local air toxics
requirements designed to address the impacts of air toxics that pose elevated risks to human
health in their area. In addition, the Gila River Indian Community, Salt River Indian Community and
Fort McDowell Indian Community, in partnership with the state of Arizona, Maricopa County and
the city of Phoenix, joined forces to conduct the Joint Air Toxics Assessment Program to identify
risks from toxics in the Phoenix area.
59http://www.epa.gov/ttn/atw/urban/workplan.pdf.
60http://www.epa.gov/ttn/fera/risk_atra_main.html.
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4.4. COMMUNITY-BASED INITIATIVES
The EPA has initiated and supported numerous state, tribal, local and community programs to
reduce risks from air toxics. The EPA became involved in community assessment and risk reduction
projects to learn more about risks from air toxics at local levels; to promote information sharing
among the EPA and state, tribal and local agencies; and to use localized risk information in the
development of the residual risk and urban air toxics programs. Beginning in fiscal year 2001, the
EPA provided supplemental funding through grants to several community risk assessment and risk
reduction projects to add value to regionally led, community projects and to learn more about
issues at the local level. One of the important benefits of these community-based efforts (beyond
addressing local health risks) is capacity building and empowerment of communities, particularly
minority, low income, tribal and indigenous populations or communities that often do not have
access to resources to address their concerns. Studying local community projects enables EPA to
find solutions that take into account the uniqueness of the problems faced by local communities
(e.g., by avoiding implementing a one-size-fits-all approach when running programs).
4.4.1. Community Air Risk Reduction Initiative (CARRI)
From fiscal year 2001 to 2005, the EPA awarded more than $2 million in grant funding with a goal
towards enabling communities to understand local air toxics issues better. CARRI funds supported
community air toxics risk screening and assessment tool development; air toxics source
identification and characterization through broad stakeholder participation; building of local air
toxics inventory and characterization capacity; and support of on-the-ground projects aimed at
reducing air toxics exposures and emissions. Using CARRI and other funding, the EPA regional
offices were able to initiate many air toxics community projects while developing expertise in
working with local communities and stakeholders. As a result of these regionally led local
initiatives, tools, guidance, and an information database, known as the Air Toxics Community
Assessment/Reduction Projects Database,61 were developed. By gathering and continuing to
evaluate information collected from these community-based projects, the EPA was able to learn
more about air toxics problems at the local level and to refine models used in projecting risk in
these communities. This information was also of value to other communities interested in
addressing similar issues in their areas. This database is no longer updated but remains available as
a reference.
4.4.2. Community Action for a Renewed Environment (CARE)
Building on the CARRI and other EPA community-based programs, the agency currently fosters
community action through the CARE program that has provided 100 cooperative agreements for
creating broad-based partnerships to identify and prioritize multimedia environmental problems,
implement local solutions to reduce toxics risks and minimize public health concerns. As outlined
in the 2009 National Academy of Public Administration report titled, "Putting Community First: A
ite. epa.gov/oar/CommunityAssessment. nsf/Welcome?OpenForm.
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Promising Approach to Federal Collaboration for Environmental Improvement,"62 many of these
grants have gone to low income, minority communities in urban areas that have identified air
toxics issues, such as diesel emissions, as high priorities. From fiscal year 2005 to 2011, the
program received $16.1 million in funding.
Through CARE, local partnerships, including non-profits, community residents, businesses, schools
and tribal/local governments, identify, prioritize and implement local solutions to reduce
environmental risks. The CARE program educates by helping them conduct community-wide
assessments of the environmental concerns they face and provides access to the EPA's partnership
programs.
The goals of the CARE program are to:
Reduce exposures to toxic pollutants through collaborative action at the local level.
Help communities understand all potential sources of exposure to toxic pollutants.
Work with communities to set priorities for risk-reduction activities.
Create self-sustaining, community-based partnerships that will continue to improve the local
environment.
Communities consider CARE grants for several reasons, including:
If a community wants to reduce levels of toxic pollution, the CARE program can help.
CARE assists communities by providing information about the pollution risks they face
and the funding to address these risks.
CARE promotes local consensus-based solutions that address risk comprehensively.
Through CARE, the EPA also provides technical assistance and resources, thereby
helping communities to identify and access ways to reduce toxic exposures, especially
through a broad range of voluntary programs.
As communities create local stakeholder groups that successfully reduce risks, CARE
helps them build the capacity to understand and address toxics in their environment.
CARE has offered two different types of cooperative agreements: Level 1 and Level 2. These can be
thought of as assistance grants and approximately $90,000 and $275,000 respectively. Level 1
Cooperative Agreements helped communities:
Join together to form a broad-based partnership dedicated to reducing toxic pollutants and
environmental risks in their local environment. Partners can be non-profit groups,
community organizations, businesses, schools, state, tribal and local government agencies,
the EPA and other federal agencies.
Identify problems and solutions. Working together, this stakeholder group assesses toxics
problems in their community and considers options for reducing environmental risks. Many
62 http://www/napawash.org/pc_management_studies/CARE/5-21-09_Final_Evaluation_Report.pdf.
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of the emission and exposure reductions will result from the application of the EPA
partnership programs. The EPA technical assistance is available to support this process.
Level 2 Cooperative Agreements are for communities that already have established broad-based
collaborative partnerships and have completed environmental assessments. Level 2 Cooperative
Agreements have helped communities:
Implement solutions and reduce risks: The partnership identifies the combination of
programs that best meet the community's needs.
Become self-sustaining: The community develops local solutions and ways to continue
their environmental work long-term (e.g., increased partnerships and sustainable
practices). CARE funds pay to implement the local actions and solutions that are
identified. These solutions will reduce risks within their community. The result:
communities will build self-sustaining, community-based partnerships that will continue
to improve human health and local environments into the future.
Not only has the CARE program helped many communities directly, but also the lessons learned
from the CARE program have been invaluable to the agency. Currently, the CARE principles are
being applied to an approach under development as part of the EPA Plan EJ 2014, which will focus
on the agency being a conduit by bringing together underserved communities with federal
agencies, private industry, businesses, foundations, universities and other institutions.
4.5. SUSTAINABLE SKYLINES INITIATIVE (SSI)
The SSI was initiated in 2007 and continued through 2010 to help areas reduce their emissions and
promote sustainability, with the goal of cleaner and healthier air. This effort encouraged
governmental, public and private sectors in a community to work together to integrate
transportation, energy, land use and air quality. The first pilot project began in Dallas, Texas, with a
grant of $250,000.63 Within 3 years, the program had grown to include more than 26 partners and
had leveraged more than $4 million from public, private and national governmental organizations.
Between 2007 and 2010, an additional $625,000 in grant funding was provided to other areas,
including Kansas City, Kansas and Missouri, Philadelphia, Boston, Indianapolis, and Upstate Forever
South Carolina consisting of a multi-county regional area in South Carolina. The program also
initiated the Seventh Generation Initiative (SGI), which focused on Native American Indian tribes,
livability and cultural preservation. Grants totaling $150,000 were split between the Leech Lake
Band of Ojibwe Tribe, Mille Lacs Band of Ojibwe Tribe and Grand Traverse Band of Ottawa and
Chippewa Tribe.
The SSI and SGI initiatives were successful in helping communities and tribes initiate community-
driven projects with a small amount of federal grant funding. These initiatives helped communities
and tribes initiate a multimedia approach to achieve environmental benefits and improve air
quality by recruiting public and private partners from within their community.
3http://www.sustainableskylines.org/Dallas/.
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4.6. COMMUNITY-SCALE AIR TOXICS AMBIENT MONITORING GRANTS
Beginning in 2003, the EPA's Office of Air Quality Planning and Standards, in conjunction with the
Office of Transportation and Air Quality, the Office of Research and Development's National
Exposure Research Laboratory and the ten EPA regional offices, have conducted periodic
Community-Scale Air Toxics Ambient Monitoring grant competitions. The grants support projects
of one and a half to three years duration that are designed to assist state, tribal and local
communities in identifying and profiling air toxics sources, characterizing the degree and extent of
local air toxics problems, and tracking progress of air toxics reduction activities. Expected
outcomes of these projects are increased state, tribal and local agency ability to: 1) characterize
the sources and local-scale distribution of HAPs; and 2) assess human exposure and risk at a local
scale. These increased capabilities are expected to facilitate increased public and industry
awareness and action to adopt control measures that will reduce HAP emissions and public
exposure. From fiscal year 2003 to 2011, the program received $22.6 million in funding.
In July 2009, the EPA issued a report that presents results from the Community-Scale Air Toxics
Ambient Monitoring projects that were completed at that time.64 Since 2004, grants have been
awarded from this program to 52 unique projects to benefit local-scale monitoring efforts, of
which 35 have sufficiently progressed to be described in this report. Geographically, grants have
been awarded across the entire United States in large, medium and small communities. Additional
points were given to those applicants who demonstrated partnerships with community members,
particularly those in EJ areas. Awarded grants fall into one of three category bins: community-scale
monitoring; method development/evaluation; and analysis of existing data. Each awarded grant
generally ran from 18 to 36 months, but might have been extended due to project initiation
difficulties. Each awardee has or will submit a final report to the EPA at the end of the project
period. Targeted pollutants generally reflected the National Air Toxics Trends System core
compounds, criteria pollutants or pollutants related to diesel particulate matter. It is important to
highlight that in the grant solicitation in 2011, one of the criteria was to ensure that communities,
particularly low income, minority and indigenous communities, are involved in the development
and implementation of the projects.
4.7. NATIONAL INITIATIVES
4.7.1. Wood Smoke Reduction Initiative
Many areas across the country experience higher levels of residential wood smoke, which contains
toxic constituents that are harmful to human health. To reduce wood smoke emissions, the EPA
developed the woodstove changeout program and Burn Wise, programs that emphasizes the
importance of burning the right wood, the right way, in the right wood-burning appliance to
protect your home, health and the air we breathe. The EPA has emphasized assisting urban and
rural communities with replacing thousands of old, dirty wood stoves and fireplaces with cleaner
64http://www.epa.gov/ttn/amtic/files/ambient/airtox/CSATAMSu mmaryReport2009.pdf.
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burning appliances and with making informed decisions about what it means to "burn wise."
The wood stove changeout program is a voluntary, education and incentive-based (e.g., rebates or
discounts) effort to encourage owners of old, inefficient woodstoves to replace or "changeout"
their stove with a cleaner burning appliance like gas stoves, wood pellet or corn stoves, or the EPA-
certified wood stoves.
Additionally, we have also negotiated with industry to design and market new wood burning
devices that can meet tighter emissions levels on a voluntary basis. The devices consist of hydronic
heaters (i.e., wood boilers) and fireplaces that are currently not covered by the EPA's regulation for
new residential wood heaters. The EPA initiated the hydronic heater partnership program in
January 2007 to reduce emissions from new outdoor wood-fired hydronic heaters. The EPA has
worked with the hydronic heater industry to reach agreement on voluntary emissions levels for
new heaters. The approach has brought thousands of cleaner heaters to market faster than under
a traditional, regulatory approach. The goal of the program is to support those areas that choose
to allow hydronic heaters by encouraging manufacturers to design and offer new, cleaner models
for sale on the market as soon as possible. The program is structured in two phases: under Phase
1, qualified new units are at least 70 percent cleaner than existing units; and under Phase 2, new
units are at least 90 percent cleaner than existing units.
Residential wood smoke contains harmful fine particle pollution, as well as hazardous air
pollutants. The HAPs produced from burning wood and other organic matter in residential wood
stoves, fireplaces and other wood-burning devices in urban homes across the country include
benzene, formaldhyde, acrolein, dioxins and furans, 1,3-butadiene, PAHs, acetaldehyde, methane,
and napthalene. The Wood Smoke Reduction Initiative encourages old appliance removal or
appliance replacement with cleaner burning appliances (e.g. EPA-certified wood stoves, pellet
stoves, gas stoves) to reduce harmful air pollution indoors and out. The program also promotes best
burning tips, which are practices known to help reduce wood smoke pollution.
Over the past years, EPA has provided funding, technical support, training, education and outreach
to more than 40 wood smoke reduction programs across the country. EPA's Wood Smoke
Reduction Initiative has supported many urban areas across the U.S. to reduce fine particle and
other hazardous air pollution from wood smoke. These areas include Fairbanks, Alaska;
Sacramento, California; Tacoma, Washington; Madison, Wisconsin; and Pittsburgh, Pennsylvania. All
of these urban areas have households that burn wood as a primary source of heat. The urban
programs have assisted these households, many of them low-income, to replace high polluting
wood-burning devices with cleaner burning appliances (e.g., EPA-certified wood stoves).
The EPA estimates program HAP reductions using an EPA-developed emissions calculator. The
calculator estimates the amount of emissions avoided if EPA-certified wood stoves replace a
number of conventional wood stoves or if fireplaces are replaced by gas logs. The calculator
contains assumptions from EPA's National Emissions Inventory and, since 2008, provides HAP
reduction estimates. As an example, Fairbanks, Alaska, has replaced 1,000 wood stoves with cleaner
burning EPA-certified stoves over the past few years. Removing the old stoves has reduced
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approximately 3 tons of benzene, 1.7 tons of formaldhyde, and .15 tons of acrolein per year. Co-
benefits include 330 tons of CO, 88 tons of VOCs and 46 tons of particle pollution per year.65
4.7.2. Collision Repair Campaign
In 2007, the EPA initiated a Collision Repair Campaign to help collision repair/autobody shops and
communities reduce harmful HAPs from this industry. The program is voluntary, with participation
from EPA headquarters and regional offices, state and local agencies and industry. The program
provides free training, technical assistance and community outreach to local collision repair shops
about established best management and pollution prevention practices. The program's goal is to
help shop owners reduce paint, solvent and related hazardous waste disposal costs. It also aims to
achieve enhanced compliance with the EPA's rule on Paint Stripping and Miscellaneous Surface
Coating Operations at Area Sources by reducing pollutants early and to levels beyond those
required by the rule.
This program has helped reduce the negative environmental and health impacts on employees and
surrounding communities by reducing air toxics, VOC and PM emissions.
The collision repair industry was identified for a campaign for several reasons:
Many communities have identified these shops as an environmental and health
concern, and hence the number of efforts across the United States to address this issue.
These shops are widespread in nature and tend to be clustered in minority, immigrant
and low-income neighborhoods.
Many of these shops are not in compliance with existing occupational and
environmental health regulations.
Many of these shops are small businesses and do not often use standard methods for
auto body repair and painting, and they do not comply with accepted industry practices
or current control technologies.
To provide information to owners and operators about the federal area source rule
designed to reduce auto body emissions.
Benefits of the campaign included:
Significantly less exposures to toxics, estimated to be reduced by 90 percent through
implementation of best practices, which included installing and maintaining control
equipment and using safer paints and solvents.
Lower HAP and VOC emissions by 3.5 million fewer pounds annually when best practices
are utilized in 1,000 shops.
Reduced paint and solvent costs and related hazardous waste disposal costs.
65Assumes 4 cords of wood are burned per wood stove.
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Better environmental stewards, happier and healthier community neighbors and
improved worker safety and health.
Earlier and greater compliance for sources subject to the National Emission Standards
for HAPs: Paint Stripping and Miscellaneous Surface Coating Operations at Area Sources
rule.
4.7.3. School Air Toxics Monitoring Project Study
In March 2009, the EPA released a list of schools that would be part of an initiative to understand
whether outdoor toxic air pollution posed health concerns to schoolchildren. Air quality
monitoring took place at 65 schools, many in low-income, minority communities in 22 states and
2 tribal areas (the tribal monitoring has continued to include activities for four other tribes). The
EPA selected the schools using results from computer modeling analyses, the 2002 NATA, results
presented in a newspaper series on air toxics at schools and in consultation with state and local air
agencies. The EPA focused on schools near large industries and schools in urban areas, where
emissions of air toxics come from a mix of large and small industries, cars, trucks, buses and other
sources.
Monitors were placed at each school for 60 days or long enough to collect 10 valid samples of each
pollutant of interest. The pollutants monitored varied by school based on the best available
information about the pollution sources, potential air concentrations and risk in each area. See
Exhibit 4-1 for a listing of the pollutants measured. The EPA and states also used equipment to
measure wind speed and direction at each school during the monitoring.
Exhibit 4-1. Pollutants Measured as Part of School Air Toxics Monitoring Study
Pollutant Groups
Carbonyls
Diisocyanates
Metals
PAHs
VOCs
Individual pollutants
Key Pollutants of Particular Interest
Acetaldehyde
Methylenediphenyl diisocyanate; 2,4-toluene
diisocyanate; 1,6-hexamethylene diisocyanate
Arsenic; cobalt; lead; manganese; nickel
Benzo (a) pyrene and other PAHs; naphthalene
Acrolein; benzene; 1,3-butadiene
4,4'-methylenedianiline and Chromium VI (Hexavalent
Chromium)
At schools where the EPA was interested in levels of lead and other metals, the agency collected
both coarse particles (particulate matter or PM10) and total suspended particulate (TSP) samples.
Initial monitoring was completed for all schools in May 2010 and is posted on the EPA's school
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monitoring website.66 For most of the schools, monitored concentrations were lower than levels
predicted by the EPA's models. Overall, the levels monitored for most pollutants were within
acceptable limits, but higher levels of certain pollutants were found in several communities.
Additional monitoring was conducted for a few schools for various reasons. All additional
monitoring was completed in early 2012, and the analysis was completed in early 2013. As a follow
on to the schools program, the EPA issued a request in 2011 for grant proposals for community-
scale air toxics ambient monitoring projects as described in section 4-6 above.
The EPA had limited information on tribal schools and limited emissions information, and
therefore, was only able to include two tribal schools. The term "tribal school" refers to any school
located within a reservation boundary or any school operated by a tribe, Bureau of Indian Affairs
or tribal agency (regardless of location). The EPA was concerned that lack of information/data did
not mean there was not a problem in Indian country and wanted to investigate further. As a result,
the EPA has worked closely with the Tribal Air Monitoring Support Center to provide additional
resources and monitoring equipment that can be loaned to tribes to conduct additional
monitoring.67
4.8. MOBILE SOURCE INITIATIVES
4.8.1. National Clean Diesel Campaign
In 2000, the EPA initiated the National Clean Diesel Campaign, which promotes clean air strategies
in urban areas and elsewhere by working with manufacturers, fleet operators, air quality
professionals, environmental and community organizations, and state and local officials to reduce
diesel emissions for existing engines that the EPA does not regulate. In addition to diesel PM,
exhaust from diesel engines contains many urban air toxics, such as acetaldehyde, acrolein,
benzene, 1,3-butadiene, formaldehyde and polycyclic aromatic hydrocarbons. Because diesel
engines can operate for 20 to 30 years, millions of older, dirtier diesel engines are still in use. The
EPA offers many strategies and programs to help make these engines operate more cleanly and
has funded diesel emission reduction programs that improve air quality and protect public health.
