Community Air Screening How-To Manual
A Step-by-Step Guide to Using a Risk-Based Approach to Identify Priorities
for Improving Outdoor Air Quality
Organize
Collect
Analyze
Mobilize
0 C QA
f C I r\
United States
Environmental Protection Agency
EPA 744-B-04-001
-------
-------
Disclaimer
Please note that any mention of a trade name or commercial
product in this Manual does not constitute an endorsement by the
U.S. Environmental Protection Agency
For additional copies of the Manual:
This Manual can be downloaded from the Internet as a pdffile at:
h ttp://www. epa.gov/opp t/cahp/howto. h tml
Document title and information for requests or citing: Community Air Screening How-To
Manual, A Step-by-Step Guide to Using Risk-Based Screening to Identify Priorities for
Improving Outdoor Air Quality, 2004, United States Environmental Protection Agency
(EPA 744-B-04-001), Washington, DC.
Permission to copy all or part of this Manual is not required.
v
Community Air Screenins How-To Manual • I
-------
II
Community Air Screening How-To Manual
-------
INTRODUCTION
The Community Air Screening How-To Manual is a resource developed to assist communities in
their efforts to understand and improve local outdoor air quality. The Manual is one of a number
of resources and tools that are being made available as part of the Agency's Community Action
for a Renewed Environment (CAKE) program. Launched in the Fall of 2004, CARE is a program
designed by the U.S. Environmental Protection Agency (EPA) to help communities work at the
local level to address the risks from multiple sources of toxics in their environment. CARE
promotes local consensus-based solutions that address risk comprehensively.
The Community Air Screening How-To Manual includes information on how to develop a
detailed source inventory, estimate ambient air concentrations, and use a risk-based screening
process to identify priorities. The Manual also includes information on consensus building in a
community which can be useful in mobilizing local resources for voluntary actions to reduce risk.
The How-To Manual is based on several community-based pilot programs and is the product of
broad Agency collaboration. A formal external peer review of the How-To Manual was
conducted by eighteen expert reviewers representing a broad spectrum of stakeholders. The draft
final of the How-To Manual is now available for public review on the EPA website at:
http://www.epa.gov/oppt/cahp/howto.html
For more information on CARE and the many other tools and resources available to
communities, visit www.epa.gov/CARE
Community Air Screenins How-To Manual • III
-------
IV
Community Air Screen ins How-To Manual
-------
Table of Contents
Part One - Overview (what everyone needs to know)
Chapter 1: How to Use This Manual 1
Chapter 2: Getting Started 7
Building a Partnership 9
Setting Goals 21
Choosing a Plan to Meet Community Goals 27
Developing a Communication Plan 42
Chapter 3: An Introduction to Risk-Based Screening 47
Chapter 4: Building the Emission Source Inventory 71
Chapters: Initial Screen 93
Initial Screen Overview 94
Step 1: Estimating Concentrations 101
Step 2: Setting the Screening Level and Developing
Screening-Level Concentrations 113
Step 3: Comparing Community Air Screening Concentrations to the
Screening-Level Concentrations 129
Chapter 6: Secondary Screen 131
Chapter 7: Final Screen 147
Chapter 8: Communicating the Screening Results and Developing Recommendations 157
Part Two - Technical Guidance (detailed guidance for technical teams)
Chapter 9: Building the Emission Source Inventory 173
Chapter 10: Initial Screen 197
Chapter 11: Secondary Screen 207
Chapter 12: Final Screen 221
Glossary 227
Community Air Screenins How-To Manual • V
-------
Appendices
Appendix A: Resources for Building a Partnership, Setting Goals, and Developing a
Communication Plan 233
Appendix B: Examples of Projects Communities Have Adopted to Improve Air Quality 235
Appendix C: Resources for Addressing Indoor Air Exposures and Acute Outdoor Air
Exposures 237
Appendix D: Summary of Lessons Learned by the Baltimore Partnership 239
Appendix E: List of Hazardous Air Pollutants (HAPs) 241
Appendix F: Air Pollution and Your Health 247
Appendix G: Examples of Available Risk Reduction and Pollution Prevention Programs 249
Appendix H: Toxicity Values and Toxicity Sources: Background for the Collection of
Information to Calculate Screening-Level Concentrations 255
Appendix I: Steps for Calculating a Screening-Level Concentration 261
Appendix J: Methods for Apportioning County Data 263
List of Figures
Figure 2-1. Outline of Options for Developing a Technical Analysis Work Plan 32
Figure 3-1. Summary of Air Screening Methodology for the Community 58
Figure 3-2. Detailed Community Air Screening Methodology 62
Figure 4-1. An Illustration of an Emission Source Inventory Database 92
Figure 9-1. Overall Procedure for Developing Emission Source Inventory 174
Figure 9-2. Template for Emission Source Inventory Database 179
Figure 9-3. Procedure for Adding Stationary Point Source Emissions Data to the Emissions
Source Inventory (when release information IS available for each
individual source) 181
Figure 9-4. Microsoft Access Query Design View Screen for NEI Point Sources 182
Figure 9-5. Sample Stationary Point Source Data in Emission Source Inventory
Database 184
Figure 9-6. Procedure for Adding Stationary Point Source Emissions Data to Emission
Source Inventory (when release information IS NOT available for each
individual source) 185
Figure 9-7. Procedure for Adding Stationary Area Source 187
Figure 9-8. Example Stationary Area Source Data 189
vi.
Community Air Screenins How-To Manual
-------
Figure 9-9. Procedure for Adding Mobile Source Emissions Data to Emission
Source Inventory 190
Figure 9-10. Sample Mobile Source Data in Emission Source Inventory Database 191
Figure 9-11. Procedure for Adding Background Concentration Data to Emission Source
Inventory 192
Figure 9-12. Sample Background Concentration Data in Emission Source
Inventory Database 194
Figure 9-13. Procedure for Adding Monitored Concentration Data to the Emission
Source Inventory 195
Figure 10-1. Procedure for Initial Screen 198
Figure 10-2. Steps for Developing a Screening-Level Concentration (SLC) 199
Figure 11-1. Procedure for Secondary Screen 208
Figure 11-2. Illustration of Pseudo-Point Layout 218
Figure 11 -3. Example of ISCST Input File Format 218
Figure 12-1. Procedure for Final Screen 222
List of Tables
Table 4-1. Summary of Information Needed to Complete Risk-Based Screening 78
Table 4-2. Source Types and Information Needed to Start Building Emission Source
Inventory Database 84
Table 5-1. Look-Up Table. Unitized Annual Average Concentration at Different
Distances from a Stack (^g/m3 perlb/year) 104
Table 6-1. Summary of Information Needed to Run the ISCST Model in the
Secondary Screen 140
Table 9-1. Information Collected for Emission Source Inventory Prior to
Initial Screen 176
Table 9-2. Required Data Elements for Emission Source Inventory from
NEI Point Source Files 183
Table 9-3. Required Data Elements for Emission Source Inventory from
TRI Point Source Files 184
Table 9-4. Emission Factors for Dry-Cleaning Operations 186
Table 9-5. Emission Rate Estimate for Dry-Cleaning Operations 186
Table 9-6. Data Elements in the 1996 NEI Area Source State Data Files 188
w v
Community Air Screening How-To Manual • Vll
-------
Table 9-7. Required Data Elements for Emission Source Inventory from
NEI Area Source Files 188
Table 9-8. Data Elements in the 1996 NEI Mobile Source State Data Files 190
Table 9-9. Required Data Elements for Emission Source Inventory from
NEI Mobile Source Files 191
Table 9-10. National Air Toxics Assessment Background Concentration Estimates 192
Table 9-11. Required Data Elements for Emission Source Inventory from NATA State
Background Concentration Tables 193
Table 10-1. SCREENS Input Parameters Used to Generate Initial Screen
Look-Up Table 200
Table 10-2. Look-Up Table. Unitized Annual Average Concentration at Different
Distances from a Stack dig/m3 per Ib/year) 201
Table 10-3. Required Data for Emission Source Inventory from NEI Point
Source Files 203
Table 10-4. Mobile Source Chemicals to be Passed to the Secondary Screen 203
Table 11-1. Area Source Categories and Apportioning Methods 216
VIII .
Community Air Screening How-To Manual
-------
Overview
How to Use This Manual
Why was this Manual written?
This Manual is designed to support the new efforts that communities
and neighborhoods across the nation are making to improve the
environmental quality and health of the places where they live and
work. Efforts to understand and improve air quality are a key part of
this work to create healthy local environments. But many
communities have found the work to understand and improve local
air quality to be complex and difficult. Even regulatory agencies with
expertise may have difficulty answering community questions
regarding the combined impacts of releases from multiple sources.
While some regulatory programs may consider combined impacts,
permitting programs have usually been set up to deal with facilities on
an individual basis and they cannot be easily used to answer
community concerns about releases from multiple sources. Similarly,
the available data on air quality, designed to support national, state,
and tribal regulatory programs, is often too general to address the
details of local air environments. This Manual was written to help
communities overcome these difficulties and find answers to some of
the basic questions about air quality that they have not been able to
answer in the past.
What does this Manual contain and how is it
organized?
There are many different approaches that communities can take to get
a better understanding of local air quality. Finding the approach that
best matches your community's resources and goals will be a key to
the success of your effort to improve air quality. Most of this Manual
provides a detailed guide to using risk-based screening, one of the
Organize
Community Air Screenins How-To Manual
-------
Chapter 1: How to Use This Manual
approaches to analyzing air quality. Chapters 3 through 12 of this
Manual contain a step-by-step guide for using the risk-based
screening approach.
If you are interested in learning more about the risk-based screening
method, please go immediately to Chapter 3 for an overview of this
method. If you decide that risk-based screening will help you reach
your goals, then this Manual will provide a lot of the assistance that
you will need.
If you don't know which approach would be best for your community
to use to get a better understanding of local air quality or if you are
just getting started in an effort to improve air quality, then Chapter 2
is designed to help you. Choosing the best approach for your
community to take to understand your air quality and doing effective
work to improve community air quality require a partnership with
adequate resources and a clear idea of what it wants to accomplish.
Chapter 2 explains how to form the partnership that you will need,
clarify your goals, and, then, choose the approach for analyzing local
air quality that best matches your resources and goals. If, after you
have considered the different approaches outlined in Chapter 2, you
decide that risk-based screening does meet your needs, then the
remaining chapters of this Manual will be helpful. If you decide to use
a different approach, then the Manual will refer you to other sources
of information for help. Even if you use a different approach, you may
still want to use some parts of this Manual as a resource for your
work.
Find the
approach that
best matches your
community's
resources and
goals
As an individual with concerns about air quality, how
could I use this Manual to start working to improve
air quality in my community?
If you are an individual or a member of a community group or
organization and you are interested in doing something to improve
local air quality, you can use Chapter 2 to help you get a partnership
started. Or, if you are not sure if there is enough interest in air quality
to form a partnership, you, or you and your organization, could first
follow one of the simpler approaches for collecting available
information on local air quality described in Chapter 2 and use this
information to help you better understand and explain the need to
improve air quality. This will help you to get others interested in
joining a partnership. Once you have a partnership and you have
worked together to clarify your goals, you can study the options for
understanding air quality presented in Chapter 2 (and others that you
Community Air Screening How-To Manual
-------
Chapter 1; How to Use This Manual
can learn about) to decide which approach to take to improve local air
quality.
We already have a partnership formed to work on air
quality or another community health concern, so
how could this Manual help us?
If you already have a partnership formed that is interested in learning
about and improving local air quality and you are clear on your goals,
then you can go directly to the section in Chapter 2 that describes
different options for understanding air quality to get help finding an
approach that matches your goals and needs. We recommend reading
the sections on partnership building and clarifying goals even if you
already have a partnership and goals, since these sections raise issues
and lessons learned from other partnership efforts to improve air
quality that may help you strengthen your work.
If, after considering the alternatives, your partnership decides that the
risk-based screening approach meets your needs, you can turn to
Chapter 3 and use the help provided there and in the subsequent
chapters to get started and complete a risk-based screening project.
If this Manual and all the work and resources needed
to improve air quality look a bit overwhelming, how
can I or my organization get started?
As you begin to go through this Manual, one of your first reactions
will probably be that the effort required to improve air quality is very
complicated and looks as if it would require a whole lot of resources
that you do not have. As a resident, the science and the scientific
terminology may appear beyond your reach. If you are a professional
working in government, industry, or academics, the work in a
community may appear equally overwhelming. But before you
abandon the idea of working on your air quality, consider the
following.
Partnerships make things possible. With a partnership, tasks that seem
impossible can get done. The truth is that none of us as an individual
working alone has a chance to improve air quality. It is a complicated
task that requires the efforts of a lot of people. But looking at the
work to improve air quality as either an individual task you must do
or as a task that someone else should do may be the problem. Like
many of the things that are most important to us, improving air
quality is a job that can only be accomplished by everyone working
Partnerships
make things
possible
Community Air Screenins How-To Manual
-------
Chapter 1: How to Use This Manual
together. All the resources you need to improve air quality are
available to your community. There are willing people with all the
skills you need to complete the job. Even if the level of trust among
residents, governments, and industry is not good, there are steps you
can take and resources you can use to begin to change this. So don't let
the size or any part of the task intimidate you. Once you get started
you will find the help and resources that you need.
You may also worry about starting an effort that will end up being a
draining experience for you, with countless meetings and a work load
that you are not sure that you could handle. But partnership projects
do not have to be draining. Of course they take work, but you will be
Meeting of the community partners of the St. Louis North Side Clean Air Project.
Community Air Screenins How-To Manual
-------
Chapter 1; How to Use This Manual
able to divide up the work to make it reasonable. And it will be up to
you to set the schedule so you can, and should, set a reasonable pace
for you and your community. Working to improve air quality can be a
great opportunity to build your community, to meet new people, to
learn new things, and to develop new relationships that your
community will need in the future. Communities tackling important
issues and building partnerships to find solutions are the essence of
our democracy at work. Instead of seeing the work to improve air
quality as draining, look at it as important work that will be
challenging, exciting, and doable.
And you will not be alone. Community organizations and
partnerships across the nation have begun to tackle the problem of
local air quality, so you will have tremendous resources to draw on to
help you make progress. What looks like an impossible task for a
single community can look manageable if it is viewed as a joint effort
of many communities working together. So plan time to learn about
and share ideas with other communities working on similar air
quality concerns. Watch for and plan to attend the national or
regional meetings that are organized to bring people together to share
ideas.
Finally, getting something done in a community always requires a few
champions or leaders who can get things started and keep them
going. Champions for these projects can come from anywhere. The
only qualification seems to be a willingness to learn and a
determination to make things happen. A resident, a leader of a
community organization or church, an engineer in a local company, a
small business owner, a local teacher, a government staffer—anyone
can be a champion for an effort to improve local air quality. If you or
your organization are willing to champion a partnership effort, you
will need patience and persistence, since it takes time to accomplish
something new, but, if you persist and don't get discouraged when
you run into the inevitable problems that come with any new effort,
you will find that your persistence will pay off. You will find that
people do want to work together and that we can explain things to
each other and make decisions together. And you will find that the
process can be exciting, challenging, and rewarding. Most
importantly, you will succeed in improving your air quality and you
will make a real contribution to the health of your community and
the health of your community's children. And when you have made
some progress, share your experiences. In fact, you and your partners
may find a way to turn your experiences into the next and improved
version of this Manual.
Communities
tackling important
issues and
building
partnerships to
find solutions are
the essence of
our democracy
at work
Community Air Screenins How-To Manual
.5
-------
Chapter 1: How to Use This Manual
Community Air Screenins How-To Manual
-------
Overview
Organize
Getting Started:
Building a Partnership
Setting Goals
Choosing a Plan to Meet
Community Goals
Developing a Communication Plan
How is this chapter organized and what does it
cover?
This chapter is divided into four parts to discuss important aspects of
the work needed to get started on a project to understand and
improve local outdoor air quality. The first part on building a
Partnership describes the work needed to get all the people and
resources together that you will need to improve local air quality. It
also describes ways of organizing the Partnership that will help to
build the trust you will need to work together effectively. The next
section of the chapter describes the work you will need to do to clarify
the goals of your Partnership. This section describes the need for all
the partners to explain what they would like to accomplish and then
work together to find the goals that everyone can share. The third
section on choosing a plan for work describes some of the different
approaches that you could take to reach your goals. Once you have
formed your Partnership and clarified your goals, you will be in a
position to discuss these different approaches and find the one that
best matches your goals and the resources that you have available.
Finally, the chapter includes a section on developing a
communication plan. This section talks about the important work
needed to communicate with and involve the broadest possible
number of community residents and businesses in the work of the
Partnership. It also discusses the importance of communicating with
all the key stakeholders outside the community to ensure that they
understand and support the work you are doing.
Community Air Screenins How-To Manual
-------
Chapter 2; Getting Started
What kind of assistance does this Manual provide to
help with building a partnership, clarifying goals, and
developing a communication plan?
This Manual focuses primarily on providing the help a community
will need to use risk-based screening to understand and improve local
air quality. The Manual provides only general information and a list
of resources for the work of building a Partnership, clarifying goals,
and communicating with the community. The Manual focuses on the
technical aspects of risk-based screening because help for this part of
an effort to improve air quality is not currently available to
communities—not because the non-technical parts are less important
or require less effort. This chapter of the Manual discusses only those
issues in the areas of building the Partnership, clarifying goals, and
communicating with the community that are particular to efforts to
improve local air quality. For a more complete discussion of these
topics, communities should supplement this Manual with other
resources that are available to help communities in these areas. A list
of resources for building a Partnership, clarifying goals, and
communicating with the community and other stakeholders can be
found in Appendix A.
8
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
• Part 1: Building a Partnership
Building a Partnership
What is the value of a Partnership?
Building a broad, working Partnership is key to the success of the
work. The effort needed to get a better understanding of and improve
local air quality is complex and will require a wide range of skills and
resources. No single sector of the community or level of government
has the ability or resources to do this work alone. Only a Partnership
will have the ability to bring together the resources, information, and
skills that will be needed. To improve air quality, a community must
reach an agreement on an effective plan for action and then work
together on its implementation. The Partnership and the work to
build the Partnership will also provide the means for different parts of
the community to share ideas and develop the trust that will be
necessary for joint action.
How will a Partnership for improving local air quality
get started and what would it look like?
The strategy for getting a Partnership started will be different for each
community. The approach will depend on factors such as the kinds of
organizations that already exist in a community, the ability to access
technical resources, and the local interest in air quality issues.
Whatever the situation, forming a Partnership will require an
organization or individuals to take the lead and act as a consistent
champion for the idea of working together to improve air quality. In
most cases, the potential members of a Partnership will have little
experience working together to address air quality issues, so it will
take time and consistent leadership to get started.
The leaders who champion this effort will start to form a Partnership
by convincing others of the value and the potential of working
together to improve local air quality. The Partnership may be formed
as a part of, or separate from, existing community organizations. If it
is possible, using existing organizations with their infrastructure and
established ties will save the Partnership from the need to build an
organization and develop ties to the community from scratch. A
Partnership to improve air quality could be viewed as an inclusive
community organization with several levels of involvement. A core
Partnership group of somewhere around 20 members would have the
responsibility to lead, organize, and carry out the work needed to
understand and improve air quality. A much larger group of
community members would participate occasionally in the
Getting Started
sw\x\s^sv
JJJJJJ
Building a
Partnership
£
Setting Goals
£
Choosing a
Plan to Meet
Community Goals
£
Developing a
Communication
Plan
Buildin3 a broad,
working
Partnership is the
key to the success
of the work
Community Air Screenins How-To Manual
.9
-------
Chapter 2: Getting Started
• Part 1: Building a Partnership
The community is the
Partnership
Only a
Partnership that
can include and
mobilize large
parts of the
community is
likely to have the
resources to
improve air
quality
Partnership by joining in activities organized by the core
Partnership group. These activities could include
collecting information on sources and helping to
communicate results to the community. At the
broadest level, the entire community can also
participate in the Partnership by attending
public meetings, providing input, and taking
part in community mobilizations to
improve air quality. Only a Partnership that
can include and mobilize large parts of the
community is likely to have the resources to
improve air quality.
Because the work to address air quality
requires broad participation of all sectors of
the community, it may help for the members of
the core Partnership group to view themselves
primarily as a community leadership group and not
as an independent organization trying to tackle air quality
issues by itself. As community leaders, the job of the core
Partnership will be to help all sectors of the community develop a
better understanding of air quality, set clear and realistic goals, and
mobilize to take the actions needed to improve air quality. Adopting
the perspective of the core Partnership as leaders of the whole
community will encourage the core Partnership group to organize its
work so that it includes as much contact and interaction with the
broader community as possible.
In forming the core group of the Partnership, it will be important to
include a balanced representation from as many different sectors of
the community as possible. Community members who have been
active around air quality issues, if there are any, will be key members,
but the core group should also include representatives from groups in
the community not currently involved in air quality issues. This broad
representation from all parts of the community will be key to
ensuring that all views will be considered and that the Partnership will
have access to the information and the support that it will need to
reach its goals. It will also be important to include members in the
core group that have the skills and resources that will be needed to
complete the project. A list of those skills is included in this section.
10
Community Air Screenins How-To Manual
-------
Chapter 2: Getting Started
• Part 1: Building a Partnership
Who might participate in the work of a Partnership
to improve local air quality?
The Partnership will be made up of a combination of members from
all sectors of the community and representatives of governments and
organizations interested in supporting the community effort to
improve air quality. If possible, the majority of the Partnership core
group should be made
up of people who live or
work in the community.
Community residents,
community health
professionals,
community businesses,
and other community
members have the most
stake in the immediate
and long-term health of
the community. They
also will be the key
source for the energy
and resources that will
be needed to improve
air quality.
To a certain extent, the
membership of the
Partnership will depend
on the goals it estab-
lishes. The development
of the Partnership and the clarification of its goals (discussed in the
next section) are inseparable. The addition of new partners may
change goals and, similarly, the refinement of goals may influence the
Partnership's composition. For example, if a community identifies
work on a particular health concern related to air quality, such as
asthma, as a goal, the Partnership might expand to include members,
individuals, and organizations with the resources and skills needed to
address this issue, such as the American Lung Association, local health
professionals, teachers or staff from local schools, and so forth.
Depending on their goals, Partnerships may use the following
"checklist" of the kinds of organizations that might be considered as
recruitment pools for membership in a local Partnership to improve
air quality.
Members of the Cleveland Clean Air Century Campaign working group and
EPA at the launch of the partnership.
Community Air Screenins How-To Manual
11
-------
Chapter 2: Getting Started
• Part 1: Building a Partnership
Places to Look for Partners
• Community residents
• Community civic, environmental, and economic
development orsanizations and associations
• Housing associations
• Churches
• Teachers and staff at public and private community
schools
• Community students and student organizations,
including environmental clubs
•Youth organizations such as 4-H and Scouting
• Local library staff
• Local businesses and industry
• Local business associations
• National business associations
• Unions representing local employees
• Colleges and universities
• College students and student organizations
• Local government, including elected officials and
agency representatives from health, environmental,
planning, permitting, development, public works,
parks, police, and fire departments
• State and tribal governments, including transportation,
environment, health, and natural resources departments
• Federal government agencies, including environment,
housing, energy, transportation, forestry, etc.
• National, state, and tribal environmental organizations
• Environmental justice organizations
• Public health organizations
• Local foundations concerned with the environment,
public health, or community development
12.
Community Air Screenins How-To Manual
-------
Chapter 2: Getting Started
• Part 1: Building a Partnership
What effort will it take to build a Partnership?
The amount of work required to build a Partnership around air
quality will depend, in part, on the existing relationships among the
potential partners. If a strong community organization with good ties
outside the community takes the lead, the work to form a Partnership
may not take long. If, however, the level of trust among potential
partners is low, and there has been a history of contention over air
quality issues, the work to form a Partnership will require significant
time and effort. In Baltimore, for example, where the level of trust was
low, the effort to form a Partnership took a year. Whatever the
situation in a community, the work to develop a Partnership is as
important to the success of the project as the technical work to
identify priorities and find solutions. Efforts invested at the outset and
throughout the work to build and maintain a successful Partnership
will pay off in results obtained later in the process. It will be especially
important to remember that partnership building is an effort that will
need to be maintained for the length of the project. Partnership
building is not just a task for the beginning of an effort. To sustain
itself, the Partnership and its members will need to do all their work
in a way that continues to build the Partnership throughout the
course of the work to improve local air quality.
What needs to be done to ensure that all members
of the Partnership participate as full and equal
partners in the process?
The Partnership will be most effective if it makes sure that all of its
members have the opportunity to be heard and to participate fully as
equals in the work and decisions of the Partnership. Input from
individuals and from leaders of community and business
organizations, schools, and churches will help to ensure that all
viewpoints are considered and that the Partnership has access to a
wide range of community resources. But building a true partnership
that can realize the full potential of the community may require an
effort to overcome some obstacles. Organizations that are used to
making decisions will need to learn to share decision-making with
residents, small community businesses, and community
organizations. And methods of conducting Partnership business that
can discourage participation of community members, such as using
e-mail to communicate between meetings or using professional terms
and technical jargon during meetings, will need to be avoided. And
even though all sectors of the community have equally important
contributions to make to the effort, the opportunity to participate
Make sure that all
members have
the opportunity
to be heard and
to participate fully
as equals in the
work and
decisions of the
Partnership
Community Air Screenins How-To Manual
.13
-------
Chapter 2: Getting Started
• Part 1: Building a Partnership
Making decisions
by consensus in a
partnership can
help to build
trust
may not be equal. Volunteer residents will normally participate in
Partnership work in the evenings after work. These volunteers may
not have as much time to devote to Partnership work as government
and industry participants, so holding too many meetings may
discourage participation. The participation of some volunteers may
also be limited because they do not have an adequate background in
the science used to understand air toxics and to identify priorities.
Similarly, government and business Partnership members who do not
live or work in the neighborhood will be limited by their lack of
knowledge or understanding of the local area. All these and other
similar obstacles to creating an effective and real partnership should
be acknowledged and considered at the beginning of the Partnership.
To compensate for these differences in resources and backgrounds,
the Partnership's organization and work can be designed in a way that
will promote the fullest possible participation of all of its members.
This can be accomplished by means such as by arranging meetings to
accommodate participants' available time and schedules, by talcing the
time to share information and provide any necessary background, by
operating by consensus, and by sharing or rotating the leadership
of the Partnership. In addition, funding for a person to provide staff
support for committee members who are volunteers and to facilitate
overall community participation may be necessary to ensure the full
participation of all community residents.
Making decisions by consensus in the Partnership can help to build
trust and ensure that all the partners participate fully. In an
organization based on consensus, decisions require the unanimous
support of all participants. Since decisions require everyone's support,
partnerships using this approach must ensure that everyone's views
are fully considered and accounted for. Taking a consensus approach
will encourage the Partnership to discuss issues thoroughly and to
search for an approach that meets the common good of the
Partnership and the community as a whole. Decisions reached by
consensus may not perfectly match all the needs of each partner, but
they will generally represent an improvement that everyone can live
with and that moves the community as a whole closer to the goals it
holds in common.
It is also important for the Partnership to have technical members
with diverse backgrounds to ensure that the scientific advice and
training the Partnership relies on to make decisions is sound and
unbiased. This can be accomplished by bringing technical expertise to
the Partnership with a variety of backgrounds, such as technical
residents of the community, community health providers, local
14.
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
• Part 1: Building a Partnership
science teachers, technical staff from governments and industry, and
faculty and students of academic institutions. If the Partnership
cannot find sufficiently diverse sources for technical advice, funding
to support an independent scientific adviser may be required.
What will the core members of the Partnership be
expected to do?
At a minimum, to develop an understanding of local air quality and
to carry out a plan for improvements, each of the core members of
the Partnership will need to be willing to do the tasks in the following
checklist.
Partnership Responsibilities Checklist
• Fairly and honestly represent the views of the community
residents, businesses, and orsanizations in Partnership
discussions and decisions
• Share information so that all Partnership members have the
understanding necessary to participate fully in the work
• Listen carefully and consider fairly the views of other
members of the Partnership and work to develop a
collaborative decision-makins process and to build
consensus
• Participate in the direction and work of any technical
analysis needed by the Partnership and make sure that the
technical work considers all appropriate information and is
done in a way that is technically sound
• Consider the new information developed by the
Partnership and use the information as a basis for
Partnership decisions
• Help to regularly communicate the work of the Partnership
to all sectors of the community to solicit their input on the
direction of the work and to keep them informed as work
progresses
• Help to develop and lead the implementation of an action
plan to make improvements in air quality
• Help with group logistics such as organizing, chairing, and
keeping records of Partnership meetings
Community Air Screening How-To Manual
15
-------
Chapter 2: Getting Started
• Part 1: Building a Partnership
Because the scope of Partnership activities will depend on the goals
that are chosen, the tasks that will need to be completed by the core
Partnership members will be developed as those goals are clarified.