The National Clean Diesel Campaign advances strategies, such as retrofits and reduced idling, to
reduce diesel emissions from school buses, truck fleets, ports and construction sites. In addition,
the EPA provides resources for state and local transportation through links to federal funding
sources for projects relating to transportation and air quality (U.S. EPA, 2011d).
Congress appropriated dedicated funding to the National Clean Diesel Campaign through the
Diesel Emissions Reduction provisions of the Energy Policy Act of 2005 (DERA). The EPA has
administered approximately $50 million in fiscal year 2008, $120 million through the 2009 and
2010 appropriations. The American Recovery and Reinvestment Act of 2009 provided $300 million
in additional DERA funding for national and state programs to support the implementation of
verified and certified diesel emission reduction technologies. Over their lifetime, these projects are
estimated to reduce at least 203,900 tons of nitrogen oxides (NOx) and 12,500 tons of PM. These
66http://www.epa.gov/schoolair/.
67http://www4. nau.edu/tams/services/tsatmproj.asp.
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clean diesel projects also are estimated to create lifetime reductions of carbon monoxide (CO) by
48,000 tons, hydrocarbon (HC) by 18,000 tons and carbon dioxide (CO2) by 2.3 million tons and fuel
savings of more than 200 million gallons. In addition, DERA projects funded in fiscal year 2011 are
using technologies and strategies that can reduce PM emissions up to 95 percent.
4.8.2. SmartWay
The SmartWay Transport Partnership is a collaborative program between the EPA and the goods
movement sector to increase the energy efficiency and energy security of our country while
significantly reducing air pollution and greenhouse gases. The Partnership creates strong market-
based incentives that challenge companies shipping products and the truck and rail companies
delivering these products to improve the environmental performance of their freight operations.
The EPA advanced the use of cleaner, more efficient technical and operational strategies by
designating clean and efficient vehicles and products, recognizing top performing partners, and
doing technical outreach and education. SmartWay partners save fuel, which contributes to our
nation's economic sustainability and energy security, while improving air quality and reducing the
risk of global climate change by reducing CC>2, NOx, PM and other harmful diesel emissions
throughout the freight supply chain. SmartWay partners assess and track fuel savings and emission
reductions using the EPA-designed tools.
In 2011, SmartWay launched a new initiative aimed at upgrading the "drayage" trucks that service
our nation's ports. Diesel emissions from port drayage trucks, which are frequently older and
dirtier than other freight trucks used in goods movement, can be a significant contributor to air
quality problems for communities located near ports. These communities often face multiple
economic and environmental challenges, including air quality concerns. The SmartWay Port
Drayage Truck Initiative provides incentives for shippers, ports and truck operators to reduce
diesel emissions, including PM emissions, and provides EPA-designed tools to track these
benefits.68
4.8.3. Clean School Bus USA
Clean School Bus USA is a national partnership to minimize pollution from school buses. Leaders
from corporate America and children's health, environmental and governmental organizations
design plans to reduce children's exposure to diesel exhaust by eliminating unnecessary school bus
idling, installing effective emission control systems on newer buses and replacing the oldest buses
in the fleet with newer ones. Currently funded under the DERA program, clean school bus retrofit,
replacement and reduced idling projects constitute about 22 percent of vehicles targeted in DERA
grants.69
6Shttp://www.epa.gov/smartway.
69http://www.epa.gov/cleanschool bus.
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4.9. NATIONAL ENFORCEMENT-BASED INITIATIVES
The EPA is utilizing the NEI, NATA, and innovative source monitoring and compliance evaluation
techniques to assist in enforcement of air toxics regulations. The EPA is using these tools to identify
communities that are in areas suspected to be affected by significant HAP emissions or to identify
previously unknown HAP emissions. In recent years, the EPA's Air Toxics Enforcement Initiative has
focused on equipment leaks and industrial flares at chemical manufacturing facilities and petroleum
refineries.70 The EPA asserts that improperly operated flares and leaking equipment are some of the
largest sources of HAP emissions at these facilities. As a result, in some cases, a facility's actual air
toxics emissions may be significantly higher than previously reported.
Air toxics have been an EPA federal enforcement initiative since 2004. Since that time, federal
enforcement cases have resulted in approximately 10 million pounds of HAP reductions and the
installing of an estimated $43 million in pollution controls. Two recent settlements can be found at
http://www.epa.gov/compliance/resources/cases/civil/caa/marathonrefining.html and
http://www.epa/compliance/resources/cases/civil/bp-whitingt.html.
4.10. CONTINUED EFFORTS
Because air toxics tend to pose greater risks in urban areas, it is critical that the EPA continue to
work in partnership with states, tribes, local governments and communities to make on-going
progress in reducing these risks. Some important ways to make these connections include building
partnerships with state, tribal and local governments and communities to integrate our strengths,
resources and expertise to resolve issues at the local level.
70http://www.epa.gov/oecaerth/data/planning/initiatives/2011airtoxics.html.
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Chapter 5: Education and Outreach
5.1. INTRODUCTION
Given the scientific complexity inherent in air toxics issues and the need to communicate
effectively about these risks to the public, the EPA has made education and outreach a key
component in the Strategy. Because of the scope of the Strategy and the unique perspectives of
key stakeholders like tribal leaders, small business owners and environmental justice communities,
public participation is a necessity to the implementation of the Strategy and to meeting our risk
reductions goals. Communication not only includes providing information to stakeholders and the
public, but it also consists of an opportunity for them to play an active role in the development of
regulations, policies and guidance that might affect them. This chapter presents the EPA's
education and outreach efforts with state, tribal and local governments as well as training,
implementation tools and information dissemination programs.
5.2. STATE, TRIBAL AND LOCAL PARTNERSHIPS
The EPA's headquarters and regional offices, and state, tribal and local agencies recognize the
importance of teamwork to ensure a successful program to protect public health and the
environment. As part of these coordination efforts, the EPA has developed partnerships to share
information on community capacity building, tools for understanding local air toxics and improving
air quality and obtaining stakeholder advice and input. Examples of several partnerships are
provided below.
The National Association of Clean Air Agencies (NACAA) represents air pollution control
agencies in 53 states and territories and more than 165 major metropolitan areas across
the United States. The primary role of the association is to encourage the exchange of
information among air pollution control officials, to enhance communication and
cooperation among federal, state and local regulatory agencies and to promote good
management of our air resources.
The National Tribal Air Association (NTAA), founded in 2002 with a grant from the EPA,
is managed by the National Tribal Environmental Council (NTEC) to advance air quality
management policies and programs, consistent with the needs, interests and unique
legal status of American Indian Tribes and Alaska Natives. All federally recognized tribes
are eligible to become members.
The National Environmental Justice Advisory Council (NEJAC), established by the EPA in
1993, includes representatives of community, academia, industry, environmental,
indigenous and state/tribal/local government groups in an effort to create a dialogue
that can define and "reinvent" solutions to environmental justice problems.
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5.3. TRAINING AND OUTREACH
The EPA's training and outreach programs provide an important mechanism to delivering critical
information on our rules and programs to state, tribal and local partners that implement air toxics
programs, the public and others. These trainings and outreach efforts are delivered in many
formats, including websites, videos, webinars, workshops and conferences. In recent years, we
have worked closely with the NACAA Training Committee to develop an annual National Training
Strategy for state and local air pollution agency staff. This effort includes implementation of a
Learning Management System (LMS), completed in November 2012, to coordinate delivery and
management of training nationwide and to promote efficient use of resources. The EPA is also
assisting in development of a curriculum to facilitate the training of state and local air pollution
agency staff on both introductory and more advanced levels. Classroom courses continue to be an
important part of training for state, tribal and local air program staff. With more and more travel
constraints, distance-learning using pre-recorded training video modules and webinars help the
agency provide "just-in-time" training on regulations and policies.
Specific and technical air pollution training can be found at the Air Pollution Training Institute
(APTI), which primarily provides technical air pollution training to state, tribal and local air
pollution professionals, although others could benefit from this training. APTI's goal is to facilitate
professional development by enhancing the skills necessary to understand and implement
environmental programs and policies.71
Educational training toolkits are available for educators, students and the general public.
Numerous on-line training opportunities and supplementary materials have been developed on
subjects such as the components of an air quality management system, a guide to air quality and
your health, the importance of burning the right wood in the right way and common air pollutants.
Much of this information is available online under the AIRNow "Learning Center."72
Tribal Training: The agency also provides on-going support for the Institute for Tribal
Environmental Professionals (ITEP). ITEP was created in 1992 to act as a catalyst among tribal
governments, and research and technical resources at Northern Arizona University (NAU), in
support of environmental protection of Native American natural resources. Their mission is to
serve tribes through culturally relevant education and training that increases environmental
capacity and strengthens sovereignty. ITEP accomplishes its mission through several programs,
including technical support for air and waste programs; program development support; and web-
based training. ITEP is a national organization and to date has served more than 500 federally
recognized tribes with environmental education, training courses, technical assistance and other
resources. In addition, the agency supports an annual conference, the National Tribal Forum, and
provides other mechanisms for capacity building, including webinars for tribes to inform them of
upcoming rules, conference calls and a tribal air newsletter to help keep the tribes involved in our
programs and rules.
71http://www.epa.gov/apti/index.html.
72http://airnow.gov/ or http://epa.gov/aircompare/.
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Environmental Justice (EJ) Community Training: The agency also provides capacity-building
activities for communities as well. In 2007, the EPA held its first Air and EJ Conference to help share
best practices on community-based activities. This conference grew in 2010 and 2011 to include
multimedia issues and activities. In addition, the agency holds regular conference calls with
communities and conducts webinars on upcoming rules and programs to keep the communities
informed. In 2012, the EPA intends to expand its capacity building to include EJ and permitting, the
use of publicly available technical tools and resources and other issues specific to addressing
community needs and concerns.73
5.4. IMPLEMENTATION ASSISTANCE TOOLS
To ensure affected sources, particularly small businesses, understand how to comply with air toxics
regulatory standards and policies, the EPA develops implementation assistance tools, such as fact
sheets, notification forms, compliance checklists, timelines, guidance manuals and trainings. These
tools help to ensure that the rules are implemented successfully, and therefore, realize the
expected emission reductions. Better compliance in turn, will help protect the public health of
citizens living and working around the regulated emission sources. All of this information is posted
on the EPA's Air Toxics website.74
To coordinate better with the Office of Enforcement and Compliance Assurance, the Office of Air
and Radiation assisted in the development of guidance for implementation of area sources that:
1. Prioritizes the area source rules to help delegated agencies and the EPA regions focus
their limited resources on the most significant standards to achieve emission reductions
to the greatest extent possible;
2. Identifies recommended approaches to ensuring compliance with individual rules; and
3. Provides delegated agencies flexibility to address regionally significant issues. In
addition, the guidance addresses other implementation issues such as data reporting.75
5.5. INFORMATION MANAGEMENT AND PUBLIC AWARENESS
The EPA's information management systems rely on electronic reporting to collect vast amounts of
data provided by the EPA, state, tribal and local agencies. These systems take advantage of the
latest technology to ensure the data are provided in an efficient and timely manner. However, it is
not enough to simply collect data. The agency and the nation's top research scientists rely upon
the information stored in these systems to develop regulatory analyses and perform health
73http://www.epa.gov/air/ej/index.html.
74http://www.epa.gov/ttn/atw/index.html.
75Area Source Rule Implementation Guidance. June 4, 2010.
http://www.epa.gov/compliance/resources/policies/monitoring/CAA/areasource.pdf.
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studies.
Information systems also fill a critical role in fostering transparency with the public. Using
websites, social media, Smartphone apps and other tools, the EPA information systems provide the
public with access to important agency data that, taken together, provide a complete picture of
the national air quality. For example, sources of air toxics emissions are available at
http://www.epa.gov/ttn/chief/eiinformation.html while air quality information is available free to
subscribers through the AIRNow iPhone app, AIRNow Facebook page and www.airnow.gov. This
allows the public to see where in their community the sources of air toxics are located and then to
see the resulting quality of the air they breathe.
The following is a list of critical information management data systems:
The Air Quality System (AQS) employs the latest in electronic reporting to house
ambient air pollution data collected by the EPA, state, tribal and local air pollution
control agencies from thousands of monitoring stations. AQS also contains
meteorological data, descriptive information about each monitoring station (including
its geographic location and its operator, and data quality assurance/quality control
information. The EPA's Office of Air Quality Planning and Standards and other AQS users
rely upon the data to assess air quality, assist in attainment/non-attainment
designations, evaluate State Implementation Plans for non-attainment areas, perform
modeling for permit review analysis and other air quality management functions.76
The AQS Data Mart is a publicly accessible database containing all of the most requested
information from AQS. The Data Mart was built as a storehouse of air quality
information that allows users to request unlimited quantities of data. It also contains
ozone data from AIRNow (the real time air quality reporting system) that participating
agencies allow to be shared with the public. Currently, the AQS Data Mart has more
than 2 billion sample values, including every measured value and the associated daily
and annual aggregate values collected and calculated by the EPA since January 1,1980.
The Data Mart serves as the back-end database for a number of agency interactive
tools.77
The Emissions Inventory System (EIS) is the agency's information system for storing all
current and historical air emissions inventory data reported electronically from the EPA,
state, tribal and local agencies. The EPA uses the EIS to receive and store emissions data
and to generate a comprehensive, multipollutant, national emission inventory that
supports regulatory and other clean air decisions. EIS provides the emissions inventory
data that are made available to the public.78
AIRNow lets the public know the quality of the air they breathe and better understand
links among local and regional control programs, personal behavior (e.g., driving,
electricity use and fuel consumption), air pollution and health effects. The EPA, the
National Oceanic and Atmospheric Administration, the National Park Service, tribal,
76http://www.epa.gov/ttn/airs/airsaqs/.
77http://www.epa.gov/ttn/airs/aqsdatamart/.
7Shttp://www.epa.gov/ttn/chief/eiinf ormation.html.
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state and local agencies developed the AIRNow website to provide daily Air Quality
Index (AQI) forecasts and real-time AQI conditions for more than 300 cities across the
United States and links to more detailed state and local air quality websites.79
EnviroFlash is sponsored by the EPA with support from state and local air quality
agencies and provides air quality information such as forecasts and action day
notifications via email for a particular area of interest. EnviroFlash provides instant
information that can be customized for the reader's own needs, allowing individuals to
adjust their lifestyle when necessary on unhealthy air quality days. Up-to-date air quality
information is especially helpful for those with sensitivities, such as the young, people
with asthma and the elderly.80
The Tribal Air website is designed to strengthen the EPA and tribal air quality programs
in Indian country by providing timely and user-friendly access to key information;
promoting the exchange of ideas; and making available relevant documents to all
environmental professionals who live and work in Indian country.81
5.6. CONTINUED EFFORTS
The EPA will continue to work in partnership with our stakeholders to inform them about the air
toxics program, including background on risks, regulatory actions, and opportunities for voluntary
reductions. Some areas for continued development include:
Partnerships with state, tribal and local agencies to share information on capacity
building, tools for understanding local air toxics and improving air quality and obtaining
stakeholder advice and input, particularly on issues affecting them.
Updating the EPA's website with the latest information on air toxics and developing
videos, webinars and workshops on particular issues.
Expanding electronic reporting of environmental data and developing applications and
technologies to provide more information to state, tribal and local agencies about risks
in local areas.
79http://airnow.gov/.
sohttp://www.envirof lash.info/about.cfm.
81 http ://www. e pa .go v/a i r/tri ba I/.
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Chapter 6: Research to Address
Knowledge Gaps
6.1. INTRODUCTION
The purpose of this chapter is to provide an update on the EPA's progress toward meeting the
research needs of the Integrated Urban Air Toxics Strategy that were identified in the first report
to Congress and to discuss the evolving landscape of air toxics research.
History of Air Toxics Research at EPA f 2000-20111
After the first report to Congress was published in 2000, the EPA developed a draft Air Toxics
Research Strategy (U.S. EPA, 2002c) and an Air Toxics Research Multi-Year Plan (MYP; U.S. EPA,
2003a), both of which were reviewed by the EPA Science Advisory Board (SAB) in 2004 (U.S. EPA,
2004). One of the critiques of the SAB was that neither the Air Toxics Research Strategy nor the Air
Toxics Research MYP was effectively integrated with other research programs. In 2007, the EPA's
budget request included a reduction in resources for air research, including a substantial reduction
in air toxics research, as the EPA began transitioning from research focused on individual
pollutants toward a multiple air pollutant research program. Consistent with this transition and
recognizing the need to better integrate and leverage air research resources, in 2008, the EPA's
Office of Research and Development integrated research programs on particulate matter, ozone
and air toxics into one Clean Air Research MYP (U.S. EPA, 2008a). In 2008, the Office of Research
and Development also created a Human Health Risk Assessment (HHRA) research program, which
addresses toxicity assessment of air toxics.
Organization of this Chapter
Similar to the previous report, this chapter is organized around the risk assessment paradigm
(Exhibit 6-1), which links the elements of risk assessment (i.e., the description of a health problem,
including whether one exists) with risk management (i.e., actions to address the risk). Consistent
with this approach, the next four sections of this chapter focus on exposure assessment, health
effects assessment (i.e., hazard identification and dose-response assessment), risk assessment/
characterization and risk management, respectively. Within each of these four sections, the
"Characterization of Needs" subsection summarizes the research needs identified in the previous
report to Congress and summarized in Exhibit 6-2 below. The "Progress thus Far" subsection
discusses research that has been done over the last 12 years to address the needs identified in the
2000 Report to Congress. This chapter is not comprehensive of all air toxics research done over this
period. Some studies are summarized in more detail in Appendix C, and the status of IRIS
assessments for urban HAPs is summarized in Appendix D. The last section in this chapter, section
6.6 "Research for the 21st Century," discusses new directions in EPA research, specifically as they
relate to air toxics.