Once the goals are set and the scope of the effort defined, it will be
important to clarify the roles and expectations of core Partnership
members so that they can plan to meet their commitments. For the
staff of governments and large businesses participating in the
Partnership, formal written agreements on roles and responsibilities
may be helpful. These written agreements can provide staff with a
means of bringing the work of the Partnership to the attention of
their organizations.
What skills will the members of the core Partnership
group need?
In forming a partnership around air quality, it will be important to
consider the skills and tasks that will be needed over the course of the
work. As many people as possible who can provide these skills should
be included in the core Partnership group. In cases where members
with the necessary skills cannot be found, a partnership may need to
find funding to provide for these skills or to provide training to
Partnership members to develop the skills.
To get the Partnership started on the right foot and to help ensure
that all partners have the skills and understanding needed to work
effectively in a partnership, it may be a good idea to set aside time at
the start to organize training for the core Partnership members in
consensus- and team-building skills. Time will also need to be set
aside to discuss and decide on key process questions such as ground
rules and organization for the Partnership. Providing this training and
organizing these discussions will help to ensure that the day-to-day
work of the Partnership is done in a way that builds trust and
strengthens the Partnership.
The following is a list of skills that will be needed to complete the
work outlined in this Manual.
Leadership: Leadership is probably the single most important skill
needed to mobilize a community to work together to improve air
quality. Successful completion of all aspects of the work will depend
on leaders with a clear understanding of the Partnership's goals and
direction. Because the Partnership will include a broad range of
participants, leadership will be needed from each of the different
sectors of the community represented in the Partnership. A core
group of community, business, academic, tribal, and government
16
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
• Part 1: Building a Partnership
leaders committed to making the Partnership succeed is the key to
success.
Willingness and ability to exchange information and to learn from
others: These skills will be important for all members of the core
Partnership group. Skills in communicating the science used in the
screening analysis to nonscientists will be especially important to the
Partnership.
Ability to collect information and data on local sources:
Government staff, members of environmental organizations,
academics, and others familiar with available data, plus community
residents and representatives of local businesses familiar with local
sources and their releases, will be essential to the collection of
information for the screening analysis.
Technical and scientific skills needed for analysis: Skills needed,
depending on the goals and work plan set by the community, may
include risk assessment, air dispersion modeling, exposure
assessment, database management, toxicology, health care,
transportation planning, environmental engineering, and pollution
prevention. Potential sources for these skills include government and
industry staff, college and university faculty and students, local
science teachers, local health professionals, residents working in
professional fields, and the technical staff of environmental
organizations.
Communication skills needed for soliciting input and reporting
the work and results to the community: Because the work of the
Partnership depends on community input, support, and
participation, the ability to explain the work of the Partnership to the
community and to solicit community input will be essential to the
success of the Partnership. This will require both communication
skills and knowledge of the community. Members of community
organizations, risk communicators, teachers, community leaders,
librarians, and journalists can work together to develop ways to
collect community views and to produce reports, press releases,
newsletters, and other means of communicating with the community.
Organizational skills: Chairing meetings, keeping records,
organizing community events and actions, developing budgets and
handling and raising funds, and other related administrative skills will
be needed over the course of the project. Some Partnership members
should have these skills, and training can be organized for other
members to meet the Partnership's needs.
Community Air Screening How-To Manual
17
-------
Chapter 2: Getting Started
• Part 1: Building a Partnership
The Partnership
will provide
opportunities for
a wide range of
activities for
community
volunteers
Facilitation skills: The ability to foster a process that will build trust,
improve communication, clarify goals, and develop participation in
the Partnership will be essential to success. These facilitation skills
may be found, or developed, in Partnership members, or professional
facilitation can be retained to support the Partnership's work.
Ability to develop and implement plans for making improvements:
Finding solutions to air quality concerns will require the active
participation of the business community, transportation planners,
and community leaders. Environmental engineers and pollution
prevention specialists from government, industry, and environmental
organizations will also be needed to help identify solutions.
Community and business leaders will be needed to help mobilize
residents and businesses to implement the plans for making
improvements.
What level of commitment will be expected of
members of the Partnership?
The core group needed to direct and implement the work of the
Partnership will need to meet regularly for the entire course of the
project. The frequency of meetings, and the pace of the project, can be
set by the members; for example, meetings of the core group could be
held once or twice a month. In addition to participating in regular
meetings, members of the core group will be expected to carry out the
work of the Partnership between meetings. For example, if the
Partnership decides to develop a local inventory of sources, some of
the core group members will work with others to gather all the
information for the inventory and then present their work for review
by the full core Partnership group. The amount of work, per month,
for the members of the core group, will depend on many factors,
including the time allowed for the project, the availability of staff or
volunteer support, and the extent of the work needed to carry out the
plan for improving local air quality. Depending on the goals,
resources, and pace of the effort, the effort to meet initial community
goals could take up to two years to complete.
In addition to the work of the core group, the Partnership will provide
opportunities for a wide range of activities for community volunteers.
Individuals, schools, businesses, and community organizations will be
needed to survey traffic, identify sources of chemical releases, develop
outreach materials, distribute information, and help to organize and
participate in community meetings and activities.
18
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
• Part 1: Building a Partnership
What kinds of things might the Partnership need to
support its work?
Depending on the situation in a community, funding to hire a person
to work for the Partnership may be helpful or, in some cases,
necessary. An active partnership will require a good deal of work to
help organize and support all the volunteer activities that will be
needed to carry out its work. Staff from existing community
organizations, governments, and businesses, or community volunteers
may be able to provide this support, but, if this is not possible,
funding to hire a full- or part-time staff person to support the
Partnership may be necessary to facilitate this work. It may be
especially important for the Partnership staff person to focus on
developing and maintaining the involvement of the community. The
staff person could support resident volunteers on the core committee
and work to keep the community at large informed and involved in
the Partnership's work.
Funding for professional facilitation may also be helpful or necessary.
Working in a Partnership, especially in communities starting with a
low level of trust among partners, can be very difficult. The ability to
have a trained facilitator focused on partnership building, and on the
process of the Partnership, can be very helpful and, in some cases,
necessary. Core committee members may have neither the facilitation
skills nor the time to focus on the facilitation that will be needed to
ensure the success of the Partnership. It is also difficult for
Partnership members to represent the views of their community or
organization while also serving as facilitator for the Partnership.
As mentioned above, depending on the availability of technical
resources, funding for an independent technical advisor may also be
necessary to assure all Partnership members that they have the
balanced scientific advice needed to make sound decisions.
The Partnership will also need to find a way to obtain or develop the
following to support its work:
• Access to meeting space for Partnership committee meetings and
for larger community meetings
• Access to a relatively new desktop computer capable of handling
the database used to store information collected by the
Partnership and for the dispersion modeling if the Partnership
decides to conduct its own analysis of local air quality
• A location in the community for the computer and for storing
the records of Partnership meetings and decisions
Community Air Screenins How-To Manual
19
-------
Chapter 2: Getting Started
• Part 1: Building a Partnership
Teachers and
students can be a
tremendous
resource for the
Partnership and
community
• Equipment or access to equipment to copy, print, and distribute
information about the Partnership's work and results
• An effective method for members of the core Partnership group
to communicate with each other between meetings
Are there things the Partnership can plan in advance
that will help to ensure the success of the efforts?
Planning ahead may be difficult since the entire Partnership is likely to be
developing its understanding as the work progresses. But some planning
may be helpful. One thing you might consider is establishing a team to
begin collecting the information you will need to develop a plan for work
at the same time as the Partnership is working to clarify its goals. If this
information is available when the discussion to clarify goals is completed,
the Partnership's work to decide on a work plan could proceed
immediately. Please see the discussion of developing a work plan below
for a description of the information that this team could collect.
Once your Partnership has developed its plan for work, try to do
some advanced planning and preparation so that you are prepared to
complete each step of the effort as the work progresses. The
Partnership could identify all the teams that it will need to form over
the course of the work and organize the teams early so that they can
begin to assemble the resources and develop the skills they will need
to carry out their tasks. These teams will work for and report to the
core Partnership group. As an example, if the Partnership decides to
use the risk-based screening approach described in this Manual, the
list of teams needed would include:
• Communications Team, described in this chapter
• Emission Source Inventory Team, described in Chapter 4
• Quality Assurance/Quality Control Team, described in Chapter 4
• Concentrations Estimation Team, described in Chapter 5
• Screening-Level Concentration Team, described in Chapter 5
• Recommendations Teams, described in Chapter 8
Partnerships, depending on their goals and plans for work, will have
their own needs and resources, so the teams your Partnership needs
may differ from these.
In addition, if the Partnership uses the work as an opportunity to
build the long-term capacity of the community (see discussion of this
issue in the next section), then some advance planning would allow
20
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
• Part 2: Setting Goals
for an early start on providing the training that community members
will need to participate in the work of the teams. Advanced planning
is especially important for involving local schools and colleges.
Teachers and students can be a tremendous resource for the
Partnership and community, but getting a school's commitment and
providing the training that the teachers will need to incorporate the
work into the school's teaching must be planned months in advance.
Advance planning is also crucial for fund-raising, so the Partnership
will almost certainly need to set up and provide training for a team to
work on fund-raising. Organizing a fund-raising team at the start of
the work will help to ensure that the Partnership has sufficient
funding to achieve its long-term goals.
Setting Goals
Why is it important to clarify goals at the beginning
of the Partnership's work?
Members of the core Partnership group will all share the goals of
understanding and improving local air quality. But, at the start of a
project, participants will almost certainly have different perceptions of
those goals. Partnership members are also likely to have other
personal objectives not directly related to air quality that they are
hoping or assuming will be included in the scope of the Partnership.
Adequate time must be spent at the beginning of the process to
discuss and understand the expectations of all the participants in
order to discover and clarify the goals that can be shared by all.
Clarifying goals will also enable the Partnership to develop a plan for
work to match its goals and to ensure that the results of the
Partnership's work and the expectations of its members are consistent.
The discussion to clarify goals in the core Partnership group should
be viewed as part of a broader process of clarifying goals for air
quality in the community as a whole. Agreement around shared goals
will be essential to uniting the community for the work that will be
needed to improve air quality. As a community leadership
organization, the core Partnership group can facilitate the discussion
of goals in the broader community. Since members of the core group
represent different sectors of the community, discussions in the core
group can help to clarify community goals, but to ensure
JJJJJ.
Building a
Partnership
*
Setting Goals
*
Choosing a
Plan to Meet
Community Goals
t
Developing a
Communication
Plan
;
Community Air Screenins How-To Manual
.21
-------
Chapter 2: Getting Started
• Part 2: Setting Goals
It will be very
important for
core group
members to
develop an
understanding of
each other's
interests
consideration of all views and to ensure that the broader community
benefits from the discussion of goals, the core Partnership group
should try to organize as much interaction with the community as
possible in the process of clarifying goals. For example, core group
members could meet to discuss goals with community leaders and
organizations, and a large community meeting could be organized to
discuss and approve the goals once they are clarified.
As noted earlier, this Manual does not provide detailed guidance on
methods communities can use to clarify goals. The discussion of goals
in this Manual is limited to issues related to efforts to improve air
quality. There are resources available that provide detailed guidance
on methods for clarifying goals. Please see Appendix A for a list of the
resources available to help organizations establish goals.
What are some important issues to consider to set
clear Partnership goals?
Identifying members' concerns and interests: It will be important,
first of all, to find out why members of the core group and the
community sectors and organizations that they represent are
interested in air quality. Some Partnership members may be interested
in air quality because of their concern for community health or
because of a concern about the siting of waste treatment facilities in
the Partnership neighborhoods. Other Partnership members may be
interested in air quality issues because of the desire to promote
economic development, expand community businesses, and revitalize
the Partnership neighborhoods. It will be very important for core
group members to develop an understanding of each other's interests
and to clarify the relationship of the Partnership's goals to the related
goals of its members.
Clarifying the relationship of the Partnership's goals to the interests
and goals of the participants will also help participants develop
realistic expectations for the results of the Partnership's work. For
example, air quality is likely to be only one of the factors affecting
community health, so the work to improve air quality, by itself, may
not be able to meet a member's goal of achieving measurable
improvements in overall community health.
Preparing for different outcomes of the work to set priorities: It
will be important for the members of the core Partnership group to
discuss all the possible outcomes of any analysis done to identify
community priorities and what each outcome would mean to each of
the members. What if small businesses, large businesses, households,
22
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
• Part 2: Setting Goals
or mobile sources are identified as the priority concern? Or better:
What would it mean if my business, my home, or my car was
identified as a community priority for potential action?
Many, perhaps most, members of the Partnership will enter the
process with a conviction about the sources that will need to be
focused on to improve air quality. Different members will have
different sources in mind for the community's priority, so the
expectations of all the Partnership members for the focus of work to
improve air quality cannot be met. A discussion of all the different
possible outcomes will allow participants to consider carefully what
the project results might mean for them and for their goals.
Setting realistic expectations for accomplishments: To clarify goals,
it will also be important to discuss, in detail, what the Partnership will
be able to do to improve air quality when the analysis is completed
and priorities have been identified. Questions that the Partnership
will need to consider include:
• What resources will be available to make changes?
• What issues can be addressed by the local community and which
ones, such as requirements for new vehicles or vehicle inspection
programs, would potentially require broader action?
• What could be done if the screening analysis identifies a concern
from a large business? Or a concern from a small business? Or
from mobile sources? Or households?
• In what circumstances would enforcement and regulatory
authority be used to improve air quality? And what kind of
information will be required to support this approach?
• If the actions will be voluntary, what resources and
commitments does the Partnership have to accomplish its goals
and, again, what kind of information would best support the
voluntary approach?
Discussing possible outcomes and the resources that may be available
to address them will help the Partnership set realistic goals for its
efforts to improve air quality.
Understanding the relationship of air quality goals to other
community priorities: Understanding and improving air quality will
not be the only community priority. Most communities will be
working on other issues, such as education, jobs, crime, and health. It
will be important to identify these other community priorities and
the ongoing work to address them, so that the work on air quality can
Community Air Screening How-To Manual
23
-------
Chapter 2: Getting Started
• Part 2: Setting Goals
Identify areas
where there is
already sufficient
agreement in the
Partnership to
bes'm immediate
work to improve
air quality
be designed to support and complement these priorities. For example,
if a community has developed a plan for improving public health as a
part of the Healthy People 2010 national program, it will be
important to understand the relationship of the work on air quality to
this community effort. With limited time and resources, communities
can work on only a limited number of priorities. The ability to
integrate work on air quality into the other priorities of a community
may be essential to finding the resources that will be needed to
address air quality issues.
Understanding other community priorities will also make it possible
to organize work to avoid unnecessary conflicts and opposition. For
example, if a community is interested in creating more jobs and
developing the local economy, including, possibly, the redevelopment
of local brownfields sites, it will be important to organize the work of
the Partnership in a way that does not undermine those community
efforts. By stressing the importance of improving local air quality as
an incentive for businesses looking for new locations and organizing
the work on air quality in a way that supports the community
development goals, the Partnership may be able to achieve its goals
without disrupting development efforts.
Consider setting short-term goals to organize immediate action to
address known community concerns: Some members of the
community and the Partnership will be more interested in action than
in studying local air quality. It will be important to identify areas
where there is already sufficient agreement in the Partnership to begin
immediate work to improve air quality and community and
environmental health. Examples of projects that might be started
include working with schools, students, and parents to address indoor
air problems, helping families address asthma concerns, developing
community plans for ozone alert days, or working to provide
pollution prevention assistance to local businesses. These concrete
efforts to improve air quality and community health will increase
awareness and trust in the Partnership's work in the community and
set the stage for broader mobilization efforts to improve air quality
that the Partnership will organize when the screening analysis is
completed. For examples of projects communities have adopted to
improve air quality, see Appendix B.
Consider making the building of long-term community capacity
to address air quality issues a Partnership goal: A discussion of
what it would mean for the Partnership to set a goal to build the long-
term capacity of the community to understand and address local air
quality issues may help to raise important issues for discussion.
24
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
• Part 2: Setting Goals
Questions to discuss may include:
• How will it be possible to retain the knowledge and skills learned in
the course of the work after the Partnership has completed its work?
• How will the community keep up with future impacts on air quality
to ensure that local air quality continues to improve?
Adopting a goal to build the long-term community capacity will
require the Partnership to plan its work so that it is done in a way that
builds community capacity to address air quality issues. A long-range
view of capacity may require more emphasis on developing long-term
relationships and trust, more emphasis on using the work to train
members of the community, more attention to organizing
information so that it can be updated to monitor future changes, and
more work to develop a permanent organization in the community
that can continue to address air quality issues.
Finding the funding that will be needed to support the future
organization and work of the Partnership will be an essential part of
building the long-term capacity of the community to address air
quality issues. Given the importance of funding, and the amount of
work and length of time required to apply for funding, the
Partnership may want to make fund-raising a key part of its work
from the start. Organizing and providing training to a fund-raising
team at the beginning of the Partnership's work would allow enough
time for the Partnership to develop the skills and complete the work
that will be needed to find sufficient funding to sustain the long-term
work of the Partnership.
How can the Partnership consolidate its process of
clarifying goals?
After a broad consideration of all the issues discussed above and as
much interaction with the broader community as possible, the
Partnership will be in a position to make some decisions and clarify
its goals. This is the time for members and the Partnership to review
and finalize goals and commitments. The Partnership will have to
decide, in the light of the clarification of the possible outcomes and
the relationship of the outcomes to the goals of the members and the
community, if its members are still committed to working in a
partnership to understand and improve local air quality. The
Partnership will also have to decide if the goals of the members and
community would be better served by expanding the scope of the
Partnership to include other issues in addition to air quality. Because
Plan work so that
it is done in a way
that builds the
community's
capacity to
address air quality
issues
Community Air Screenins How-To Manual
.25
-------
Chapter 2: Getting Started
• Part 2: Setting Goals
Communicating
the statement of
goals will establish
the process of
soliciting review
and input from
the community
of differing resources and situations, the decision on goals and
approaches will be unique to each community.
For example, the Partnership could decide to add resources and
expand the work of the Partnership to include a more general
approach to community health or economic development. If that is
the case, the work on air quality would become a part of a larger
community effort addressing multiple issues. The Partnership might
also decide that it does have broader goals, but that they are already
being addressed by other means in the community and a partnership
to address air quality would complement and support the work on the
other goals. A community might also decide that, while it does have
other goals, it does not have enough resources to address more than
one goal at a time. In that case, the Partnership could set long-term
goals for the work to improve air quality as one of the steps in a long-
term plan.
Completing all this planning and discussion is important because it
will make sure that the Partnership's work on air quality will be
integrated into the work going on in a community and that all the
members of the Partnership have a common and realistic
understanding of the work they are about to begin.
Once the Partnership has reached a consensus on its goals, it will be
important to consolidate the discussion and decisions by writing a
clear statement of its goals. This goal statement should include a
summary of the discussions of all the important issues related to the
goals. The work to develop a written explanation of Partnership goals
will ensure that everyone in the Partnership is clear on the goals of the
work. In addition, the written explanation that is produced can be
used to communicate with the broader community to solicit their
review and input. A written goal statement can also serve as a
reminder that the Partnership can use to stay focused as work
progresses. The statement of goals could include:
• A statement of the Partnership's goals
• A list of the members of the core Partnership group
• A summary of the work that the Partnership will do to reach its
goals
• A discussion of the relationship between the Partnership's goals
and the other goals of the members of the core Partnership
group
• A discussion of the relationship between the Partnership's goals
and the other goals of the community
26
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
• Part 3: Choosing a Plan to Meet Community Goals
• A discussion of results that can be expected from the work
• A discussion of any limitations of the work that is to be done
• A discussion of the different possible outcomes of the screening
analysis to identify priorities and the realistic expectations for
results in improving air quality for each of the possible outcomes
• A discussion of what the Partnership will do to use its work to
build the long-term capacity of the community to address air
concerns
This statement of goals may be the Partnership's first product
available for communication to the community. Communicating the
statement of goals will establish the process of soliciting review and
input from the community. It will also begin the process by which the
core Partnership group summarizes its work to inform and educate
the community on local air quality. The statement of goals can be
used to develop and implement the communication plan discussed in
the final section of this chapter.
Choosing a Plan to Meet
Community Goals
What preparations will we need to develop a work
plan to reach our goals?
Once your community has set its goals, you will need to develop a
plan for the work you will need to do to reach your goals. Developing
an effective work plan may require attention to identifying priorities,
finding solutions, and communicating with and mobilizing the
community for potential action. Since the Partnership will need to
make decisions on all of these aspects of the work plan, this may be an
important time for the Partnership to take some time to make sure
that all of its members have the background necessary to participate
fully in the effort to develop and choose an effective plan for work.
This will require Partnership members to exchange information with
each other. Residents and business representatives will need to begin
sharing their understanding of the community and their insight into
how the community, both businesses and residents, can be motivated
to take actions to improve air quality. Technical members of the
Partnership will need to share their understanding of the science that
Getting Started
JJJJJ.
Building a
Partnership
t
Setting Goals
*
Choosing a
Plan to Meet
Community Goals
t
Developing a
Communication
Plan
;
Community Air Screenins How-To Manual
.27
-------
Chapter 2: Getting Started
• Part 3: Choosing a Plan to Meet Community Goals
Indoor air and
acute effects of
chemicals in
outdoor air are
important aspects
of community air
quality
will be needed to understand air quality and to choose an effective
method for identifying priorities for potential community action.
Choosing a work plan is crucial to the success of the project, so
adequate time should be taken at this point to ensure that all
members of the Partnership have all the information they need to
participate fully in this choice.
How will this section help us to develop a work plan
to reach our soals?
To help you decide on a plan for work, this section of the Manual will
describe options for collecting information and carrying out the
technical analysis to understand local air quality. This section also
provides some examples of approaches that communities have used to
carry out this technical analysis. You can use this discussion to help
you develop your own plan for work.
What aspects of local air quality will be addressed by
the work plan options presented in this section?
The options described here focus on understanding the potential
chronic, long-term effects, such as cancer, of chemicals in outdoor
air on community health. If your goals include understanding and
improving other aspects of air quality, you will need to consider work
plan options beyond those described in this section. Most
importantly, options for developing a work plan for understanding or
improving indoor air quality and for understanding and
addressing the acute, short-term effects of the chemicals in
outdoor air are not included.
Both indoor air and the acute effects of chemicals in outdoor air are
important aspects of community air quality. Because people spend
much of their time indoors, exposure to chemicals in indoor air can
be significant. And many communities have concerns about acute
effects due to events such as summer high-ozone days or peak releases
from facilities with control equipment failures, or releases due to
maintenance or accidents. Understanding these aspects of local air
quality can be important to setting community priorities and working
to effectively reduce risks due to air toxics. You may want to consider,
and we recommend, organizing a team to collect the information and
develop the work plan options needed to address these issues. Many
of the methods used to address chronic effects described in this
Manual could be adapted to address acute effects. For references to
sources for information and assistance on indoor air and acute effects
28
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
• Part 3: Choosing a Plan to Meet Community Goals
of chemicals in outdoor air, please see Appendix C. In the future, we
hope to expand this Manual or develop supplemental guides to
provide more assistance to communities to address these issues.
In addition to the effects of air quality on the health of the
Partnership's community, some communities may also be interested
in other important aspects of air quality, such as the impact of local
sources on the health of other communities or issues such as visibility
or effects on ecological health. These important aspects of air quality
are beyond the scope of this Manual, and the Partnership will need to
rely on the expertise of its own members or other resources if it wants
to address concerns not related to community health.
And one final reminder: Obviously risks from air toxics are not the
only health concerns facing communities. Partnerships will want to
ensure that all significant environmental and non-environmental
health risks, such as childhood lead poisoning, drinking water
contamination, and drugs, are being addressed and that work on air
quality is done in a way that complements other efforts to improve
community health. Some communities with limited resources may
have to choose to address some risks before others.
Are there other considerations to keep in mind as
we develop our work plan?
As you consider the options presented here and the examples of
approaches used in other communities, please remember that the
work to understand and improve local air quality is still developing,
so no one is really sure of the best way to approach this work.
Community partnerships will have to use their best judgment to
choose a plan for work and then, if possible, communicate their
experiences to other communities so that we can all learn from each
other in our efforts to improve local air quality. Other options may be
available, so use the approaches presented as a way to start your
discussion, not as a way to limit your choices. To help facilitate
communication among communities working on local air quality,
EPA's Air Office has set up a database with information on completed
and ongoing community efforts to improve air quality. This database,
the Community Assessment and Risk Reduction Database, is available
on the Internet at http://epa.gov/ttn/atw/urban/urbanpg.html.
It may also be helpful to keep a few thoughts in mind as you consider
the options for the technical aspects of your work plan. To build
consensus and to work effectively to improve local air quality, you will
have to avoid two errors: developing a work plan with too much
Partnerships will
have to use their
best judgment to
choose a plan for
work
Community Air Screenins How-To Manual
.29
-------
Chapter 2: Getting Started
• Part 3: Choosing a Plan to Meet Community Goals
Each community
will have to find
the balance
between analysis
and action that
results in the most
improvement in
local air quality
analysis that results in long delays to getting to the work to improve
air quality, or too little analysis that results either in not having
enough consensus in the community to take action or in taking
actions that do not effectively address important community risks.
Each community will have to find the balance between analysis and
action that results in the most improvement in local air quality.
Depending on factors such as the level of agreement in the
community and available resources, this balance will differ for each
community. And as you develop your work plan, remember also to
consider the possibility, discussed in the section on setting goals, of
doing the technical parts of the work plan in a way that builds the
long-term community capacity to address air quality concerns. If you
choose this approach, your work plan will need to include specific
plans for building capacity.
And remember, this is the section of the Manual that will help you
determine if the risk-based screening method described in Chapters 3
through 12 of the Manual is appropriate for your community. Risk-
based screening is one of the options discussed below. If, after
considering the options, you choose to use all or part of the risk-based
screening approach, then the remaining chapters of this Manual will
provide you with detailed assistance.
Also, please note that this Manual focuses primarily on the technical
analysis aspect of the work to improve local air quality. For assistance
in developing plans for the other key parts of the work, such as
partnership building, education, communication, and mobilizing the
community to take action, you will have to rely on members of your
Partnership and on sources of assistance listed in Appendices A and B.
What if my community is interested in just one or a
small number of facilities and their potential impact
on our community?
The approaches discussed in this section and in the risk-based
screening chapters of the Manual are designed for communities that
have decided to review all outdoor sources of air pollution and to
identify priorities for improving local air quality. Your community
may choose to focus on a particular facility or source and its effects on
the community or a particular location in the community. Analyzing
the potential effects of releases from one or a small number of sources
will take less time and resources. This effort could be used as a pilot to
give the community a feel for what it can accomplish using a
partnership. Of course, if you narrow the focus of your analysis of
local air quality, you will not have enough information to identify
30.
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
Part 3: Choosing a Plan to Meet Community Goals
which sources have the greatest impact on your community. So, if you
do start with a narrow focus, we recommend continuing your work
until you are able to include all sources of air pollution. If you choose
to start with a focus on a particular source to begin your efforts, you
will need to modify the options below and the chapters on risk-based
screening to fit your focus.
What are the technical aspects of a work plan to
understand and improve air quality?
The technical aspects of a work plan to understand and improve
outdoor air quality can be broken into three parts:
1. A plan to identify the sources of toxics in community air and to
collect information on the amounts and types of their releases,
and information, if available, on air concentrations measured in
or near the community
2. A plan to analyze all the information on releases and measured
concentrations to figure out which chemicals and sources to
identify as community priorities
3. A plan to identify ways to reduce risks from the chemicals and
sources identified as community priorities
This section will describe options for addressing the first two
technical parts of a work plan for improving air quality. Please see
Figure 2-1 for an outline of the options presented here. For a
discussion of the third part of a work plan, identifying ways to reduce
risks for the sources and releases identified as community priorities,
please see Chapter 8.
What are the options to consider to identify sources
and collect information on their releases?
There are two approaches that the Partnership can take to accomplish
this task.
Option One: The Partnership can use available state, tribal, and
national databases to find information about the sources and releases
affecting local air quality. Information on concentrations measured in
or near your community may also be available in state, tribal, or
national databases. Please see Chapter 3 of this Manual for a
description of these databases and their contents.
Community Air Screenins How-To Manual
.31
-------
Chapter 2: Getting Started
• Part 3: Choosing a Plan to Meet Community Goals
Options for Developing a Plan to Identify and
Collect Information on Sources and Releases
Option 1
Use available information
Option 2
Collect new and more detailed informatior
on local sources and releases
Options for Developing a Plan to Analyze
Information on Sources and Releases
Option 1
Use information on
release volumes
(first cut only; cannot take
differences of toxicity into
account)
Option 2
Use toxicity-weighted method
(accounts for toxicity but
not exposure)
Option 3
Use information on risk
(recommended for priority
setting; accounts for both
toxicity and exposure)
Use available risk information
(e.g., NATA or studies of
similar communities)
Use risk-based screening
(clear information on priorities with
minumum of resources, but no risk
information; method used in this Manual)
using monitoring or air dispersion
modeling, or a combination of both
to estimate air concentrations
Develop your own risk information
using more detailed information
on your community
Use risk assessment
(both priorities and risk, but most
resources required) using
monitoring or air dispersion
modeling, or a combination of both
to estimate air concentrations
Figure 2-1.
Outline of Options for Developing a Technical Analysis Work Plan
32
Community Air Screenins How-To Manual
-------
Chapter 2: Getting Started
Part 3: Choosing a Plan to Meet Community Goals
Option Two: The Partnership can decide to collect new information
to add to the information contained in the existing state, tribal, and
national databases. This work to improve the information on sources
affecting local air quality may be the most important work you can do
to get a better understanding of local air quality. State, tribal, and
national databases usually cover too large an area to include all the
local details that may affect your air quality. For example, state, tribal,
and national databases may not have the most accurate location
information for some of the sources in your area, or they may not
include some very small sources. Sometimes state, tribal, and national
databases combine small sources and give only a county-wide total for
the releases from these sources. Collecting detailed and accurate
information on all large and small sources and their releases in your
area will provide you with the best foundation for understanding
local air quality and for identifying priorities for improving local air
quality. Chapter 4 provides detailed guidance for collecting
information on local air sources if you decide to include this as part
of your work plan. Chapter 4 will also give you an idea of the
resources you will need to collect this information.
In addition to planning for the collection of the information on
sources and their releases, you will also need to decide on the method
you will use to analyze this information to identify your priorities.
Methods for analyzing information on releases will be discussed next.
What are options the Partnership can choose from to
analyze the information on sources and releases to
identify priorities for potential action?
The following are three options to consider to help you develop your
plan for analyzing the information on sources and releases to identify
priorities:
Option One: Comparison of release volumes: In this approach to
setting priorities, a higher volume means a higher concern. This is the
simplest method to use, and it can provide information to help set
priorities, but its use as a priority-setting tool is very limited. This
method should only be used as a first cut, since the toxicity of
chemicals varies and the volumes of releases by themselves are not
adequate to identify the chemicals that have the greatest impact on
the community. For example, if this method is used, a highly toxic
chemical released in small amounts might not be identified as a
priority even though its impact on the community may be greater
than a less toxic chemical with larger releases.
Community Air Screenins How-To Manual
33
-------
Chapter 2: Getting Started
• Part 3: Choosing a Plan to Meet Community Goals
Approaches using
risk information
are the most
thorough
methods to use
to identify
priorities for
potential
community
action
Option Two: Comparison of toxicity-weighted scores calculated
for releases: This method accounts for the varying toxicity of
chemicals by assigning a value to each chemical to reflect the toxicity
of the chemical: the more toxic the chemical, the higher the value.
This value is usually multiplied by the release amount to produce a
toxicity-weighted score for each chemical release. This approach can
give a community a pretty good idea of the potential of releases to
affect the community, and the toxicity-weighted scores are relatively
easy to calculate. But this approach cannot account for differences in
exposure to chemicals. For example, if the releases of a chemical are
distant from the community, they may have little impact despite their
toxicity or volume. And small releases of a toxic chemical close to a
house or school would not be identified as a priority using this
method even though they may affect the community. EPA's Risk-
Screening Environmental Indicators (RSEI), a risk screening tool that
is available to communities, includes a set of toxicity values that the
Partnership could use for implementing this hazard-based approach.
Information on the RSEI model and its toxicity values can be found at
http://www.epa.gov/oppt/rsei/.
Other uses for the risk-related perspective provided by the RSEI tool
are discussed below.
Option Three: Comparison of the risks of releases: The approaches
using risk information are the most thorough methods to use to
identify priorities for potential community action. If your community
has sufficient resources, this is the recommended option to use to
identify priorities to improve air quality. The potential impact of a
release on a community depends on both the toxicity of the chemical
and on the amount of exposure to the chemical that individuals in the
community receive. Using risk information allows for a consideration
of both of these elements. Because the risk approach combines
information on exposure and toxicity, the impacts of any release
amount and any release location, close to or distant from the
community, can be more accurately portrayed. This enables a
community to target its resources and energy to the reduction efforts
that will have the greatest benefit for the community. Clear
information on priorities also provides a firm foundation for building
the consensus needed for effective action.
34
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
Part 3: Choosing a Plan to Meet Community Goals
If a community decides to use risk information to
analyze sources and releases, what approaches can it
take?
If your Partnership decides to use information on risk to identify
community priorities, there are two different approaches to choose
from or combine to find the approach that best matches your goals
and resources. First, you can use existing risk information on air
releases for your community and communities similar to yours, and
second, you can develop your own risk information for your
community to add to and improve the existing risk information.
If you choose to develop your own risk information, you can use a
risk-based screening approach, the approach described in this
Manual, or you can conduct a risk assessment. Each of these options
is discussed briefly below.
How could a community use existing risk information
to set community priorities?
A good deal of information on the risks from toxics in ambient air is
now available to communities. As a part of EPA's National Air Toxics
Assessment (NATA), EPA has conducted a national-scale assessment
of 33 air pollutants (a subset of 32 air toxics on the Clean Air Act's list
of 188 air toxics, plus diesel particulate matter, or diesel PM). This
assessment, which will be updated to reflect new release information
every three years, when used in combination with other local-scale
information, is a valuable source of risk information for communities.
In addition to EPA's national-scale assessment, detailed studies of air
toxics risks for a major metropolitan area and for several urban
neighborhoods have also been completed, and the results of these
studies are available. They can be used to give you an understanding
of the risks in areas that may be similar to yours. Studies of
neighborhoods in Baltimore, St. Louis, Port Neches and Houston,
Cleveland, and Portland are available. Other studies of air risks in
neighborhoods and cities were under way at the time of publication
of this Manual and may now be available. A clearinghouse for studies
of ambient air risks, including those mentioned above, can be found
at http://epa.gov/ttn/atw/urban/urbanpg.html.
Additional valuable information on urban risks can be found in the
study of ambient air in the Los Angeles metropolitan area conducted
Community Air Screenins How-To Manual
35
-------
Chapter 2: Getting Started
• Part 3: Choosing a Plan to Meet Community Goals
It is probably a
good idea for
every partnership
to start by
collecting
information that is
readily available
on releases and
risks
CLEVELAND
Clean Air
Century
Campaign
by the California's South Coast Air Management Board. This study
can be found at http://www.aqmd.gov.
In addition to studies of neighborhoods and cities similar to yours,
information that allows you to easily perform screening-level analyses
of chemical releases from most of the largest facilities in your area is
available from EPA. The RSEI model uses Toxics Release Inventory
(TRI) data to perform screening-level analyses comparing chemical
releases using risk-related as well as hazard-related and pounds-based
perspectives. This model is easy to access and run, so you will be able
to use this tool to help identify priorities for your community.
Information on accessing and using RSEI can be found at http://
www.epa.gov/oppt/rsei/.
Please remember that this tool, since it only compares releases from
large facilities, needs to be used with information on other sources of
air toxics, such as mobile sources, to adequately identify community
priorities.
You may want to assign a Partnership team to gather and summarize
the available information on both releases and risks from air toxics
and present this information to the Partnership. This effort could take
several weeks, so if possible, it would be good to get a team started on
this work while the Partnership works to clarify its goals. When all the
available information on releases and risks relevant to your
community is assembled, you may then decide that you already have
enough information on risks from air toxics in communities similar
to yours for you to identify the priorities that you will work on in
your community. For example, in the review of existing information,
you will find that risks from some sources, such as mobile sources, are
consistently high in all the available studies. Based on this
information, you may decide that there is sufficient information to
target these sources as priorities. Several neighborhoods in Cleveland
took this approach, enabling them to focus quickly on the work to
find solutions. A summary of the Cleveland project can be found at
http://www.ohiolung.org/ccacc.htm.
It is probably a good idea for every partnership working on improving
air quality to start with this step of collecting the information that is
already available on releases and risks. Even if you decide that you
need to do more study of the risks in your community, this
information will be very informative, and it may point to some
priorities that you can begin to work on immediately.
As an option, you may consider collecting the available release and
risk information described above and see if you can use this
36
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
• Part 3: Choosing a Plan to Meet Community Goals
information to reach agreement on some obvious priorities to begin
work on immediately, and, at the same time, organize the Partnership
to collect the information for a detailed local inventory of sources and
releases. When this inventory is completed, you can then review the
information and decide whether your community will need to do
additional work to use risk information to analyze the new
information on releases and sources to see if there are additional
sources and chemicals to add to the community's list of priorities.
When should the Partnership consider developing
new risk information to help set community
priorities?
Some communities may decide that the available information on risk
is not sufficient for them to identify community air toxic priorities,
and they may decide to develop their own risk-based analysis of the
toxic releases affecting their community. There are several reasons a
community might choose to do this analysis. In some communities, a
partnership may find that it needs to do its own analysis to come to
an agreement on priorities. Some members of a partnership may
consider the situation in their community to be different from other
communities, or they may think that available studies do not
accurately portray the releases in their community. Some
communities may also feel that the limited number of chemicals
covered in available risk studies may not be sufficient to understand
the risks in their community. Working together on an analysis of
community air risks can help give the participants a sense of
ownership of the process and a willingness to commit to decisions
based on the analysis.
Another reason a partnership may consider developing its own risk
information may be to analyze releases from small businesses more
carefully. The National Air Toxics Assessment (NATA), because it is a
national-scale study, sometimes combines releases from small
businesses to estimate risks. Communities may also feel more certain
of the accuracy of risk information if they deal directly with facilities
and ensure that the release information used in the analysis is
accurate and up to date. And, if a community has identified the
strengthening of community capacity as a goal, conducting a
community risk-based analysis may provide an opportunity to
educate the community on the details of risk science and air quality.
Some communities may also want to learn how to develop their own
risk information so that they will have the ability to use this capacity
to provide risk information on any changes that may occur if new
Working together
on an analysis of
community air
risks can help give
participants a
sense of
ownership of the
process and the
results
Community Air Screenins How-To Manual
.37
-------
Chapter 2: Getting Started
• Part 3: Choosing a Plan to Meet Community Goals
facilities or releases are being considered in their communities.
If a community decides to develop new risk
information to set priorities, what are the
approaches it can take?
If you decide to do your own risk-based analysis to supplement
existing risk information, you will have two basic approaches to use:
risk-based screening and risk assessment.
Risk-based screening is designed to identify the chemicals and
sources that have the greatest potential to affect the health of some or
all community members, using the minimum possible expenditure of
community resources. The method of analysis described in Chapters
3 through 12 of this Manual is an example of this approach. Risk-
based screening minimizes resources by screening out low-risk
chemicals and by simplifying the estimation of exposure to develop
relative risk estimates for each chemical concentration and each
source. Because of these simplifications, risk-based screening has
limitations. It can identify chemicals above screening levels and
identify the chemicals and sources with the greatest potential impact
on the health of members of the community. In most cases, this gives
communities the information they need to set effective priorities. But
risk-based screening does not estimate the actual risks resulting from
releases and sources. And, because risk-based screening does not
attempt to estimate risk, it cannot be used to estimate the cumulative
risk from all or some of the chemicals. To get a more detailed
overview of the risk-based screening method, its advantages and
limitations, and an idea of the resources required to use this method,
please see the introduction to risk-based screening in Chapter 3.
Risk assessment will be necessary if your community decides that it
needs or wants to estimate the risk from chemicals and sources or the
cumulative risk from multiple chemicals and sources. Information on
risk and cumulative risk may be important to reaching a consensus on
action. Information on risks from air toxics will also allow you to
compare these risks to other community risks so that you can set
priorities to reduce risk most effectively. Risk assessment is also a
good indicator that can be used to measure progress. Estimating risk
goes beyond risk-based screening by replacing the simplified method
of estimating exposure used in risk-based screening with an
additional step to more accurately estimate actual exposures in the
community. As a result, risk assessment requires more resources and
more technical expertise than risk-based screening. For detailed
38
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
Part 3: Choosing a Plan to Meet Community Goals
guidance on estimating risks at the local level, please see EPA's Air
Toxics Risk Assessment Library. This resource can be found on the
Internet at EPA's Fate, Exposure, Risk Assessment (FERA) site at
http://www.epa.gov/ttn/fera/.
As an option, a partnership may decide to combine parts of the risk-
based screening method outlined in this Manual with risk assessment.
For example, a partnership could use the screening method to identify
the higher-risk chemicals and sources and then conduct a risk
assessment on only those higher-risk chemicals. A screening step is, in
fact, a part of most risk assessments, including both the national-scale
assessment done as a part of the NATA and the study done of the Los
Angeles metropolitan area.
In the future, new tools and models will be available to help
communities with risk assessment. These tools may reduce the
resources needed for risk assessment, making it a practical option for
most communities. Tools now under development or modification to
make them accessible for community risk assessments include
E-FAST, a screening-level model available now on the Internet, and
IGEMS, a model that will combine air dispersion and exposure
models with toxicity information to estimate risk. IGEMS will also
include geographic information system (GIS) capability as a future
enhancement. A description of E-FAST and IGEMS and updates on
their development can be found at http://www.epa.gov/oppt/
exposure/.
Other tools for the assessment of air pollutant fate, exposure, and risk
are available on EPA's Technology Transfer Network web page at
http://www.epa.gov/ttn/.
Included among these tools are HAPEM, the model used for
estimating exposures for EPA's National Air Toxics Assessment as well
as other exposure models. EPA's Region 6 is also developing a risk-
based tool, RAIMI (Regional Air Impact Modeling Initiative), that will
characterize risk-related impacts and include GIS capability.
Information on this model and its availability can be found at
http://www.epa.gov/Arkansas/6pd/rcra c/raimi/raimi.htm.
Are there different approaches to risk-based
screening and risk assessment for the Partnership to
consider?
There are different approaches that risk-based screening and risk
assessment can take. Approaches differ primarily in the method used
to determine the concentrations in community air. Air concentrations
Community Air Screenins How-To Manual
39
-------
Chapter 2: Getting Started
• Part 3: Choosing a Plan to Meet Community Goals
can be obtained in two ways: by actually measuring the
concentrations (monitoring) or by using air dispersion modeling to
estimate the concentrations. Risk-based screening and risk assessment
can be accomplished using one or a combination of these two
methods for developing air concentrations.
Monitoring directly measures what is in the air either at fixed
locations in a community or as the air is breathed by someone living
in the community through personal monitors worn by community
volunteers. Since monitoring relies on neither estimates based on
computer modeling nor on the reliability of release data, it can
provide accurate measures of concentrations at specific locations or
for specific individuals. Setting up new monitoring is an appropriate
and thorough way to analyze community air, but it can be expensive
and it will require at least a year of measurements for estimates of
long-term effects. Because of its cost, monitoring can usually be done
in only a limited number of locations in a community. The
information on concentrations from monitoring also has some limits.
By itself, monitoring does not provide information on the sources of
the chemicals measured at the monitoring location. And most
monitoring involves sampling air at regular intervals, so monitored
concentrations can represent only the concentrations in the air at the
times of measurement. And, because of the expense or the availability
of appropriate analytical methods, the list of chemicals measured in
monitoring will also be limited.
Air dispersion modeling is also a valid tool used by regulatory
agencies and health agencies to estimate concentrations in
community air. Air dispersion modeling also has some advantages
because it does allow a community to estimate concentrations at any
location in the community and it does identify the sources of the
concentrations. Risk-based screening studies that use air dispersion
modeling can differ depending on the number of sources that are
modeled. Accurate air dispersion modeling of all releases provides the
most information, but collecting and using detailed information on a
large number of sources can be costly and resource intensive. To
conserve resources, tiered screening approaches, such as the one
described in Chapters 3 through 12 of this Manual, can be used to
limit the amount of air dispersion modeling that is required to make
decisions.
Communities can use monitoring and modeling in different amounts
depending on their resources and goals. If a community has resources
for either monitoring or comprehensive modeling, it will be able to
get more accurate or complete information. Complete monitoring
40
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
Part 3: Choosing a Plan to Meet Community Goals
and comprehensive modeling can, for example, be used as part of a
risk assessment to answer questions about the cumulative risk
resulting from all chemicals in community air. Tiered screening
methods, such as the one described in this Manual, cannot be used to
address cumulative risk from all chemicals.
Community and government partnerships are currently engaged in
assessments using different
combinations of modeling
and monitoring.
• For an example of a
community study based
on monitoring see St.
Louis Community Air
Project at http://
www.stlcap.tripod.com/.
• For an example of
comprehensive
modeling, see EPA
Region 6's Port Neches
study at http://
www.epa.gov/Arkansas/
6pd/rcra c/raimi/
raimi.htm.
• For an example of
combined modeling and
monitoring, see the
South Coast Air
Management District's
study of air in the Los
Angeles regions at http:/
/www.aqmd.gov.
The risk-based screening method described in Chapters 3 through 12
of this Manual is designed to use the minimum of resources to
identify priorities. It uses monitoring information if it is available but
it does not require new monitoring. Instead of new monitoring, it
relies on air dispersion modeling to estimate concentrations, and it
uses a tiered screening process to limit the amount of air dispersion
modeling needed to make decisions. For a more detailed description
of this method, please see Chapter 3.
Community residents inspect a neighborhood air
monitoring station
Sl. ] mils
CAP
COMMUNITY
AIR PROJECT
Community Air Screenins How-To Manual
41
-------
Chapter 2: Getting Started
• Part 4: Developing a Communication Plan
started
JJJJJ.
Building a
Partnership
*
Setting Goals
*
Choosing a
Plan to Meet
Community Goals
t
Developing a
Communication
Plan
;
Developing a Communication
Plan
Why should the Partnership focus on
communication?
The success of the Partnership depends on the participation of the
community for setting goals and standards, for collecting
information, and for mobilizing the resources that will be needed to
improve air quality. Participation of the community will depend on
the Partnership's ability to answer community questions about air
quality and to develop a consensus in the community on priorities
and on a plan to improve air quality. As a result, providing
information to and getting input from the community are at the heart
of the Partnership's work.
A list of resources to support the communication work of the
Partnership can be found in Appendix A. This section of the Manual
addresses communication issues particular to air quality partnerships.
How much time and effort will it take for the
Partnership to communicate effectively?
Because the participation of the broad community is crucial to the
success of the Partnership, it is likely that communication will take as
much time and effort as
the collection and
analysis of information.
Time will be needed to
develop effective
communication
materials, hold meetings
in the community, and
revise Partnership plans
based on community
input. Partnerships may
Partnership team presents its work at a community
meeting for discussion.
42
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
• Part 4: Developing a Communication Plan
want to consider the recommendation of the Baltimore Partnership
that the focus of meetings of the core Partnership group should
alternate between conducting the screening analysis and planning
outreach to the community. This schedule allows for the time the
Partnership group will need to develop and provide regular updates
for the community.
When should the Partnership communicate with the
community and its stakeholders?
Beginning with the outreach to develop and distribute its goal
statement, the Partnership should communicate with the community
regularly throughout the course of its work. This interaction will
ensure that the community is informed and current about
Partnership activities and has adequate opportunity to provide input
into the Partnership's direction and activities. The process of
communicating the information developed by the Partnership and
developing the consensus in the community that will be needed to
improve air quality will take time. Regularly scheduled, step-by-step
communication of the work of the Partnership, and regular feedback
from the community throughout the course of the Partnership's work,
will provide the best chance for success.
Who in the Partnership will work on communication?
Although there may be several members of the core Partnership
group that take primary responsibility for preparing communication
materials and organizing outreach, all members of the core group are
likely to participate in the communication efforts. Each member will
take the initiative to communicate directly with the organizations or
groups that they represent. For example, industry representatives
could take the initiative to keep the business community informed
and involved, and representatives of community churches could do
the same for their own organizations. The core Partnership group
may also want to organize teams to plan for once-a-month meetings
with community groups, organizations, or block clubs to explain the
Partnership's progress and to gather input from the community.
Different members of the core group will also be called on to explain
aspects of the work to large community meetings and to local media.
Effective communication will require a joint effort from all the
members of the Partnership's core committee.
Communication
will take as much
time and effort as
the collection and
analysis of
information
Community Air Screenins How-To Manual
.43
-------
Chapter 2: Getting Started
• Part 4: Developing a Communication Plan
Examples of
communication materials
developed by a
Partnership
Who should the Partnership include on its list for
regular communication?
The goal of the Partnership should be to reach as many members of
the community as possible. Targeting existing community
organizations and institutions may be the most effective way to
communicate with the community. The Partnership can meet
regularly with key organizations, such as community and
neighborhood associations, churches, schools, parent-teacher
associations, community clubs, youth organizations, housing
associations, and business associations. Reaching out to these groups
regularly with information and encouraging and assisting them to
communicate this information to their members will be important.
Local media and local libraries will also be important for
communicating information to the community.
In addition to outreach to the community in general, the Partnership
should also consider targeting community leaders to keep them
informed about the work of the Partnership. A list of elected officials
and leaders of community organizations can be developed and plans
made for interacting regularly with these leaders.
It will also be important for the Partnership to develop a list of key
stakeholders outside the community that will need to be informed
about the work of the Partnership. Local, state, tribal, and
national elected officials and organizations that may be
interested in the work of the Partnership could be
included on this list and updated on a regular basis.
What methods could the
Partnership use to prepare
understandable
communication materials?
Presenting information to community
groups and paying attention to their
questions and responses are good ways
to learn how to develop materials that
can communicate effectively. With
regular practice, Partnership
communication should improve over
the course of the project. Involving
members of the community who are
not working directly in the Partnership
Nc\\ Community Office
IN US TO IMPROVE
US COMMUNITY!.'
S. llmiintr Slrec!
Baltimore, Mi)
44
Community Air Screening How-To Manual
-------
Chapter 2: Getting Started
• Part 4: Developing a Communication Plan
to help prepare Partnership materials can also help. Local teachers and
high school classes can also be a resource for preparing effective
communication materials. For key Partnership reports and
information, such as the goal statement and the final report, it may be
helpful to try out materials in small groups in the community before
finalizing them for wide distribution.
Should the Partnership develop a communication
plan?
A communication plan is a description of the activities that the
Partnership will undertake to communicate with the community and
stakeholders. Developing a written communication plan at the start of
the project will help the Partnership to plan adequately for this work.
A communication plan could include some or all of the items listed
on the following page.
What are the next steps once the Partnership has
been built, goals have been clarified, and plans for
work and for communicating with the community
have been developed?
The following chapters of this How-To Manual are designed to help a
community use risk-based screening to understand and improve air
quality. Step-by-step guidance is provided for all aspects of risk-based
screening.
If your partnership has chosen a different approach to improving air
quality, then some of the content of the following chapters will not be
relevant to your work. But even if you choose a different approach,
some of the information may still be useful. For example, many
communities will be interested in collecting information on the
sources and releases in their areas. Guidance for collecting this
information and building a local source inventory can be found in
Chapter 4. Communities can also find some help in identifying
solutions to their concerns in Chapter 8 and a description of air
dispersion modeling and its use in Chapter 6. Please feel free to use
any part of this Manual if it can help you to understand and improve
your air quality.
Developins a
written
communication
plan at the start
of the project will
help the
Partnership to
plan adequately
for this work
Community Air Screenins How-To Manual
.45
-------
Chapter 2: Getting Started
• Part 4: Developing a Communication Plan
Communication Plan Checklist
•A discussion of how the core Partnership group will organize itself to carry out the
communication work: This could include the identification of who will lead and
participate in the communication work and who will have the main responsibility for
communicating with each sector of the community and with each of the organizations
and governments participating in the Partnership.
•A list of the key milestones in the Partnership's work that will require a communication
effort: This list could include the completion of the goal statement and each of the five
other steps of the screening process. Partnership initiatives requiring community
volunteers will also require communication efforts.
•A plan for facilitating community input and response to Partnership communications
and activities: This could include large and small community meetings, comments in
writing or responses over the Internet, focus groups and telephone surveys.
•A description of the kinds of outreach materials the Partnership will produce, such as
newsletters, reports, presentations, talking points, posters, leaflets, brochures, press
releases, an Internet web page, e-mails, and letters.
•A description of how these outreach materials will be written and copied or printed
for distribution.
•A plan for distributing Partnership communication materials in the community,
including where and how to distribute materials.
• A list of contacts for local press and media and a plan for communicating with and
providing Partnership materials to them on a regular basis.
•A list of key local organizations that the Partnership will rely on to distribute outreach
materials to their members, and a plan for meeting regularly and providing speakers,
outreach materials, and assistance to these organizations.
•A list of key community leaders and key stakeholders outside the community that the
Partnership will need to keep informed and a plan for communicating regularly with
them.
•A plan for communicating Partnership information to the organizations and
governments participating in the Partnership.
• A plan for handling communication for any crisis or emergency that may occur during
the Partnership's work. For example, if an accidental chemical release should occur in
the Partnership area during the course of the work, the community will look to the
Partnership for assistance. Developing a plan for communicating in this and similar
situations would help prepare the Partnership to respond effectively.
46
Community Air Screening How-To Manual
-------
Overview
An Introduction to
Risk-Based Screening
What is risk-based screening?
Risk-based screening is a method a community partnership can use to
identify all the chemicals in the community's outdoor air, estimate the
concentrations of those chemicals in community air that result from
the combined releases from all sources, and analyze this information
to find the chemicals and sources that have the greatest potential to
affect the health of some or all community members. Communities
using risk-based screening choose a level of risk and use this level to
screen chemicals and sources to find those that present a risk above
the screening level to some or all community members. This
information allows a community to set priorities and focus its efforts
to improve air quality where they will do the most good.
The risk-based screening method described in this Manual is also a
process that will help to develop the agreement you need in your
community to get things done. Doing the work will also build the
long-term capacity of your community to understand and address air
quality concerns that might come up in the future.
Is there an example of a community using risk-based
screening that can help us understand how it would
work?
To help you understand how this might work in your community,
here is an example of how this process worked in the industrial
neighborhoods in Baltimore, where the screening process described in
this Manual was first developed. For years, residents of several
industrial neighborhoods in Baltimore had concerns about the
potential impacts of chemical releases from all the many sources in
and around their community. To try to address these concerns,
Organize
Community Air Screenins How-To Manual
47
-------
Chapter 3: Introduction to Risk-Based Screening
Com pie tins the
screening process
allowed the
Baltimore
Partnership to set
priorities and
focus its energies
where they could
most effectively
improve local air
quality
community organizations, governments, and a local university
formed a partnership to work together to improve local air quality.
Through this partnership, the knowledge of the details of the local
community and the scientific expertise needed to understand the
potential impacts of chemical releases on community health were
combined. The partnership began by collecting information from
government databases and from local residents on all the releases and
sources in and around the partnership area. The Baltimore
partnership found 172 different chemicals in community air coming
from 125 different sources. The Partnership then estimated the
concentrations in community air that resulted from these releases and
used the risk-based screening process to sort through these estimated
concentrations to find the community's priority chemicals and
sources. The Baltimore Partnership found four chemicals released
from 17 different sources with concentrations in community air that
exceeded the community's risk screening level. These chemicals and
sources were identified as community priorities, and teams were
formed to develop recommendations to address the chemicals and
their sources.
Completing this screening process to identify the chemicals and sources
that presented the greatest potential to impact the health of members
of the community allowed the Baltimore Partnership to set priorities
and focus its energies where they could most effectively improve local air
quality. A Baltimore Health Department official summed up the value of
the screening project like this: "For many years we have all been trying
unsuccessfully to answer the concerns of these neighborhoods about their
air quality. With the partnership and the screening process, we now, for
the first time, have the ability to work together to begin to address those
concerns."
What questions can communities answer using
risk-based screening?
The Manual will help communities answer questions such as:
• What are the sources of outdoor air pollution in my community?
• What are the levels of chemicals in community air that result
from the combination of all of the sources in and around our
community?
• Are the levels of chemicals in community air high enough to be
identified as community priorities to evaluate for possible
action?
48
Community Air Screening How-To Manual
-------
Chapter 3: Introduction to Risk-Based Screening
• What are the sources of the chemicals that are identified as
community priorities?
• What should our priorities be in working to improve air quality?
• How does the air in our community compare with other
communities?
What results could a community expect from using
the risk-based screening process described in this
Manual?