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Exhibit 6-1. The Risk Assessment Paradigm
Information
Information
RISK
ASSESSMENT
RISK
MANAGEMENT
RESEARCH
Epidemiological
studies
Hazard dentmcation
Controlled human
exposure studies
Animal studies
In vitro, in silico, and
genornics studies
Modeling
Dose-Response
Assessment
Risk Characterization
Exposure
Assessment
Research
Needs
Assessment
Needs
Source: Adapted from National Academies' Risk Assessment and Risk Management Model (NRC 1983) used by EPA
Exhibit 6-2. Research Needs Identified in the 1999 Report to Congress
Research
Need
Research Need Name
Exposure Assessment Needs
1
2
3
4
5
6
7
Improved ambient monitoring methods, characterization and network design to support a national
ambient air toxics monitoring network
Improved area source emissions estimation methodologies and spatial allocation
Methodologies that allow for identification and speciation of important HAPs and
and transformation products
methods
their combustion
A more accurate nonroad mobile source emissions characterization
Improved characterization of air toxics from trucks and improvement of modal emissions modeling
capabilities for all vehicle classes
Development of source-based urban-scale air quality models for the urban HAPs
An understanding of the distribution of human exposures (including susceptible subpopulations)
and the pathways by which HAPs reach humans
Health Effects - Hazard Identification and Dose-response Assessment Needs
8
Use alternative sources of human health effects data (chronic and acute) for urban HAPs to
develop and update dose-response assessments
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9
Development of statistical and mode of action methods for developing acute and chronic dose-
response assessments
Risk Characterization and Risk Assessment Needs
10
11
Improved risk assessment methods for mixtures
Development of better information for more effective techniques for communicating health risk
assessment results for urban HAPs
Risk Management Needs
12
13
Identification of processes contributing to the HAP emissions from area source categories, and
listing of control options and pollution prevention (P2) alternatives for these processes
Identification of pollution prevention alternatives for HAP emissions from mobile sources
6.2. EXPOSURE ASSESSMENT
This section focuses on the exposure assessment information needs, which includes research
related to source emissions, environmental concentration, and human exposures. The EPA has
conducted research to better characterize HAP emissions from select sources, to improve
monitoring methods, to quantify ambient and personal exposure levels and to improve modeling
approaches that allow for prediction of HAP concentrations at different scales (e.g., regional,
urban, personal exposure) and in a multipollutant context.
6.2.1. Characterization of Need
Seven specific areas for exposure assessment research were highlighted in the previous report
(Exhibit 6-2), including research on source emissions (Needs 2, 4, and 5), ambient monitoring
methods (Needs 1 and 3), air quality modeling (Need 6) and human exposures (Need 7).
Emissions
The research needs for source emissions were broad, covering area and onroad and nonroad
mobile sources. Improved methods for estimating emissions from area sources and for spatial
allocation of these sources were needed. For mobile sources, research was needed to more
accurately estimate nonroad mobile source emissions (e.g., emissions from small engines used in
lawn equipment). For mobile sources, improved characterization of air toxics emissions from
diesel-fueled trucks was needed, including better emission factors, data on operating patterns, and
information on emissions changes for new engines. In addition, the ability to model emissions
accurately from all vehicle classes needed improvement; specifically, a more sophisticated
modeling approach to obtain highway vehicle emission estimates accurately resolved in space and
time was needed.
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Ambient Monitoring Methods
Improved monitoring methods for characterizing environmental concentrations were also
identified as an area for further research. Improvements to current ambient monitoring methods
were needed to lower detection limits, for example, and to develop new methods for certain HAPs
and evaluate and refine new methods for use in a national monitoring network. The need for
methods of characterizing individual HAP species (e.g., VOCs, mercury), particularly at the source
category emissions level, was also identified.
Air Quality Model!
Improved source-based air quality models were needed to predict better the relationship between
source emissions and ambient air concentrations for air toxics. Information on the chemical and
physical properties of HAPs under typical atmospheric conditions was needed to improve model
predictions of the fate and transport of urban HAPs. In addition, air dispersion modeling tailored
specifically to the local urban environment was needed.
Human Exposure
Several research needs related to human exposure to HAPs were identified, specifically for
modeling of human exposures and the measurement data needed to improve and evaluate the
models. For human exposure modeling, research needs included refinement in the spatial scale to
estimate population distributions of exposures in an urban environment, development of models
capable of providing probabilistic estimates of the number of persons exposed to different
concentrations of HAPs, and development of models and data that consider key human exposure
microenvironments. Regarding human exposure measurement data, research needs included
studies of exposure concentrations and activity patterns to support model evaluations for urban
HAPs. For example, studies of indoor air exposures to better understand indoor/outdoor ratios of
urban HAPs and movement of HAPs between indoors and outdoors. Personal monitoring and
development of biological markers of exposure to characterize personal exposure were also
identified as research needs.
6.2.2. Progress Thus Far
Substantial progress has been made to address these exposure assessment research needs. The
following provides an overview of the major research activities that have contributed to improving
the understanding of source emissions, environmental concentrations, and human exposures for
urban HAPs. Further details for specific studies are provided in Appendix C as noted.
Emissions
The EPA has made progress towards improving methods for estimating area source emissions,
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including spatial allocation methods. The EPA has also made progress towards improving the NEI
and the 2008 inventory that was released in April 2012 (U.S. EPA, 2008b).
Mobile sources account for a significant proportion of HAP emissions in the NEI, and include both
onroad and nonroad sources. In the 1999 NEI, the nonroad small engine source sector was the
second largest contributor to mobile source gaseous HAP and VOC emissions behind light duty
vehicles. The EPA researchers investigated the relative contribution of small nonroad engines in
the NEI. The EPA conducted limited testing to better characterize air toxic emissions from small
nonroad spark ignition engines from equipment such as lawn mowers, chain saws, leaf blowers
and string trimmers to better understand the relative contribution of small nonroad engines
(Baldauf et al., 2006; Volckens et al., 2007, 2008). This research provided the highest quality data
the EPA had on HAP emissions from small spark ignition engines.
Recently, the EPA released the MOVES model, a state-of-the-art tool for estimating emissions from
highway vehicles.82 The model is based on analysis of millions of emission test results and
considerable advances in the agency's understanding of vehicle emissions. The more detailed
approach to modeling allows the EPA to incorporate large amounts of in-use data from a wide
variety of sources, such as data from vehicle inspection and maintenance (I/M) programs, remote
sensing device (RSD) testing, certification testing, and portable emission measurement systems
(PEMS). This approach also allows users to incorporate a variety of activity data to better estimate
emission differences such as those resulting from changes to vehicle speed and acceleration
patterns. Also in support of MOVES development, the agency conducted a landmark study of PM
emissions, testing nearly 500 in-use gasoline-fueled light-duty cars and trucks in Kansas City,
Missouri. The Kansas City Light-Duty Vehicle Emissions Studya collaborative effort, including the
EPA, the U.S. Department of Transportation (DOT), the U.S. Department of Energy (DOE) and the
automotive and petroleum industriesconfirmed that PM emissions from light-duty gasoline-
fueled vehicles are higher than earlier predicted and clearly showed that cold ambient
temperatures can dramatically increase PM emissions at engine start-up (Fulper et al., 2010; Nam
et al., 2010). The EPA has also tested vehicles with new technologies to investigate how different
factors such as fuel type, temperature and operating activities affect emissions (e.g., Baldauf et al.,
2005). The EPA's understanding of emissions from heavy-duty vehicles has also continued to
improve. The EPA has been able to analyze data on more than 400 in-use trucks, some in the
laboratory and some with onroad measurement equipment. This allowed the agency to
understand how real trucks pollute at a range of speeds and driving conditions. The EPA also has
been able to better incorporate emissions from heavy-duty diesel crankcase ventilation and from
extended idling, two emission processes that were relatively unstudied previously.
Ambient Monitoring Methods
The EPA has made progress in advancing monitoring methods for air toxics. As part of a research
program on fugitive emissions, the EPA has investigated different fence-line monitoring
approaches that included both time-resolved and time-integrated measurement methods.
Deployment of time-integrated passive diffusive samplers with subsequent laboratory analysis
2http://www.epa.gov/otaq/models/moves/index.htm.
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might be a promising and cost-effective fence-line monitoring approach for long-term assessments
or screening applications. For example, the EPA conducted a year-long field study to quantify
fence-line benzene concentrations at a refinery in Corpus Christi, Texas, that demonstrated the
utility of using passive diffusive samplers (Thoma et al., 2011). The EPA has also conducted a
number of studies investigating air toxic emissions and concentrations near large roadways that
have utilized an innovative combination of monitoring techniques, including stationary passive,
continuous and integrated monitoring together along with mobile monitoring. The EPA developed
mobile monitoring capabilities to characterize the spatial variability of air pollutants using a zero-
emissions electric vehicle equipped with air monitoring instruments and high-resolution global
positioning system (GPS).83 Mobile monitoring is a powerful and cost-effective method to study the
impact of sources on concentrations in the surrounding area. Using fast-response air monitoring
instruments while driving, the vehicle can rapidly collect location-resolved air pollutant
measurements and produce high-resolution maps of concentrations. This type of measurement
strategy can be used to quantify spatial variability of air toxics near an emission source, assess
potential mitigation opportunities and identify uncontrolled emission points.
New methodologies for identification and speciation of important HAPs and their combustion and
transformation products have also been a focus of EPA research. The EPA has conducted research
on methods for characterizing individual VOC and mercury species for both ambient concentrations
and source emissions. The EPA has developed novel methods for measuring trace levels of
semivolatile organic compounds (SVOCs) in particulate matter (e.g., PAH and POM). These methods
have been used to improve our understanding about changes in the composition of particulate
matter emitted from biomass burning and anthropogenic combustion sources, including aircraft,
light- and heavy-duty vehicles and stationary energy sources such as residential and large-scale
commercial and industrial boiler systems (Hays et al., 2003, 2008, 2011; Kinsey et al., 2010, 2011).
These methods have also been used to determine PAH SVOC concentrations in airborne particulate
matter. Further, the FAA and the EPA have collaboratively developed best practices for quantifying
speciated organic gas emissions from certain aircraft engines (U.S. FAA and U.S. EPA, 2009).
The EPA is also completing a study in Cleveland, Ohio, to investigate the relative contributions of
local and regional mercury sources using advanced monitoring methods that measure mercury
species in air, precipitation chemistry and direct dry deposition across multiple sites. This study is
evaluating passive air sampling and surrogate surface methods for their ability to help understand
the spatial distribution of mercury. This comprehensive approach to characterizing mercury
deposition in northeast Ohio, using novel measurement methods, will be used to quantify wet and
dry deposition of mercury.84
Air Quality Model!
The EPA has conducted research on source-based air quality models that has led to an improved
understanding of the relationship between source emissions and ambient concentrations for HAPs.
In 2004, the EPA released an updated version of the Community Multi-Scale Air Quality (CMAQ)
model, which was the first fully-integrated air quality model to account for the wide range of
S3http://www.epa.gov/nrmrl/appcd/nearroadway/pdfs/G MAPv3_2.pdf.
S4http://www.epa.gov/research/ca/pdf/ca-factsheet-cmaps.pdf.
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complex chemical and physical processes that affect concentrations of air toxics across the entire
United States.85 The model predicts concentrations of several gas and particulate toxic compounds
emitted into the atmosphere such as VOCs and toxic metals, including predictions for the fate and
transport of atmospheric mercury (Bash, 2010). CMAQ also simulates the formation of air toxics
from atmospheric chemistry and their effects on ozone production in addition to the
photochemical decay, atmospheric transport and removal of air toxics (Hutzell and Luecken, 2008,
Luecken et al., 2006). The EPA now uses CMAQ as its multipollutant modeling platform to evaluate
the integrated benefits and effectiveness of numerous proposed and final control programs (e.g.,
Renewable Fuel Standards (RFS) rules, see Cook et al., 2011).
A focus of recent EPA research has also been on the combined use of regional-scale air quality
models such as CMAQ with local-scale dispersion models such as the American Meteorological
Society (AMS) and U.S. EPA Regulatory Model (AERMOD; Cimorelli et al., 2005) to improve the
prediction of spatial and temporal concentration gradients associated with large urban point
sources and near roadways (e.g., Isakov et al., 2009; Wesson et al., 2010). Appendix C includes
more information on two studies that incorporated this approach, the Detroit Multipollutant Pilot
Project and the New Haven Air Accountability Feasibility Study. These studies also advanced the
use of roadway link data in the mobile source emissions modeling to improve air quality models
predictions at the urban scale.
Human Exposure
Through research efforts on modeling human exposure to air pollutants and the measurement
data needed to improve and evaluate the models, the EPA has advanced the understanding of
human exposures to selected HAPs.
Human Exposure Modeling
The EPA has developed probabilistic human exposure models for predicting the population
distribution of air pollutant inhalation exposures.86 The Hazardous Air Pollutant Exposure Model
(HAPEM) has been developed specifically for the national-scale screening level assessments
conducted as part of NATA, while the Air Pollutant Exposure (APEX) model was developed for
population exposure and risk characterization for NAAQS pollutants at the urban-scale, and has the
flexibility to be applied for multiple air pollutants, including HAPs. In addition, the EPA has
developed the Stochastic Human Exposure and Dose Simulation (SHEDS) model as part of its
human exposure research program. These models simulate the movement of individuals through
time and space and estimate their exposure in various microenvironments (e.g., outdoors, indoors
at home, in a vehicle) based on the ambient air concentration data used as input to the model.
Data on indoor/outdoor concentration relationships, population demographics and human activity
patterns are also used as input. The models estimate an expected range of inhalation exposure
concentrations for the simulated individuals. Recent exposure modeling research has led to
improved spatial resolution within urban areas to better characterize impacts of local sources on
S5http://www.epa.gov/AMD/CMAQ/release45.html.
S6www.epa.gov/ttn/fera.
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exposures to multiple air pollutants, such as for the Air Accountability Study in New Haven,
Connecticut, described in Appendix C. In addition, researchers are evaluating socioeconomic and
racial differences in exposure to traffic-related air pollution across the U.S. using a geographic
information system (GlS)-based approach.
The EPA's human exposure modeling research has also developed databases needed for human
exposure modeling, including demographic and commuting databases based on U.S. Census data,
distributions of exposure factors such as residential air exchange rates that depend on housing
characteristics and daily temperature ranges, and a database of human activity patterns called the
Consolidated Human Activity Database87 (CHAD; Glen et al., 2008; Graham and McCurdy, 2004;
Isaacs et al., 2007; McCurdy and Graham, 2003). These databases are used by all of the EPA's
probabilistic human exposure models, whether for screening level assessments such as in NATA or
for urban-scale multipollutant assessments using APEX or SHEDS, and need to be continually
updated as new information becomes available.
Human Exposure Measurements
Human exposure measurement studies have also been conducted to provide a better
understanding of relationships between outdoor concentrations, indoor concentrations and
personal exposures for urban HAPs and human activity patterns to support exposure model
evaluations. Appendix C includes more information on these studies. One study conducted by the
EPA was the Detroit Exposure and Aerosol Research Study (DEARS).88 DEARS was designed to
determine the spatial and temporal variability of air pollutants across the urban area and the
ability of central site (ambient) monitors to act as an appropriate surrogate for human health risk
assessments. The 3-year field monitoring campaign (2004-2007) included personal, residential
indoor, residential outdoor and ambient-based exposure monitoring for a variety of air toxics,
including select VOCs, SVOCs and carbonyls (Williams et al., 2009). The exposure data collected
during the DEARS and other human exposure studies conducted by the EPA have provided many
benefits to air toxics exposure research as summarized in Appendix C. A few highlights include that
passive VOC monitors were proven to be an effective means of exposure data collection,
community-based VOC concentrations often had pronounced day-to-day variability and were
primary drivers of exposures outdoors in residential neighborhoods, and personal exposures for
many VOCs were often higher than concentrations measured outdoors indicating the residential
indoor environment can be a major source of human exposures to these air toxics (George et al.,
2011; Johnson et al., 2010; McClenny et al., 2005).
In January 2003, the Health Effects Institute (HEI)89 issued a Request for Applications (RFA 03-1)
titled, "Assessing Exposure to Air Toxics" that sought studies aimed at identifying and
characterizing exposure to elevated ambient concentrations of air toxics from a variety of sources.
Five studies, which represent a diversity of possible hot-spot locations and air toxics, were funded
under this RFA and are described in more detail in Appendix C. As an example, the study by Lioy et
87 www.epa.gov/chadnetl/.
sswww.epa.gov/dears.
S9HEI is an independent, nonprofit corporation supported jointly by the EPA and industry. The focus of their research is on the
health effects of pollutants from motor vehicles and other sources in the environment.
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al., (2011) compared two low-income neighborhoods within Camden, New Jersey, hypothesizing
that one was a pollution "hot spot." They examined the impact of local industrial and mobile
source pollution on personal exposures and ambient concentrations. For most pollutants,
measured personal concentrations were higher than ambient concentrations at fixed monitoring
sites, and the two did not generally vary together. As the independent study by the HEI Health
Review Committee concluded, this finding highlights the difficulty of relating personal exposure
and ambient concentrations measured at a central monitoring site.
The EPA has also focused research efforts on understanding near-road exposures and health
effects, and the role of MSATs was investigated as part of the EPA's near-road studies described in
further detail in Appendix C. In 2006, the EPA conducted a field study in Raleigh, North Carolina, to
assess the impacts of traffic emissions on air quality and particle toxicity near a heavily traveled
highway. This study integrated several novel-monitoring techniques to provide new insights on the
impacts of motor vehicle emissions on near-road air quality and adverse health effects, including
real-time traffic and meteorological monitoring, multipollutant and highly time-resolved
measurements, and multi-location measurements to identify the spatial zone of influence of motor
vehicle-emitted pollutants. Data from this study revealed a complex mixture of mobile source
pollutants elevated near the road that generally increased with increasing traffic activity (Baldauf
et al., 2008; Olson et al., 2009; Venkatram et al., 2009). The Raleigh study provided a foundation
for subsequent field studies to characterize mobile source air pollutants adjacent to roadways and
impacts on neighboring communities. The EPA has collaborated with the U.S. Department of
Transportation's Federal Highway Administration on the National Near-Roadway MSATs study to
understand better the relationship between traffic emissions and air pollution at various distances
from roadways.90 Monitoring studies were conducted along a major highway in Las Vegas, Nevada,
from 2008-2009 and in Detroit, Michigan, from 2010-2011, and analyses of the data from these
studies are currently ongoing.
The EPA has also studied how roadway design and roadside features (e.g., noise barriers,
vegetation) affect air pollutant concentrations and human exposures (Baldauf et al., 2008). Also in
2010, the EPA began a study to characterize air quality and exposures for children with persistent
asthma who live near major roadways in Detroit, Michigan. The NearRoad Exposures and Effects
from Urban Air Pollutants Study (NEXUS) is a collaborative effort between the EPA's Office of
Research and Development and the University of Michigan through an EPA cooperative
agreement.91 The NEXUS will utilize an exposure assessment approach that combines
observational data of key exposure determinants from the field study with predictive modeling
tools to estimate near-road air quality and exposures. The air quality and exposure modeling
results will be used in assessments of respiratory effects by the University of Michigan to
investigate the relationships between traffic-related exposures and observed health effects in the
cohort of asthmatic children. Ultimately, results from the EPA's near-road studies will provide the
scientific knowledge and understanding needed to identify the most effective strategies and tools
to reduce exposure to air pollution from major roads and protect people who live, work or go to
school nearby.