The following results can be achieved by carrying out the science-
based process described in this Manual:
• An inventory of all significant sources of pollutants in outdoor
community air, with information about type and quantity of
chemicals emitted to the air in the study area
• Estimates of the concentrations of chemicals in community air
that result from all the sources in and around the community
• A comparison of chemical concentrations in community air
to risk-based screening-level benchmarks set by the
community to identify priorities to be evaluated for possible
community action
• Clear priorities for focusing community efforts for actions on
the chemicals and sources that present the greatest potential to
impact the health of members of the community
• A baseline and the ability to measure progress in improving air
quality
• An increased community capacity to understand and address
air issues in the long term that results from the knowledge,
understanding, and trust gained in completing the process
• A better agreement within the community on air issues based
on the improved understanding provided by the work
• The ability to compare community air quality to air quality in
other communities where air concentrations have been
measured or estimated
As discussed in Chapter 2, the screening process described in this
Manual is designed to identify priorities based on health risks due to
the chronic, long-term health effects of chemicals in outdoor air. Risks
due to short-term, acute effects of chemicals in outdoor air and risks
due to indoor air exposures are not considered by the method
Community Air Screenins How-To Manual
.49
-------
Chapter 3: Introduction to Risk-Based Screening
Combining the
local knowledse
of the community
and its businesses
with the science
of air quality
specialists is an
effective way to
answer questions
about local air
quality
considered in this Manual. Please see a more detailed discussion of
the limits of the method used in this Manual at the end of this
chapter.
What's in the Manual that allows a community to get
these results?
Chapters 3 through 12 of the Manual provide a step-by-step guide to
using the environmental science and information needed to
understand and improve local outdoor air quality. Science-based
tools, such as risk-based screening, are available to help make sense of
local environmental data, but not usually in a form accessible to
communities. This Manual is an attempt to make this science
accessible so that communities can identify and find solutions to their
concerns. The Manual presents and explains the science of risk-based
screening and the process that a community can use to identify and
inventory local sources of chemical releases, to review these sources to
identify known hazards that might present a health risk to the
community, and to set priorities for action to improve local air quality
if they are needed.
In addition to making science accessible to communities, the Manual
incorporates a process designed to bring all sectors of the community
and scientists together to share information and to work to improve
local air quality. Combining the local knowledge of the community
and its businesses with the science of air quality specialists is an
effective way to answer questions about local air quality and to
mobilize the resources needed to make improvements. In the process
described in this Manual, non-technical community residents work
side by side with technical experts to carry out all aspects of the effort,
with each contributing essential parts to the analysis and work. The
process, and the sharing of information that takes place to complete
the process, helps to build the trust and the agreement needed to take
effective action to improve air quality.
Is risk-based screening more suitable to support
voluntary or regulatory actions?
Risk-based screening is designed to make risk science accessible to
communities with limited resources. It uses enough science to allow a
community to identify priorities and develop an effective plan for
action. Risk-based screening is not a full risk assessment and, as a
result, it is most appropriate for use by community partnerships
committed to working together to find voluntary solutions to
community air concerns. Non-voluntary regulatory or enforcement
50.
Community Air Screening How-To Manual
-------
Chapter 3: Introduction to Risk-Based Screening
actions are likely to require the additional analysis of a full risk
assessment. The work done to complete a risk-based screening project
can, if necessary, serve as the foundation for a full risk assessment.
Who is the intended audience for Chapters 3 through
12 of this Manual?
Chapters 3 through 12 are designed for community partnerships
interested in using risk-based screening to understand and improve
local outdoor air quality. The Manual is designed for both the non-
technical and the technical members of a community partnership
effort. The Manual can also be used by community leaders familiar
with air quality issues to get an overview of the risk-based screening
method to decide if it is an appropriate approach for meeting
community goals.
How is the description of risk-based screening in
Chapters 3 through 12 organized and how should
these chapters be read?
This Manual is divided into two basic parts: An Overview section,
Chapters 3 through 8, that contains the information that everyone
working in the Partnership will need to know to fully participate in an
effort to use risk-based screening to understand and improve air
quality, and a Technical Guidance section, Chapters 9 through 12,
that contains the detailed information that the technical members of
the Partnership will need to carry out the technical aspects of the risk-
based screening methodology for the Partnership.
This chapter, Chapter 3, "An Introduction to Risk-Based Screening,"
provides a summary of the risk-based screening method used in this
Manual as well as information on the resources that a partnership will
need to implement the method described in the Manual. The
Partnership can use this information on the resources that will be
needed to carry out a risk-based screening project to begin planning
and organizing its work. The remaining chapters of the Overview,
Chapters 4 through 8, provide the basic information that the
members of a partnership will need to carry out each step of the
process.
If a community partnership decides to use this Manual, it may want
to review all of these chapters at the beginning of a project and take
them up again, one at a time, as the project progresses. Partnership
members who read the Manual on their own should not be surprised
or discouraged if they find some parts of the Manual to be unclear or
Community Air Screenins How-To Manual
51
-------
Chapter 3: Introduction to Risk-Based Screening
Each partnership
will have to draw
on its members
throushout the
process to
provide
additional
explanations and
illustrations to
explain the
concepts and
methods used in
the Manual
confusing at first. The chapters of the Manual are designed to cover all
the elements of the screening process, but they are only summaries
and they will need to be supplemented with further explanations by
members of the Partnership who have expertise in the different areas
of the screening and partnership process. Both technical and non-
technical members of a partnership will find sections of the Manual
that they may not understand completely without supplemental
explanations. For example, the descriptions of scientific concepts like
risk and of technical tools like air dispersion modeling are brief, and
the non-technical members of the Partnership will probably need
additional explanations and illustrations to ensure that they can fully
participate in decisions involving these concepts. Similarly,
community residents will have to explain and provide examples of
local knowledge to the technical members of the Partnership to
supplement the Manual. Each partnership will have to draw on its
members throughout the process to provide the additional
explanations and illustrations that will be needed to adequately
explain the concepts and methods used in the Manual. In addition,
references to additional support materials that could be used to help
supplement this Manual are made throughout the text. If your
Partnership develops an effective tool to explain or illustrate a part of
the screening process, please be sure to share it with other
communities.
Both the Overview section and the Technical Guidance section are
organized around six steps, beginning with partnership building and
ending with the implementation of recommendations to improve air
quality. The six steps will be discussed later in this chapter.
How was this Manual developed?
This Manual was developed over several years in a multi-step process.
As a result, it incorporates the ideas and experiences of a very large
number of people. The risk-based air screening process described in
this document was originally developed by a partnership for the study
in Baltimore, Maryland, that is described above. In this effort,
residents, local organizations, schools, industry, and government
worked together for three years to design and implement an air
screening methodology for five Baltimore neighborhoods. As
mentioned above, these neighborhoods faced the challenge of trying,
with limited resources, to understand the potential impact on their
community of 125 facilities with 400 releases of 175 different
chemicals. The result of this Partnership effort was a screening
methodology that formed the starting point for this Manual. A
52
Community Air Screening How-To Manual
-------
Chapter 3: Introduction to Risk-Based Screening
summary of the work of the Baltimore Partnership is available in a
case study titled Baltimore Community Environmental Partnership Air
Committee Technical Report, Community Risk-Based Air Screening: A
Case Study in Baltimore, MD (EPA 744-R-00-005). This document can
be downloaded or ordered on the web at: http://www.epa.gov/oppt/
cahp/case.html.
A summary of lessons learned by the Baltimore Partnership, a part of
the case study, can be found in Appendix D. We have tried to
incorporate these lessons into the guidance contained in this Manual.
Following the completion of the efforts in Baltimore, the screening
methodology was reviewed by independent peer reviewers, EPA staff,
and community leaders. Based on the suggestions provided by these
reviewers, the methodology developed in Baltimore was expanded
and improved to develop this How-To Manual.
Finally, the Manual was sent out again for both an internal EPA
review and a formal external peer review by a panel of independent
experts. Both of these reviews resulted in significant improvements in
the Manual. Lists of both the EPA and the external independent
reviewers of this Manual are provided on the acknowledgment page
of this Manual. Information on how to get a summary of the external
peer review comments and an explanation of how they were
addressed in the development of this Manual can be found on the
internet at: http://www.epa.gov/oppt/cahp/howto.html.
EPA hopes to amend and update the methodology and Manual as
communities gain more experience in their efforts to understand and
improve their air quality. Future updates to this Manual will be
available on the web site provided above.
Should a community using this Manual view it as a
finished product or make changes to the Manual as
needed?
This Manual is a summation of experiences of the Partnership in
Baltimore and the ideas of all those who helped with or commented
on this effort. Although every effort was made to make it as useful as
possible, the fact that it is based on limited experience means that it
can be improved as other communities develop additional practice.
Every community is different and will have to address issues specific
to their community, so this Manual should be seen as a work in
Community Air Screenins How-To Manual
53
-------
Chapter 3: Introduction to Risk-Based Screening
Risk-based
screening
combines
information on
concentration
and toxicity into a
practical method
that allows a
community to
identify priorities
with the minimum
possible use of
resources
progress. As the EPA team that pulled together all the comments to
produce this Manual, we encourage you to share your experiences
with us so that the Manual can be updated and other communities
can benefit from your experiences. You may visit the How-To Manual
web site to learn how to share your experiences or look for recent
updates to the Manual. The Manual web site can be found at:
http://www.epa.gov/oppt/cahp/howto.html.
How does risk-based screening described in this
Manual work to help a community identify priorities?
To identify community priorities, the How-To Manual first explains
how a community can estimate the concentration of each of the
chemicals in community air that result from all the sources of that
chemical in and around the Partnership area. Using concentrations to
set community priorities is much better than just looking at the
volume of releases because the concentration, not the volume
released, is the key to understanding the effects that the chemical
might have on individuals in the community. Small releases can result
in high concentrations in parts of the community that are close
enough to the source. On the other hand, large releases may result in
only small concentrations in the community if the source is far away
or if the releases come from a tall stack. (The details of how to
estimate the concentrations are discussed below and in the
subsequent chapters of the Manual.)
But just estimating concentrations alone would not be sufficient to
tell communities where to focus their energies. The Manual also
allows the community to incorporate information on the toxicity of
the chemicals released into its air. A low concentration of a very toxic
chemical may be more harmful than a high concentration of a less
toxic chemical. The How-To Manual allows communities to combine
information on the concentration and the toxicity of the chemicals in
their air to decide which chemicals should be targeted for potential
community action. (The details for using information on the toxicity
of chemicals can be found in the "Initial Screen," Chapter 5.)
Finding a practical way to develop and use information on both the
concentrations and the toxicity of chemicals was the challenge faced
by the Partnership in Baltimore. The Partnership chose risk-based
screening as the method it would use to identify the chemicals it
needed to target. Risk-based screening combines information on
concentration and toxicity into a practical method that allows a
community to identify community priorities with the minimum
54.
Community Air Screening How-To Manual
-------
Chapter 3: Introduction to Risk-Based Screening
possible use of resources. This Manual is designed to make the risk-
based screening method developed in Baltimore more accessible to
communities.
Risk-based screening is widely used by scientists to identify
contaminants of concern. It works by setting an acceptable level of
risk and then determining the concentration of a chemical that would
result in that level of risk in a hypothetical individual exposed to the
concentration, usually an individual with a reasonable maximum
exposure. This concentration is set as the risk-based screening
concentration for that chemical. (An alternate approach to risk-based
screening that uses the proportion of total risk to screen chemicals
instead of screening-level concentrations is possible. Although this
Manual does not provide detailed guidance for that approach, a fuller
explanation of screening by proportion of risk can be found in
Chapter 5.)
To adapt risk-based screening for community purposes, a community
first decides on the level of risk that it finds adequate to protect
community health. Based on this decision, the community calculates
the concentration that would result in the chosen level of risk in a
hypothetical community member who is exposed to that
concentration. This concentration becomes the community risk
screening level. Deciding on how the risk screening concentrations are
set allows the community to choose levels that match its values and
needs. If a chemical concentration in community air is found to be
higher than the screening concentration, then that chemical will be
identified as a priority to be evaluated for possible community action.
Chemicals with concentrations that are lower than the community
screening concentrations can be set aside as lower priorities.
(Chemicals set aside should be reevaluated periodically to account for
changes in information.) As a result, by using the risk-based screening
method, the community will be able to identify all the chemicals that
need its attention. This will allow the community to focus its limited
resources in a way that will most effectively improve the community's
health and environment.
Using risk-based screening to improve local air quality depends on an
agreement in the community to work together to try to find ways to
reduce releases of chemicals that have concentrations above the risk
screening level. Reaching this agreement, and developing the
understanding of local air quality that it requires, are key to the
success of the method described in this Manual. (A discussion of the
task of setting the community's screening level of risk can be found in
the "Initial Screen," Chapter 5.)
Using risk-based
screening to
improve air
quality depends
on an agreement
in the community
to work together
to try to find ways
to reduce
releases of
chemicals that
have
concentrations
above the risk
screening level
Community Air Screenins How-To Manual
.55
-------
Chapter 3: Introduction to Risk-Based Screening
Finding and
implementing
effective ways to
improve local air
quality are the
goals of the effort
described in this
Manual
Here is a list of the technical tasks described in the Manual that a
community partnership will need to complete to identify priorities
for potential action to improve its air quality:
• Identify and collect release information on all sources of air
pollution in and around the Partnership area.
• For each chemical released, estimate the air concentration in the
community that results from all the sources of the chemical.
• Choose a level of risk to serve as the community's risk screening
level.
• Calculate the risk screening concentration, that is, the
concentration equivalent to the risk screening level, for each
chemical in community air.
• Compare the concentration for each chemical in community air
to its risk screening concentration and identify chemicals above
their screening level as community priorities.
Once the community has identified priority
chemicals, what actions can be taken to reduce their
levels?
Finding and implementing effective ways to improve local air quality
are the goals of the effort described in this Manual. The screening
analysis described in the Manual is designed to help all sectors of a
community work together to get a better understanding of local air
quality. This common understanding will form a solid foundation for
taking action, if necessary, to improve local air quality. This action,
discussed more fully in Chapter 8, could take various forms, such as a
voluntary effort by local businesses to reduce the emissions of priority
chemicals, work to address mobile source emissions, or a campaign to
reduce the use of toxic chemicals around the home. Communities
might also decide to work with public health agencies to identify and
address community health concerns. Monitoring or further analysis
to verify or clarify issues raised in the screening analysis may also be
necessary. Finding and taking effective actions to improve the
community's health and environment are the goals of the work
described in this Manual.
56
Community Air Screening How-To Manual
-------
Chapter 3: Introduction to Risk-Based Screening
What does the Manual do to help limit the resources
a community will need to use the risk-based
screening method?
Completing all of the analysis described above will require significant
community resources. Estimating the concentrations in the air that
result from all the releases, the second step described above can, in
particular, require significant technical resources. Because many
communities have limited technical resources for estimating air
concentrations, this Manual uses a tiered screening process designed
to minimize the resources needed to estimate concentrations. The
first tier of the screening process estimates concentrations using a
simple look-up table that allows the Partnership to screen out
chemicals with a minimum of effort. The second and third screening
steps repeat the analysis, each time using better information and more
sophisticated methods to estimate concentrations. The use of this
tiered approach means that the Partnership will not have to use the
resource-in tensive effort needed to accurately estimate concentrations
for all the chemicals in community air. Each of these screening steps is
described in more detail below and in Chapters 5, 6, and 7.
What steps would a partnership take if it uses this
Manual?
The overall methodology described in this Manual, including
partnership building, the tiered risk-based screening approach, and
the work to improve air quality, can be carried out in the six steps
outlined below. Each of these steps is described in more detail in a
separate chapter of the Manual. The chapters detailing each step are
listed below. Please see Figure 3-1 for a summary of the community
air screening methodology and Figure 3-2 for a detailed description
of each of the six steps for the air screening methodology discussed in
the Manual.
Step 1: Build a Partnership, Clarify Goals, and Develop a
Communication Plan (Chapter 2)
The process begins with the effort to form a broad partnership to
understand and improve local air quality. The Partnership should aim
to include as many sectors of the community as possible. Interested
local citizens, community leaders, and representatives of community
organizations, the local business community, schools, churches,
nearby colleges and universities, and local, state, tribal, and federal
governments should all be included, if possible. The Partnership will
Community Air Screenins How-To Manual
57
-------
Chapter 3: Introduction to Risk-Based Screening
Step 1 in Manual
(Discussed in Chapter 2)
Organize
Organize Partnership
and plan work
Community
Outreach
and Input
Step 2 in Manual
(Discussed in Chapter 4)
Steps 3, 4, and 5 in Manual
(Discussed in Chapters 5, 6, and 7)
Identify and collect
information on
emission sources
and releases
Analyze
Estimate air
concentrations and use
risk-based screening
to identify health-
based priority
sources and chemicals
Community
Outreach
and Input
Community
Outreach
and Input
Step 6 in Manual
(Discussed in Chapter 8)
Mobilize
Identify possible options
and mobilize
community to take
action to address
priority sources
and chemicals
Community
Outreach
and Input
Figure 3-1.
Summary of Air Screening Methodology for the Community
58
Community Air Screenins How-To Manual
-------
Chapter 3: Introduction to Risk-Based Screening
be the source of the local knowledge, resources, and technical skills
needed to complete all steps of the screening process and to
implement the plan for improving local air quality. It will also serve as
a community forum for participants to share ideas and to develop the
trust and agreement that will be necessary to take effective action. The
first step of the Partnership will be to clarify the goals of the project
and develop a work plan to accomplish the community's goals. The
Partnership will also need to develop a clear plan for communicating
with the community at large, both to keep them informed on progress
and to solicit their input as the work progresses. If the Partnership
decides to use risk-based screening to analyze local air quality, then
the following five steps will be used.
Step 2: Build an Inventory of Air Pollution Sources (Overview in
Chapter 4; Technical Guidance in Chapter 9)
Once the Partnership is established and goals are set, the first task will
be to identify and collect information on all the sources of air
pollution in and around the target community. Local residents,
businesses, and technical members of the Partnership will work
together to identify and locate local sources such as local business and
industrial facilities, power plants, landfills, cars, trucks and buses,
household heating, burning of trash, municipal incinerators, etc.
Information on the location, type, and amount of pollutants released
from each of the sources will be collected or estimated. The Emission
Source Inventory, based on the detailed information on local sources,
will be unique for each community. Once completed, the source
inventory will provide the community with a comprehensive database
containing most of the information necessary to complete the
screening process.
Step 3: Conduct the Initial Screen (Overview in Chapter 5; Technical
Guidance in Chapter 10)
The Initial Screen begins the review of the information in the
inventory to find if there are any releases that result in concentrations
in community air that are above the community screening levels. To
start this work, the Partnership will need to choose the screening level
that will be used throughout the screening process. An evaluation of
scientific information and community values and goals will form the
basis for this choice. The Partnership must also set the standards and
procedures that the technical members of the Partnership will use to
select the information that will be used in the analysis. Setting these
standards will ensure the quality of the technical work and legitimacy
of the results.
Community Air Screenins How-To Manual
59
-------
Chapter 3: Introduction to Risk-Based Screening
To complete the first step in the screening process, a community will
need to review a large number of chemicals and releases. Estimating
the concentrations in community air that result from all these releases
can be very resource intensive. To minimize the resources needed, the
first screening step uses simple calculations and a look-up table to
estimate the concentrations. The calculations and look-up table are
designed to be conservative, which means that they are designed to
overestimate the concentrations that would result from the releases.
Conservative estimates of releases, meaning overestimates, are used at
this step, and this also contributes to the overestimation of
concentrations. Comparing these conservative overestimations to the
community screening levels gives the community Partnership an easy
way to set aside many chemicals and releases that result in
concentrations equal to or below the community screening levels.
(For the subsequent screening steps, the simple calculations and look-
up table are replaced with more accurate methods of estimating
concentrations. With fewer chemicals left to review in the Secondary
and Final Screening steps, the Partnership will be able to use better,
and more resource-intensive, methods to estimate concentrations.)
When the Initial Screen is completed, the community will be left, it is
hoped, with a shorter list of the chemicals and releases with
concentrations above the community screening levels. These will be
kept in the process for further analysis. It is important to remember
and communicate clearly to the community that the list of chemicals
that come out of the first screening should not be identified as
chemicals of concern. Since the calculations and look-up table
overestimated the concentrations, further and more accurate analysis
may show that they are not a concern. These chemicals remain on the
list for further analysis, but at the Initial Screening step it is still too
early to identify the results as community priorities or concerns.
Step 4: Conduct the Secondary Screening (Overview in Chapter 6;
Technical Guidance in Chapter 11)
The Secondary Screening starts with the chemicals identified in the
first screening step. These chemicals and releases are analyzed using
the same method, only this time, in place of the simple calculations
and the look-up table used in the first step, air dispersion modeling is
used to provide more accurate estimates of the concentrations in
community air. These more accurate estimates of concentrations are
then compared again to the community screening levels. Chemicals
60
Community Air Screening How-To Manual
-------
Chapter 3: Introduction to Risk-Based Screening
with concentrations equal to or below the screening levels are set
aside; chemicals with concentrations above the community screening
levels are kept for further analysis. For the Secondary Screening, the
same conservative estimates (overestimates) of releases used in the
first step are again used to complete the air dispersion modeling. As a
result, the estimated concentrations in community air are, again,
likely to be overestimates, so the chemicals will need further analysis
to determine if they should be identified as community priorities.
Step 5: Conduct the Final Screen (Overview in Chapter 7; Technical
Guidance in Chapter 12)
In the Final Screen, concentrations for the chemicals identified for
further analysis in the second screen are once again compared to
community screening values, only this time the most accurate
information available is used to estimate the concentrations. With a
limited number of chemicals left to review, the Partnership will have
the resources to collect detailed information on releases from all of
the sources of the chemicals reviewed in the Final Screen. This more
accurate release information replaces the conservative estimates used
in the first and second screens, resulting in the best possible estimates
of concentrations in community air. Each of the sources can be
contacted and asked to provide detailed information on their releases.
State, tribal, and local agency files and databases can also be searched
for more accurate information on the releases under review. Details
on release amounts, location of releases, height of release stacks, etc.,
are collected and used with air dispersion modeling to provide the
best possible estimates of concentrations. Concentrations estimated in
this final step that are still above the community screening values are
identified as priorities to be evaluated for possible community action.
Step 6: Develop Recommendations and Communicate Results
(Overview in Chapter 8)
Once the priority chemicals are identified, the Partnership focuses on
developing recommendations for potential actions that can be taken
to reduce the impact of these chemicals on community health. Input
from all the members of the Partnership will be needed to develop
these recommendations. If they are not already members of the
Partnership, any industrial, commercial, and institutional sources for
the priority chemicals are invited to join the Partnership to help with
Community Air Screenins How-To Manual
61
-------
Chapter 3: Introduction to Risk-Based Screening
Slep 1
Build Partnership
(Chapter 2)
Form Partnership, Clarify Goals,
Develop Work and Community Outreach Plan
Community
Outreach
and Input
Slep 2
Emission Source Inventory
(Chapter 4)
Build
Emission Source Inventory
Develop Explanation and
Outreach Material
Inventory and Outreach Materials
I
Community
Outreach
and Input
Slep 3
Initial Screen
(Chapter 5)
Use SCREENS Look-Up Table
to Estimate Concentrations
Develop Explanation and
Outreach Materials
Screen with
Health-Based Values
A
Materials
I
Community
Outreach
and Input
Slep 4
Secondary Screen
(Chapter 6)
Use ISC Dispersion Model with
Readily Available Information
to Estimate Concentrations
Develop Explanation and
Outreach Materials
Screen with
Health-Based Values
Results and Outreach Materials
Community
Outreach
and Input
Slep 5
Final Screen
(Chapter 7)
Use ISC Dispersion Model with
Detailed Information
to Estimate Concentrations
Screen with
Health-Based Values
Develop Explanation and
Outreach Materials
*
Slep 6
Recommendations and
Communication
(Chapter 8)
Materials
Community
Outreach
and Input
Figure 3-2.
Detailed Community Air Screening Methodology
62
Community Air Screenins How-To Manual
-------
Chapter 3: Introduction to Risk-Based Screening
the development of recommendations. The Partnership also needs to
communicate the results of the screening and its recommendations to
the broader community. A final report, presentations to community
groups, press releases, and other forms of communication can be
used. This communication of the results and recommendations is the
basis for mobilizing the community for the work that will be needed
to carry out the recommendations to improve air quality. Figure 3-2
presents a flow chart summarizing all these steps and the relationship
of this work to the community.
What resources would a community need to
complete the process described in this Manual?
This Manual is designed to help a community partnership understand
and improve air quality. All the work described in the Manual is
designed to be done by the Partnership—not by someone or some
institution working for the Partnership. The effort to build a
partnership and trust, collect and analyze data, write and
communicate results, and develop and implement plans for making
improvements will require a significant commitment of time and
resources to complete. Improved long-term community capacity to
understand and address local air quality issues can justify this effort,
but a community must recognize and plan adequately for this work to
be able to complete the process and improve air quality. Please refer to
Chapter 2 for a fuller discussion of the resources needed for building
a partnership.
Past experience shows that it may take anywhere from one to two
years, depending on the resources and size of the community, to
complete the risk-based screening analysis and to develop and begin
to implement recommendations for action. Remember that because
of the time required to adequately understand local air quality, it will
be important to find ways to take some actions to improve air quality
as the screening process proceeds to reduce known risks, maintain
community interest, and satisfy members of the Partnership more
interested in action than analysis. As suggested in Chapter 2, using
available information on typical community air risks may be
sufficient for the Partnership to agree to take action on some likely
high-risk sources and chemicals while simultaneously using the risk-
based screening analysis to get a better understanding of the
community's sources and priorities.
With the overall time frame in mind, the following is a checklist of
resources that may be needed to carry out the process described in
this Manual.
All the work
described in this
Manual is
desisned to be
done by the
Partnership—not
by someone or
some institution
worklns for the
Partnership
Community Air Screenins How-To Manual
.63
-------
Chapter 3: Introduction to Risk-Based Screening
Resources Checklist
•An organization or person to champion and to facilitate the formation of the
Partnership to start this effort. This could be a community or business leader or
organization, a local school, or a government.
•A core committee of partners, with up to 20 members, willing to meet
regularly for the length of the project and commit significant time to organize
and implement the work. The core group should be a broad partnership
committee with representation from as many community sectors,
organizations, and governments as possible. The expertise needed for the
project will come from this Partnership.
•A person devoted to organizing and sustaining community involvement. This
person will support the volunteer community members of the core committee
and help communicate the work of the core committee to the broader
community. Community volunteers on the core committee will likely be
participating in the Partnership after working on their regular full-time jobs, so
they will need this support to effectively participate and reach out to the
broader community.
• A trained facilitator. This facilitator, either from the community or brought in
from outside, can concentrate on building trust and making sure the process
works effectively.
• A regular meeting space.
•Access to a relatively new desktop computer to hold the community
database.
•Access to an air dispersion model. Funding for this modeling may be
necessary if the modeling capability is not available in the Partnership.
• Means to communicate effectively with the broad community: newsletter,
flyers, meeting space for large meetings, printing and duplicating costs, etc.
Existing means could be used or special ones created depending on
community resources.
64
Community Air Screening How-To Manual
-------
Chapter 3: Introduction to Risk-Based Screening
What skills will the members of the core Partnership
group need to complete the process described in
this Manual?
Please see the list of skills discussed in the Partnership section of
Chapter 2. All the skills listed there will be needed to use risk-based
screening to understand and improve local air quality.
What advance planning can be done to help ensure
the success of the risk-based screening effort?
If possible, it would be good for the Partnership to get an
understanding of the full process and do some advance planning and
preparation so that it is prepared to complete each step of the effort as
the work progresses. For example, the Partnership could identify all
the teams that it will need to form over the course of the work and
organize the teams early so that they can begin to assemble the
resources and develop the skills they will need to carry out their tasks.
The list of teams proposed in the Manual include:
• Communications Team (Chapter 2)
• Emission Source Inventory Team (Chapter 4)
• Quality Assurance/Quality Control Team (Chapter 4)
• Concentrations Estimation Team (Chapter 5)
• Screening-Level Concentration Team (Chapter 5)
• Recommendations Team (Chapter 8)
In the organization described in this Manual, each of these teams
works for and reports to a core Partnership group or core committee
with overall responsibility for the work. This form of organization
helps to provide coordination and ensure that all the work meets
community needs. But each Partnership will have its own needs and
resources, so organizations will differ. This list of teams and their
description in the Manual are offered only as suggestions to help
begin the discussion of how to best organize the work in your
community.
Please see the Partnership section of Chapter 2 for a discussion of
other aspects of advance planning, including planning for fund-
raising and for work with schools.
Community Air Screenins How-To Manual
.65
-------
Chapter 3: Introduction to Risk-Based Screening
Using the Manual
will provide an
important part of
the picture of
community risk,
but not the
complete
picture
Do the community residents who are members of the
Partnership need a background in science to
participate?
No, the process is designed so that the science necessary to participate
in the effort is provided to the residents and other non-technical
participants as the project progresses. This Manual and the technical
members who will provide the scientific expertise needed for the
work of the Partnership will provide the science background that the
non-technical members will need to participate fully in all decisions.
In fact, all committee members will need to devote time to share
information and help each other understand all the aspects of the
community and the science that will be needed to reach the
Partnership's goals of improving air quality.
What are important limitations of this screening
process that a community needs to understand
before it starts?
While risk-based screening does provide important benefits to the
community, it is important for the community to understand the
limits of the methodology so that your expectations will be in line
with the results you will get. A list of the limits, that is, things that
cannot be accomplished with risk-based screening, is provided later in
this section. As you read this list of things that cannot be
accomplished, you may start to wonder why any community would
want to adopt this approach. Providing this list of limits is not
intended to discourage you. It is presented here to make sure that you
understand up-front the things that using this Manual can and
cannot accomplish. Some of the limits described later in this section
flow directly from limits in current science or gaps in available
information. Others are a result of the Manual's focus on a particular
part of the complex set of factors that influence community health.
Using the Manual will provide an important part of the picture of
community risk, but not the complete picture. As discussed in the
section on setting goals in Chapter 2, some partnerships may decide
to supplement the information provided by using this Manual so that
they can broaden the scope of concerns that they address. For
example, for a better overall picture of risks from air toxics, the
Manual recommends a consideration of other aspects of air quality,
such as the acute effects of outdoor air toxics and the risks from
indoor air exposures. Understanding clearly the overall picture that
this method fits into will help your Partnership and community
understand how to use and, if necessary, supplement the information
66
Community Air Screening How-To Manual
-------
Chapter 3: Introduction to Risk-Based Screening
this Manual provides. To help form a balanced picture, a summary of
the results that can be obtained from the use of this Manual is
provided following the list of limits.
A good way to begin to understand the limits of the method used in
this Manual is to start with a discussion of the Manual's relationship
to questions about community health and about illnesses that may
have occurred in the community. The risk-based screening method
used in this Manual cannot be used to establish the cause of current
instances of disease in the community. Illnesses that have occurred in
the community may have resulted from environmental exposures; or
they may have been caused by non-environmental factors such as
stress, diet, tobacco smoke, or genetics; or they may have resulted
from a combination of environmental and non-environmental
factors. This Manual focuses on current exposures to chemicals in
outdoor air, so it considers only one among many potential causes of
community illness. In addition, the method used in the Manual looks
at current air quality, so it provides information on exposures that
may result in illnesses that would occur in the future. Current
illnesses are the result of exposures and other factors that occurred in
the past. And, since the analysis looks only at outdoor inhalation
exposures, it does not include all the environmental exposures that
may affect community health, such as exposures to biological
contaminants in the air, or exposures to pollutants in food and
drinking water, or in indoor air and at the workplace, or to lead paint
in the community's homes. So, as a result of its focus on outdoor
inhalation exposures, the method in this Manual is not sufficient to
identify causes of community illness. Using the Manual provides the
information a community needs to identify and to use risk
information to prioritize chemicals in outdoor air so that effective
actions can be taken to reduce outdoor air risks. To more fully
address community health concerns, the Partnership would need
to broaden its scope to consider more of the factors that may affect
community health. The work to understand outdoor air quality, the
focus of the Manual, is only one piece of a broader community effort
needed to understand and improve community health.
And, as discussed in the section describing work plan options in
Chapter 2, the risk-based screening methodology does not include all
the necessary analysis to assess the risk in the community that results
from the chemicals in community air. For example, the methodology
does not attempt to fully measure exposures in the community. A
detailed exposure study would consider time spent in the
neighborhood, activity patterns, population characteristics such the
number of men and women and adults and children, etc. The
Community Air Screening How-To Manual
67
-------
Chapter 3: Introduction to Risk-Based Screening
information needed to set risk-based priorities does not require these
measures, so to save resources, guidance for assessing risk is not
included in this Manual. If a community is concerned about the levels
of exposure and risk in the community due to outdoor air quality, a
more detailed exposure assessment could follow this screening
exercise. Suggestions for how to supplement the analysis described in
this Manual to measure exposure and assess risk are provided in
Chapter 7.
Because the methodology does not assess risk, it cannot provide
information on the cumulative effects of multiple chemicals or all
chemicals in community air. To get information on cumulative risk,
the community would need to complete the exposure assessment for
some or all of the chemicals in its inventory.
And, except in some limited cases, this screening analysis does not
provide information on the possible effects of the mixtures of
different chemicals in community air. It is possible that chemical
mixtures could have more or less risk than the sum of the risk from
each chemical in the mixture considered separately. The science to
understand the effects of chemical mixtures is not very well
developed.
In addition, all forms of risk analysis, including the risk-based
screening used in the Manual, cannot, with certainty, account for all
of the risks associated with the chemicals found in a community's air
because some hazards may be unknown. Toxicity information for
some chemicals may be unavailable or incomplete. New testing, such
as the testing for effects on children and for effects on endocrine
systems, may identify additional hazards that are currently unknown.
Given the limits of the currently available toxicity information, the
methodology is a review of known hazards, not all hazards. To take
this into account, the Manual recommends a periodic review of
community air quality so that any new information on the toxicity of
chemicals can be used to adjust community priorities, if necessary.
And, since the methodology used in the Manual looks at only a part
of the overall air quality picture, it may also be helpful to list the
aspects of air quality that are not covered by this Manual. The
methodology does not include indoor air and indoor air sources or
short-term effects of chemicals in the outdoor air. Exposures resulting
from air deposition, such as exposure that are the result of eating fish
contaminated with mercury resulting from air releases, are also not
considered. Nor does the method account for chemical
transformations that may take place in the air after chemicals are
released. Some chemicals break down rapidly and others are
68
Community Air Screening How-To Manual
-------
Chapter 3: Introduction to Risk-Based Screening
transformed into new toxic chemicals by reactions that take place in
the atmosphere. None of these chemical transformations and their
results can be accounted for with the method used in this Manual. In
addition, aspects of air quality, such as visibility and dust, that are not
related to toxic chemicals are not included in the analysis. All of these
aspects of air quality mentioned above are important considerations
for developing community priorities and community plans to address
air quality. Information on each of these aspects of air quality can be
found, and the Partnership will need to consider supplementing the
information provided by using the Manual to develop a clearer overall
picture of local air quality.
So, as a review, what part of the community environment does this
Manual address and what can it do to help communities improve
their health? In sum, this Manual provides guidance to help
communities understand and address the chronic health effects that
may result from breathing toxic chemicals in the community's
outdoor air. The Manual helps communities identify the chemicals,
and the sources of those chemicals, in outdoor community air that
have the greatest potential to affect community health and that
present a risk above a screening level set by the community. This
information allows communities to set priorities and focus their
efforts to improve outdoor air quality where they will do the most to
reduce health impacts.
In more detail, a community can expect the following results from
using this Manual:
• An inventory of all the significant sources of pollutants in your
community's outdoor air
• Estimates of the combined concentrations of chemicals in
community air resulting from all sources, and a comparison of
these concentrations to risk-based screening levels set by the
community
• Clear risk-based priorities for focusing community efforts where
they can do the most good to improve outdoor air quality
• A partnership and better agreement in the community on
priorities as the basis for mobilizing resources to make
improvements
• A set of recommendations for improving local outdoor air
quality
• Improved long-term capacity of the community to understand
and improve local air quality
Community Air Screenins How-To Manual
69
-------
70
Community Air Screenins How-To Manual
-------
Overview
Building the
Emission Source Inventory
What is the Emission Source Inventory?
The Emission Source Inventory is a collection of information on all
the known sources of air emissions in and around the Partnership
area. To start, the inventory will contain information on the amount
of the releases of all the chemicals from all the sources that can be
identified in and around the Partnership area and information on the
location of all point sources. Eventually it will contain all the
information on sources that the Partnership will need to complete all
the steps of the air screening exercise described in this Manual. The
inventory will serve as a permanent community database that can be
updated periodically and used to measure progress in improving
community air quality.
The Emission Source Inventory and all of the information that it will
contain on local emission sources can also be used as a tool to educate
the Partnership and the community. This educational work on the
local sources of air pollution will lay the foundation for the future
work of the Partnership to improve air quality.
This chapter gives an overview of the work needed to set up the
database, identify and locate stationary point sources, and collect the
information on the amount of the releases from all sources.
Additional instructions for collecting the information needed for each
screening step can be found in the subsequent chapters of the
Overview and in the Technical Guidance sections of the Manual.
Collect
Community Air Screenins How-To Manual
71
-------
Chapter 4; Building the Emission Source Inventory
How is the Emission Source Inventory used in the risk
screening exercise?
As described in the Introduction, the screening methodology used in
this Manual contains guidance for developing estimates of
concentrations of chemicals in community air and guidance for
comparing these concentrations to community screening-level
concentrations to identify priority chemicals. The information on
sources and air emissions collected in the inventory provides the basis
for the Partnership's work to develop the estimates of concentrations
of chemicals in community air. Once completed, the Emission Source
Inventory will contain all of the source information needed to
estimate concentrations for all the steps of the screening process.
How does the Partnership set started in develop ins
the Emission Source Inventory?
The first step is to define your study area, that is, the area that will be
the focus of the Partnership's air screening effort. The boundaries of
the study area should, if possible, follow existing boundaries, such as
the boundaries defining neighborhoods or community organizations.
Adjusting these existing boundaries so that they fit the way data are
organized in state and federal air quality databases (e.g., ZIP codes)
may be helpful in collecting the information. In Baltimore, the study
area was defined by five adjacent Baltimore neighborhoods that were
located in two primary ZIP codes, 21225 and 21226. The residents in
those neighborhoods joined together with local, state, and federal
government agencies to form the Community Environmental
Partnership.
Is there a need to include sources beyond the study
area boundaries?
Sources outside the study area can have an impact on the air quality
within the study area depending on their strength (emission quantity)
and the meteorological conditions, such as the prevalent wind speed
and direction in your area. For example, if your study area is
downwind from a large source like a power plant or refinery, then
there is the potential for air quality to be affected by this source. For
this reason, it should be considered for inclusion in the analysis.
Similarly, a downwind source may not affect the study area and may
not need to be included in the analysis. Both large and small sources
that are very close to the Partnership area will probably need to be
included.
72
Community Air Screening How-To Manual
-------
Chapter 4: Building the Emission Source Inventory
To decide on how far out from the study area to go and which
facilities to include, the Partnership will need to rely on the
professional judgment of its technical members. This decision will be
based on review of all the factors needed to determine the potential of
a source to affect the Partnership's study area. For example, in
Baltimore a decision was made to include all large facilities within five
miles of the Partnership area. This added eight additional ZIP codes
(i.e., 21060, 20161, 21090, 21122, 21219, 21222, 21227, 21230) to the
primary ZIP codes (i.e., 21225 and 21226).
The Partnership may also want to consider adding especially large
emitters on an individual basis that are outside the boundaries the
Partnership sets for including large facilities. Information on these
large sources, such as a large power plant or industrial facility, could
come from members of the committee or from a search of databases
such as the National Emissions Inventory (NEI) or the Toxics Release
Inventory (TRI). In Baltimore, this was considered, but no such
facility was identified.
Will all emissions be captured by this study?
While the goal is to capture as many of the sources as possible, it may
not be possible to account for all the emissions that affect the
Partnership area. Examples of situations in which emissions and
chemicals might be missed are provided below. Partnerships will need
to consider their resources and goals to decide how much effort to
expend on identifying all possible sources.
Missing sources: Some sources, such as small businesses operating
without permits, may not be included in the release and permit
databases maintained by federal, state, tribal, and local governments.
The Partnership will make use of all of its members to organize an
effort to identify these kinds of sources, as discussed later in this
chapter, but some small sources may still be missed.
Missing chemicals: Even if all the sources are accounted for, one or
more of the sources may release a chemical that is not included in any
of the existing databases and, as a result, the chemical and its releases
could be missed. The Partnership will need to rely on the knowledge
and expertise of its members to try to identify all of the chemicals that
need to be included in the Partnership's Emission Source Inventory. It
may be helpful, if sufficient resources are available, to check the list of
chemicals stored in local facilities, which is maintained by the Local
Emergency Planning Committee, to see if there are any chemicals that
should be added to the Partnership's inventory. And facilities,
Community Air Screenins How-To Manual
73
-------
Chapter 4: Building the Emission Source Inventory
especially large facilities likely to use or release multiple chemicals, can
be asked to report on any releases they might have of chemicals not
included in the existing databases.
Missing releases: Even if all sources and chemicals are accounted for,
the Partnership may also miss some releases of these chemicals if it
relies only on the information in the existing release and permitting
databases. Accidental releases and releases due to maintenance may
occur and are sometimes reported in special databases or files kept at
the local or state level. It is also possible that some accidental,
maintenance, and even regular production releases may not be
reported at all. Input from committee members with a detailed
knowledge of the study area, along with state, local, and tribal
government staff with an understanding of all the information
collected and stored at the state and local level, will be crucial for
including as many significant releases as possible in the inventory.
Please keep in mind that short-term releases, such as accidental and
maintenance releases, are not likely to change the annual average
release amounts used to identify the priorities in the screening
method used in this Manual. Periodic peak releases, either accidental,
maintenance, or production, are more likely to be of concern for
understanding short-term acute effects. Although these acute effects
are important to the community, it was not possible to include an
analysis of them in this Manual.
Secondary formation of chemicals: In some cases air pollutants are
formed by chemical reactions that occur in the atmosphere with some
of the chemicals that are released. Studies have shown that the
secondary formation of chemicals (e.g., formaldehyde, acetaldehyde,
and acrolein) in the atmosphere, especially from chemicals released by
mobile sources, is an important source of chemicals in urban air. The
methods used to estimate this secondary formation of chemicals in
the atmosphere are complicated and beyond the scope of the
screening methods included in this Manual. The Partnership can
include chemicals formed in the atmosphere in the screening process
if local monitoring data for these chemicals are available. Information
on these chemicals and their concentrations can also be found in the
National Air Toxics Assessment (NATA) database. The NATA database
is available at http://www.epa.gOv//ttnatw01/nata/.
74
Community Air Screening How-To Manual
-------
Chapter 4: Building the Emission Source Inventory
What skills and resources are needed to complete
the Emission Source Inventory?
The Partnership will need skills and resources in the following areas
to complete its inventory and communicate its work to the
community:
• Familiarity with the data available at the local, state, tribal, and
federal levels on sources and emissions
• Knowledge of the community and the sources of emissions in
the community
• Community leaders to mobilize the community to assist with
information collection
• Communication skills to inform the community on the sources
of local air pollution
• Familiarity with database management or spreadsheet programs
• Ability to use estimation factors or other estimation methods to
estimate emissions from sources when no data are available
• A desktop computer with Internet access and spreadsheet
software
• Geographic Information System (CIS) skills to geographically
illustrate and locate local sources of air pollution, if available
Staff from the state, tribal, or local departments of the environment
will be familiar with the state, tribal, and national databases that
contain information on sources. Those agencies may have already
assembled a comprehensive air emission inventory for the National
Toxics Inventory. This will be an excellent starting point for
constructing the Emission Source Inventory for the study area.
Members of the Partnership from governments, environmental
organizations, industry, or academic institutions and community
professionals will have the technical skills needed for accessing and
using databases and for estimating emissions.
Resident and industry members of the Partnership will have the
detailed knowledge of the study area to help finalize the inventory
through "ground-truthing," identifying sources that may have been
missed as well as ones that have gone out of business. And community
leaders in the Partnership will be able to help mobilize the
community to collect any information not available in the databases.
Community Air Screenins How-To Manual
75
-------
Chapter 4: Building the Emission Source Inventory
Only the
knowledge and a
broad level of
participation of
local residents
and businesses
will ensure that as
many sources as
possible are
identified and
included in the
inventory
The Emission Source Inventory can be stored on a computer using
spreadsheet software. In the Baltimore project, the inventory was
stored using a commercially available spreadsheet. The Emission
Source Inventory computer should have access to the Internet so that
publicly available databases can be accessed.
The skills needed for communicating the inventory work to the
broader community can come from the different members of the
Partnership working on the communication team.
How will the Partnership collect the data?
The Partnership will probably want to appoint a technical team from
among its members to plan and carry out the work of completing the
Emission Source Inventory. Ideally, this team, referred to as the
Inventory Team in this Manual, would include both technical
members of the Partnership and non-technical community members
interested in collecting information on local sources. The Inventory
Team will be needed to collect new information at each step of the
screening process, so its work will continue throughout the project.
The work of the Inventory Team will range from assembling
information from databases for the Initial Screen to organizing
members of the Partnership and community to visit sites to collect
the detailed information that will be needed in the Final Screen.
Please remember that although the Inventory Team will be able to
collect much of the data on its own, it will need to rely on the
resources of the full Partnership and the community to assist in the
data collection and to review the information collected to ensure that
it is accurate and complete. For example, only the knowledge and a
broad level of participation of local residents and businesses will
ensure that as many sources as possible are identified and included.
The full Partnership committee will also have to explain the Emission
Source Inventory to the broader community. Therefore, it will be
important for the entire Partnership committee to understand the
work of its Inventory Team and the variety of information that the
Partnership will collect and store in the Emission Source Inventory
database. The information that all the members of the Partnership
will need to understand and to help build the Partnership's Emission
Source Inventory are provided in this and subsequent chapters of the
Overview. Detailed technical guidance to help the Inventory Team
collect the information needed to complete the screening is provided
in the Technical Guidance section of the Manual.
76
Community Air Screening How-To Manual
-------
Chapter 4: Building the Emission Source Inventory
What will the Inventory Team need to do to plan for
the work to complete the Emission Source
Inventory?
In addition to setting up the inventory database and collecting
information on releases and stationary point source locations, the
Inventory Team will also need to develop a plan for collecting the rest
of the information that will be needed to complete all of the screening
steps. To develop this plan, the Inventory Team will need to review all
of the chapters of the Manual to get an understanding of the
information that will be needed. Table 4-1 summarizes the source
types and information that needs to be collected to complete the risk-
based screening (i.e., Initial, Secondary, and Final Screening steps).
Explanations of the information listed in this table will be provided in
this and subsequent chapters of the Overview. The Inventory Team
will also need to work closely with the Partnership team that has the
responsibility for using the information in the inventory to estimate
concentrations. These two Partnership teams will need to make sure
that they share the same understanding of the information that will
be needed. In addition, some of the information requirements will
depend on the decisions that the team responsible for estimating
concentrations will make. For example, for the Initial Screen, the team
estimating concentrations will have a choice of methods to use, and
the information the Inventory Team will be required to collect will
depend on this choice. Details of this choice will be explained in the
Initial Screen Overview and Technical Guidance section.
The Inventory Team's plan for collecting information will also have to
take into account the fact that the team will not know in advance
which chemicals will be identified at each step of the screening
process. For example, detailed information on stack releases, such as
the temperature of the gases on release, will be needed to estimate
concentrations in the Final Screen. But collecting this information for
all the stack releases in the inventory would be a waste of time, since
the information will only be needed for the small number of
chemicals left after the Secondary Screen is completed.
Despite the fact that the Inventory Team will need to wait for the
screening to proceed to know which chemicals to collect information
for, it is still important for the team to understand all the data that
will be needed to complete the screening. Understanding all the data
needs will allow the team to take advantage of easy opportunities to
collect information if they arise. For example, if all the detailed
information on releases that will be needed in the Final Screen comes
in the same database used to collect the information on the amount
Community Air Screenins How-To Manual
77
-------
Chapter 4: Building the Emission Source Inventory
Table 4-1.
Summary of Information Heeded to Complete Risk-Based Screening
TYPE OF SOURCE
INITIAL SCREEN
INFORMATION
NEEDED
SECONDARY
SCREEN
INFORMATION
NEEDED
FINAL SCREEN
INFORMATION
NEEDED
SOURCE OF
INFORMATION
STATIONARY SOURCES:
Stationary Point Sources:
All large and small
commercial, industrial,
and public facility sources
(sources will be modeled
individually)
• Sources with release • Chemicals released
information available • Release amounts
• Distance to nearest
receptor
• Release type: stack or
fugitive
•Approximate stack height
• Sources with release • Chemicals released
information not • Release amounts
available • Distance to nearest
receptor
• Release type: stack or
fugitive
• Approximate stack height
• (Type of business)
• (Chemical use or business
activity measure)
• (Emission factors)
• Chemicals released
• Release amounts
• Source location
• Modeling release
parameters
• (Local meteorological data)
• Chemicals released
• Release amounts
• Source location
• Modeling release
parameters
• (Local meteorological data)
• Detailed release
information provided by
facilities
• Detailed release
information provided by
facilities
• State, tribal, local, and
federal databases
• Local knowledge
• Business databases
• Facility contacts for
detailed business or
release information
• State, tribal, local, and
federal databases
• Local knowledge
• Business databases
• Facility contacts for
detailed business or
release information
Stationary Area Sources: • Total release amounts for
Household, small office county
building, and other
miscellaneous sources
(sources combined for
modeling)
• Chemicals released • Same as
• Total county emissions Secondary Screen
• (Local meteorological data)
• (Census tract geographical
information and
centra ids)
• (Information needed to
apportion county
emissions)
• National Emissions
Inventory (NEI) and
NATA databases
• State databases
• Business databases
• Local knowledge
Note: Information required for screening, but not included in the Emission Source Inventory, is listed in parenthesis.
of releases, and if the information is in a form that will allow it to be
transferred electronically into the Partnership's inventory, then
detailed information on all the chemicals can be collected from the
beginning with minimal effort. Even if the detailed information is not
78.
Community Air Screenins How-To Manual
-------
Chapter 4: Building the Emission Source Inventory
Table 4-1.
Summary of Information Needed to Complete Risk-Based Screening (continued)
INITIAL SCREEN
INFORMATION
TYPE OF SOURCE NEEDED
MOBILE SOURCES:
On-road • Not estimated in Initial
Screen (information
needed for Secondary
Screen collected for
inventory)
Non-road • Not estimated in Initial
Screen (information
needed for Secondary
Screen collected for
inventory)
SECONDARY
SCREEN
INFORMATION
NEEDED
• Chemicals released
• Total county emissions
• (Local meteorological data)
• (Census tract geographic
information and centroids)
• (Information needed to
apportion county
emissions)
• Chemicals released
•Total county emissions
• (Local meteorological data)
• (Census tract geographic
information and centroids)
• (Information needed to
apportion county
emissions)
FINAL SCREEN
INFORMATION
NEEDED
• Traffic counts
• If necessary, information
needed for Mobiles mobile
source emission model
and ISCST line source
modeling
• Detailed information for
large, non-road sources, if
any
SOURCE OF
INFORMATION
• Local knowledge
• Transportation planning
organization
• Local knowledge
• State, tribal, and federal
modeling expertise
BACKGROUND
SOURCES:
MONITORED
CONCENTRATIONS:
• National background
concentration
measurements
• Annual average
concentrations
• Same as Initial Screen
• Annual average
concentrations
• Same as Initial Screen
• Annual average
concentrations
• State, tribal, and local
monitoring authorities
• Monitoring databases
• Local, state, tribal, and
national monitoring
databases
Note: Information required for screening, but not included in the Emission Source Inventory, is listed in parenthesis.
easy to collect, understanding that it may be needed will, at a
minimum, allow the Inventory Team to note where the information
can be found if it is needed at a later date.
As it carries out its plan to collect information, the Inventory Team
will also need to report back to the full Partnership committee on any
sources for which data are not available and let the Partnership know
where the team will need help to collect missing information. The full
Partnership committee can then help to mobilize the community to
collect this information. For example, if the information about the
number of vehicles using a road through the community is not
available, the Partnership may ask a participating high school to
organize a traffic survey.
Community Air Screenins How-To Manual
.79
-------
Chapter 4; Building the Emission Source Inventory
How will the Partnership ensure that the work of its
Inventory Team and all of the work of the Partnership
is done accurately and according to the standards
set by the Partnership?
Over the course of the work, the Partnership and its teams will collect
and transfer detailed information on hundreds of releases, carry out
hundreds of calculations to develop screening concentrations for all
the chemicals, and set up and run computer models containing large
amounts of information. Since the Partnership and the community
will rely on all of this work to make decisions and to commit
resources, it will be essential to ensure that all the work is done
accurately and according to the Partnership's guidelines. Even small
errors in transferring information from one database to another, such
as the misplacement of a decimal point, could change the outcome of
the screening process for a chemical. Since the teams may make some
unintentional errors during the course of their work, some system for
checking work and identifying errors will need to be established.
Quality control methods for ensuring data quality and accuracy are
available and the Partnership should consider the available resources
and establish its own system to ensure the accuracy of the screening
work. If enough resources are available, the Partnership may want to
set up a separate quality control committee and give it the
responsibility for reviewing the work of all the technical committees.
Setting up a separate committee for data quality would allow the
reviewers to be different from the persons doing the work. Teams
checking their own work usually have a more difficult time spotting
errors. If a separate committee is not possible, each team will have to
set up a system to double check all of its work to make sure that it is
accurate.
What are the different types of emission sources that
may exist in the Partnership area?
There are a wide variety of air emission sources that need to be
included in the Partnership inventory, ranging from large chemical
facilities and power plants to the gasoline-powered lawnmowers that
community members may use to cut their grass. The following is a list
of the different kinds of sources that may be found in communities,
with examples to illustrate each type of source. As is customary, this
list is divided into stationary, mobile, and background sources.
80
Community Air Screening How-To Manual
-------
Chapter 4: Building the Emission Source Inventory
Stationary sources: Stationary sources include all the emission
sources that come from fixed locations. This type of source includes
both large and small stationary sources, ranging from large sources
such as electric utility plants, chemical plants, steel mills, oil refineries,
and hazardous waste incinerators, to small stationary sources such as
the neighborhood dry-cleaners and auto repair and refinishing shops.
Small stationary sources also include all the emission sources from
homes and small office buildings, such as wood stoves, gas-fired home
heating, and even household chemical uses.
In this Manual, these stationary sources are divided into two separate
groups based on the methods that will be used to estimate the
concentrations that result from their releases. The first group of
stationary sources includes all the sources whose concentrations will
be estimated individually. All the large and small businesses, from
large chemical facilities and steel mills, to the gasoline station on the
neighborhood corner, are included in this group. Publicly owned
facilities such as incinerators and water treatment plants are also put
into this group. Each of these facilities will have the concentrations
resulting from its releases estimated individually. For consistency and
to avoid repeating the long description of this group, in this How-To
Manual, all of these stationary sources (i.e., those whose concen-
trations will be estimated individually) are called stationary point
sources.
The second group of stationary sources includes all the sources that
are too numerous or irregular to handle practically as individual
sources. Household sources such as heating furnaces, small offices,
and exterior painting are examples of these sources. Because the
releases from these sources are too numerous to have their concen-
trations estimated individually, they are combined together by type.
For example, the releases from all the home furnaces are grouped
together, and the concentration that results from the combined
releases is estimated. In this Manual, all of these lands of sources, that
is, sources whose releases will be combined for estimation, are called
stationary area sources. The sources that are treated as stationary area
sources are listed here, using the categories established in the National
Toxics Inventory:
• Agricultural production
• Asphalt paving: cutback asphalt
• Consumer products usage
Community Air Screenins How-To Manual
81
-------
Chapter 4: Building the Emission Source Inventory
• Gasoline distribution stage 1
• Industrial boilers: distillate oil
• Institutional/commercial heating (all types)
• Natural gas transmissions and storage
• Non-industrial asphalt roofing
• Pesticide application
• Residential heating (all types)
• Residential heat (wood)
• Structure fires
• Surface coatings: architectural
• Surface coatings: industrial maintenance
• Surface coatings: traffic markings
Mobile sources: Mobile sources include all the emission sources that
move or can be moved from place to place. This group contains all
types of vehicles and equipment, from cars and trucks to construction
equipment and lawnmowers.
Databases with information on mobile sources are divided into two
categories: mobile on-road and mobile non-road. The Partnership's
inventory database will also use these categories to store its
information on mobile sources. On-road mobile sources include all
cars, buses, trucks, and any other vehicle used on streets and
highways. The non-road mobile sources include everything from
airplanes and ships to construction equipment and lawnmowers.
Background sources: There are three types of sources contributing to
community air concentrations that are called background sources:
very distant sources, such as the major power plants in the Midwest
that contribute to air concentrations in Eastern cities; natural sources,
such the production of methyl chloride by naturally occurring
bacteria in bodies of water; and chemicals persisting in the
environment from past human uses, such as the releases from soil
contaminated with carbon tetrachloride, a chemical widely used in
the past.
82
Community Air Screening How-To Manual
-------
Chapter 4: Building the Emission Source Inventory
What information on these emission sources will the
Inventory Team collect to start the Emission Source
Inventory database?
As the Partnership prepares to conduct its screening the Inventory
Team will focus first on collecting information on the amounts of
releases from the emission sources and on identifying and locating
stationary point sources. The additional information that will be
needed to complete each step of the screening process is discussed in
the subsequent chapters of the Manual. The release amount
information that will be collected and entered into the inventory
database for each kind of source is described below:
• Stationary point sources: the release amounts for each chemical
from each source.
• Stationary area sources: the total emission amount for the
county in which the Partnership is located for each type of area
source.
• Mobile on-road sources: the total emission amount for the
county for all on-road mobile sources.
• Mobile non-road sources: the total emission amount for the
county for all non-road mobile sources.
• Background sources: Estimated background concentrations
provided by the EPA Air Office. Universities may also have
research information on local background concentrations.