90http://www.fhwa.dot.gov/environment/air_quality/air_toxics/research_and_analysis/near_road_study/.
91http://www.epa.gov/nerl/documents/NearRoad wayTechnical_external_fact_sheet_071910.pdf.
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6.3. HEALTH EFFECTS - HAZARD IDENTIFICATION AND DOSE-
RESPONSE ASSESSMENT
6.3.1. Characterization of Need
Estimates of risk from exposure to urban HAPs hold some degree of uncertainty because,
depending on the HAPs at issue, we may have insufficient data on various types of health effects,
modes of action, and chemical interactions, among other factors. In the first report to Congress,
the EPA identified several hazard identification and dose-response assessment needs to improve
our understanding of health effects (i.e., cancer and acute and chronic noncancer hazard
identification and dose-response assessment) and to develop risk assessment approaches for
combining data, producing statistical likelihoods of risk from HAPs exposure and reducing
uncertainty through better extrapolation models (e.g., animal to human, acute to chronic, high
dose to low dose).
6.3.2. Progress Thus Far
Significant work has been done to further our understanding of cancer and noncancer health
effects and to develop new analytical approaches to reduce the overall level of uncertainty in risk
assessments/characterization. In addition to the research and assessments described below, EPA
has developed or updated several guidance documents to improve the assessment of hazard
identification and dose-response relationships. For example, Guidelines for Carcinogen Risk
Assessment (U.S. EPA, 2005a), Supplemental Guidance for Assessing Susceptibility from Early-Life
Exposure to Carcinogens (U.S. EPA, 2005b), and Policy and Procedures for Conducting IRIS Peer
Reviews (U.S. EPA, 2009) have all been released since the previous report.
Since 2000, the EPA has completed or updated hazard identifications and dose-response
assessments for several of the 33 urban HAPs through the IRIS Program.92 As of December 2011,
19 of the 33 urban HAPs have undergone IRIS assessment, with 12 of these assessments completed
since 2000. Currently, 12 urban HAPs are undergoing assessment in the IRIS program. Refer to
Appendix D for more information.
In addition to IRIS assessments, EPA has conducted many studies over the last several years to
improve our understanding of the health effects of various HAPs. The EPA has completed several
studies of the acute and chronic toxicity of VOCs, many of which are urban HAPs. For this work,
EPA scientists developed methods and models to generate data and to use existing health effects
data quantitatively to understand the acute effects, dose-response relationships, mechanisms and
implications of acute VOC exposure in the human population. Experimental studies involved tissue
culture models and experimental rodent models to determine cellular targets, effects and dose-
92The EPA's IRIS is a human health assessment program that evaluates risk information on effects that may result from
exposure to environmental contaminants. Through the IRIS program, the EPA provides the highest quality science-based human
health assessments to support the agency's regulatory activities. The IRIS database contains information for more than 550
chemical substances containing information on human health effects that may result from exposure to various substances in
the environment. Accessed at: http://www.epa.gov/IRIS/.
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response relationships of VOCs. Computational pharmacokinetic models were employed to relate
inhaled exposures to target tissue doses and to improve cross-species extrapolation of dose from
rodents to humans. Meta-analytic methods were developed to use existing human data to relate
the experimental results from rodent models to human exposures, and to estimate the potential
cost of VOC exposure to public health. Effects of both acute and chronic exposures were
addressed. Studies of volatile HAPs and a HAPs metal (i.e., manganese) are discussed in more
detail below.
Studies of the Acute Effects of VOCs
Dose-response relationships in rodents and in humans were investigated for several VOCs,
including toluene, trichloroethylene, perchloroethylene and 2,2,4-trimethylpentane (iso-octane).
Key findings from this work are:
The primary acute effects of VOCs are mediated by the central nervous system (CNS)
and are reversible after exposure ceases (Bushnell et al., 2005);
The critical measure of dose for acute effects is the concentration of the VOC in the
brain at the time the effect is measured (Boyes et al., 2005; Bushnell et al., 2007b);
The concentration of the VOC in any target tissue can be accurately estimated using
physiologically based pharmacokinetic (PBPK) models under a wide variety of exposure
scenarios (Benignus et al., 2006; Kenyon et al., 2008);
When dose is based on concentration in the brain, humans and rats do not differ in their
sensitivity to VOCs (Benignus, 2001; Benignus et al., 2007);
The test method affects the apparent potency of the VOC (higher concentrations are
needed to disrupt highly-motivated behavior) (Benignus et al., 2009b); and
When dose is based on the estimated number of molecules in the brain, VOCs do not differ in their
efficacy (strength of effect) or in their potency (the amount of the VOC necessary to cause the
effect) (Benignus et al., 2009b).
Mechanistic studies to identify cellular targets of VOCs in the brain revealed clear dose-response
relationships for interactions with neuronal ion channels (Bale et al., 2002, 2005, 2007; Bushnell et
al., 2007a). These results are consistent with published literature with VOCs and with ethanol. In
addition to sharing neuronal targets, VOCs and ethanol produce a similar suite of acute effects,
including slowing of reaction time (Benignus et al., 2005b). The public health costs of exposure to
VOCs could be estimated by comparing the effects to those caused by ethanol intoxication, such as
car crashes (Benignus et al., 2005b; Bushnell et al., 2007a). This analysis estimated that the
cumulated 30-year increase in the incidence of fatal single-car crashes caused by the behavioral
impairments from acute inhalation of toluene at concentrations below the EPA's RfC for toluene
were equivalent in magnitude to the cumulative 30-year increase in mortality from benzene-
induced leukemia (Benignus et al., 2011).
This surprising observation suggests that acute effects of inhaled VOCs should be considered in risk
assessments, because their cumulative effect on public health is similar to the well-established
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long-term effect of exposure to a carcinogen. Further work in the Office of Research and
Development examined the role of tolerance as a factor that could reduce the impact of acute VOC
exposure. Tolerance is a process by which the effect of a chemical on an animal or human is
reduced with prolonged or repeated exposure. Studies in rats showed that prolonged exposure to
airborne toluene (6 to 24 hour) both limited the concentration of toluene reaching the brain and
reduced its behavioral effects (Oshiro et al., 2011), but this "acute tolerance" did not appreciably
increase the amount of inhaled toluene estimated to elevate the risk of a fatal car crash. On the
other hand, repeated exposure to ethanol and VOCs under conditions involving behavioral practice
during exposure can greatly reduce the effect of the VOC on behavior (Bushnell and Oshiro, 2000;
Oshiro etal., 2001, 2007).
Studies of the Effects of Repeated Exposure to VOCs
Whereas the acute effects of VOCs are robust and readily replicable, persistent effects of repeated
exposure are less consistent and typically of smaller magnitude. Nevertheless, published literature
suggests that public health could be impacted by chronic exposure to concentrations in the range
of occupational settings, and meta-analyses of these studies by the EPA scientists confirmed some
of these suggestions (Benignus et al., 2005a, 2009a; Boyes et al., 2007; Bushnell et al., 2007a). The
EPA scientists therefore conducted animal studies to develop experimental models of the
persistent effects of repeated exposure to toluene, a high-production-volume VOC that others
have shown to affect behavior and sensory function after repeated exposure. These studies
included daily exposures to toluene for 13 weeks (subchronic scenario) (Beasley et al., 2010) or
4 weeks (sub-acute scenario) (Beasley et al., 2011); they yielded no consistent changes in behavior,
but some evidence of reduced visual function was present.
Manganese Exposure
Potential neurotoxicity from airborne manganese exposure has been a community concern for
more than a decade, specifically in Region 5 (e.g., Ohio, Michigan). Airborne manganese research
has been conducted through the Regional Applied Research Effort (RARE) program.93 In 2009, San
Francisco State University received an EPA grant to conduct a neurologic epidemiological health
study comparing adults living in Marietta, Ohio, where there is an industrial source of manganese
emissions, and Mount Vernon, Ohio, which is nearly identical demographically, but without the
industrial activity and manganese emissions. This study focused on the effect of long-term, low-
level manganese exposures on the general population, which was a data gap in the scientific
literature. Initial Marietta-Mount Vernon comparisons generally indicated a lack of major health
effect differences between the two towns. However, despite not finding significant differences
between Marietta adults versus Mount Vernon adults for manganese in blood, demographics or
major health outcomes, the study showed subtle but statistically significant movement and
postural sway deficits in Marietta adults (Kim et al., 2011). The study also found an association
between environmental manganese exposure and anxiety states (Bowler et al., 2011). Whether
93RARE is a mechanism used by the EPA's Regional Science Program to respond to high-priority, near-term research needs of
the EPA's regional offices and improve collaboration between regions and EPA headquarters.
http://www.epa.gov/osp/regions/rare.htm.
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this association is due to direct neurotoxic effects of manganese-air or concern about the health
effects of air pollution remains an open question. Follow-up work is underway to conduct a similar
neurologic epidemiological health study of adults in East Liverpool, Ohio, to compare data from
East Liverpool with data from Marietta and Mount Vernon.
The EPA has also performed numerous updates in its quantitative approach to hazard
identification and dose-response assessment, including developing and refining more robust dose
response and statistical tools such as Benchmark Dose Software (BMDS) and categorical regression
(CatReg), and modifying PBPK models. Use of BMDS and PBPK have contributed to reducing
uncertainty in dose-response assessment and the previous dosimetric conversions (i.e., calculating
human equivalent values from animal data), respectively (See Exhibit 6-2) (U.S. EPA, 2006, 2010a).
CatReg holds a great deal of potential for analyzing aggregate and categorical data and will be
particularly useful for data-rich chemicals (U.S. EPA, 2002b, 2011a). Use of these quantitative
methodologies, and recent EPA guidance documents, will enhance future EPA analyses by
maximizing the utility of limited data and limiting the degree of uncertainty associated with
reference doses (RfD), reference concentrations (RfC), and cancer reference value derivation.
Exhibit 6-2. Basic Processes for PBPK Modeling and BMDS94
Evaluate studies with chemical of interest
and select endpoint(s) to model
exposure
II Attempt to calculate a BMD for each endpoint
Equivalent ^^^ Target tissue
i I
rjose exposure Select a point of departure (POD) based on
endpoints modeled, if appropriate
PBPK directly models the target tissue Document key modeling results
exposures and equates them when
estimating human equivalent doses or
concentrations.
Advancing the Next Generation of Risk Assessment f NexGenl
The EPA has established a new program, "Advancing the Next Generation of Risk Assessment"
(referred to as NexGen),95 to better navigate the changing landscape of risk assessment. NexGen
can help move towards a more solution-oriented, efficient risk assessment process, advocated by
Science and Decisions: Advancing Risk Assessment (NRC, 2009). The changes are largely being
driven by new advances in medicine and molecular biology, the advent of several recent and
important reports from the National Research Council and volumes of new test data emerging
from Tox21 and the European Union's Registration, Evaluation, Authorization and Restriction of
94Adapted from (U.S. EPA, 2010a, 2006).
95http://www.epa.gov/risk/nexgen/.
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Chemicals (REACH) program. NexGen is a collaborative program among: EPA's Computational
Toxicology Program; the National Institute of Environmental Health Sciences' National Toxicology
Program; the Agency for Toxic Substances and Disease Registry; the National Human Genome
Research Institute; the U.S. Food and Drug Administration's National Center for Toxicological
Research; and California EPA.
Overall, NexGen aims to create a less expensive, faster and more robust system for health effects
research (i.e., hazard identification and dose-response assessment) by incorporating advances in
molecular systems biology. By incorporating emerging molecular systems biology knowledge, the
EPA anticipates implementing a new tiered health assessment paradigm aimed at creating hazard
identification and dose-response assessments that are more responsive to the needs of program
offices, including the ability to cost effectively and more rapidly assess chemicals.
NexGen is currently using data-rich case studies to validate new approaches. Two prototype
chemicals are HAPs - benzene and PAHs. Through comparison of omic (e.g., genomics, proteomics
or metabolomics) and traditional data for these chemicals, the use of omic data in risk assessment
is being evaluated. The approaches developed and tested can be applied to chemicals with omic
data, but limited or no traditional data. Eventually, this approach could expand and make more
robust potential risk analyses for efforts such as the NATA. One aim of the NexGen program is to
understand how to utilize the data for 10,000 chemicals currently undergoing high throughput
molecular biology-based testing in the Tox21 program in risk assessment.96
6.4. RISK ASSESSMENT AND RISK CHARACTERIZATION
6.4.1. Characterization of Need
The exposure assessment and hazard identification and dose-response assessments are combined
and interpreted in the risk characterization portion of a risk assessment. This section of the first
report to Congress focused on the needs to improve risk assessments of chemical mixtures and to
communicate risks better. One of the most prominent gaps in the general risk assessment
framework for HAPs is the lack of data, models and methods for evaluating risk from chemical
mixtures. Multiple HAPs can be emitted from the same sources, and, in real-world scenarios,
humans are exposed to a complex mixture of HAPs. Combined exposures to multiple pollutants
might produce synergistic or antagonistic effects. The cumulative impact of multiple emission
sources on minority populations and low income populations in urban areas is of particular concern.
6.4.2. Progress Thus Far
The EPA is evaluating mixtures in several cases. Currently, the EPA is in the process of finalizing the
development of a Relative Potency Factor (RPF) Approach for Polycyclic Aromatic Hydrocarbon
(PAH) Mixtures (External Review Draft) (U.S. EPA, 2010b), which will aid in establishing a scientific
basis for the risk assessment of mixtures that could ultimately be applicable to other chemical
96 http ://www. e pa .go v/n cct/Tox21.
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groups, including other HAPs. PAHs are a subset of POM, mentioned above and for which health
effects information was identified as a research need in the first report to Congress. The IRIS
Program is also developing a human health hazard identification and dose-response assessment for
polychlorinated biphenyls (PCBs) in which quantitative analyses are based on toxicity data from studies
of PCB mixtures similar in composition to those found in the environment. This approach is in line with
that recommended by the Supplementary Guidance for Conducting Health Risk Assessment of Chemical
Mixtures (U.S. EPA, 2000a). Similarly, the IRIS Program is developing a cumulative health
assessment for six phthalates based on the National Research Council (NRC) report "Phthalates
and Cumulative Risk: The Tasks Ahead" (NRC, 2008). The approach for this health assessment also
could be a model for evaluating other chemical mixtures, including HAPs.
Additionally, in 2003, the EPA developed a Framework for Cumulative Risk Assessment thai was the
first step in a long-term effort to develop cumulative risk assessment guidelines, and it fostered
consistent approaches to cumulative risk assessment within the EPA (U.S. EPA, 2003b). The report
defines cumulative risk as "the combined risks from aggregate exposures to multiple agents or
stressors," which can be chemical or non-chemical (i.e., physical or biological). Cumulative risk
assessment is defined as "an analysis, characterization, and possible quantification of the
combined risks to health or the environment from multiple agents or stressors." Cumulative risk
analysis can be applied to environmental justice concerns, where multiple stressors affect highly
burdened communities, and help to create risk management strategies. Over the last several years,
the EPA has held workshops and supported research related to cumulative risk and environmental
justice. For example, in 2007, the EPA held the Workshop on Research Needs for Community-Based
Risk Assessments.97 Since then, the EPA published a request for applications for research on
understanding the role of nonchemical stressors and developing analytic methods for cumulative
risk assessment98 and organized the Symposium on the Science of Disproportionate Environmental
Health Impacts." There is still much work needed on cumulative risk assessment.
Science and Decisions: Advancing Risk Assessment
In 2009, the NRC released a final report, requested and sponsored by the EPA, titled, Science and
Decisions: Advancing Risk Assessment, also referred to as the "Silver Book" (NRC, 2009). This book
complements the widely used 1983 Risk Assessment in the Federal Government: Managing the
Process, which illustrated a risk assessment framework widely adopted by numerous agencies and
public health institutions (NRC, 1983). Science and Decisions described several challenges in the
implementation of the risk assessment framework, most notably, a disconnect between the
"products" of the risk assessment and the decisions that need to be made by risk assessors. The
report identified scientific and technical recommendations to address these challenges, including
an influential recommendation to embed the traditional risk assessment framework within a
broader framework for risk-based decision-making.
A broader framework for risk-based decision-making can be more relevant to the forthcoming risk
management decisions. This framework includes a "problem formulation and scoping" phase, at
97http://www.epa.gov/ncer/cbra/workshop.html.
9Shttp://epa.gov/ncer/rfa/2009/2009_star_cumulative_risk.html.
"http://www.epa.gOV/compliance/ej7multimedia/albums/epa/d isproportionate-impacts-symposium.html.
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the beginning, to help risk assessors identify the types of analysis needed and the required level of
scientific depth necessary to support decisions and a "confirmation of utility" phase near the end
to evaluate whether the risk assessment meets the needs outlined in the planning phase. It also
calls for formal stakeholder involvement throughout the process. Ultimately, utilizing a risk-based
decision-making framework seeks to enhance the value of the risk assessment for the risk manager
and improve efficiency in the overall decision-making process.
The Silver Book also made recommendations related to uncertainty and variability, the selection
and use of defaults, developing a unified approach to dose-response assessment and cumulative
risk assessment.
6.5. RISK MANAGEMENT
6.5.1. Characterization of Need
The final stage of the risk assessment paradigm is risk management, or decision-making based on
the risk assessment/characterization. The first report to Congress identified development of risk
management tools and information, including engineering information on emissions and emission
reductions as needs to support regulatory strategies and compliance programs that are integral to
the reduction of HAP emissions and associated reductions in health risk. Specifically, in addition to
needs identified in previous sections that are also relevant to risk management, the report
identified two primary research needs related to risk management: area source HAP emissions
characterization, control options and pollution prevention alternatives and mobile source HAP
pollution prevention.
The report acknowledged that many issues are multimedia in nature, or at least that multimedia
issues arise with common problems requiring a systems approach. It was recognized that there
were opportunities for pollution prevention research to address these crosscutting issues. The
report specifically mentioned development of life-cycle analysis tools, pollution prevention
technology, cleaner production design and generic decision-making tools for reducing risk.
In addition, it focused on transportation system management options as broadly being defined as
pollution prevention. Again, this type of risk management might require an interdisciplinary
approach and could focus on direct (e.g., use of different fuel formulations for motor vehicles) or
indirect (e.g., changes in transportation system infrastructure) emissions reductions.
6.5.2. Progress Thus Far
Of particular interest in risk management under the Strategy is the need to address
disproportionate impacts from HAPs in urban areas, or geographic "hot spots." The EPA has
engaged in three important projects in this regard in Cleveland, Ohio; Detroit, Michigan; and Las
Vegas, Nevada, all mentioned above in section 6.2. The project in Detroit, for example, was
designed to apply and evaluate alternative risk management tools (specifically a multipollutant
approach, described in more detail below) for reducing human health and cancer risk associated
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with exposure to PlVh.s, ozone and HAPs in a densely populated area (U.S. EPA, 2011b).