Information on background source concentrations may also be
obtained by reviewing local monitoring data.
Table 4-2 summarizes the source types and the information that
needs to be collected to start the Emission Source Inventory database.
Information on the amount of releases for all of the large and some of
the small stationary point sources will be available for each individual
source in state, tribal, and national databases. For some small
stationary point sources, the Inventory Team will be able to find only
estimates of the combined releases for all of the sources in a category.
For example, in some states, releases for dry-cleaning facilities are not
available for each facility. Only an estimated total release amount for
all the dry-cleaners in a county will be available. In that case, since all
of the concentrations for all the stationary point sources need to be
estimated individually, the Inventory Team will need to estimate
releases for each of the dry-cleaners in the Partnership area. To
estimate the releases from these sources, the Partnership may need to
collect information such as the chemical use or sales volume of the
Community Air Screenins How-To Manual
83
-------
Chapter 4: Building the Emission Source Inventory
business. Methods to estimate the releases based on these kinds of
information are available, and directions on their use are provided for
the Inventory Team in the Technical Guidance section of the Manual.
During the Initial and Secondary Screening steps, the Partnership will
be using readily available release data based on maximum permitted
release amounts as inputs for the look-up table and the ISCST model,
respectively. If the release data available to the Partnership are only
Table 4-2.
Source Types and Information Heeded to Start Building Emission Source
Inventory Database
TYPES OF SOURCES
INFORMATION NEEDED TO
START BUILDING THE EMISSION SOURCE
INVENTORY DATABASE
STATIONARY SOURCES:
Stationary Point Sources: All large and
small commercial, industrial, and public
facility sources (sources will be modeled
individually)
• Sources with individual release information
available
• Sources with release information not
available
Stationary Area Sources: Household, small
office building, and other miscellaneous
sources (sources will be combined for
modeling)
•Release amounts and location for each
source
• Location information plus additional
information needed to estimate release
amounts for these sources
• Total county release amount for each type of
source
MOBILE SOURCES:
On-road: All truck, buses, cars, and any other
street or highway vehicle
Non-road: Trains, airplanes, ships,
construction equipment, lawn equipment
• Total county release amount for all on-road
sources
• Total county release amount for all non-road
sources
BACKGROUND SOURCES:
Releases from very distant sources and
releases that are not the result of current
human activity, including both natural
and past human sources
•Concentrations for each background
chemical
84
Community Air Screenins How-To Manual
-------
Chapter 4: Building the Emission Source Inventory
estimated actual release amounts and not maximum permitted release
amounts for stationary sources, the Partnership will need to increase
these release estimates, possibly multiplying the release amount by a
factor agreed on by the Partnership, to ensure that the Initial and
Secondary Screens are conservative. For example, release estimates
taken from the TRI database are estimated actual releases, not
maximum permitted releases, so the Partnership's technical team will
need to increase these amounts to ensure that the Initial and
Secondary Screens are conservative. For the Final Screening step the
Partnership will have the resources to contact each of the remaining
stationary sources to obtain actual release data.
What chemicals will be included in the Emission
Source Inventory?
The goal of the Partnership will be to include as many chemicals as
possible in its inventory. To do this, the Partnership will have to access
several databases or information sources maintained by different
government agencies. Each of these databases and data sources
contains information on its own list of chemicals. Many of the
chemicals will be the same in all of the data sources, but some
chemicals will be found in only one and not the other databases. The
Partnership will use all of the available data sources to ensure that it
has information on as many chemicals released in its area as possible.
Further guidance on accessing these data sources can be found below
and in the Technical Guidance section of the Manual.
Since some of the releases from a source can be found in more than
one database, the Partnership will have to be careful to avoid double
counting releases. If the same releases are recorded in more than one
database, the Partnership's Inventory Team will use only the
information from the database with the most up-to-date information.
It is also possible that some releases may have been entered more than
once in the same database by error. If there are multiple releases of the
same chemical from the same facility, the Inventory Team may want
to check to be sure that they are actually different releases and not
multiple entries for the same release. Checking to make sure that the
release amounts entered into the Partnership's database are not the
result of counting the same release more than once will be a key part
of the Partnership's quality control work.
Community Air Screenins How-To Manual
85
-------
Chapter 4: Building the Emission Source Inventory
If monitoring information is available for the
Partnership area, should it also be included in the
Emission Source Inventory?
First, some brief background: Monitoring directly measures what is in
the air either at fixed locations in a community or as the air is
breathed by someone living in the community through personal
monitors worn by community volunteers. Since monitoring relies
neither on estimates based on computer modeling nor on release data,
it can provide accurate measures of concentrations at specific
locations. Setting up new monitoring is an appropriate and thorough
way to analyze community air, but it can be expensive, and it will
require at least a year of measurements for estimates of long-term
effects. Because of its cost, monitoring can only be done in a limited
number of locations in a community. The information on
concentrations from monitoring also has some limits. By itself,
monitoring does not provide information on the sources of the
chemicals measured at the monitoring location. And most
monitoring involves sampling air at regular intervals, so monitored
concentrations can only represent the concentrations in the air at the
times of measurement. The screening methodology described in this
Manual uses existing monitoring information, if it is available, but, to
minimize resources, it does not require new monitoring. The
possibility of monitoring to verify the results of the screening exercise
is discussed in Chapter 7.
In place of new monitoring, the screening method in this Manual
makes use of the information from monitoring stations that have
been set up and are operating in cities across the nation. If a
monitoring station is located in or near the Partnership
neighborhood, and the Partnership has determined that the
monitoring data are appropriate for use, the Inventory Team should
collect all the available information on monitored concentrations and
enter the information into the Emission Source Inventory database.
(Remember that monitoring stations measure concentrations of
chemicals. This concentration information is different from the
release information collected for the Initial Screen for each source, so
it will need to be separated from the release data and labeled
appropriately in the Emission Source Inventory database.) These
concentrations will be screened along with the concentrations
estimated with air dispersion models. The availability of appropriate
monitored concentrations will allow the Partnership to verify the
accuracy of its modeling. The monitoring can also be used to help
ensure that all the sources of monitored chemical emissions have been
86
Community Air Screening How-To Manual
-------
Chapter 4: Building the Emission Source Inventory
identified. Guidance for using the monitored concentrations will be
provided in subsequent chapters.
How will the Partnership decide if the available
monitoring information is appropriate for use in its
screening exercise?
This Manual encourages the use of ambient air monitoring data to
supplement and verify concentrations estimated by air dispersion
modeling. However, when considering how to use monitoring data,
the team must understand the goals of the monitoring program
collecting the data and the limitations in the spatial and temporal
coverage of the data. For example, a program designed to determine
the average concentrations of air pollutants across a city might not be
an appropriate surrogate for the concentrations of pollutants at the
fencelines of facilities releasing the chemicals.
Several things should be considered when deciding whether or not to
use monitoring data instead of estimated airborne pollutant
concentration.
• Does a monitoring network exist for the pollutants of interest
and what are the averaging times of concern?
• What is the location of the air monitor in relation to the study area?
• Was any air modeling already done to locate the monitoring
station?
• Will the local topography greatly influence the local air patterns
and dispersion?
• Has the monitoring network been designed to locate points of
maximum concentrations, average concentrations, or other?
• Do the data set and analysis allow the impact of the most
important individual sources to be identified if more than one
source or emission point is involved?
• Is at least one full year of valid ambient data available ?
These questions are intended to help in making the decision whether
to use monitoring data on concentrations to supplement the
concentrations estimated by air dispersion modeling. It is
recommended that this discussion take place and that the decision on
the usefulness of available monitoring data be made prior to entering
the data into the Emission Source Inventory database.
Community Air Screenins How-To Manual
87
-------
Chapter 4: Building the Emission Source Inventory
What are sources for the information that will be
needed?
To collect the information needed to complete the Emission Source
Inventory database, the Partnership technical team will have to draw
on a variety of different sources. In some cases, where information has
not been collected or is not available, the Partnership may need to
mobilize its members and the community to collect the information
that will be needed. The following is a list of information sources for
the data and information that will be needed to complete the
inventory.
Local knowledge: Members of the Partnership and community,
including residents and local businesses, will have a lot of information
on the location and releases from sources in the Partnership area. This
local knowledge will be used to "ground-truth" and supplement the
information collected from the government databases discussed
below. For example, local residents and businesses may be able to
identify sources not listed in databases, releases not reported, or
heavily used roads and unusual truck traffic. And in the cases where
important information is not available, the Partnership can also
organize the collection of information needed to complete the
screening process such as traffic counts or information on small
businesses.
State, tribal, and local government air permitting databases: The
state, tribal, or local government authority responsible for permitting
releases to air maintains a database with information on local sources
and their releases. This is the primary source for government
information on local air sources. The amount and kind of
information collected will depend on the local authority. The state,
tribal, and local databases, since they often contain the most up-to-
date information available, are recommended as the preferred source
of data for this screening exercise. If access to the database covering
your state is not available, information can be obtained from the
National Emissions Inventory, described next.
National Emissions Inventory (NEI): This database of air emissions
information is prepared by EPA with input from numerous state and
local air agencies, from tribes, and from industry. This database
contains information on stationary and mobile sources that emit
criteria air pollutants and their precursors, as well as hazardous air
pollutants (HAPs). A list of the HAPs is shown in Appendix E.
Criteria pollutants are used by EPA as indicators of air quality. The
88.
Community Air Screening How-To Manual
-------
Chapter 4: Building the Emission Source Inventory
criteria pollutants are ozone (O,), carbon monoxide (CO), nitrogen
oxides (NOx), sulfur dioxide (SOx), participate matter with diameter
less than or equal to 10 micrometers (PM10), particulate matter with
diameter less than 2.5 micrometers (PM2 s), lead (Pb), volatile organic
compounds (VOCs), and ammonia (NH3). HAPs are generally
defined as those pollutants that are known or suspected to cause
serious health problems. Section 112(b) of the Clean Air Act currently
identifies a list of 188 pollutants as HAPs, including solvents such as
benzene, toluene, and xylene. More information about the NEI
database and the compilation of criteria pollutant and HAP emissions
inventories, and links to the database, are available on the CHIEF NEI
web page at http://www.epa.gov/ttn/chief/net.
The list of HAPs is available at http://www.epa.gov/air/urbanair/
6poll.html. The list of HAPs is also provided in Appendix E.
Toxics Release Inventory (TRI): The Toxics Release Inventory (TRI)
is a publicly available EPA database that contains information on toxic
chemical releases and other waste management activities reported
annually by certain covered industry groups as well as federal
facilities. This inventory was established under the Emergency
Planning and Community Right-to-Know Act of 1986 (EPCRA) and
expanded by the Pollution Prevention Act of 1990.
The TRI program has expanded significantly since its inception in
1987. The Agency has issued rules to roughly double the number of
chemicals included in the TRI to approximately 650. Seven new
industry sectors have been added to expand coverage significantly
beyond the original covered industries, that is, manufacturing
industries. Most recently, the Agency has reduced the reporting
thresholds for certain persistent, bioaccumulative, and toxic (PBT)
chemicals in order to be able to provide additional information to the
public on these chemicals. Information on the TRI is available at
http://www.epa.gov/tri/.
Ambient air monitoring databases: Federal, state, tribal, and local
agencies sometimes establish monitoring stations to directly measure
the levels of chemicals in the air. This monitoring will be increased
over the next several years as a result of the new National Air
Monitoring Program established by the Clean Air Act. Information on
the measurements of chemicals at monitoring stations in or near the
Partnership area may be available. Government staff members of the
Partnership will know how to access this information. For
information see http://www.eua.aov/ttn/amtic/stratmem.html.
Community Air Screening How-To Manual
89
-------
Chapter 4: Building the Emission Source Inventory
Local transportation planning organizations: The information
needed to estimate concentrations for mobile sources may be
available from the organizations that plan for local transportation. As
a part of their efforts to plan for transportation needs, these
organizations are required to estimate mobile source emissions for
urban metropolitan areas. Roadway information and the number of
vehicles traveling on the roads may be available from this source.
National Air Toxics Assessment (NATA): The NATA program
provides background concentrations based on monitored values
identified in the Cumulative Exposure Project, a study that estimated
nationwide 1990 ambient concentrations of air toxics. Based on that
study, nationwide background concentration values for 13 toxic air
pollutants were developed. Details for including these background
concentrations in the Emission Source Inventory can be found in
Chapter 9, the Technical Guidance chapter for building the Emission
Source Inventory. Additional information on these background
concentrations can be found at http://www.epa.gov/ttnatwO 1 /nata/
backcon.html.
Commercial business databases: There are a number of commercial
databases that list and describe business activity for every part of the
nation. These sources of information can be used to help find and
identify all the businesses in the area that may be using and releasing
chemicals. These data sources may also contain information on the
size and activity of the businesses. If release information for small
businesses is not available, this information may help the Partnership
technical team to develop release estimates for these businesses. In
Baltimore, the Partnership used the commercially available Dunn and
Bradstreet database to help identify area businesses.
Chemical Emergency Preparedness and Prevention Office
(CEPPO): EPA's Chemical Emergency Preparedness and Prevention
Office provides leadership, builds partnerships, and offers technical
assistance to prevent and prepare for chemical emergencies, respond
to environmental crises, inform the public about chemical hazards in
their community, and share lessons learned about chemical accidents.
Their web site is at http://www.yosemite.epa.gov/oswer/ceppoweb.nsf/
content/mission.htm.
They maintain a Local Emergency Planning Committee database,
providing over 3,000 listings by state at http://www.epa.gov/ceppo/
leuclist.htm#bvstate.
90
Community Air Screening How-To Manual
-------
Chapter 4: Building the Emission Source Inventory
What will the Emission Source Inventory database
look like?
Figure 4-1 is an illustration of an Emission Source Inventory database
with sample stationary point source data.
What happens once the Emission Source Inventory is
completed?
The completed Emission Source Inventory database and summaries
of the data should be presented at a meeting of the entire Partnership
committee. The inventory can then be shared with the broader
community, both for input and as an opportunity to educate the
community on the project's progress. Once the database is complete,
the work can then proceed to the next step, the Initial Screening step,
where all the information collected in the Emission Source Inventory
will be used to make the first cut at identifying the chemicals and
sources that will be community priorities. This step is described in the
next chapter.
What can the Partnership committee do to involve
the broader community in the review of the Emission
Source Inventory database?
The Partnership may want to prepare summaries and organize
community meetings to ask the community to check to make sure
that all of the local sources are included in the Emission Source
Inventory database. Maps and the Geographic Information System
(GIS) can be used to illustrate the sources and their locations. This
will be an excellent opportunity to educate the community, both
residents and businesses, on the sources and the releases that take
place in and around the Partnership area. This will also be an
excellent opportunity to build the Partnership and recruit new
members from sectors of the community not yet involved in the work.
Questions that are likely to arise concerning the meaning of this
information and the possible effects of releases on community health
will provide the Partnership with an opportunity to explain the goals
of the Partnership and the next steps of the screening process.
Community Air Screenins How-To Manual
91
-------
12 Microsoft Excel - Source lnventory.xls [^ ]|w J^1]
P] File Edit View Insert Format
D >i \ Template / Area Sources
Ready
tools Data Window Help Adobe PDF
in
NUM
' ','jStaffiT r^0asc Paint Shop Pro ^fc J:\EW_OPSKOMMO... E Microsoft Excel -Sour... \^- ;*-%p> £*_%* W:35:AM
Figure 4-1.
An Illustration of an Emission Source Inventory Database
92
Community Air Screening How-To Manual
-------
Overview
Initial Screen
Initial Screen Overview
Step 1: Estimating Concentrations
Step 2: Setting the Screening Level and
Developing Screening-Level
Concentrations
Step 3: Comparing Community Air
Screening Concentrations to
the Screening-Level
Concentrations
Analyze
How is this explanation of the Initial Screen
organized?
This Initial Screen section of the How-To Manual Overview is divided
into the following four parts:
Initial Screen Overview: a general overview of the Initial Screen
Step 1: Estimating Concentrations: a description of the method that
will be used to find or estimate concentrations of chemicals in
community air
Step 2: Setting the Screening Level and Developing Screening-
Level Concentrations: a description of how the Partnership will set
its risk screening level and its risk-based screening concentrations
Step 3: Comparing Community Air Screening Concentrations to
the Screening-Level Concentrations: a description of how the
Partnership will compare the estimated concentrations to the
screening-level concentrations to identify chemicals that need
further review
Community Air Screenins How-To Manual
.93
-------
Chapter 5: Initial Screen
• Initial Screen Overview
Initial Screen Overview
How does the screening process work?
As described in the Introduction, the Initial Screen is the first of three
screening steps designed to identify the chemicals in community air
that have concentrations that are above the community risk screening
levels. These three screening steps are designed to provide a practical
way for a community to use the minimum possible amount of
resources to sort through all the air releases in and around their area
and identify the priority chemicals and sources. A general explanation
of the screening methods used in this Manual is provided in Chapter
3. You may want to review that explanation as background for this
chapter. A detailed explanation of the Initial Screen, the first of the
three screening steps, is provided in this chapter.
What is the purpose of the Initial Screen?
With a large number of chemicals and sources, the task of accurately
estimating concentrations in community air would be a resource-
intensive effort for a community partnership. To avoid this problem,
the Initial Screen uses a simpler method that requires fewer resources
to review all the chemicals and sources to find those chemicals that
have concentrations that are clearly at or below the community
screening levels. Because these chemicals are at or below the
community screening levels, they will be set aside as a lower priority.
They will not need further review in this screening process.
Eliminating these chemicals in the Initial Screen means that the
resource-intensive methods needed to more accurately estimate
concentrations that will be used in the Secondary and Final Screening
steps will have a smaller number of chemicals to review.
Can the Partnership be sure that the chemicals
eliminated from further review by the Initial Screen
do not have concentrations in the community air
that are above the community screening level?
The community can be confident that the chemicals eliminated
during the Initial Screen do not have concentrations in community
air that are above the community screening levels because the
methods used to estimate concentrations in the Initial Screen are
designed to overestimate the concentrations in community air.
94.
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
• Initial Screen Overview
Instead of using the resource-intensive methods necessary to more
accurately estimate concentrations, the Initial Screen uses methods
that assume a kind of "worst case" scenario that is designed to
overestimate the concentrations. The method, for example, assumes
that the direction of the wind in the community is always in the
direction that results in the highest concentration and that the
releases are always at the maximum permitted level. If the
concentrations estimated using these worst-case assumptions are still
at or below the community screening levels, then the community can
confidently set these chemicals aside and focus on the chemicals that
remain after completing the Initial Screen that may have
concentrations above the community screening levels. (Also
remember that all mobile source chemicals will be passed to the
Secondary Screen for analysis.)
It is, however, important to keep in mind that the Initial Screen
estimates are only as good as the information they are based on. If the
releases are actually greater than the releases recorded in the
Partnership's Emission Source Inventory database, or if the
community inaccurately estimates the distance from a source to the
nearest exposed community members, then the Initial Screen
estimation of concentrations could be too low, i.e., the Initial Screen
could underestimate instead of overestimate the concentration. Also,
release amounts could be inaccurate if there are unknown sources or
if the sources are releasing more than they are reporting. So
confidence in the results of the Initial Screen depends on the accuracy
of the information the Partnership has collected and entered in the
Emission Source Inventory database.
It is also important to remember that chemicals set aside in this
screening exercise should be reviewed periodically to see if there are
any changes in release amounts or changes in any of the factors that
might affect the screening levels. (These will be explained below.)
Eliminating a chemical from further review in a screening exercise
does not mean eliminating it permanently from review. All chemicals
and releases should be reviewed periodically so that the Partnership
can incorporate any new information that may affect the results of the
screening. In addition, the Partnership may want to flag chemicals
screened out during the Initial Screen that have concentrations that
are close to the screening-level concentrations for further
consideration in the future.
All chemicals and
releases should
be reviewed
periodically so
that the
Partnership can
incorporate any
new information
that may affect
the results of the
screening
Community Air Screenins How-To Manual
.95
-------
Chapter 5: Initial Screen
• Initial Screen Overview
How does the Initial Screen differ from the
Secondary and Final Screens?
The Secondary and Final Screens differ from the Initial Screen only in
the methods used for estimating concentrations. The level of risk and
the screening-level concentrations developed in the Initial Screen will
stay the same throughout the screening exercise. In place of the simple
methods used to overestimate concentrations in the Initial Screen, the
Secondary and Final Screening steps use more sophisticated methods
and better release information to produce more accurate estimates for
the concentrations of chemicals in community air.
What steps will the Partnership need to complete in
the Initial Screen?
To complete the Initial Screening step, the Partnership will start with
the information on releases collected and stored in the Emission
Source Inventory database and use this information to complete the
following steps.
Summary of Steps to
Complete the Initial Screen
Step 1: Set up a quality assurance/quality control (QA/QC)
procedure to ensure that all of the work of the Initial
Screen is accurate and complete.
Step 2: For each chemical considered in the Initial Screen,
estimate the ambient air concentration for all chemical
emissions that results from all the sources of the
chemical.
Step 3: Choose a level of risk to serve as the community's risk
screening level.
Step 4: Calculate the risk screening concentration, i.e., the
concentration equivalent to the risk screening level, for
each chemical in community air.
Step 5: Compare the concentration for each chemical in
community air to its risk screening concentration and
identify the chemicals with concentrations above their
screening levels. These chemicals will be looked at more
closely in the remaining steps of the screening process.
96.
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
• Initial Screen Overview
A detailed description of each of these steps is provided in this
chapter. Please note that mobile source chemicals and certain other
sources will not be reviewed until the Secondary Screen.
How can the Partnership organize itself to effectively
carry out the tasks needed to complete the Initial
Screen?
To complete all the technical
tasks necessary to estimate
concentrations and to
calculate community
screening levels, the
Partnership will probably
need to appoint one or two
teams from among its
members. Partnership
members with the necessary
technical skills to complete
the tasks will join with other
interested members to
complete the work and
present it to the full
Partnership committee for
review and approval. If
enough resources are
available, organizing two teams, one for estimating concentrations
and one for developing screening concentrations, will save time, since
these tasks can move forward simultaneously.
What are the key decisions that the Partnership will
need to make during the Initial Screening to ensure
that screening meets its needs?
There are two important decisions that will need to be made during
the Initial Screen that will require input from the full Partnership
committee. First, the Partnership will need to decide on the level of
risk to use for screening. Setting the level of risk that the community
agrees to use as the screening level is a key decision for the
Partnership and the community. A full discussion of the meaning of
this risk screening level and a discussion of factors to consider in
setting this level are provided later in this chapter.
St. Louis Community Air Project (CAP) team at work.
There are two
important
decisions that will
need to be made
during the Initial
Screen that will
require input from
the full
Partnership
committee
Community Air Screenins How-To Manual
.97
-------
Chapter 5: Initial Screen
• Initial Screen Overview
To make the
decisions needed
to calculate
screening
concentration
values, the
Partnership will
need to consider
a broad range of
views and
perspectives
Second, the full Partnership committee will need to make decisions to
ensure that the screening-level concentrations that it will use to screen
chemicals meet its needs. As explained below, the full Partnership
committee will rely on a technical team from among its members to
calculate screening concentrations. To ensure that its technical team
calculates screening concentrations that meet the Partnership's needs,
the full Partnership committee will have to decide on the rules and
standards that its technical team will follow to develop the screening-
level concentrations. The participation of the full Partnership
committee in choosing the level of risk and setting the rules for the
development of the screening concentrations will ensure that the
screening steps are carried out in a way that best reflects community
values and needs.
What new information will be needed to complete
the Initial Screen?
The Partnership's Inventory Team will collect the information about
emissions needed to estimate ambient air concentrations during the
Initial Screen. The new emissions information that will be needed is
described below. The Partnership will also need to collect the
information needed to calculate the screening-level concentrations for
each of the chemicals in its Emission Source Inventory database.
These screening-level concentrations will be used during the Initial,
Secondary, and Final Screening steps. The Partnership team with the
responsibility for calculating screening-level concentrations will
collect this information and add it to the Emission Source Inventory
database. This information is also described below. Detailed guidance
to help the teams collect this information can be found in Chapter 10,
in the Technical Guidance section of the Manual.
What resources and skills will be needed to
complete the Initial Screen?
The Initial Screen will require the skills and resources of most of the
Partnership committee. The following is a list of the skills and
resources the Partnership will need to complete the Initial Screen.
Deliberative skills: In its decisions on the level of risk to use for the
screening process and on the standards for choosing and calculating
screening concentration values, the Partnership will need to consider
a broad range of views and perspectives. The ability of the members
of the Partnership to use deliberative skills to consider different
98.
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
• Initial Screen Overview
viewpoints and help the Partnership find common ground on this key
issue will be crucial to the success of the project. It will also be
important for the Partnership to solicit input from the broader
community on these decisions so that the community is prepared to
support potential actions that might be needed to improve local air
quality.
Technical skills: The Partnership committee will need to appoint
teams from its members to carry out the technical work of estimating
concentrations and finding or calculating screening values. To
accomplish these tasks for the Partnership, the technical teams will
need expertise with air dispersion modeling, risk, and the calculation
of risk screening concentrations. Familiarity with available databases
with screening values and toxicity data would also be helpful. Science
teachers, science students, science faculty, technical government staff,
retired engineers and scientists, and industry scientists could provide
these skills. Expertise in the science of toxicology will be especially
important for calculating screening-level concentrations.
Science education skills: Most of the risk science that will be used in
the screening process is introduced in the Initial Screening step. It will
be important for all the members of the Partnership committee to
understand and be comfortable with this science. Individuals with
skills in explaining science and technical models to non-technical
audiences will be needed to help with the explanation of this science
and its use in the screening process. Teachers and technical writers on
the committee could provide these skills.
Communication skills: Explaining the Initial Screen and its results to
the broader community will be an important part of the Partnership's
work during and at the completion of the Initial Screen. (See the
discussion of communication in Chapter 2.) The Partnership
committee will need individuals with the ability to communicate the
work of the Partnership to the community. Community members,
teachers, journalists, or possibly a team that combines community
members with professional writers could provide these skills.
Community Air Screening How-To Manual
99
-------
Chapter 5: Initial Screen
• Initial Screen Overview
A strong and
effective working
relationship
among all
members of the
Partnership is an
essential
component of
long-term
community
capacity
How can the Partnership carry out the work of the
Initial Screen in a way that helps to build the Ions-
term capacity of the community to understand and
improve air quality?
Here are a couple of ideas that may help the Partnership to conduct
its work in a way that builds the long-term capacity of the community
to understand and improve air quality. First, making the decision on
the level of risk that will be used for screening, a key Partnership and
community decision, will require considerable discussion, debate, and
education. If the Partnership conducts these discussions and makes its
decision in a way that respects and values the opinions of all of its
members, the experience will go a long way to building trust and
strengthening the relationships among the Partnership members. A
strong and effective working relationship among all the members of
the Partnership is an essential component of long-term community
capacity.
Second, the Initial Screen presents an excellent opportunity to provide
the background education that the broader community will need to
understand and participate in the work to improve local air quality.
Providing education and organizing discussion in the community
focused on the key decisions associated with setting and calculating
risk screening levels will help to develop the community's long-term
capacity to address air quality issues.
And third, working with community residents, teachers, and students
to estimate concentrations and calculate screening levels will help to
ensure that the technical skills needed for future work exist within the
community. The technical teams could focus on training a core of
community residents and teachers in the skills necessary to complete
the technical work of the Initial Screen and then work with them to
carry out the work. Establishing a center for this work in a local high
school or college would also help to ensure that the community
maintains these skills. Focusing on using the technical work to build
the long-term capacity of the community will take more resources,
but the benefits gained in building community capacity and
community confidence in the validity of the work may justify the
extra time and effort.
100.
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 1: Estimating Concentrations
Step 1:
Estimating Concentrations
Where does the information on air concentrations of
chemicals come from?
There are two sources for the information on the concentrations of
chemicals in community air. The first source is the ambient air
monitoring stations that may be located in or close to the Partnership
area. These monitoring stations collect air samples on a regular basis.
These samples are analyzed to determine the concentration of
chemicals present in the air at the monitoring station. The measured
concentrations can be combined to provide annual average
concentrations for the chemicals that are monitored. Local
monitoring data is a very important resource and it is included in the
Emission Source Inventory database prior to any modeling exercise to
help identify potential chemicals of concern that could require
additional attention.
While these monitored concentrations are an accurate measure of
concentrations at specific locations, the number of monitoring
stations is limited, and many communities and neighborhoods may
not have a station in or near their area. In addition, monitoring
stations measure concentrations at the station locations only, so,
depending on the location of sources in the community,
concentrations at other locations in the community may be different
from the concentrations at the monitoring station.
The second source for information on the concentration of chemicals
in community air, the primary source used in this Manual, comes
from air dispersion modeling. Air dispersion modeling uses a
computer to combine information on local wind direction and
meteorological conditions and the behavior of chemical plumes to
model the dispersion of chemicals as they are released from different
sources. (Air dispersion modeling is described in more detail below.)
While air dispersion modeling relies on modeled estimates and not on
actual measurements taken at monitoring stations, this method of
estimating concentrations has been extensively tested and verified to
provide reliable estimates of the concentrations that result from
chemical releases. Information on the reliability of air dispersion
modeling is available in Appendix W at the Support Center for
Regulatory Air Models (SCRAM) web site at http://www.epa.gov/
scramOO 1 /tt25 .htm#guidance.
Initial Screen Step
AfWWN
JJJJJJ
Step 1:
Estimating
Concentrations
*
Step 2:
Setting the Screening
Level and Developing
Screening-Level
Concentrations
*
Step 3:
Comparing
Community Air
Screening
Concentrations to
the Screening-Level
Concentrations
Community Air Screenins How-To Manual
.101
-------
Chapter 5: Initial Screen
• Step 1: Estimating Concentrations
An example of a plume. Air dispersion modeling
can be used to estimate concentrations of
chemicals resulting from these and
other types of releases.
Air dispersion modeling can also provide some information that
monitoring cannot. With air dispersion modeling, a community has
the ability to estimate concentrations at key locations in the
community where no monitors are located, such as at a school or near
a group of homes. Air dispersion modeling can also be used to find
the location in a community with the highest concentration of a
chemical. And, perhaps most importantly, air dispersion modeling
makes it possible for a community to estimate the contribution that
different sources make to the concentrations identified as community
priorities. This provides the information needed to target the effort to
reduce releases from selected sources to the appropriate levels.
To use air dispersion modeling, it is important to remember that
modeled estimates are only as good as the information that is put into
the model. Accurate estimates of air concentrations depend on good
information about the sources and their releases. This information is
collected by the Partnership and stored in its Emission Source
Inventory database.
How does air dispersion modeling work?
As chemicals are released from a source, they form a plume and begin
to disperse. The smoke plumes that we commonly see leaving
chimneys or smokestacks are examples of
visible plumes of pollutants dispersing in the
air. Scientists have studied these plumes and
developed models that can predict how
chemicals will disperse as they leave a source
and then can estimate the resulting
concentrations in surrounding locations.
These models are called air dispersion
models, and many of them are available for
use on desktop computers.
What air dispersion models will be
used in the screening process?
The screening process in the How-To Manual
utilizes two EPA air dispersion models:
SCREENS for the Initial Screen and ISCST3
for the Secondary and Final Screens. For the
air dispersion models to estimate
concentrations, information about the
sources and their releases must be collected
and entered into the models.
102
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 1: Estimating Concentrations
How will the SCREENS air dispersion model be used
in the Initial Screen?
With all the sources and releases affecting community air to review,
the Partnership needs a simple way to use air dispersion modeling to
estimate concentrations. These concentrations will be reviewed
during the Initial Screen to identify those that will need more detailed
analysis during the Secondary and Final Screens and those that can be
eliminated because they are definitely below the community screening
levels. Setting up and running an air dispersion model for all the
chemicals and sources in the Partnership's Emission Source Inventory
database would require a lot of resources, so for the Initial Screen, the
SCREENS air dispersion model was used to develop a look-up table
that the Partnership can use to quickly estimate ambient air
concentrations for many of the releases in its database. This look-up
table was developed by running the SCREENS model for a unit
release amount for a range of different stack heights and receptor
distances. The results from SCREENS modeling were used to create
the look-up table shown on Table 5-1. (The mathematical shorthand
used in this table will probably be unfamiliar to most non-technical
members of the Partnership. Members of your technical team will be
able to explain it and demonstrate that using the table to estimate
concentrations is actually quite easy.)
To use this look-up table to estimate a concentration for stationary
sources, the Partnership's technical team will use the information on
stack height and the distance to the closest receptor in the Emission
Source Inventory database to find the appropriate unit concentration
in the look-up table. The team will use this unit concentration and the
release amount to calculate an estimate of the concentration resulting
from the release. This procedure will be followed for each of the
stationary source releases in the Emission Source Inventory database.
If the technical team and Partnership do not have sufficient resources
to collect the information needed to use the look-up table, an
alternative method of estimating ambient air concentration values
using a simple conversion factor based on the SCREENS look-up
table can be used to estimate concentrations. A description of this
conversion factor and discussion of its potential use can be found in
Chapter 10 of this Manual. This conversion factor is also used to
estimate the concentrations resulting from stationary area sources.
Chapter 10 also provides guidance to help the technical team estimate
concentrations resulting from releases from stationary area sources.
Community Air Screenins How-To Manual
103
-------
Chapter 5: Initial Screen
• Step 1: Estimating Concentrations
Table 5-1. Look-Up Table.
Unitized Annual Average Concentration at Different Distances from a Stack fagAn3 perlb/year)
,?t?c,k Distance to Receptor
Height
(m) 15m 20m 50m 100m 200m 300m 400m 500m
3 1.59E-02 1.55E-02 1.04E-02 3.97E-03 1.19E-03 5.78E-04 3.50E-04 2.39E-04
5.63E-03 7.05E-03 5.42E-03 3.33E-03 1.13E-03 5.64E-04 3.45E-04 2.37E-04
8 1.05E-03 2.20E-03 2.93E-03 2.23E-03 1.01E-03 5.33E-04 3.33E-04 2.31 E-04
10 2.35E-04 9.51 E-04 1.94E-03 1.57E-03 9.12E-04 5.08E-04 3.23E-04 2.26E-04
20 1.70E-09 1.08E-06 4.05E-04 4.59E-04 3.37E-04 2.79E-04 2.06E-04 1.55E-04
30 - - 6.98E-05 2.10E-04 1.76E-04 1.30E-04 1.22E-04 1.04E-04
40 - - 6.34E-06 1.02E-04 1.02E-04 8.53E-05 6.49E-05 6.49E-05
50 - - 3.00E-07 4.79E-05 7.03E-05 6.08E-05 4.94E-05 3.81 E-05
75 ... 3.74E-06 2.95E-05 2.95E-05 2.54E-05 2.36E-05
100 - - - 1.11E-07 1.28E-05 1.63E-05 1.59E-05 1.41 E-05
104.
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 1: Estimating Concentrations
Why are these simplified methods for estimating
concentrations using a look-up table appropriate for
the Initial Screen?
As discussed in the Overview section of this chapter, the simplified
use of air dispersion modeling, incorporated in the look-up table,
assumes that the direction of the wind in the community is always in
the direction that results in the highest concentration. This
assumption, and the method for combining concentrations from
different sources discussed below, means that concentrations
estimated using the look-up table are very likely to be overestimated,
i.e., the estimated concentrations will likely be higher than the actual
concentrations in the community air. The fact that the look-up table
overestimates concentrations makes it appropriate for use as the first
step in this screening process. If the concentrations estimated using
the look-up table are below the community screening values, then a
more accurate estimate of the concentrations would be even further
below the screening values. As a result, the look-up table based on the
SCREENS model can be used to identify and eliminate those chemical
releases that need no further review. Limiting the number of
chemicals in the review process will make the resource-intensive
modeling in the next steps of the screening more manageable. That, in
fact, is the purpose of this Initial Screen: to provide an easy way to
find and eliminate chemicals with concentrations that are definitely
below the community screening levels to minimize the resources that
will be needed to perform the more sophisticated air modeling
required during the Secondary Screen.
Who will the Partnership rely on to complete the
technical work of estimating concentrations in the
Initial Screen?
The Partnership will need to appoint a technical team from among its
members to estimate the concentrations for each chemical in the
Emission Source Inventory database. Detailed guidance to help this
team estimate concentrations is provided in the first section of
Chapter 10. The technical team will need to establish clear quality
control procedures to ensure that the estimated concentrations are
calculated and recorded accurately for the Partnership. When the
team has completed its work, it can present the results to the full
Partnership committee for review. The Partnership's Inventory Team
Community Air Screenins How-To Manual
105
-------
Chapter 5: Initial Screen
• Step 1: Estimating Concentrations
will work with the technical team estimating concentrations to collect
the additional information that will be needed to complete the Initial
Screen. The information requirements for the Initial Screen are
discussed below.
What skills will the technical team need to estimate
concentrations in the Initial Screen?
Skills needed will include:
• Ability to create, import, manipulate, and query databases
• Experience in using air dispersion modeling to estimate
concentrations
• Ability to implement QA/QC procedures
College and university students and faculty, high school teachers and
their students, interested community residents, retired professionals,
government staff, and industry and business technical staff are all
likely to have the necessary skills.
Which of the sources and chemicals will have their
concentrations estimated usins the SCREENS look-
up table?
The Emission Source Inventory database contains information on
four types of sources: stationary point, stationary area, mobile on-
road, and mobile non-road. Stationary point sources include all large
and small commercial, industrial, and publicly owned facility sources.
Stationary area sources include household sources such as heating,
wood stoves, and other kinds of sources that are too numerous or
difficult to estimate individually. Mobile on-road sources include all
trucks, buses, cars, and any other street or highway vehicles. Mobile
non-road sources include trains, airplanes, ships, and construction
and lawn equipment. The SCREEN3 look-up table and conversion
factor based on the look-up table will be used to estimate the ambient
air concentrations for stationary point and stationary area sources
only. Concentrations resulting from mobile sources will not be
estimated using the look-up table. This look-up table was developed
to estimate concentrations for stationary sources only. There is no
simple way to use air dispersion modeling to develop a similar look-
up table for mobile sources. In addition, concentrations resulting
106
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 1: Estimating Concentrations
from mobile source emissions are well documented and are likely to
be close to or above the community screening levels. (A list of the
mobile source chemicals is provided in Table 10-4.) For these reasons,
all the chemicals associated with mobile sources will be automatically
moved to the Secondary Screen, where more sophisticated air
dispersion modeling will be used to estimate their concentrations.
This also means that if any chemicals released from stationary sources
are also mobile source chemicals, the Partnership will not estimate
their concentrations during the Initial Screen. Instead, the stationary
source releases of these chemicals will be evaluated during the
Secondary Screen.
In addition, releases from all stationary point sources that are less
than 15 meters (approximately 49 feet) from a place where
community members might be exposed, such as a home or school or
business, will also be automatically moved from the Initial Screen to
the Secondary Screen. The look-up table is not designed to screen for
concentrations at these close distances, so to ensure that these sources
are adequately reviewed, their concentrations will be estimated using
the more sophisticated modeling in the Secondary Screen. The
maximum distance to receptor in the look-up table is 500 meters.
Receptors that are located further than 500 meters from the source are
modeled at 500 meters using the look-up table. This is conservative
because concentrations decrease as the distance to the receptor
increases.
Here is a summary of the sources that will and will not be reviewed in
the Initial Screen.
Sources Reviewed in Initial Screen Sources Not Reviewed in Initial Screen
Stationary point sources more than 15 • Mobile sources, on-road and non-road
meters from closest community exposure
• Stationary point sources less than 15
Stationary area sources meters from closest community exposure
Community Air Screenins How-To Manual
107
-------
Chapter 5: Initial Screen
• Step 1: Estimating Concentrations
What information will be needed to use the SCREENS
air dispersion model?
The information for each source that will be needed to use the
SCREENS model includes the following:
For stationary point sources:
• Amount of release (pound/year) for each chemical
• Type of release: stack or fugitive
• Approximate height of the stack (meters)
• Distance to the closest exposed person in the community
(meters)
For stationary area sources:
• Total county release amount of each chemical from each area
source (pound/year)
Stationary point source releases are divided into stack and fugitive
release types in the Emission Source Inventory database. Examples of
stack releases include a release from a roof vent of a dry-cleaning
business and a release from a large stack like the kind used for most
municipal trash incinerators. Examples of fugitive releases include
emissions from the surface of a treatment pond or from the nozzles at
a gas filling station.
All the information needed to complete the Initial Screen will be
collected and stored in the Partnership's Emission Source Inventory
database by the Inventory Team. An explanation of how this
information will be used in the Initial Screen to estimate
concentrations is provided in the next section.
How will the Partnership's technical team estimate
concentrations for the stationary point sources?
Detailed guidance and examples for estimating concentrations during
the Initial Screen are provided for the technical team in Chapter 10.
The overview provided in this and the next sections are designed to
provide all the Partnership members with an understanding of the
work that will be done by its technical team.
Concentrations from stack and fugitive releases from stationary
point sources will be estimated as follows:
108
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 1: Estimating Concentrations
• To estimate a concentration for each chemical resulting from
a stack release, the technical team will use the information
contained in the Emission Source Inventory database on
release amount, release type, stack height, and the distance to
the closest community exposure with the look-up table to
calculate the concentration resulting from the stack release.
The estimated concentrations resulting from the stack releases
from all the stationary point sources 15 or more meters from the
closest community exposure will be calculated.
• To estimate a concentration for each chemical resulting from a
fugitive release, the technical team will use the same look-up
table and assume that the release is from a three-meter stack.
Although the look-up table is designed for stack releases, using
this assumption will ensure that the concentrations resulting
from the stationary fugitive source releases are overestimated, as
is appropriate for the Initial Screen.
When completed, the technical team will have a list for each chemical
of the concentrations resulting from the stationary point sources,
stack and fugitive, releasing the chemical. (If resources are limited, the
technical team may choose, with Partnership consent, to eliminate the
collection of new information and use a simpler conversion factor,
discussed in Chapter 10, instead of the look-up table to estimate
concentrations.)
How will the technical team estimate the
concentrations from the stationary area sources for
the Initial Screen?
Stationary area sources include household sources such as heating,
wood stoves, and other kinds of sources too numerous or difficult to
estimate individually. To estimate the concentrations resulting from
these sources, the technical team will, for each chemical, add the
county-wide release amounts from all the area sources together and
then estimate the concentration by using a conversion factor based on
SCREEN3. A detailed description of this conversion factor can be
found in Chapter 10. Using this conversion factor and the county-
wide releases for each source, instead of the releases that come from
the sources in the Partnership area only, will likely result in
overestimation of the concentrations appropriate for the Initial
Screen.
Community Air Screenins How-To Manual
109
-------
Chapter 5: Initial Screen
• Step 1: Estimating Concentrations
How will the concentrations that result from the
combined releases of the same chemical from all the
sources in the community be estimated?
If there are multiple stationary sources of the same chemical in or
around the Partnership area, the concentration in air at a location in
the community may be the result of a combination of these sources.
This occurs when the dispersion plumes from the sources overlap.
Since the look-up table only provides estimates for each point source
and for the area sources separately, some method for estimating the
combined (aggregate) concentration resulting from all the stationary
sources must be included in the Initial Screen.
The simplest method to accomplish this is to add the concentrations
from all the stationary sources. This is very likely to be an
overestimate since not all the plumes will overlap, especially those
from small sources. And where the plumes from sources do overlap,
the concentrations at the point of overlap will not always be the
highest concentration, which is the concentration that is calculated
using the look-up table. But, again, overestimation is appropriate
during the Initial Screen since the goal is to eliminate chemicals that
are clearly below the community screening values.
Finally, to estimate the total concentration resulting from all sources
reviewed in the Initial Screen, the technical team will look in the
Emission Source Inventory database to see if there are any
background concentrations for the chemicals under review. These
background concentrations will then be added to the total stationary
source concentrations to get the total estimated concentration for a
chemical. This is the concentration that will be compared to the
community's screening concentration for that chemical.
What are all the steps the technical teams will need
to complete to estimate the concentrations for each
of the chemicals released by stationary sources?
The following page has a summary of all the steps the Partnership's
technical teams (the Inventory Team and the Concentrations
Estimation Team) will need to complete to estimate concentrations in
the Initial Screen, starting with all the chemicals in the Partnership's
Emission Source Inventory database.
110
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 1: Estimating Concentrations
Summary of Steps to Estimate Concentrations
in the Initial Screen
Step 1: Set up QA/QC procedures for data collection, data
entry, and calculations.
Step 2: Collect information on release type, stack height, and
receptor distance for stationary point sources. (If the
technical team has Limited resources and chooses to use
the conversion factor to estimate concentrations, then
skip this part of step 2.) Check to be sure that county-
wide release amounts for all stationary area sources have
been collected.
Step 3: Identify all stationary point sources that are less than 15
meters from the nearest community exposure and move
all the chemicals emitted from these sources to the
Secondary Screen for evaluation. These chemicals will
not be reviewed during the Initial Screen.
Step 4: Move all the chemicals from mobile sources to the
Secondary Screen for evaluation. These chemicals will
not be reviewed in the Initial Screen. (Note: In urban
areas this means that many important monitored
pollutants will not be examined during the Initial
Screen.)
Step 5: For each chemical and for each of the stationary point
sources releasing the chemical, estimate the
concentration using the look-up table or conversion
factor method. Add all the concentrations to get a total
point source concentration.
Step 6: For each chemical released from stationary area sources,
add the county-wide releases from all the area sources
and estimate the concentration using the conversion
factor.
Step 7: Obtain the background concentration, if any, for each
chemical.
Step 8: For each chemical, add the total stationary point source
concentration, the total stationary area source
concentration, and the background concentration, to
obtain the total concentration from all sources.
Community Air Screenins How-To Manual
111
-------
Chapter 5: Initial Screen
• Step 1: Estimating Concentrations
What are the next steps once the technical team has
estimated concentrations for all the chemicals in the
Emission Source Inventory database?
Once the Partnership has estimates for the concentrations of
chemicals from stationary sources in the community's air, it will
compare these concentrations to the Partnership screening-level
concentrations. Any chemical with a concentration above the
Partnership screening level will be kept for further review. All other
chemicals will be removed from the screening process and set aside as
low priority for now. As mentioned above, these chemicals should be
reviewed periodically to check for any changes, such as increased
releases or new toxicity information, that might change the decision
to drop the chemical from the review process.
112
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 2: Setting the Screening Level and Developing Screen ing-Level Concentrations
Step 2:
Setting the Screening Level
and Developing Screening-
Level Concentrations
Now that the Partnership has estimated the
concentrations in community air for the chemicals in
its inventory, how will it begin the screening process
to identify the priority chemicals that will be
evaluated for possible community action?
To begin the screening process, the Partnership chooses the risk
screening level it will use to identify priorities. Then, using this risk
screening level, the Partnership calculates screening-level
concentrations for each chemical. And, finally, the Partnership
compares the concentrations in community air that were estimated
using the method discussed in the previous section to the screening-
level concentrations. The chemicals with concentrations in
community air that are above the screening-level concentrations will
be kept for further review. Chemicals with concentrations that are at
or below the screening-level concentrations will be set aside. (Please
refer to the more detailed explanations of the screening method in
Chapter 3.)
The following is an illustration of the use of the full screening process
to identify a priority chemical for the community.
A cancer-causing chemical, such as benzene, is one of the chemicals
present in community air. The Partnership chooses a one in 1 million
risk level as its risk-screening level. It then calculates the lifetime
continuous exposure concentration for benzene associated with that
risk level. This concentration becomes the Partnership's benzene
screening level. The Partnership compares its estimated ambient air
concentration for benzene to the screening-level concentration for
benzene. If the estimated benzene concentration in community air is
above the benzene screening-level concentration in the Initial,
Secondary, and Final Screens, the Partnership assumes the risk
associated with benzene's estimated concentration would be more
than one in 1 million and, as a result, the Partnership identifies
benzene as a priority chemical to be evaluated for possible
community action.
Initial Screen Step
/WV\^A
JJJJJJ
Step 1 :
Estimating
Concentrations
£
Step 2:
Setting the Screening
Level and Developing
Screening-Level
Concentrations
£
Step 3:
Comparing
Community Air
Screening
Concentrations to
the Screening-Level
Concentrations
Community Air Screenins How-To Manual
113
-------
Chapter 5: Initial Screen
• Step 2: Setting the Screening Level and Developing Screen ing-Level Concentrations
The detailed explanation of and guidance for choosing the
community risk screening level and calculating the screening level
concentrations equivalent to the risk screening level are provided in
this section and in Chapter 10 of the Technical Guidance section of
the Manual.
Please note that there is an alternate approach to risk-based screening
that uses a proportion of risk and hazard instead of screening-level
concentrations to screen chemicals. While this alternate approach is
not detailed in this Manual, a brief description of this method is
provided later in this chapter.
What skills and resources will the Partnership need
in order to find or calculate the screening-level
concentrations?
While the screening exercise will require input from all the members
of the Partnership, the work to develop the screening-level
concentrations will require special technical skills. As a result, the
Partnership committee will need to appoint a technical team from
among its members to develop the screening-level concentrations that
the Partnership will use. Technical guidance to help this technical
team can be found in Chapter 10 of this Manual.
To develop screening-level concentrations, the technical team will
need the following skills and resources:
• Working knowledge in one or more scientific fields, including
chemistry, biology, toxicology, industrial hygiene, and public
health. These experts will also need to identify and use the types
of numerical (quantitative) information used to calculate
screening-level concentrations.
• Computer skills to access and search web sites for the most
current and best available chemical toxicity information for
calculation of screening-level concentrations.
• Familiarity with the use and management of computerized
databases (e.g., those that provide existing screening-level
concentrations and chemical toxicity information). Such
familiarity would be helpful for identification, retrieval, and
storage of information used to calculate screening-level
concentrations.
• Computer skills for the calculation, storage, and presentation of
community screening-level concentrations.
114
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 2: Setting the Screening Level and Developing Screen ing-Level Concentrations
Professionals living or working in the community, health
professionals, college and university faculty and students, high school
science teachers, government, industry and business technical staff,
and retired professionals can provide these skills.
What is a community risk screening level?
Before the technical team can calculate screening-level concentrations,
the Partnership will need to choose the level of risk that will serve as
the community's risk screening level. Each Partnership and
community will develop its own risk screening level, based on its own
goals and values. The risk screening level will be used to identify
community priorities. By agreement of the Partnership, any chemical
in community air that results in a level of risk above the risk screening
level will become a community priority and will be evaluated for
possible community action. These priority chemicals will be
identified during the Final Screen at the end of the screening process.
Once agreed upon, the risk screening level will be used to develop the
screening-level concentrations for all of the community chemicals.
The method for developing screening-level concentrations will be
discussed below.
The Partnership risk screening level relates specifically to risks of
adverse health effects caused by long-term (chronic) exposure to
chemicals in the community. Short-term (acute) effects are not
considered in this screening process. Screening levels for chronic
exposures are generally lower than acute screening levels. Acute
exposures were not included in the Baltimore project, so step-by-step
guidance for including them in a screening process are not included
in this Manual. In particular, guidance for collecting information on
the peak releases and meteorological conditions that may result in
high short-term concentrations, guidance for estimating short-term
concentrations, as well as guidance for developing the screening-level
concentrations for acute effects are not included. Acute effects are
likely to be important community concerns, so we recommend that
the Partnership, if possible, draw on it technical members to develop
an effective way to identify and address these concerns.
Community Air Screenins How-To Manual
115
-------
Chapter 5: Initial Screen
• Step 2: Setting the Screening Level and Developing Screen ing-Level Concentrations
Are there different risk screening levels for cancer
and non-cancer effects?
For long-term chronic exposures, there may be two types of risk screening
levels from which the Partnership will calculate screening-level concentra-
tions, depending on whether or not the chemical is considered
carcinogenic. The Partnership will use one type of risk screening level for
cancer and a second type of risk screening level for other effects. When a
chemical has a potential to cause cancer as well as some other long-term
health effect, the Partnership will calculate two screening-level
concentrations for the chemical, using each of the two types of risk
screening levels. The Partnership will then use the screening-level
concentration that provides the most conservative or most protective (i.e.,
the lowest) concentration as its screening level concentration. In most
cases, this will be the screening-level concentration calculated by using the
Partnership's cancer risk screening level.
The risk screening level used to calculate a screening-level
concentration when cancer is the long-term toxicity concern is
expressed in statistical terms called a unit risk. A unit risk is a measure
of a probability of risk that the Partnership considers appropriate for
identifying priorities for chemicals with some identified cancer-
causing potential. For example, a community's priority-setting level of
risk for these potentially cancer-causing chemicals might be set at a
risk of one excess cancer case in 1 million exposed people. This means
that if a chemical in community air has a concentration level that is
estimated to cause more than one in 1 million excess cancer cases,
then it will be identified as a priority chemical and will be evaluated
for possible community action.
As is discussed below, several EPA programs have used one in a
million excess cancer cases as a risk screening level. The Partnership
can select a more or less conservative target cancer risk level. For
example, the Partnership could choose the more conservative risk of
one excess cancer case in 10 million exposed people, or the less
conservative risk of one case in 100,000 exposed people. Whatever
value the Partnership agrees on as its cancer risk screening level, it
remains the same for the calculation of the screening-level
concentration for each chemical with some identified cancer-causing
potential.
The risk screening level that is used to calculate a screening level
concentration for non-cancer effects is expressed as a ratio. This ratio
is referred to as a hazard quotient, and it is used by the Partnership to
develop screening concentrations for non-cancer effects. The hazard
116
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 2: Setting the Screening Level and Developing Screen ing-Level Concentrations
quotient is the ratio of the potential exposure to the substance and
the level at which no adverse effects are expected. If the hazard
quotient is calculated to be less than 1, then no adverse health effects
are expected as a result of exposure. If the hazard quotient is greater
than 1, then adverse health effects are possible. Unlike the cancer risk
screening level expression, the hazard quotient cannot be translated
to a probability that adverse health effects will occur, and is unlikely
to be proportional to risk. It is important to note that a hazard
quotient exceeding 1 does not necessarily mean that adverse effects
will occur.
For example, a community's level of risk for non-cancer-causing
chemicals might be expressed as a hazard quotient of 1. In this
example, the concentration in community air that would identify a
chemical as a community priority would be a concentration that is
greater than the concentration used as a measure of the chemical's
toxicity potential. A hazard quotient of 1 is used by several EPA
programs as a trigger for considering action. Just as in the case of
cancer-causing chemicals, the Partnership can choose a risk screening
level more or less conservative than a hazard quotient equal to 1 for
its non-cancer risk level. And, as for the cancer-causing chemicals,
whatever value the Partnership agrees on as its non-cancer risk
screening level, it will remain the same for calculating the screening-
level concentrations for each chemical that can cause long-term, non-
cancer effects.
What should the Partnership consider in choosing a
risk screening level to use for its screening-level
concentration-setting process?
The Partnership needs to choose a risk screening level that fits
community values and helps to identify priorities, so that local air
quality can be effectively improved. There are several considerations
that may help a Partnership choose a risk screening level that meets
these two goals.
First, it may be helpful to remember that the risk screening level is the
level of risk that a community agrees should be used to identify the
priority chemicals and sources that will be evaluated for possible
community action, most likely voluntary, to reduce risk. Since the risk
screening level is based on a community agreement, it can only result
from a dialogue and an effort to build a consensus within the
community. The broader the consensus, the more meaningful the
screening level will be. Taking the time to build a community
consensus is essential to the effort to improve air quality.
Taking the time
to build a
community
consensus on a
risk screening
level is essential
to the effort to
improve air
quality
Community Air Screenins How-To Manual
.117
-------
Chapter 5: Initial Screen
• Step 2: Setting the Screening Level and Developing Screening-Level Concentrations
Also, keep in mind that setting the risk screening level does not bind a
partnership to any kind of specific action. The Partnership will need
to carefully evaluate the options that are available for addressing
priority chemicals and sources before deciding on the course of action
that best meets community needs. (See Chapter 8 for suggestions on
developing options for addressing priority chemicals and sources.)
Feasibility and cost will need to be considered and balanced with
other community concerns to find the best course of action. Some
sources identified as community priorities may require an action,
such as a vehicle inspection program, that is beyond the scope of any
single local community. In that case, the action identified by the
community may be an effort to influence other communities to join
in the larger effort that would be required to initiate a regional or
even national risk reduction effort. Efforts to reduce emissions from
other kinds of sources, such as local businesses, households, and local
diesel-powered truck and bus traffic, can be more easily addressed by
a local Partnership alone. So, the risk screening level will help to
identify priority air risks, but it cannot determine how, or if, the
Partnership will decide to address them. Only careful consideration by
the Partnership will determine how to best address the priorities
identified by the screening level.
In choosing a risk screening level, it is also important to remember
that it can be either too stringent or not stringent enough to
effectively identify priorities. If a Partnership sets a very conservative
(stringent) screening level, too many of the chemicals in community
air could be identified as priorities. Unless the Partnership devises
some way to prioritize this list of chemicals, it will not be able to find
the chemicals that have the greatest potential to adversely affect the
health of members of the community. On the other hand, setting a
risk screening level that is not stringent enough could result in too
few or no chemicals being identified as priorities. This would also
make it difficult for a Partnership to identify the actions that would
most effectively reduce air risks in the community. Communities can
experiment with different target levels of risk to find the one that
results in the most effective actions to improve local air quality.