Some of the risk assessment research activities mentioned previously in this chapter also support
risk management objectives, as do projects the Office of Air and Radiation has implemented. For
example, the development of source monitoring measurement methods provides tools for risk
management activitiesparticularly the development of fence-line monitoring approaches. In
addition, the mobile source emissions and multipollutant air quality modeling tools are also
valuable tools for informing risk management decisions. As discussed in Chapter Four, the Office of
Air and Radiation has implemented several mobile source initiatives that focus on reducing
pollution from the transportation sector.
As mentioned in the introduction to this chapter, the Office of Research and Development has
focused on a multipollutant framework, which is a useful tool for organizing research to inform
integrated and cost-effective risk management strategies. This approach considers the complex
array of contributing sources, atmospheric chemistry and indoor and outdoor exposures, which
more adequately characterizes a real-world scenario for exposure to HAPs. The EPA continues to
develop and implement new tools, assessment methodologies and new approaches for assessing
progress for specific scenarios.
6.6. RESEARCH FOR THE 21ST CENTURY
The environmental issues that we face today and will face in the future are more complex and
subtle than those we have addressed to date. Therefore, protecting human health and the
environment in the 21st century will require research that is innovative, integrated and completed
using Transdisciplinary approaches. In addition, identifying the most effective and enduring
solutions to these environmental issues will require research that emphasizes and promotes broad
systems thinking to ensure sustainability.
The concepts of sustainability and systems thinking are closely related. Sustainability is based on
the principle that everything we need for our survival and well-being depends on our natural
environment (Marsh, 1964). Sustainable policies "create and maintain the conditions under which
humans and nature can exist in productive harmony and fulfill the social, economic and other
requirements of current and future generations" (NEPA, 1969). At the EPA, the concept of
sustainability has emerged as a result of significant concerns about the unintended social,
environmental and economic consequences of rapid population growth, economic growth and
consumption of our natural resources. The EPA is moving from solely controlling pollution to
preventing it by considering sustainability and using systems thinking (U.S. EPA, 2011e). "Systems
Thinking" is central to the concept of sustainability because it leads to an understanding of how
various parts of a whole are related to and influence each other, thereby avoiding unintended
environmental, economic or social consequences now and in the future.
The EPA is exploring ways to better incorporate sustainability and related concepts, such as
"Systems Thinking," in its decision-making process. To support these efforts, the agency requested
the NRC to explore the scientific basis for sustainability as a key driver for protection of human
health and the environment and to recommend a framework for integrating sustainability into the
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agency's activities. In the NRC's report, "Sustainability and the U.S. EPA," known as the "Green
Book," the NRC developed a sustainability framework and sustainability assessment and
management approach to provide guidance to the EPA on incorporating sustainability into decision
making. The EPA has discretion in implementing sustainability and is taking steps to incorporate it
into the agency's culture and process of protecting human health and the environment.
Consistent with overall agency efforts, the research programs at the EPA have also been
restructured to promote more integrated systems approaches in order to develop sustainable
solutions. The remainder of this section summarizes future air toxics research needs in the context
of the Office of Research and Development's new research programs focused on "Systems
Thinking" and sustainability.
Air. Climate, and Energy
Taking action on climate change and improving air quality are agency priorities. To develop
innovative and sustainable solutions to improve air quality and address climate change, it is
necessary to understand the interplay between air quality, climate change and the changing
energy landscape more fully. The EPA's Air, Climate and Energy (ACE) Research Program100 has
been designed to address this challenge by providing research to:
Assess ImpactsAssess human and ecosystem exposures and effects associated with
air pollutants and climate change at individual, community, regional and global scales.
Prevent and Reduce EmissionsProvide data and tools to develop and evaluate
approaches to prevent and reduce emissions of pollutants to the atmosphere,
particularly environmentally sustainable, cost-effective and innovative multipollutant
and sector-based approaches.
Respond to Changes in Climate and Air QualityProvide human exposure and
environmental modeling, monitoring, metrics and information needed by individuals,
communities and governmental agencies to adapt to the impacts of climate change and
make public health decisions regarding air quality.
By design, most of the research within the ACE program is not pollutant specific, and thus there
are only limited efforts related to specific air toxics. There are, however, several research activities
in the ACE program that will include research related air toxics as part of larger integrated efforts.
Specific examples of air toxics related research in the ACE program include the following:
Development and evaluation of ambient monitoring methods for key air toxics, such as
acrolein.
Development, evaluation and application of measurement methods to characterize
emissions of pollutants (including air toxics) from stationary and mobile sources.
100More information on the Air, Climate and Energy Research Program can be found in the Strategic Research Action Plan 2012-
2016 (U.S. EPA, 2012a).
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Studies to characterize emissions, exposures and potential health impacts near sources,
such as roadways and ports.
Characterization of emissions, exposures and potential health effects of emerging
energy options, including biomass.
Development and evaluation of sensor technologies to enhance the measurement of air
toxics in communities and potentially lower the costs of monitoring.
Development, evaluation and application of multipollutant modeling tools, including
fine scale modeling tools to characterize air quality concentrations and exposures at
local/urban levels.
Development and evaluation of Green Chemistry alternatives for solvents containing air
toxics.
Sustainable and Healthy Communities
A top EPA priority is supporting sustainable and healthy communities by protecting human health
and well-being and the ecosystem services or natural benefits upon which they depend, such as
clean water and air, including air toxics. Communities are increasingly challenged to find
sustainable solutions to urbanization; competition for food, materials and energy; growing waste
streams; changing climate; and socioeconomic inequities, among other pressures. The Sustainable
and Healthy Communities (SHC) research program was designed after extensive dialogue with
community leaders, stakeholders and non-governmental organizations across the nation to
understand better the challenges they face and is consistent with the EPA's priorities of
sustainability and environmental justice. The SHC research program will develop and evaluate
methods and tools that can be used to better weigh and integrate human health, socio-economic
and environmental factors into decisions about both built and natural environments.101 Some
examples of research activities in the SHC research program related to air toxics include:
Decision Analysis and Support.
Research to Inform and Assess Decisions to Improve Community Public Health,
including:
o Identification of prevalent public health conditions and the prioritization of
environmental and health-related factors.
o Development of indicators and indices to identify vulnerable life stages and sub-
populations and their links to community/tribal-specific environmental and
health-related conditions, to inform decisions, and to assess changes.
o Development of integrated methods, measurements and models and science-
based, user-friendly, community-focused decision support tools.
o Community-based participatory case studies.
l:1SHC Research factsheet: http://www.epa.gov/ord/priorities/docs/SHC+fact+sheet_+FINAL.pdf.
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Science to Support Environmental Justice.
Integrated approaches to decisions for sustainable outcomes related to:
o Buildings and Infrastructure.
o Land Use Practices.
o Transportation.
o Waste and Materials.
More information on the Sustainable and Healthy Communities Research Program can be found in
the Strategic Research Action Plan 2012-2016 (U.S. EPA, 2012c).
Human Health Risk Assessment
Every day, the EPA must make decisions about environmental pollutants that impact human health
and the environment. There are currently more than 80,000 chemicals in commerce, and more are
introduced each year. Only a small fraction of these chemicals has been adequately assessed for
potential risk, often because of limits in existing data, tools and resources. The Human Health Risk
Assessment (HHRA) research program helps address this problem by providing state-of-the-science
products in support of risk assessment.
The work conducted by the HHRA Research Program responds directly to the needs of the EPA's
program and regional offices and to issues of shared concern among the broader risk assessment
and risk management community. The HHRA research program plays a unique role in serving the
needs of the EPA's programs and regions, by identifying, evaluating, synthesizing and integrating
scientific information on individual chemicals and chemical mixtures. The state-of-the-science,
independently peer-reviewed hazard identification and dose response assessments prepared by
HHRA scientists provide a critical part of the scientific foundation for much of the EPA's decision-
making (e.g., site specific cleanups, regulations), thereby enabling the EPA to better protect human
health and the environment.
The HHRA Research Program is comprised of four complementary and integrated research themes:
IRIS Health Hazard and Dose-Response Assessments: IRIS assessments and updates and
scientific technical support documents are used widely by the EPA's programs and
regions, states, international organizations and the general public as a critical part of
their scientific foundation for decision-making (e.g., site-specific cleanups, rules,
regulations, and health policy).
Integrated Science Assessments (ISAs) of Criteria Air Pollutants: ISAs summarize the
state-of-the science for the six criteria air pollutants: ozone, particulate matter, sulfur
and nitrous oxides, carbon monoxide and lead. Additionally, the Office of Research and
Development is working in consultation with other EPA offices to develop a
Multipollutant Science Assessment to support the reviews of the primary (health-based)
national ambient air quality standards. This assessment will allow for an evaluation of
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the combined health effects of exposures to mixtures of air pollutants, and a more
effective evaluation of health effects of exposures to single pollutants in a
multipollutant context, than what is currently provided using single pollutant ISAs.
Community Risk and Technical Support (CRTS) for Exposure and Health Assessments:
This support includes quick turn-around exposure and risk assessments, crisis-level
technical support, the development of Provisional Peer Reviewed Toxicity Values
(PPRTVs) and tools and guidance for exposure assessments and methods to conduct
cumulative impact assessments, all of which enhance the ability of the EPA regional
offices to quickly make sound, risk-based decisions regarding emerging issues.
Modernizing Risk Assessment Methods: Key elements of work under this theme include
designing and implementing tools to make developing hazard identification and dose-
response assessments more efficient; providing support and training for risk assessment
through the Health and Environmental Research Online (HERO) database and the Risk
Assessment Training and Experience (RATE) program; and developing innovative
approaches to link information to users' needs in a more effective fashion. For example,
translation and practical application of the research in molecular biology and
computational science developed throughout the Office of Research and Development
and from peer-reviewed sources into practical applications for hazard identification and
dose-response assessments increases the efficiency and effectiveness of the EPA risk
assessments.
More information on the HHRA Research Program can be found in the Strategic Research Action
Plan 2012-2016 (U.S. EPA, 2012b).
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Chapter 7: Conclusions and Looking
Ahead
Overall, air toxic emissions have significantly declined since 1990. Reductions of air toxic emissions
have been achieved through the EPA's standards, state, tribal and local programs, community
grants and other initiatives to address the most important sources of air toxic risks in urban areas.
We have shown that, since 1990, over 1.5 million tons of air toxics have been removed from the air
on an annual basis through air toxic standards for stationary sources. In addition, mobile source
emissions have been reduced by 50 percent since 1990, and will continue to decrease as the fleet
turns over; by 2030, mobile source emissions will be approximately 80 percent lower than 1990
levels, reflecting both absolute reductions in emissions relative to 1990 levels and offsets in
emissions increases due to economic and population growth.
On March 21, 2011, the EPA completed its requirement under the Clean Air Act to assure that area
sources accounting for 90 percent of the aggregate area source emissions of each of the 30 urban
HAPs are subject to regulation. Simultaneously, the EPA issued a notice that the Agency had
completed its requirement under the Clean Air Act to assure that sources accounting for not less
than 90 percent of the aggregate emissions of each of the seven HAP enumerated under Section
112(c) (6) are subject to standards.102
While there have been substantial progress and efforts in each of these areas, resulting in lower
emissions and less exposure to these chemicals in communities across the country, significant risks
from air toxics remain. The EPA understands the importance of promptly addressing air toxics
emissions that pose the greatest risk to public health. The EPA recognizes the importance of risk
reductions that can be achieved by voluntary initiatives as well as regulatory programs and the
value of informing the public about air toxics risks in a more effective and timely manner. We would
be remiss in this report if we did not identify these issues so that the public conversation can
engage on the future of air toxics efforts. Areas where continued effort is needed include:
> Cumulative impacts research - more work is needed to determine the impacts of
simultaneous exposure to multiple pollutants.
> Improved emissions data -the current systems for reporting emissions of air toxics do not
provide a comprehensive picture.
> Ambient data in more areas and of more pollutants - air toxics emissions and public
exposure are highly localized. Improved monitoring data would make it easier to identify
these areas and develop strategies that improve public health.
Topham to Docket, Emission Standards for Meeting the 90 Percent Requirement Under Section 112(c)(6) of the Clean Air
Act (found in Docket ID EPA-HQ-OAR-2004-0505).
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> New monitoring technologies that are less costly and can provide information that is more
transparent and accessible to communities and businesses - these new technologies can
play an important role in identifying air toxic hot spots.
> Better integration of air toxics, pollution prevention and voluntary programs in regulatory
and non-regulatory efforts -voluntary programs that target specific air toxic issues unique
to a particular area could complement national and state regulatory efforts.
> Regulatory tools - our national regulatory efforts should be directed at the source
categories where there are emissions that pose significant risk.
A strong integration of national, state, tribal and community resources and efforts is essential if we
are to continue to make progress in our efforts to reduce threats to public health from air toxics.
The EPA hopes that this report will provide an opportunity for a renewed and expanded discussion
of the most effective ways to protect public health through the reduction of air toxic emissions and
to encourage the implementation of high priority, cost-effective efforts.
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Appendix A. Standard-Setting Activities
A.I. SOURCE CATEGORIES SUBJECT TO STANDARDS UNDER SECTIONS
112 AND 129
The cumulative projected reductions presented in Chapter Three, section 3.2 were calculated
summing the estimates of emission reductions developed during each individual rulemaking listed
in Exhibit A-l. This table includes final rule Federal Register citations, through May 2012, where the
projected annual emission reductions associated with each final rule can be found. The projected
emission reductions are included in the preamble for each rule, usually in the section titled,
"Impacts of the Final Rule" or "Summary of Environmental, Energy, Cost, and Economic Impacts."
The projected reductions begin in the year during which the rule is fully implemented. Several
source categories are marked with an asterisk (*) which denotes that the reductions associated
with the rule have not yet been realized because the compliance date has not yet arrived.
Exhibit A-l. Source Categories Subject to Standards
NESHAP NAME
MAJOR SOURCE STANDARDS
Aerospace Manufacturing and Rework Facilities
Asphalt Processing and Asphalt Roofing Manufacturing
Surface Coating of Automobiles and Light Duty Trucks
Benzene Waste Operations
Boat Manufacturing
Brick and Structural Clay Products and Clay Ceramics
Cellulose Products Manufacturing
Chromium Emissions from Hard and Decorative Chromium Electroplating and
Chromium Anodizing Tanks (Major and Area)
Coal- and Oil-fired Electric Utility Steam Generating Units and Standards of
Performance for Fossil-Fuel-Fired Electric Utility, Industrial-Commercial-
Institutional, and Small Industrial-Commercial-lnstitutional Steam Generating
Units*
Coke Ovens: Pushing, Quenching, and Battery Stacks
Coke Ovens: Charging, Top Side, and Door Leaks
Chemical Recovery Combustion Sources at Kraft, Soda, Sulfite, and Stand-
Alone Semichemical Pulp Mills
Ethylene Oxide Commercial Sterilization and Fumigation Operations
Halogenated Solvent Cleaners
Dry Cleaning Facilities (Major and Area)
Electric Arc Furnace Steelmaking Facilities
FR CITATION
60 FR 45948
68 FR 24561
69 FR 22602
55 FR 8298
66 FR 44218
68 FR 22690
67 FR 40044
60 FR 4948
77 FR 9303
68 FR 18008
58 FR 57898
66 FR 3180
59 FR 62585
59 FR 61801
58 FR 49354
72 FR 74088
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NESHAP NAME
Engine Test Cells/Stands
Printing, Coating, and Dyeing of Fabrics and Other Textiles
Ferroalloys Production: Ferromanganese and Silicomanganese
Flexible Polyurethane Foam Fabrication Operations
Flexible Polyurethane Foam Production
Friction Materials Manufacturing Facilities
Gasoline Distribution (Stage 1)
Generic MACT
Hazardous Waste Combustors
Hazardous Organic NESHAP (HON)
Hydrochloric Acid Production
Industrial Cooling Towers
Integrated Iron and Steel
Industrial, Commercial & Institutional Boilers & Process Heaters (Major and
Area)*
Iron and Steel Foundries
Surface Coating of Large Appliances
Leather Finishing Operations
Lime Manufacturing
Magnetic Tape Manufacturing Operations
Manufacturing of Nutritional Yeast
Marine Tank Vessel Loading Operations
Mercury Emissions from Mercury Cell Chlor-Alkali Plants
Surface Coating of Metal Cans
Surface Coating of Metal Coil
Surface Coating of Metal Furniture
Mineral Wool Production
Miscellaneous Coating Manufacturing
Surface Coating of Miscellaneous Metal Parts and Products
Miscellaneous Organic Chemical Manufacturing
Municipal Solid Waste Landfills
Oil and Natural Gas Production and Natural Gas Transmission and Storage
Offsite Waste and Recovery Operations
Organic Liquids Distribution (Non-Gasoline)
Paper and Other Web Coating
Pesticide Active Ingredient Production
Petroleum Refineries
Petroleum Refineries - Catalytic Cracking Units, Catalytic Reforming Units,
and Sulfur Recovery Units
Pharmaceuticals Production
FR CITATION
68 FR 28744
68 FR 32172
64 FR 24750
68 FR 18062
63 FR 53980
67 FR 64498
59 FR 64303
64 FR 64854
70 FR 59402
59 FR 19402
68 FR 19076
59 FR 46339
68 FR 27646
76 FR 28662
69 FR 21905
67 FR 48254
67 FR 9156
69 FR 394
59 FR 64596
66 FR 27876
60 FR 48388
68 FR 70904
68 FR 34431
67 FR 39794
68 FR 28606
69 FR 29489
68 FR 69164
69 FR 130
68 FR 63852
66 FR 2227
64 FR 32610
61 FR 34140
69 FR 5038
67 FR 72330
64 FR 33550
60 FR 43244
67 FR 17762
63 FR 50280
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NESHAP NAME
Phosphoric Acid and Phosphate Fertilizers Production
Surface Coating of Plastic Parts and Products
Plywood and Composite Wood Products
Polyether Polyols Production
Polymers and Resins 1
Polymers and Resins 2
Polymers and Resins 3
Polymers and Resins 4
Polyvinyl Chloride and Copolymers Production (Major and Area)
Portland Cement Manufacturing
Primary Aluminum Reduction Plants
Primary Copper Smelting
Primary Lead Smelting
Primary Magnesium Refining
Printing and Publishing Industry
Publicly Owned Treatment Works
Pulp and Paper Cluster MACT 1 & III
Reciprocating Internal Combustion Engines (RICE)
Reciprocating Internal Combustion Engines (RICE)
Reciprocating Internal Combustion Engines (RICE)
Refractory Products Manufacturing
Reinforced Plastics Composites Production
Rubber Tire Manufacturing
Secondary Aluminum Production
Secondary Lead Smelters
Semiconductor Manufacturing
Shipbuilding and Ship Repair (Surface Coating) Operations
Site Remediation
Solvent Extraction for Vegetable Oil Production
Stationary Combustion Turbines
Steel Pickling - HCI Process Facilities and Hydrochloric Acid Regeneration
Plants
Taconite Iron Ore Processing
Wet-Formed Fiberglass Mat Production
Surface Coating of Wood Building Products
Wood Furniture Manufacturing Operations
Wool Fiberglass Manufacturing
COMBUSTION SOURCE STANDARDS
FR CITATION
64 FR 31358
69 FR 20968
69 FR 45944
64 FR 29419
61 FR 46906
60 FR 12670
65 FR 3275
61 FR 48208
77 FR 22848
75 FR 54970
62 FR 52384
67 FR 40478
64 FR 30194
68 FR 58615
61 FR 27132
64 FR 57572
63 FR 18504
69 FR 33474
75 FR 9648
75 FR 51570
68 FR 18730
68 FR 19375
67 FR 45588
65 FR 15690
60 FR 32587
68 FR 27913
60 FR 64330
68 FR 58172
66 FR 19006
69 FR 10512
64 FR 33202
68 FR 61868
67 FR 17824
68 FR 31746
60 FR 62930
64 FR 31695
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NESHAP NAME
Sewage Sludge Incineration (Section 129 Emission Guidelines and New
Source Performance Standards)
Hospital/Medica I/Infectious Waste Incinerators (Section 129 Emission
Guidelines and New Source Performance Standards)
Large Municipal Waste Combustors (Section 129 Emission Guidelines and
New Source Performance Standards)
Other Solid Waste Incinerators (Section 129 Emission Guidelines and New
Source Performance Standards)
Small Municipal Waste Combustors (Section 129 Emission Guidelines and
New Source Performance Standards)
Commercial and Industrial Solid Waste Incinerators*
ARE A SOURCE STANDARDS
Oil and Natural Gas Production (Area Sources)
Primary Copper Smelting
Secondary Copper Smelting
Primary Non-Ferrous Metals: Zinc, Cadmium, Beryllium
Acrylic and Modacrylic Fibers Production
Carbon Black Production
Chemical Manufacturing: Chromium Compounds
Flexible Polyurethane Foam Production and Fabrication
Lead Acid Battery Manufacturing
Wood Preserving
Glass Manufacturing
Clay Ceramics Manufacturing
Secondary Non-Ferrous Metals
Hospital Ethylene Oxide Sterilizers
Iron and Steel Foundries
Paint Stripping and Miscellaneous Surface Coating Operations at Area
Sources
Gasoline Distribution Bulk Terminals, Bulk Plants, and Pipeline Facilities; and
Gasoline Dispensing Facilities
Reciprocating Internal Combustion Engines (Area Sources)
Plating and Polishing Operations
Ferroalloys Production Facilities (Area Sources)
Aluminum, Copper, and Other Non-Ferrous Foundries
Chemical Manufacturing Area Sources
Asphalt Processing and Asphalt Roofing Manufacturing (Area Sources)
Paints and Allied Products Manufacturing
Chemical Preparations Industry
Prepared Feeds Manufacturing
FR CITATION
76 FR 15372
62 FR 48348
60 FR 65387
70 FR 74870
65 FR 76349
76 FR 36377
65 FR 75338
72FR26
72 FR 2930
72 FR 2930
72 FR 2930
72 FR 38864
72 FR 38864
72 FR 38864
72 FR 38864
72 FR 38864
72 FR 38864
72 FR 73180
72 FR 73180
72 FR 73180
72 FR 73611
73 FR 226
73 FR 1738
73 FR 1916
73 FR 3568
73 FR 37728
73 FR 78637
74 FR 30366
74 FR 56008
74 FR 63236
74 FR 63504
74 FR 69194
75 FR522
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NESHAP NAME
Gold Mine Ore and Ore Processing and Production
Nine Metal Fabrication and Finishing Source Categories
FR CITATION
76 FR 9450
73 FR 42978
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A.2. RISK AND TECHNOLOGY REVIEW (RTR) PROGRAM
The RTR is a combined effort to evaluate both risk under section 112(f) and technology under
section (112)(d)(6) of the CAA after the application of MACT standards. Exhibit A-4 represents a list
of the completed risk and technology reviews and their publication dates through May 2012. For
up-to-date information, please refer to the EPA website.103
Exhibit A-4. Risk and Technology Review Rules
Rules
Stage 1 Gasoline Distribution
Industrial Cooling Towers
Hospital Sterilizers
Magnetic Tape
Dry Cleaners (Major, Area, and Co-Residential)
Hazardous Organic NESHAP (HON)
Polysulfide Rubber
Ethylene Propylene Rubber
Butyl Rubber
Neoprene
Epoxy Resins
Non-Nylon Polyamides
Acetal Resins
Hydrogen Fluoride
Marine Tank Vessel Loading
Pharmaceuticals
Printing and Publishing
Epichlorohydrin Elastomers Production
Hypalon Production
Nitrile Butadiene Rubber Production
Polybutadiene Rubber Production
Styrene Butadiene Rubber and Latex Production
Shipbuilding and Ship Repair (Surface Coating)
Wood Furniture Manufacturing Operations
Proposed
08/10/2005
10/24/2005
10/24/2005
10/24/2005
12/21/2005
06/14/2006
12/12/2007
12/12/2007
12/12/2007
12/12/2007
12/12/2007
12/12/2007
12/12/2007
12/12/2007
10/21/2010
10/21/2010
10/21/2010
10/21/2010
10/10/2008
10/21/2010
10/21/2010
10/21/2010
12/21/2010
12/21/2010
Final
04/06/2006
04/07/2006
04/07/2006
04/07/2006
07/27/2006
12/21/2006
12/16/2008
12/16/2008
12/16/2008
12/16/2008
12/16/2008
12/16/2008
12/16/2008
12/16/2008
04/21/2011
04/21/2011
04/21/2011
04/21/2011
04/21/2011
04/21/2011
04/21/2011
04/21/2011
11/21/2011
11/21/2011
103http://www. epa.gov/ttn/atw/rrisk/ rtrpg.html.
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Primary Lead Processing
Secondary Lead Smelting
02/17/2011
05/09/2011
11/15/2011
01/05/2012
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Appendix B. Air Toxics Assessments
B.I. NATIONAL AIR TOXICS TRENDS STATION (NATTS) NETWORK
SITES
The objective of the NAATS program104 is to provide long-term monitoring data across
representative areas of the country for priority pollutants (e.g., benzene, formaldehyde, 1,3-
National Air Toxics Trends Station (NATTS) Network
Last Update: 04Junol2
/ utdtinn
Roxbur y MA
Providence Rl
Unoerhill VT
Bfon» NY
ft on* NY
RuLhii-iti'i KY
Washirxjlon DC
Richmond VA.
UmjiH H
Pmellas Counly FL
Altania GA
Hazard KY
GaysonlakeKY
Chesterfield SC
Detroit Ml
Chicago IL
MayviileWI
Honcon /.'I
l-:m:-.lon TX
K.:-n.u:k TX
:'.- ..in,-. '.': =
Bountiful UT
Grand Junction CO
San Jose CA
PtweriK AZ
LosAngetesCA
Rutxtoux CA
Seattle WA
La Grande OR
Portland OR
()ptx;rnraiif:-l.Vi Vl.iriinuiii^nl
GA Department of Nalural Resources
KY Departmenl of Envronmental Proledion
KV Departmenl of Envconmenlal Protection
SC Department ol Health ana Environment! Conservation
Ml Department of Environmental Quality
IL Envfonmentil Protection Agency
Wl Department of Natural Resources
Wt Departmenl of Natural Resources
";< . Commit HI) un Ciwiun-'unMi O.i,;ii:6
j.-!u':c:tj!:^
06037-1103
OS-065-8001
53033-0060
,11-I.V,1 ill 111
41 OS 1-0246
Srl,V.V/
Urban
Urban
Rural
Urban
Ul.;m
Urban
Urban
l,-ti;iri
Urban
Urban
Urban
Rural
Rural
Rural
Urban
1 ..-tun
:;. ir.il
Rural
Urban
;;ur.il
Urban
Urban
Rural
Urban
Urban
Urban
Uban
Urban
Rural
Urban
Added Januaty 2007
Added January 2008
Added July 2008
Discontinued Aim 2003
CHsconbrued December 2009
AtkJod Decent* 2009
Discont.nu*d June 2010
Added JJy 2010
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butadiene, hexavalent chromium and polycyclic aromatic hydrocarbons (PAHs] such as
naphthalene] in order to establish overall trends. Below is a listing of the NAATS network.
B.2. URBAN HAP TREND ANALYSIS
The goal of the urban HAP Trend Analysis presented in Chapter Three, section 3.3, Exhibit 3-3 was
to provide a representative overview of urban area trends for air toxics. The national urban
analysis focused on trend sites available from 2003 through 2010, which represent a much larger
fraction of urban areas over that time period.
For this trends analysis, trend sites were selected if they were within a county located in a Core-
Based Statistical Area (CBSA) with a population greater than 250,000. A map of monitoring sites
and the pollutant groups monitored at those sites is shown in Exhibit B-2.
Exhibit B-l. Map of monitoring sites used in the trend analysis. Colors indicate pollutant groups
that were monitored at each site.
r
United States of America
* !
ama* V £
104 http://www.epa.gov/ttn/amtic/natts.html.
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Data Treatment
Annual Averages
Annual averages were evaluated for all air toxics in AQS for the years 2001-2010. All data reported
below the method detection limit (MDL) were substituted with MDL/2 (which is the MDL divided
by 2) to create annual averages. Data without this substitution were not available. Then the data
were screened on annual averages along the following criteria:
1. Completeness. A 75 percent sampling completeness was required for all data. For more
specific information refer to Exhibit B-3.
2. Sample completeness was calculated upon extraction; annual averages were filtered
based on the reported completeness.
3. Exceptional events. If there were no exceptional events, then that value was selected.
If an exceptional event occurred, then the option that included them in the annual
average was selected.
4. Annual averages equal to zero. Of the 106,837 annual averages, 118 reported annual
average and maximum values of zero, despite data below the MDL supposedly being
substituted with MDL/2. These annual averages were excluded from the analysis.
5. Fraction of data below MDL. Annual averages were flagged if more than 65 percent of
values for a given year were below the MDL.
Trend Selection
After screening out annual averages, pollutants were grouped by AQS site code and parameter
occurrence code (POC) to determine whether there were sufficient years of data available to
perform the trend analysis. (Pollutants measured at too few trend sites to be considered nationally
representative are indicated in Exhibit B-3.) Based on this, it was determined that the greatest
number of valid trends and longest trend length were available using the time period 2003-2010.
Using a longer trend period significantly reduced the number of valid trends. The following criteria
were used to determine trend validity.
1. Completeness. 75 percent completeness criterion was applied across the 2003-2010
trend period. At least 6 years of data were required between 2003 and 2010.
2. Representativeness. Trends were required to have valid annual averages spread across
the time period. Trends were removed if two consecutive years of data were missing
from the trend period (e.g., 2003 and 2004 were missing). Additionally, trends were
removed if the start and end year were missing (i.e., 2003 and 2010 were missing).
3. Trends below the MDL. If more than 65 percent of data reported were below the MDL
for at least half of the years of a given trend, the trend was removed. For example, a site
with 4 annual averages with 75 percent of data below the MDL would be removed. In
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contrast, a site with 2 annual averages with 100 percent of data below MDL would be
included, as long as less than 65 percent of data were below the MDL for the other
years.
4. POC and sites. POCs in the AQS indicate a specific instrument or measurement method
at a site. Collocated measurements of a pollutant at a site may provide multiple annual
averages for a given year. While collocated measurements are excellent for quality
control purposes, they are not needed to represent trends at a site over time. Thus,
when presented with multiple POCs with valid trends at a monitoring site, only a single
POC was chosen, if possible. POCs were selected based on the following criteria:
a. A POC meeting trend completeness criteria 1-3 above was used, if available.
b. If multiple POCs met criteria 1-3, then the POC with more samples and higher
data completeness across the trend period was chosen.
c. If no single POC met criteria 1-3, then the POC code was allowed to float across
the time period. For any given year, the POC with the most samples/highest data
completeness was used.
Exhibit B-2. List of 33 Urban Air Toxics
Acetaldehyde
Arsenic compounds
Benzene
1, 3-butadiene
Carbon tetrachloride
Chloroform
Formaldehyde
Lead compounds
Manganese compounds
Dichloromethane
Nickel compounds
Tetrachloroethylene
Acrolein
Acrylonitrile
Beryllium compounds
Cadmium compounds
Chromium compounds
Coke oven emissions
Dioxin
Ethylene dibromide
Propylene dichloride
1, 3-dichloropropene
Ethylene dichloride
Ethylene oxide
Hexachlorobenzene
Hydrazine
Mercury compounds
Polychlorinated biphenyls (PCBs)
Polycyclic organic matter (POM)
Quinoline
1, 1, 2, 2-tetrachloroethane
Trichloroethylene
Vinyl chloride
Note: Pollutants in the left column were measured at a sufficient number of sites and are included in this
analysis. Pollutants in the center and right columns were either not measured at a sufficient number of trend
sites or, where monitored, measured below detection limits and, therefore, are not included in the analysis.
Trend Generation
Trends were calculated by plotting the individual sites' annual average concentrations and applying
an ordinary least squares regression to the time series. An example trend plot is displayed in
Exhibit B-4. The slope of the linear regression is divided by the 1st year's annual average
concentration and multiplied by 100 to calculate the percentage change in concentration by year.
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In the example below, the value is -6.3 percent per year.
Exhibit B-3. Formaldehyde concentration (ng/m3) trend at site 120952002 in the Orlando, Florida,
CBSA. Error bars indicate the standard deviation in the annual average concentration.
"Si
o
'a
u
o
°
Formaldehyde
AQSSitecode 120952002
Orange County -
Orlando, FL CBSA
y = -0.24x + 476.90
R* = 0.90
The value of the percentage change per year were then tabulated across all trend sites for each
pollutant of interest. The distribution values of the percentage change per year was then
calculated by determining the 10th, 50th, and 90th percentile and average change per year across all
urban sites for each pollutant. The distribution of urban trends nationally is displayed for
pollutants with at least 30 urban monitoring sites nationwide. For each pollutant, the range and
midpoint of trends across the middle 80 percent of urban trend sites are shown. Pollutants with
distributions skewed to the left of the zero line are generally decreasing at most sites. Only
chloroform and dichloromethane are increasing at more urban sites than they are decreasing.
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Appendix C. Urban Air Toxics Studies
C.I. OVERVIEW
This appendix contains studies performed by the EPA, the HEI and various states. These
assessments illustrate that while some general similarities are evident, the identity and
concentration of air toxics vary significantly from area to area depending on the particular sources
present (or dominant), the substances emitted, the local meteorology and other factors. The EPA
acknowledges that this list is not comprehensive and the EPA does not endorse the methodologies
or results of those studies completed outside the EPA. These studies, however, contribute to our
understanding of the potential nature and magnitude of exposures and health risks in specific
urban areas and to the pollutants and sources contributing to those exposures and risks.
EPA Studies:
EPA Office of Research and Development (ORD), Detroit Exposure and Aerosol Research
Study (DEARS); July 2004-February 2007
EPA ORD and Federal Highway Administration (FHWA), Las Vegas and Detroit Near-Road
Studies; 2008-present
EPA ORD, Air Accountability Feasibility Study, New Haven, Connecticut; 2009
EPA Office of Air Quality Planning and Standards (OAQPS), Detroit Multipollutant Pilot
Project; 2008
EPA and University of Michigan (EPA STAR Grant), Near Roadway Exposures to Urban Air
Pollutants Study (NEXUS); September 2008-February 2012
HEI Studies:
Health Effects Institute (HEI), Air Toxics Hot Spots Studies; 2003-2012
HEI, Measurement and Modeling of Exposure to Selected Air Toxics for Health Effects
Studies and Verification by Biomarkers; May 2005-May 2007
HEI, Concentrations of Air Toxics in Motor-Vehicle-Dominated Environments;
Summer/Fall 2004
HEI, Air Toxics Exposure from Vehicle Emissions at U.S. Border Crossing: Buffalo Peace
Bridge Study; July 2004-January 2006
HEI, Assessing Personal Exposure to Air Toxics in Camden, New Jersey; June 2004-July
2006
HEI, Air Toxics Hot Spots in Industrial Parks and Traffic; December 2012
HEI, Traffic-Related Air Pollution: A Critical Review of the Literature; 2010
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State/Local Studies:
Industrial Economics, Inc., Section 812 Prospective Study of the Benefits and Costs of
the Clean Air Act Air Toxics Case Study: Health Benefits of Benzene Reductions in
Houston; 1990-2020
Oregon Department of Environmental Quality (DEQ), Portland Air Toxics Assessment
(PATA); 1999-2000
South Coast Air Quality Management District, Multiple Air Toxics Exposure Study
(MATES) II; 1998-2000
South Coast Air Quality Management District, MATES III; 2005-2006
Texas Commission on Environmental Quality, Houston Exposure to Air Toxics Study
(HEATS); 2005-2009
C.2. SUMMARIES OF STUDIES
EPA ORD, Detroit Exposure and Aerosol Research Study (DEARS); July 2004-
February2007
The Detroit Exposure and Aerosol Research Study (DEARS) was a multi-season, multipollutant,
repeated measure human exposure study that collected data on air pollutant exposures on a
personal, residential and community-wide level. These data were then combined with survey data
on personal behaviors, spatial distribution of pollutant point sources and health measures. Wayne
County, Michigan, was chosen for the study because of its large metropolitan population and
variety of pollution sources. Additionally, Detroit had significant air quality issues and was in non-
attainment status for many NAAQS. Forty people were enrolled in the study each year, resulting in
a total of 120 participants.
The main objectives of DEARS were to understand: relationships between different sources of
exposure and an individual's personal exposure; how chemical and environmental factors might
influence an exposure level; and relationships between different scales of exposure measurements
(personal, residential and community-wide level). DEARS focused on understanding these factors
to develop or improve existing models of air pollution exposure. Data were collected on four
levels: (1) personal measurements taken from air monitoring vests worn by study participants
recorded the actual exposures that an individual encountered as they moved throughout their day,
outside, at home, at work and during their commute; (2) stationary residential monitoring systems
recorded the exposure attributable to indoor home environments; (3) stationary outdoor
monitoring systems recorded the air pollution levels within a neighborhood (and notes were made
about which sources of exposure existed in those communities); and (4) an ambient air monitoring
system, which is part of a national system of air monitoring stations, recorded air pollutant data for
the entire study area.
Although data are still being analyzed, initial conclusions from DEARS support its foundational
hypothesis that significant outdoor air pollution mass concentrations can exist across metropolitan
areas, and the composition of the pollutants can vary depending on where in that metropolitan
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area it is measured. Personal exposures are poorly associated with daily ambient-based
measurements taken in a single location for the area. Further, season, meteorological factors,
human behaviors and environmental exposure factors, as well as the specific pollutant type, were
all found to be important factors for understanding pollutant and exposure variability.
DEARS found that neighborhood outdoor pollutant levels for fine and course PM could vary by as
much as 15 percent from the central ambient monitoring site, indicating that local sources of PM
contributed significantly to day-to-day variations in pollution levels. Additionally, personal
exposures to calcium, iron, zinc and leadelemental components of PMsometimes far exceeded
the exposure level measured by ambient monitors. Exposure to VOCs measured on a personal level
using the exposure vests was, on average, twice as high as exposure measured by the ambient
monitors. These findings illustrate the role of indoor environments and personal activities on
pollutant exposure. Results showed that about half of the total fine PM exposure was from non-
ambient sources such as indoor environments and time spent travelling, and that high personal
exposures related to increased blood pressure. Ambient monitoring data did not correlate with
personal blood pressure data, indicating that ambient air quality monitoring data might not be
sufficient for epidemiological studies of the effects of PM on human health. This study resulted in
the following conclusions:
Passive VOC monitors were proven to be an effective means of exposure data collection.
These low burden devices have sensitivities providing for time-integrated
measurements on the order of one day to several weeks.
Community-based VOC concentrations are a primary driver of outdoor exposures at
residential settings and often experience pronounced day-to-day (temporal) variability.
Impacts from VOC concentrations in close proximity to a roadway are best determined
using the distance from the road surface to the target as well as the meteorology of the
area. ORD developed a new distance to roadway proximity metric, which significantly
improved the EPA's ability to estimate near roadway VOC air toxic impacts in such
settings.
Personal exposures to many VOCs are often multifold higher than concentrations
measured by ambient monitoring. The residential indoor environment can be a major
source of human exposures to these air toxics. Consumer goods, such as carpeting, wall
coverings and other household products could be contributing significantly to the total
exposure burden.
In comparing NATA risk exposures for benzene to the much higher direct human
measures in the DEARS, the EPA determined that the contributions from non-ambient
sources, unaccounted for in NATA, have the potential to result in significant
underestimation of total exposure risk for the Detroit metropolitan area.
PAHs were often fairly uniformly distributed over the Detroit metropolitan urban area.
High spatial variability in the residential outdoor PAH concentrations was occasionally
observed on days of unusually high PAH source emissions in heavily industrialized areas.
Passive carbonyl samplers used in the DEARS were easy to deploy and recover.
Subsequently, the EPA performed collocated comparisons in multiple regional field
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studies with standard air toxic measurement methods. DEARS and the regional
comparison studies indicated that significant research needed to be performed on all of
the methods to improve their performance and degree of acceptable data quality.
http://www.epa.gov/dears/
EPA ORD and Federal Highway Administration (FHWA), Las Vegas and Detroit
Near-Road Studies; 2008-present
The National Near-Roadway Mobile Source Air Toxics (MSAT) Study is a collaborative effort
between the EPA and the DOT's Federal Highway Administration. The study was developed as a
result of a lawsuit settlement between the Sierra Club and the DOT regarding improvements to
U.S. Highway 95 in Nevada. The main goal of the study is to better understand the relationship
between traffic emissions and air pollution at various distances from a roadway. Secondary goals
include assessing human exposure levels, investigating potential health effects and investigating
how barriers like walls and vegetation can reduce near-road pollutant levels. Ultimately, study
results will provide the scientific knowledge and understanding needed to identify the most
effective strategies and tools to control exposure to air pollution from major roads, including
natural and man-made mitigation strategies to protect people who live, work or go to school
nearby.
Continuous monitoring and data collection began in a near-road location along U.S. Highway 95 in
Las Vegas, Nevada, in December 2008, and was completed by February 2010. Monitoring
instruments were set up 10, 100, and 350 meters from the road to analyze how pollutants disperse
from the road. MSAT data collection occurred once every 12 days and criteria pollutant data
collection was continuous. Data on traffic counts, vehicle types, roadway characteristics and
meteorological conditions (including wind speed and direction, temperature and humidity) were
also collected. The EPA is currently completing a report for the Las Vegas portion of the study.
Similar monitoring and data collection began in a second site along Interstate 96 in Detroit,
Michigan, in October 2010. Monitoring instruments were placed 10,100, and 300 meters from the
road, MSAT data was collected quarterly and criteria pollutant data was collected continuously.
EPA is currently analyzing the data from the Detroit portion of the study.
Basic information: http://www.epa.gov/nrmrl/appcd/nearroadway/index.html or
http://www.fh wa.dot.gov/environment/air_quality/air_toxics/research_and_analysis/near_road_stu
dy/
Specific location/stages of study:
1. Las Vegas:
http://www.fh wa.dot.gov/environment/air_quality/air_toxics/research_and_analysis/near_road_stu
dy/nrves08.cfm
2. Detroit:
http://www.fh wa.dot.gov/environment/air_quality/air_toxics/research_and_analysis/near_road_stu
dy/nrvesdet.cfm
EPA ORD, Air Accountability Feasibility Study, New Haven, Connecticut; 2009
The purpose of this project was to assess the feasibility of conducting a city-level assessment of
cumulative air pollution reduction activities on the federal, state, tribal and local voluntary levels
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and their impact on public health. Study goals included assessing the availability of human health
data, ambient exposure data and studies examining linkages between exposure to air pollution and
health effects; determining data collection methods needed to cover gaps in available data;
assessing available modeling methodologies; and quantitatively determining the statistical
feasibility of carrying out an air accountability study in New Haven, Connecticut. Findings revealed
only four ambient monitors in the domain of the study, and no existing human exposure to air
pollution data available. Several databases were identified for data concerning health effects;
however, no one database containing all necessary information was found. Modeling projected an
overall decrease in median pollutant concentrations from local sources between 2001 and 2010,
and slight decreases in median pollutant concentrations from 2010 to 2030. Stochastic Human
Exposure and Dose Simulation model for Air Toxics (SHEDS-Air Toxics) and the modified Hazard Air
Pollution Exposure Model (HAPEM6) showed differences in both magnitude and spatial patterns of
air concentrations of air toxics and exposures. This highlights the importance for exposure
modeling in these assessments. The study evaluated 34 specific linkages between pollutants and
health outcomes and found 4 potentially feasible linkages that could be used in an accountability
study. The information collection activities performed in this study will serve the EPA as a resource
for future air accountability research planning.
http://ctdatahaven.org/know/images/5/5a/AWMA_ApriI_2009_Combing_Reg_IocaI-smI.pdf
EPA Office of Air Quality Planning and Standards (OAQPS), Detroit
Multipollutant Pilot Project; 2008
The Detroit Multipollutant Pilot Project was conducted as part of the OAQPS Air Quality
Management Plan (AQMP) Pilot Project, and was designed to help develop test methods, tools and
a functional framework for a multipollutant approach to air quality management and control. This
project was implemented in response to a 2004 NRC report recommending that the United States
transition to a multipollutant air quality management plan. Detroit was chosen as the urban test
area for this project because of emission levels of PM2.5 and air toxics of concern. The project used
a hybrid CMAQ and AERMOD modeling approach to compare a "status quo" control approach
achieving separate ozone and PM2.5 attainment goals with a multipollutant risk-based approach
designed to meet or exceed air quality improvements at monitors and reduce PM2.5, ozone and
HAP exposure throughout the region. The two approaches were evaluated based on improved
ozone and PM2.s air quality at monitors; improved regional air quality of PM2.s, ozone and selected
air toxics; monetized PM2.s-and ozone-related health benefits; and reductions in cancer and
noncancer risk.
Results of the Detroit Multipollutant Pilot Project showed that the multipollutant risk-based
control approach met all of the criteria for a successful management plan. Modeling predicted the
same or greater reductions for PM2.5 and ozone at all monitors, including projected non-
attainment monitors, and improved regional air quality for ozone, PM2.5, and selected air toxics
under the multipollutant management plan. A greater reduction in noncancer risk was shown
under the multipollutant management plan than the "status quo" plan, and a benefit-cost
comparison revealed a much higher benefit-cost ratio under the multipollutant plan. This study
was the first to analyze the benefits of a multipollutant air quality management plan and will
support future development and implementation of such plans.
http://www.epa.gov/ttn/scram/reports/aqmp_presentation_detroit_jan08.pdf
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EPA and University of Michigan (EPA STAR Grant), Near Roadway Exposures to
Urban Air Pollutants Study (NEXUS); September 2008-February 2012
An EPA study of traffic-related air pollution near roadways close to the residences of asthmatic
children is currently underway in Detroit, Michigan, to determine which measures of traffic-related
pollution most closely associate with asthmatic aggravation and related respiratory infections. The
NEXUS study participantschildren 6 to 14 years of age with persistent asthmalive in 3 different
proximities to roadways: within 150 meters of high volume, high diesel roads; within 150 meters of
high volume but low diesel roads; and more than 300 meters from roads. The study was designed
to develop a set of exposure metrics for each health study participant using measured and
modeled data of varying spatiotemporal complexity at the ambient, residential and personal levels.
Temporal variability in exposures was included in the study design to address the frequency,
magnitude and duration of exposures to traffic-related air pollutants. To achieve these objectives,
an integrated measurement and modeling approach was implemented in the NEXUS to
quantitatively estimate the contribution of traffic sources to near-roadway air pollution and
evaluate predictive modeling tools for assessing the impact of near-roadway pollution on the
children's exposures. Through a cooperative agreement with the University of Michigan, the
relationships between traffic-related exposures and respiratory health effects in children with
persistent asthma will be investigated.
http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/dispIay.abstractDetaiI/abstract/8977
http://www.epa.gov/nerI/documents/NearRoadwayTechnicaI_externaI_fact_sheet_071910.pdf
HEI, Air Toxics Hot Spots Studies; 2003-2012
Air toxics hot spots are areas that have high concentrations of toxic compounds due to proximity
to one or more pollutant sources. Hot spots offer researchers the ability to characterize spatial and
temporal characteristics of pollutant exposure and then study potential health effects of exposure
to pollutants on a representative sample of the general public. HEI has funded five studies to
identify and characterize exposure in hot spots across the United States and United Kingdom.
www.healtheffects.org
HEI, Measurement and Modeling of Exposure to Selected Air Toxics for Health
Effects Studies and Verification by Biomarkers, May 2005-May 2007; Report
released June 2009
The goal of this project was to develop personal exposure models that considered
microenvironments. This was achieved by collecting and analyzing the biomarkers and behaviors of
100 study participants. The personal sampling consisted of five, 24-hour exposure measurements
from personal samplers, urine samples to test for biomarkers of exposure, and time-activity diaries
to link exposures to activities. Finally, 24-hour air quality measurements were taken in the homes
and workplaces of participants. In addition to having varying daily activities, participants lived in
different urban, suburban and rural areas of the United Kingdom and therefore experienced
different vehicular traffic environments and exposure to mobile-source emissions. Results
indicated that personal exposures were predominately influenced by residential environments.
Higher personal exposures occurred in participants who were exposed to fossil fuel combustion on
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daily commutes, spent time in environments with tobacco smoke or used certain solvents or
consumer products. Predictive models were developed to estimate exposures based on the
observed microenvironmental factors and lifestyle. The models were useful for predicting
exposures to VOCs but were not as predictive for PAHs. In addition, low exposures were better
predicted by the model than high exposures. This study illustrated the extent to which personal
exposure can vary based on personal activities and spatial variations. It also stressed that not
enough is understood about exposure to produce accurate models for personal exposures across
varied microenvironments and human behaviors.
http://pubs.healtheffects.org/getfile.php?u=515
HEI, Concentrations of Air Toxics in Motor-Vehicle-Dominated Environments;
Summer/Fall 2004; Report released February 2011
Investigators measured the concentration of pollutants (carbon monoxide, nitrogen oxides, and
several mobile-source air toxics) on urban highways and at fixed off-highway sites in the Los
Angeles County area. Onroad measurements were taken by driving a monitoring van for 1 hour
during morning rush hour and 1 hour during afternoon rush hour, on 3 different commuter
highways and 1 freeway with a higher proportion of diesel trucks. Following the morning onroad
measurements, the monitoring van stopped at locations at varying distances off the major highway
and took measurements at off-highway locations. Additionally, 24-hour stationary monitoring sites
were set up in 3 near-road locations. Main findings were that concentrations of all pollutants
measured were higher on-highway than at fixed off-highway sites. Gasoline exhaust was the main
source of VOCs, accounting for 100 percent of the onroad VOC concentration and about
70 percent of the near-road concentration. Diesel exhaust accounted for 46 percent to 52 percent
of the total particulate carbon in near-road locations, compared to only 10-17 percent from
gasoline exhaust in the peak summer season. Approximately 40-50 percent of total particulate
carbon was not due to mobile sources. The full results from this study will serve as an important
baseline for information on MSATs on and near roads as motor vehicle emissions control standards
and fuel types change in coming years.
http://pubs.healtheffects.org/getfile.php?u=617
HEI, Air Toxics Exposure from Vehicle Emissions at U.S. Border Crossing: Buffalo
Peace Bridge Study; July 2004-January 2006; Report released July 2011
Peace Bridge, in Buffalo, New York, is one of the busiest border-crossing locations in the United
States and suspected to be a hot-spot for MSATs. Emissions of more than 40 MSATs were
measured both upwind and downwind of the bridge plaza to study the relationship of traffic at the
bridge and ambient air pollution. Pilot studies in July 2004 and January 2005 established fixed
sampling sites directly upwind and downwind of the bridge and in a nearby neighborhood slightly
downwind of the bridge, collected traffic data, including number and type of vehicles crossing the
bridge, and measured spatial dispersion of pollution originating from bridge by measuring personal
exposure along four routes commonly used by pedestrians through the neighborhood next to the
bridge. Two-week sampling campaigns were then carried out in July 2005 and January 2006. The
study results showed that the Peace Bridge area was not necessarily a hot-spot for MSAT pollution
compared to other areas in the United States. Concentrations of different pollutants observed in
the upwind, downwind and dispersed downwind areas near the bridge were highly dependent on
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wind conditions. On a small spatial scale, hot spots for different pollutants could develop and shift
with changing wind speed and direction.
http://pubs.healtheffects.org/getfile.php?u=656
HEI, Assessing Personal Exposure to Air Toxics in Camden, New Jersey; June
2004-July 2006; Report released August 2 Oil
Investigators measured concentrations of 32 compounds, including VOCs, aldehydes, PAHs and
PIVh.s, in two nearby neighborhoods in Camden, New Jersey. One neighborhood, Waterfront
South, was an industrial center close to several highways, and the other, Copewood-Davis, did not
have any industrial pollutant sources. Personal exposure was measured in 107 nonsmoking study
participants for 24-hour periods in the summer and winter, on a weekend and weekday, and
ambient pollution levels were measured at 38 fixed sites in the neighborhoods. Study results
showed that Waterfront South was a hot-spot for PAH, toluene, xylene and Plvh.s pollution
compared to neighboring Copewood-Davis; however, concentrations of ambient benzene, methyl
tertiary butyl ether, chloroform, carbon tetrachloride, hexane and acetaldehyde in Copewood-
Davis were similar to, or higher than, concentrations in Waterfront South and elevated compared
to studies in other regions of the country. Additionally, personal exposure measurements were
higher than ambient measurements, indicating a role for non-outdoor sources. This study showed
that hot-spots can be identified on a small scale of one neighborhood to the next, as well as on a
regional or national scale. This illustrates the need to design future air toxics exposure/health
effects studies to include multiple pollutant sources, meteorological factors and spatial scales
when choosing hot-spots and reference sites.
http://pubs.healtheffects.org/view.php?id=364
HEI, Air Toxics Hot Spots in Industrial Parks and Traffic; December 2012
This study, added to an ongoing study by the National Cancer Institute, measured air toxics and PM
levels upwind, downwind and along the dock perimeters of 15 different truck terminals in the
United States to identify the potential impacts of truck terminals on air pollution in the
surrounding area. This study is part of the National Cancer Institute's ongoing initiative to
investigate the relationship between diesel exhaust exposure and lung cancer mortality in truck
drivers and dockworkers at more than 200 truck terminals in the United States (study was
completed in mid-2012).
http://www.pubs.healtheffects.org/view.php?id=393
HEI, Traffic-Related Air Pollution: A Critical Review of the Literature; 2010
Published in 2010, the HEI "Traffic-Related Air Pollution: A Critical Review of the Literature on
Emissions, Exposure, and Health Effects" was the culmination of research efforts funded by an EPA
Assistance Award. A panel of experts reviewed, summarized and synthesized data from air
pollution emissions, exposure and health studies focused on urban and near-roadway settings.
Several major conclusions were drawn, including the identification of an "exposure zone" up to
300-500 meters from a major roadway where traffic emissions and exposures are greatest. The
Panel noted that epidemiological and toxicological evidence related to health effects of air
pollution is incomplete, but a causal relationship between traffic and asthma is supported.
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http://pubs.healtheffects.org/getfile.php?u=553
Industrial Economics, Inc., Section 812 Prospective Study of the Benefits and
Costs of the Clean Air Act Air Toxics Case Study - Health Benefits of Benzene
Reductions in Houston; 1990-2020
This case study demonstrated the benefits of CAA programs in reducing health impacts related to
benzene exposure in the Houston-Galveston area of Texas. Investigators modeled exposure to
benzene and health impacts in 1990, 2000, 2010, and 2020, under a scenario of no benzene
control activities and a scenario of regulatory programs limiting benzene due to the CAA. The
difference between the two models illustrated the impact of the CAA. Benzene emissions were
estimated for point, non-point, onroad and nonroad sources. Emissions were converted to
estimated ambient benzene concentrations across the study area to estimate time-weighted
average benzene exposures for the study population. To express the health impacts of reduced
benzene emissions, investigators used a risk assessment model to estimate the avoided cases of
leukemia. Investigators applied economic valuation terms (value of statistical life estimates and
medical cost adjustments) to determine a monetary value (in 2006 USD) gained from avoided
illness. The case study illustrated that the monetary benefits from 1990 through 2020 due to
reductions in benzene in the Houston area as a result of CAA, totaled between $8.7 to $12 million
U.S. dollars.
http://www.epa.gov/air/sect812/dec09/812CAA_Benzene_Houston_FinaI_Report_Juty_2009.pdf
General information on the Second Prospective Study:
http://www.epa.gov/oar/sect812/prospective2.html
Oregon Department of Environmental Quality (DEQ), Portland Air Toxics
Assessment (PATA); 1999- 2000; Report released 2006
PATA was a collaborative effort by the Oregon DEQ, the EPA and Portland's metropolitan regional
government to conduct computer modeling and estimate risk from 12 toxic air pollutants in
Portland. This project aimed to refine the EPA's NAT A, by modeling factors such as emissions from
motor vehicles, regional weather data and regional topography. PATA estimated air toxics
exposure and risk at the census-block level and attributed air toxics to specific source categories,
providing important data from which the DEQ can develop air toxics exposure and risk reduction
strategies. Emissions inventories covered the 1999 calendar year and air monitoring data was from
July 1999-July 2000. Modeling results showed a correlation between source location and pollution
levels and illustrated the spatial variance in exposure throughout the Portland area. Diesel
emissions, motor vehicle exhaust and open burning were identified as major sources of air toxics.
http://www.deq.state.or.us/aq/toxics/pata.htm
South Coast Air Quality Management District, Multiple Air Toxics Exposure Study
(MATES) II: 1998-2000
MATES II was a landmark monitoring and evaluation study, emissions inventory update and risk
modeling effort conducted across four urban counties in southern California. Ten fixed monitors
recorded air contaminant levels for more than 30 pollutants, every 6 days from April 1998 to
March 1999, and three mobile platforms surveyed an additional 14 residential communities. Study
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results showed that the cancer risk from air pollution in the region was about 1,400 per 1 million
people. Seventy percent of that risk was attributed to diesel particulate emissions, 20 percent to
other mobile sources and 10 percent to stationary air pollution sources such as industries and
businesses. Model results showed higher risk levels in south-central Los Angeles, the harbor area
and near freeways. These findings supported the conclusions of monitoring that mobile sources
are the main contributors to cancer risk. Seasonal variations were strong and monitoring showed
that benzene, butadiene and elemental carbon peaked in late fall and early winter and was lowest
in the spring and summer.
http://www.aqmd.gov/matesiidf/matestoc.htm
South Coast Air Quality Management District, MATES III: 2005-2006
This study is a follow up to the previous MATES II study and includes similar monitoring and
evaluation, emissions inventory updates, and risk modeling. Ten fixed-site monitors, placed in the
same locations as the fixed-site monitors used in MATES II, recorded pollution levels every 3 days
from April 2004 through March 2006. Additionally, 5 locations were surveyed using mobile
platform monitors. Study results showed that the cancer risk from air pollution in the region was
about 1,200 per 1 million people. Approximately 94 percent of that risk was linked to mobile
sources and only 6 percent to stationary air pollution sources like industries and businesses.
Approximately 84 percent of the total risk was attributable to diesel exhaust. The study found an
8 percent decrease in risk for air toxics exposure in the region compared to the MATES II study.
Highest risk areas were the same as during MATES II: near the port, central Los Angeles and near
transportation corridors.
Report released September 2008: http://www.aqmd.gov/prdas/mateslll/mateslll.html
Texas Commission on Environmental Quality, Houston Exposure to Air Toxics
Study (HEATS); 2005-2009
The primary goal of HEATS was to measure and compare personal exposure to eleven different
HAPs for residents who lived in an area of Houston with a high density of point source emissions to
residents who lived in an area with only a few point source emissions. A total of 78 adults and
35 children participated in the study. Exposure was measured during two 24-hour periods each
6 months apart, using personal monitoring devices, stationary indoor and outdoor residential
monitoring devices, as well as fixed site ambient monitoring stations. Personal activity logs and
questionnaire responses regarding perceived environmental risk and health symptoms were also
recorded. The results of HEATS showed that personal exposure as measured through personal
exposure monitoring devices was higher than exposure measured by ambient air monitors. Total
personal exposure to VOCs was more closely associated with residential indoor measurements
than to ambient or stationary outdoor measurements. There were not significant differences in
personal exposure or health symptoms between residents living in an area of high point source
density compared to low point source density; however, the number of study participants might
have been too low to adequately reflect differences. There were differences observed in emissions
at the fixed outdoor monitoring; however, these emissions were not considered good predictors of
personal exposure due to the amount of time that study participants spent indoors. Overall,
personal exposures were similar in the two areas observed, and as such were not dependent on
the density of emissions sources or the outdoor pollutant concentrations in each of the study
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areas.
http://www.tceq.texas.gov/toxicology/research/heats.htmlffreport
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Appendix D. Integrated Risk Information
System (IRIS) Status
D.I. STATUS OF PROGRESS OF UPDATES TO IRIS ASSESSMENTS
The EPA's IRIS is a human health assessment program that evaluates risk information on effects
that could result from exposure to environmental contaminants. Through the IRIS program, the
EPA provides the highest quality science-based human health assessments to support the agency's
regulatory activities. The IRIS database contains information for more than 550 chemical
substances containing information on human health effects that could result from exposure to
various substances in the environment.105
Since 2000, the EPA has completed or updated hazard identifications and dose-response
assessments for several of the 33 urban HAPs through the IRIS program. As of October 2012, 32 of
the 33 urban HAPs have undergone IRIS assessment, 28 of which have one or more quantitative
inhalation values. Twelve of these assessments have been completed since 2000. Currently, 12
urban HAPs are undergoing assessment in the IRIS program.
i°5http://www.epa.gov/IRIS/.
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Exhibit D-l. Status of IRIS Risk Assessments for the 33 Urban HAPs
Contaminant
Acetaldehyde
CAS: 75-07-0
Acrolein
CAS: 107-02-8
Acrylonitrile
CAS: 107-13-1
Arsenic
Compounds
Benzene
CAS: 71-43-2
Arsine (7784-42-
1)
Inorganic (7440-
38-2)
Beryllium Compounds
CAS: 7440-41-7
Cancer Classification3
B2 - Probable human
carcinogen
Data are inadequate
Bl- Probable human
carcinogen
Not assessed
A- Human carcinogen
A- Human carcinogen
Bl- Probable human
carcinogen
Cancer Inhalation Unit
Risk
Value
Yes
Noc
Yes
Not
assessed
Yes
Yes
Yes
Date
1991
2003
1991
NA
1998
2000
1998
RfC
Value
Yesb
Yesb
Yesb
Yes
Not
assessed
Yes
Yes
Date
1991
2003
1991
1994
NA
2003
1998
RfD
Value
Not
assessed
Yes
Not
assessed
Not
assessed
Yes
Yes
Yes
Date
NA
2003
NA
NA
1993
2003
1998
Status of
Assessment
Reassessment is
currently under
development. For
the most current
information see:
IRISTrack.
Assessment
completed in 2003.
Reassessment is
currently under
development. For
the most current
information see:
IRISTrack.
Reassessment is
currently under
development. For
the most current
information see:
IRISTrack.
Noncancer
assessment
completed in 2003.
Cancer assessment
completed in 2000.
Reassessment is
currently under
development. For
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Exhibit D-l. Status of IRIS Risk Assessments for the 33 Urban HAPs
Contaminant
1, 3-Butadiene
CAS: 106-99-0
Cadmium
CAS: 7440-43-9
Carbon tetrachloride
CAS: 56-23-5
Chloroform
CAS: 67-66-3
Chromium
Compounds
(chromium VI
[18540-29-9];
chromium III
[16056-83-1])
Cancer Classification3
Carcinogenic to
humans
Bl- Probable human
carcinogen
Likely to be
carcinogenic to humans
B2 - Probable human
carcinogend
A- Human carcinogen6
D- Not classifiable
Cancer Inhalation Unit
Risk
Value
Yes
Yes
Yes
Yes
Yes
Nof
Date
2002
1992
2010
2001
1998
1998
RfC
Value
Yesb
Not
assessed
Yes
Not
assessed
Yes
Noc
Date
2002
NA
2010
NA
1998
1998
RfD
Value
Noc
Yes
Yesb
Yes
Yes
Yes
Date
NA
1994
2010
2001
1998
1998
Status of
Assessment
the most current
information see:
IRISTrack.
Assessment
completed in 2002.
Noncancer
reassessment
completed in 1994.
Cancer assessment
completed in 1992.
Assessment
completed in 2010.
Reassessment is
currently under
development. For
the most current
information see:
IRISTrack.
Noncancer
reassessment is
currently under
development. For
the most current
information see:
IRISTrack.
Assessment
completed in 1998.
D-3
-------
National Air Toxics Program
The Integrated Urban Strategy Report to Congress
Exhibit D-l. Status of IRIS Risk Assessments for the 33 Urban HAPs
Contaminant
Coke oven emissions (including coal
tar, creosote, coal tar pitch)
CAS: 8007-45-2
Dioxin§
CAS: 1746-01-6
Ethylene dibromide (1,2-
dibromoethane)
CAS: 106-93-4
1,2-Dichloropropane
(propylene dichloride)
CAS: 78-87-5
1,3-Dichloropropene
CAS: 542-75-6
1,2-Dichloroethane
(Ethylene dichloride)
CAS: 107-06-2
Cancer Classification3
A- Human carcinogen
Not assessed
Likely to be
carcinogenic to humans
Not assessed
B2 - Probable human
carcinogen
B2- Probable human
carcinogen
Cancer Inhalation Unit
Risk
Value
Yes
Not
assessed
Yes
Not
assessed
Yes
Yes
Date
1994
NA
2004
NA
2000
1991
RfC
Value
Not
assessed
Noc
Yesb
Yes
Yes
Not
assessed
Date
NA
2012
2004
1991
2000
NA
RfD
Value
Not
assessed
Yes
Yes
Not
assessed
Yes
Not
assessed
Date
NA
2012
2004
NA
2000
NA
Status of
Assessment
Assessment
completed in 1994.
Noncancer
assessment
completed in 2012.
Cancer assessment
is currently under
development. For
the most current
information, see:
IRISTrack.
Assessment
completed in 2004.
Assessment
completed in 1991.
Assessment
completed in 2000.
Reassessment is
currently under
development. For
the most current
information, see:
IRISTrack.
D-4
-------
National Air Toxics Program
The Integrated Urban Strategy Report to Congress
Exhibit D-l. Status of IRIS Risk Assessments for the 33 Urban HAPs
Contaminant
Ethylene oxide8
CAS: 75-21-8
Formaldehyde
CAS: 50-00-0
Hexachlorobenzene
CAS: 118-74-1
Hydrazine
CAS: 302-01-2
Lead Compounds (inorganic)
CAS: 7439-92-1
Manganese
CAS: 7439-96-5
Mercury
Compounds
Elemental
Mercury
Cancer Classification3
Not assessed
Bl- Probable human
carcinogen
B2- Probable human
carcinogen
B2- Probable human
carcinogen
B2 - Probable human
carcinogen
D- Not classifiable
D- Not classifiable
Cancer Inhalation Unit
Risk
Value
Not
assessed
Yes
Yes
Yes
Not
assessed
Nof
Nof
Date
NA
1990
1996
1991
NA
NA
NA
RfC
Value
Not
assessed
Not
assessed
Noc
Noc
Not
assessed
Yesb
Yes
Date
NA
NA
NA
NA
NA
1993
1995
RfD
Value
Not
assessed
Yes
Yes
Not
assessed
Noc
Yes
Not
assessed
Date
NA
1991
1991
NA
2004
1996
NA
Status of
Assessment
Assessment is
currently under
development. For
the most current
information, see:
IRISTrack.
Reassessment is
currently under
development. For
the most current
information, see:
IRISTrack.
Assessment
completed in 1996.
Assessment
completed in 1991.
Assessment
completed in 2004.
An updated
Integrated Science
Assessment (ISA)
for lead is
anticipated in
2012.
Assessment
completed in 1996.
D-5
-------
National Air Toxics Program
The Integrated Urban Strategy Report to Congress
Exhibit D-l. Status of IRIS Risk Assessments for the 33 Urban HAPs
Contaminant
(7439-97-6)
Methylmercury
(22967-92-6)
Mercuric
chloride
(7487-94-7)
Methylene chloride
(dichloromethane)
CAS: 75-09-2
Nickel
Compounds
Nickel, soluble
salts (various
CAS)
Nickel refinery
dust
(no CAS)
Nickel carbonyl
(13463-39-3)
Nickel subsulfide
(12035-72-2)
Cancer Classification3
C- Possible human
carcinogen
C- Possible human
carcinogen
Likely to be
carcinogenic to humans
Data are inadequate
A- Human carcinogen
B2- Probable human
carcinogen
A- Human carcinogen
Cancer Inhalation Unit
Risk
Value
Not
assessed
Not
assessed
Yes
Not
assessed
Yes
Not
assessed
Yes
Date
1995
NA
2011
1994
1991
1991
1991
RfC
Value
Not
assessed
Not
assessed
Yes
Not
assessed
Not
assessed
Not
assessed
Not
assessed
Date
NA
1994
2011
NA
NA
NA
NA
RfD
Value
Yes
Yesb
Yes
Yes
Not
assessed
Not
assessed
Not
assessed
Date
2001
1995
2011
1996
NA
NA
NA
Status of
Assessment
Assessment
completed in 1995
Assessment
completed in 2001.
Assessment
completed in 1995.
Assessment
completed in 2011.
Reassessment is
currently under
development. For
the most current
information, see:
IRISTrack.
Assessment
completed in 1991.
Assessment
completed in 1991.
Assessment
completed in 1991.
D-6
-------
National Air Toxics Program
The Integrated Urban Strategy Report to Congress
Exhibit D-l. Status of IRIS Risk Assessments for the 33 Urban HAPs
Contaminant
Polychlorinated
biphenyls(PCBs)
CAS: 1336-36-3
POM1
Aroclor 1016
(12674-11-2)
Aroclor 1248
(12672-29-6)
Aroclor 1254
(11097-69-1)
benzo(o)pyrene
/ n_ n\ .
i KH y \
yL^UI If
benz[a]anthrace
ne; chrysene;
benzo[b]fluorant
hene;
benzo[k]fluorant
hene;
dibenz[a,h]anthr
acene1 and
Cancer Classification3
B2- Probable human
carcinogen1
B2 - Probable human
carcinogen
B2 - Probable human
carcinogen
Cancer Inhalation Unit
Risk
Value
Yes
("PCBs1")
Not
assessed
Not
assessed
Date
1997
1994
1994
RfC
Value
Not
assessed
Not
assessed
Not
assessed
Not
assessed
Not
assessed
Date
NA
NA
NA
NA
NA
RfD
Value
Yes
Noc
Yes
Not
assessed
Not
assessed
Date
1996
1996
1996
NA
NA
Status of
Assessment
Cancer assessment
completed in 1997.
Reassessment of
PCBs is currently
under
development for
noncancer health
effects. For the
most current
information, see:
IRISTrack.
Cancer
classification
completed in 1994.
Reassessment is
currently under
development. For
the most current
information, see:
IRISTrack.
Assessments
D-7
-------
National Air Toxics Program
The Integrated Urban Strategy Report to Congress
Exhibit D-l. Status of IRIS Risk Assessments for the 33 Urban HAPs
Contan
Quinoline
CAS: 91-22-5
ninant
indeno[l,2,3-
cd]pyrene
Polycyclic
aromatic
hydrocarbon
(PAH) mixtures
1,1,2,2-Tetrachloroethane
CAS: 79-34-5
Tetrachloroethylene
(Perchloroethylene)
CAS: 127-18-4
Trichloroethylene
CAS: 79-01-6
Vinyl chloride
CAS: 75-01-4
Cancer Classification3
Not assessed
B2- Probable human
carcinogen
Likely to be
carcinogenic to humans
Likely to be
carcinogenic to humans
Carcinogenic to
humans
A- Human carcinogen
Cancer Inhalation Unit
Risk
Value
Not
assessed
Noc
Noc
Yes
Yes
Yes
Date
NA
2001
2010
2012
2011
2000
RfC
Value
Not
assessed
Noc
Noc
Yesb
Yes
Yes
Date
NA
2001
2010
2012
2011
2000
RfD
Value
Not
assessed
Noc
Yesk
Yesb
Yes
Yes
Date
NA
2001
2010
2012
2011
2000
Status of
Assessment
completed in 1994.
This assessment is
currently under
development. For
the most current
information, see:
IRISTrack.
Assessment
completed in
200 l.J
Assessment
completed in 2010.
Assessment
completed in 2012.
Assessment
completed in 2011.
Assessment
completed in 2000.
a These chemicals may have a cancer hazard classification of:
- known, probable, or possible human carcinogens (under the 1986 EPA cancer guidelines (U.S. EPA 1986); or
- carcinogenic to humans, likely to be carcinogenic to humans, or suggestive evidence of carcinogenic potential (under the 2005 EPA cancer guidelines (U.S.
EPA, 2005a).
b UF= 1000 or greater.
D-8
-------
National Air Toxics Program
The Integrated Urban Strategy Report to Congress
c A cancer unit risk value, RfD value, or RfC value of "No" implies data were insufficient to determine a toxicity value at the time of the IRIS assessment.
d Chloroform is likely to be carcinogenic to humans by all routes of exposure under high-exposure conditions that lead to cytotoxicity and regenerative
hyperplasia in susceptible tissues. Chloroform is not likely to be carcinogenic to humans by any route of exposure under exposure conditions that do not
cause cytotoxicity and cell regeneration.
e Chromium VI s classified as Group A - known human carcinogen by the inhalation route of exposure. Carcinogenicity by the oral route of exposure cannot be
determined and is classified as Group D. Under the proposed guidelines (EPA, 1996), Cr(VI) would be characterized as a known human carcinogen by the
inhalation route of exposure on the following basis. The oral carcinogenicity of Cr(VI) cannot be determined. No data were located in the available literature
that suggested that Cr(VI) is carcinogenic by the oral route of exposure.
f Inadequate data to determine carcinogenicity; therefore a quantitative unit risk was not developed.
8 Chemical is currently not part of the IRIS database.
h Integrated Science Assessments (ISAs) are synthesis documents of the current science used to support the review of National Ambient Air Quality Standards
(NAAQS). Therefore, IRIS values are not derived in ISAs.
1 Polycyclic organic matter (POM) includes polycyclic aromatic hydrocarbons (PAHs), their nitrogen analogs, and a number of oxygen-containing POM
compounds.
J A comprehensive review of toxicological quinoline studies was completed in 2006, concluding insufficient health effects data to derive an RfD.
k UF = 1000 only for the chronic oral RfD - subchronic oral RfD UF = 300.
1 The cancer classification of Polychlorinated biphenyls (PCBs) is: B2 - Probable human carcinogen.
Sources:
IRIS database 2011 (available at http://cfpub.epa.gov/ncea/iris/index.cfm?fuseaction=iris.showSubstanceList)
IRISTrack 2011 (available at http://cfpub.epa.gov/ncea/iristrac/)
D-9
-------
National Air Toxics Program
The Integrated Urban Strategy Report to Congress
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Environmental Protection Outreach and Information Division August 2014
Agency Research Triangle Park, NC
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