It is also important to remember that the real goal of everyone in the
Partnership is to improve local air quality. The decision to set a target
level of risk should not take so long that it delays a community from
getting to the work to improve local air quality. Setting a risk level that
everyone can agree on, conducting the screen, and finding and getting
to work on practical efforts to reduce risk may be more important
than trying to decide, finally, on what is the best screening level for
118
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 2: Setting the Screening Level and Developing Screen ing-Level Concentrations
the Partnership to use. Once work is under way, where feasible, on the
chemicals that have the greatest potential to affect the health of
members of the community, the Partnership can return to the
question of the risk screening level, adjust it, and identify more
chemicals to be evaluated for possible risk reduction.
Finally, the Partnership may want to review examples of risk screening
levels that have been used by other communities and by governments
for different environmental programs. A few examples are provided
below.
Baltimore Community Environmental Partnership: The
Partnership in Baltimore chose a risk screening level of one in 1
million for cancer-causing chemicals, and a hazard quotient of 1 for
non-cancer-causing chemicals. There was considerable discussion in
the Baltimore Partnership over the choice of this screening level,
especially since the state of Maryland uses a risk screening level of one
in 100,000 at the fenceline of a facility. The Partnership decided to use
the more conservative screening level and make a special effort to
make sure that the community understood that any actions taken
based on its screening level would be voluntary. The screen resulted in
identifying four priority chemicals to be evaluated for possible
community action. Details of the Baltimore screening exercise can be
found in the Baltimore Case Study. This study is available at http://
www.epa.gov/oppt/cahp/case.html.
St. Louis Community Air Project (CAP): The St. Louis screening
project chose one in 100,000 as their cancer risk screening level, partly
because they are using air monitoring instead of modeling to measure
concentrations, and, for some of the chemicals, the monitors are not
able to accurately measure the very small concentrations associated
with the one in 1 million risk level. The educational handout prepared
for the St. Louis Partnership's discussion of target risk levels is
included in Appendix F.
What is a community screening-level concentration?
Once the Partnership has chosen a risk screening level to use for
screening, the next step is to calculate the air concentration that
corresponds to the community's risk screening level for each chemical
in community air. In other words, the Partnership must calculate for
each chemical the concentration that would result, after a lifetime of
exposure, in a risk equal to the risk screening level chosen by the
Partnership. These concentrations will be used by the Partnership as
Community Air Screenins How-To Manual
119
-------
Chapter 5: Initial Screen
• Step 2: Setting the Screening Level and Developing Screening-Level Concentrations
the screening-level concentrations. The concentrations in community
air estimated during the Initial Screen will be compared to these
screening-level concentrations.
To understand the use of screening level concentrations, it may be
helpful to look at another benzene example. If the Partnership
chooses one in 1 million excess cancer cases as its risk screening level,
and if benzene is found in community air, the Partnership will need
to determine the concentration (the level or amount) of benzene in
the air that will result in a risk of one in 1 million in a hypothetical
person continuously exposed to that concentration for a lifetime. This
will be the screening-level concentration for benzene. The Partnership
will compare the benzene concentration in community air that it has
estimated to the benzene screening-level concentration. If the benzene
concentration in community air is larger than the benzene screening
level concentration, the risk from the benzene concentration is above
the risk screening level, one in 1 million, and benzene would be kept
for further review.
The Partnership will need to find or calculate a risk screening level
concentration like the benzene example used above for each chemical
in community air. The risk screening concentration for each chemical
will be different because the toxicity of each chemical is different. For
example, if you compare the screening-level concentrations for two
chemicals with different toxicity, the screening-level concentration for
the more toxic chemical will be smaller than the screening level for
the less toxic chemical. This is because it takes a relatively small
concentration of a more toxic chemical to produce a risk equivalent to
the risk screening level. The following examples of risk screening
values for hexavalent chromium, benzene, and toluene used by the
Baltimore Partnership illustrate the difference in concentrations that
result in an equivalent one in 1 million risk, the risk screening value
chosen for use by the Baltimore Partnership. (These screening
concentrations may differ from those calculated by your technical
team for use in your screening exercise, since the method
recommended in this Manual for calculating screening concentrations
Example screening-level concentrations used in Baltimore study
Hexavalent Chromium 0.00015 jig/m3
Benzene 0.22 ^g/m'1
Toluene 420 jig/m3
120.
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 2: Setting the Screening Level and Developing Screening-Level Concentrations
is different from the method used in the Baltimore project. See the
discussion below.)
Remember that this use of screening-level concentrations in the risk-
based screening method identifies priority chemicals, but it does not
measure the actual risk that these chemicals present to the
community. Risk is determined by the toxicity of a chemical and by
the amount of exposure to the chemical. To save on resources, risk-
based screening uses estimated air concentrations as a surrogate for
exposure. It does not attempt to measure the actual amount of
exposure that members of the community have to the priority
chemicals. Estimating exposure is a key step in determining potential
health risk. People move around from one location to another, outside
to inside, so exposure isn't the same as the concentration at a static
site. People also breathe at different rates depending on their activity
levels, so the amount of air they take in varies. For these reasons, the
average concentration of a pollutant that people breathe (i.e.,
exposure concentration) may be significantly higher or lower than the
concentration at a fixed location (i.e., the estimated ambient
concentration).
Keep in mind that the estimated air concentration that the
Partnership uses as a surrogate for the exposure concentration is just
one of the factors used to calculate screening-level concentrations.
The conservative nature of other factors used to calculate the
screening concentration, such as the duration of exposure and the
hazard value for the chemical, is likely to be protective of sensitive
populations at the level of risk chosen by the Partnership. If the
Partnership is concerned about using screening calculations that are
protective of sensitive populations, it has the option of choosing a
more conservative risk level to ensure protection. A partnership can
also use a less conservative risk screening level to identify priorities,
evaluate the priority chemicals identified by the screen to find feasible
risk reduction actions, begin work on risk reduction actions, and
then, as risk reduction work proceeds, reevaluate the screening
concentrations to see if they need further adjustment to protect
sensitive populations.
If a community, in addition to identifying priority chemicals, wants
information on the amount of risk these chemicals present to the
community, they will need to complete a risk assessment. A discussion
of this option and a reference to guidance for conducting a risk
assessment can be found in the section on choosing a work plan in
Chapter 2. There will also be further discussion of this issue in the
Secondary and Final Screen chapters of this Manual. At these steps of
the screening process, the more accurate methods used to estimate
Community Air Screenins How-To Manual
121
-------
Chapter 5: Initial Screen
• Step 2: Setting the Screening Level and Developing Screen ing-Level Concentrations
concentrations provide better information on ambient concentrations
that could be used to estimate exposure and risk.
How will the Partnership calculate the screening-
level concentrations for each of the chemicals in
community air?
Because the work to develop these screening-level concentrations is
technical, the Partnership committee will need to appoint a technical
team to calculate the screening-level concentrations that it will use.
This technical team will need to find and use information on toxicity
for each chemical found in community air. Once the technical team
has assembled the necessary toxicity information for each of the
chemicals in community air, the team will calculate the risk screening
concentration by combining the Partnership's risk screening level
with the toxicity value found for each chemical.
Here is an example of the calculation for arsenic, a cancer causing
chemical, and acrylic acid, a non-cancer-causing chemical.
EXAMPLE 1: Arsenic compounds as cancer screening-level concentration (SLC) example
SLC (cancer) ng/m3 = 1.0E-06 = 2.3E-04 ng/m3
4.3E-03perM.g/m3(fromlRIS)
EXAMPLE 2: Acrylic acid as non-cancer screening-level concentration (SLC) example
SLC (non-cancer) ^g/m3 = 1 * 1.0E-03 mg/m3 (from IRIS) * 1000 ^g/mg = 1.0 |
The Partnership's technical team will be able to explain these
examples in detail, including the technical notation used to express
the numbers. The toxicity values used in these calculations come from
a database developed by EPA's Office of Air Quality Planning and
Standards (OAQPS) accessible at http://www.epa.gov/ttn/atw/
toxsource/summary.html.
For cancer-causing chemicals, the unit risk estimates used to calculate
the screening-level concentrations are considered plausible upper-
bound estimates of an individual's probability of contracting cancer
over a lifetime of exposure, meaning that they represent a plausible
upper limit to the true value. The true risk is likely to be less but could
be greater. As a result, the risk that would result from exposure to the
screening-level concentration is also an upper-bound estimate of risk.
122
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 2: Setting the Screening Level and Developing Screen ing-Level Concentrations
The true level of risk that would result from exposure to the
screening-level concentration is likely to be lower than the
community risk screening level, but it could be greater. The
Partnership can rely on its technical team to explain the use of
upper-bound estimates of risk.
The method for calculating screening-level concentrations described
above differs from the method used in Baltimore. In Baltimore, the
Partnership used risk based concentrations that are available in EPA
Regional databases set up for the Superfund program. These risk
based concentrations were calculated using a different approach for
cancer-based values. The method suggested above is recommended to
take advantage of current Agency methodology and a database of
toxicity information developed by EPA's Office of Air Quality,
Planning, and Standards (OAQPS) that was not available for the
Baltimore project.
Could the Partnership use a proportion of risk to
screen chemicals as an alternative or supplement to
the use of screen ing-level concentrations?
There is an alternate method for conducting a risk-based screening
that uses a proportion of total risk to screen chemicals instead of
screening level concentrations. The Partnership in Baltimore, after
considerable discussion, decided that screening-level concentrations
would be easier to explain to the community and would be less likely
to be mistaken for estimates of true risk, so the proportion-of-risk
screening approach was not used in Baltimore. Consequently, only a
brief description of how to use proportion of risk as a screen is
provided here. If you decide to use this approach, you will have to rely
on the technical members of your Partnership to provide detailed
guidance. If your Partnership adopts this approach, please summarize
and share your experiences so that other communities can learn from
them and more detailed guidance can be developed.
To use proportion of cumulative risk to screen chemicals, a
partnership would first estimate exposure concentrations or might
agree to use ambient air concentration estimates as surrogates for
exposure. Then, for each chemical with cancer-based toxicity values,
the Partnership would multiply the estimated ambient concentration
by the chemical's unit risk estimate to get the risk value. Since the
estimated ambient air concentration is a surrogate measure of
exposure, the risk value produced by this method would not be an
estimate of true risk in the community. But this risk value could be
used to develop a relative ranking of chemicals by risk.
Community Air Screenins How-To Manual
123
-------
Chapter 5: Initial Screen
• Step 2: Setting the Screening Level and Developing Screen ing-Level Concentrations
To ensure the
quality of its
analysis, the
Partnership will
want to make
sure that its
technical team
finds and uses the
best available
data
As an alternative to using risk screening concentrations to identify the
chemicals needing further analysis, the Partnership could rank
chemicals by their relative risk and pick the chemicals with the highest
relative risk for further analysis in the Secondary Screen and as
priorities to be evaluated for possible community action in the Final
Screen. The Partnership could also choose a proportion of the total of
all risk values calculated for all the chemicals to screen chemicals. The
Partnership could calculate the percentage that each chemical
contributes to the total risk value associated with all chemicals in this
assessment and rank the chemicals by percentage of risk they
contribute to the total. The Partnership could choose a percentage of
risk for use during the screen and screen chemicals using this
percentage. For example, if a partnership chose 95% as its screening
percentage, it would start with the chemical contributing the greatest
relative risk and go down the ranked list of chemicals until 95% of the
total of the risk values is accounted for. These chemicals would be
kept for further review and the chemicals contributing the remaining
5% of the total of the risk values would be dropped. If a partnership
uses this method to screen chemicals, it would have an idea of the
proportion of total air toxics risk that the community is addressing
once it has completed its screen and identified its priority chemicals
and sources. The ability to demonstrate that a high proportion of the
risk will be addressed by working on the priorities identified by the
screen may increase the community's confidence in the screening
method.
How will the Partnership provide guidance to its
technical team in choosing the sources of chemical
toxicity information?
Since toxicity information is available in many databases, and since
the information on toxicity in these databases may differ, the technical
team will need to select the toxicity information that will be used to
calculate screening-level concentrations. To ensure the quality of its
analysis, the Partnership will want to make sure that its technical team
finds and uses the best available information. The easiest way to
identify the best available information may be to decide on a
hierarchy for the available toxicity databases that ranks them,
according to the quality of the data they contain, from the database
with the highest quality of information to the database with the
lowest. The toxicity information from the highest ranking database
with information on a chemical can then be used for calculating
screening-level concentrations.
124.
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 2: Setting the Screening Level and Developing Screen ing-Level Concentrations
The quality of the information in databases depends on factors such
as the level of peer review and the currency of the data. The level of
peer review is an indication of the level of review by independent
scientists that the data included in a database have undergone. Peer
review levels can range from complete review of all data by
independent scientists, to review by scientists within the same
organization publishing the data, to no peer review. The Partnership's
confidence in the data contained in a database will vary depending on
the amount and kind of peer review a database has undergone. The
Partnership's technical team will probably not be able to find the
information they need to calculate screening-level concentrations for
all of the chemicals in community air if they use only the databases
with the highest level of peer review. The information available on
many chemicals has not undergone the highest level of peer review.
Currency of the data refers to the time when the information on a
chemical was developed and reviewed. New testing and new
information on chemicals is being developed all the time, so the
information on chemicals in databases needs to be updated regularly.
To assist with efforts to understand risks associated with air toxics,
EPA's Office of Air Quality Planning and Standards (OAQPS) has
developed a method of ranking databases and has combined available
toxicity information for hazardous air pollutants in one database,
available on the web at http://www.epa.gov/ttn/atw/toxsource/
summary.html.
To create this database, EPA's OAQPS established a hierarchy of
sources of dose-response or toxicity assessments based on the quality
of the data they contain and then used this hierarchy to select the
toxicity value to include in their database. Links are provided in this
web site to tabulated dose-response assessments that OAQPS uses for
risk assessments of hazardous air pollutants. Tables are provided with
values for long-term (chronic) inhalation and oral exposures and for
short-term (acute) inhalation exposures. The tables compile
assessments from various sources for many of the 188 substances
listed as hazardous air pollutants ("air toxics") under the Clean Air
Act Amendments of 1990. Each assessment in these tables is best
visualized as an estimate within a range of possible values,
surrounded by uncertainty and variability. This range of possible
values may change as better data become available.
We recommend using this database as the primary source for the
toxicity information needed to calculate the Partnership's screening-
level concentrations. Using this database not only will make the job of
Community Air Screenins How-To Manual
125
-------
Chapter 5: Initial Screen
• Step 2: Setting the Screening Level and Developing Screening-Level Concentrations
the technical team easier and ensure the quality of the data used, it
will also make it possible for the Partnership to compare the results of
its risk-based screening to other communities using the same
database. But keep in mind that the quality of information in this
toxicity database, like all databases, varies from chemical to chemical.
For chemicals identified as priorities, the Partnership's technical team
may want to examine the quality of the toxicity value and summarize
this information to help inform any decisions the Partnership might
make that would be based on this information.
In general, it is important to remember that the quality of the data
contained in toxicity databases can vary from chemical to chemical
depending on the level of peer review and currency of the
information. In addition, the OAQPS database and other databases,
for example, the Agency for Toxic Substance and Disease Registry's
Minimal Risk Levels (MRLs) for Hazardous Substances and the
California Environmental Protection Agency's Toxicity Criteria
Database, all contain some degree of uncertainty because of the lack
of precise toxicological information on the people that might be most
sensitive (e.g., infants, elderly, and nutritionally or immunologically
compromised) to the effects of hazardous substances. To address these
uncertainties, toxicity values are calculated using a conservative (i.e.,
protective) approach.
Chemicals in community air that are not on the Clean Air Act list of
hazardous air pollutants may not be included in the OAQPS toxicity
database (e.g., aldicarb, allylamine, benzamide, bifenthrin, bromine,
carbofuran, creosote, diazinon, dichlorobromomethane). For these
chemicals, the Partnership's technical team will need to search other
available toxicity databases to find toxicity information. To ensure
that the technical team uses the best available information, the
Partnership will need to establish a ranking of the available databases
and instruct its team to use the information from the highest ranked
database. If there are chemicals in community air that are not
included in the OAQPS database, the Partnership's technical team can
present the Partnership with a plan for finding the highest quality
data for discussion and approval. To be consistent, the Partnership
may want to adopt the hierarchy of data sources used by OAQPS to
develop its database for the 188 Clean Air Act hazardous air
pollutants.
As the Partnership's technical team develops screening-level
concentrations and enters them into the Partnership's database, it
would be helpful if the team also indicated the source of the
information used so that the Partnership would be able to easily
126
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 2: Setting the Screening Level and Developing Screen ing-Level Concentrations
consider the strengths and weaknesses of the assessment that
underlies each of its screening-level concentrations. This information
will be especially important at the end of the screening process if a
chemical is identified as a priority and the Partnership needs to
consider possible actions based on this information.
Why is it important for the Partnership to agree on
and set clear standards for choosing the sources of
data that its technical team will use?
The goals of the Partnership's screening exercise are to reach
agreement in the community on the chemicals that need attention
and to mobilize the community to take effective action to reduce the
risks from these chemicals. If everyone in the Partnership agrees at the
start of the screening exercise that the decisions made in setting
screening-level concentrations are reasonable and valid, then the
Partnership will have a sound basis for taking action on the chemicals
identified as priorities. Taking time to thoroughly discuss and reach
agreement on all the decisions that will be made in the screening
process will help to avoid the problem of second-guessing the work of
the Partnership once the results are in and will help to avoid any
questions on the screening methods that could delay the community's
efforts to improve air quality.
Taking the time
to thoroughly
discuss and reach
agreement on all
the decisions that
will be made in
the screening
process will help
to avoid the
problem of
second-guessing
the work of the
Partnership once
the results are in
Community Air Screenins How-To Manual
.127
-------
Chapter 5: Initial Screen
• Step 2: Setting the Screening Level and Developing Screen ing-Level Concentrations
What are all the decisions and steps required to
develop the screening-level concentrations that the
Partnership will use?
Here is a summary of the decisions and steps that the Partnership and
its technical team will need to complete to develop the screening-level
concentrations.
Summary of Steps to
Develop Screening-Level Concentrations
Step 1: Partnership appoints a technical team to calculate risk
screening concentrations following QA/QC procedures
Step 2: Partnership provides the education that its members
will need to participate fully in the decisions that will
need to be made to ensure that the work to set
screening-level concentrations meets community goals
and values
Step 3: Partnership decides on the risk screening level that it
will use to trigger possible action
Step 4: Technical team develops a plan for accessing toxicity
information and calculating screening-level
concentrations to present to the Partnership for
discussion and approval
Step 5: Partnership approves plan for accessing toxicity
information and calculating screening-level
concentrations
Step 6: Technical team develops risk screening concentrations
for the Partnership and stores them in the Partnership
database
128.
Community Air Screening How-To Manual
-------
Chapter 5: Initial Screen
Step 3: Comparing Community Air Screening Concentrations to the Screening-Level Concentrations
Step 3:
Comparing Community Air
Screening Concentrations to
the Screening-Level
Concentrations
What does the Partnership do once it has screenins-
level concentrations for the chemicals in community
air?
The final step of the Initial Screen is to compare the estimated
concentration for each chemical to its corresponding screening-level
concentration. The Partnership uses this comparison step to identify
all the chemicals that have estimated concentrations that exceed their
corresponding screening-level concentrations. The Partnership
identifies these chemicals as candidates for further analysis. Chemicals
with concentrations equal to or less than their screening levels are
eliminated from further review in this screening exercise.
Why should the chemicals kept for further review by
the Initial Screen not be described as community
priorities?
The conservative assumptions that are built into the Initial Screen,
described in the introduction to this chapter, mean that the
concentrations estimated for the Initial Screen are likely to be
overestimated. As a result, the actual concentrations in community air
of the chemicals identified by the Initial Screen may not be above the
Partnership's risk screening concentrations. Only the more accurate
information and methods that will be used to estimate concentrations
in the Secondary and Final Screening steps will be sufficient to
determine if a chemical will be identified as a community priority.
Until these more accurate estimates are developed, the Partnership
will not have enough information to identify its priorities. The
primary purpose of the Initial Screen is to find and eliminate the
Initial Screen Step
/S/\/W\/\
JJJJJJ
Step 1 :
Estimating
Concentrations
£
Step 2:
Setting the Screening
Level and Developing
Screening-Level
Concentrations
t
Step 3:
Comparing
Community Air
Screening
Concentrations to
the Screening-Level
Concentrations
Community Air Screenins How-To Manual
.129
-------
Chapter 5: Initial Screen
• Step 3: Comparing Community Air Screening Concentrations to the Screening-Level Concentrations
chemicals that the Partnership can confidently assume are below the
community screening concentrations. This allows the more resource-
intensive effort needed to produce more accurate estimates in the
Secondary and Final Screens to focus on the remaining chemicals that
may be above the screening levels. Bottom line: The chemicals
identified during the Initial Screen must be further evaluated during
the Secondary and Final Screening steps before they can become
candidates for possible community action.
130
Community Air Screening How-To Manual
-------
Overview
Secondary Screen
What is the purpose of the Secondary Screen?
The Secondary Screen is designed to take the chemicals left after the
Initial Screen and, using a more sophisticated method to estimate
concentrations, once again sort through them to find those that can
be set aside and those that will require further review. This is the
second step in the risk-based screening process designed to identify
the chemicals that will become community priorities.
The Secondary Screen will also, for the first time, review the chemicals
released by mobile sources and by stationary point sources that are
closer than 15 meters to the nearest community exposure. All the
chemicals released by these sources were passed through the Initial
Screen and kept in the screening process for review in the Secondary
Screen.
How does the Secondary Screen work?
The screening steps outlined in this Manual were designed to find an
effective way to sort through a large number of chemicals and sources
with the minimum expenditure of resources. The Initial Screen uses a
simplified method to estimate concentrations so that all the chemicals
in community air can be reviewed efficiently and the chemicals with
concentrations obviously below community screening levels can be
eliminated from the screening. With a smaller set of chemicals left
after the Initial Screen, it is now possible for the Partnership to use a
more resource-intensive method to get a more accurate estimate of
the concentrations in community air. The more accurate
concentrations estimated in the Secondary Screen are, once again,
compared with the screening-level concentrations that were set for
Analyze
Community Air Screenins How-To Manual
131
-------
Chapter 6: Secondary Screen
the Initial Screen. Chemicals whose new estimated concentrations are
still above the community screening levels will need further review
and will be kept for the Final Screening. They will remain as possible
candidates for the community's list of priority chemicals. The
chemicals whose more accurately estimated concentrations are now at
or below the community screening concentrations can be set aside.
They will not need further review in the Final Screen.
What does the Partnership do in the Secondary
Screen to set more accurate estimates of community
air concentrations?
For the Secondary Screen, instead of using the conservative
assumptions and the simplified SCREEN3 look-up table, the
Partnership will use the ISCST air dispersion model to provide more
accurate estimations of concentrations in community air.
What is the ISCST air dispersion model and what
does it do?
The ISCST air dispersion model is a widely used model developed by
EPA to estimate the air concentrations that result from chemical
releases. ISCST can be downloaded from an EPA web site and run on
a standard desktop computer. Please see the general explanation of air
dispersion modeling in the Initial Screen section of the Overview. In
the future, communities will have the option of accessing and using
this model via the Internet using the Internet Geographic Exposure
Modeling System (IGEMS), a program under development by EPA.
Information on IGEMS can be accessed at http://www.epa.gov/oppt/
exposure/.
To use the ISCST air dispersion model, the Partnership will enter
information on the location and characteristics of the sources, the
releases, and the local meteorological conditions from the nearest
meteorological station into the model. Using this information, the model
will predict the dispersion of chemicals from the sources (predict the
plumes) and estimate the concentrations that will result from the releases
at selected points in the Partnership area. If a chemical is released by more
than one source, the ISCST air dispersion model will calculate the
concentration that will result from all the sources combined together at
the selected points in the Partnership area. The Partnership will decide on
the locations in the community that are of special concern, such as
schools, nursing homes, and residential areas, and the model will estimate
the concentrations of chemicals from all sources at these locations. The
132
Community Air Screening How-To Manual
-------
Chapter 6: Secondary Screen
model can also be used to identify any locations in the community that
have estimated concentrations that are above the community screening
level. The model will estimate the concentrations in community air for
each of the chemicals identified by the Initial Screen.
What background information will the Partnership
need to provide its members to ensure that they
have the ability to oversee the technical work and
communicate the results to the community?
At this point, it will be important for the full Partnership to take time
to make sure that all of its members have a good understanding of the
value and limits of air dispersion modeling in general, and the ISCST
model, in particular. This background will be essential both to ensure
that the Partnership has the ability to oversee the technical work of
the screening and to communicate that work to the broader
community. Members of the Partnership with experience in
explaining technical information can take the lead in providing this
background. If necessary, the Partnership could request help from
outside the Partnership to provide this education. As a part of this
education, a demonstration of the model and its use may be especially
helpful to the Partnership. As discussed below, the Partnership will
need to appoint a technical team to carry out the air dispersion
modeling for the Partnership. Although the task of this team will be to
complete the technical modeling work for the Partnership, the
members of this technical team could assist or take the lead in the
educational work as well. EPA is currently developing educational
materials for use in the classroom to explain and demonstrate air
dispersion modeling. These materials will be available to help
communities with educational efforts in the future.
Why does the ISCST air dispersion model provide
more accurate estimates of concentrations than the
Initial Screen?
The method used to estimate concentrations in the Initial Screen is
designed to overestimate concentrations. It does this by assuming
that the meteorological conditions that result in the greatest
concentrations will remain the same for every day of the year and
by assuming that the sources are all in the same exact location so that
the highest concentrations resulting from each of the sources can be
added together. The ISCST air dispersion model, in contrast, uses the
actual meteorological conditions as measured at the weather station
It will be
important for the
full Partnership to
take time to make
sure that all of its
members have
a good
understanding of
the value and
limits of air
dispersion
modeling
Community Air Screenins How-To Manual
.133
-------
Chapter 6: Secondary Screen
closest to the Partnership area and the actual locations of sources to
estimate concentrations. With this more realistic information, the
model can estimate the dispersion of releases from each source and
provide a more realistic estimation of the combined concentrations
that occur if the plumes from the sources overlap.
With the more realistic input, the concentrations estimated using the
ISCST Air Dispersion Model should be lower than the estimates made
in the Initial Screen and closer to the actual concentrations in
community air. But, keep in mind, for stationary sources these new
estimates of concentrations are still designed to be conservative, i.e.,
overestimates, because in the Secondary Screen the Partnership will
still be using readily available release data based on maximum
permitted release amounts as input to the model. For the next, and
final, screening step, with the number of chemicals left in the process
further reduced, the Partnership will have the resources to contact
each of the remaining stationary sources to obtain the most accurate
release data. The Final Screening step will be explained in detail in the
next section of the Manual.
If the release data available to a community Partnership only has
estimates of actual release amounts and not maximum permitted
release amounts for stationary sources, the Partnership will need to
increase these release estimates, possibly multiplying the release
amount by a factor agreed on by the Partnership, to ensure that the
Secondary Screen is conservative. Release estimates taken from the
TRI database, for example, are estimates of actual releases, not
maximum permitted releases, so the Partnership's technical team will
need to increase these amounts to ensure that the Secondary Screen is
conservative.
Are there any special characteristics of a community
that need to be accounted for in air dispersion
modeling?
The ISCST model has many features and options that allow the model
to estimate dispersion in a variety of special situations. This Manual,
following the principle of effectively identifying community priorities
with a minimum expenditure of community resources, does not
provide guidance for using all of the detailed modeling capabilities of
the ISCST model. The Manual recommends the use of a simplified
version of ISCST modeling to estimate concentrations. In some
communities, this simplified use of the ISCST model may not be
adequate to estimate concentrations.
134
Community Air Screening How-To Manual
-------
Chapter 6: Secondary Screen
There are two situations, in particular, that may call for your
Partnership to use more sophisticated modeling to effectively estimate
concentrations: complex terrain, such as a community located in a
valley surrounded by high hills or on hillsides higher than the sources
of emissions, and the presence of high buildings close to a source or
sources. Unusual terrain features can cause changes in wind patterns
that affect dispersion as well as shift the position of the receptor closer
to the higher concentrations in the plume.
High buildings close to sources can cause an effect called "building
downwash" that results in higher concentrations close to the building.
References to guidance for identifying when and how to use ISCST to
account for terrain and buildings are provided for your technical team
in the Technical Guidance section of the Manual. If your community
may fit one of these special circumstances, you will need to work with
your technical team to be sure that you are using adequate air
dispersion modeling. In some unusual circumstances, you may even
need to consider use of a different air dispersion model to effectively
estimate concentrations. The Partnership, with the help of its
technical team, should discuss this issue and agree on the plan for
modeling to make sure that everyone has confidence in the results of
modeling.
The guidance provided in this Manual does account for differences in
the dispersion of releases that are in the form of particles rather than
gases. Particles tend to settle more rapidly than gases, so their
dispersion pattern can be significantly different than the pattern for a
gas. Releases of metals and many releases resulting from combustion,
including releases from the burning of diesel fuel, are more effectively
modeled as particulates. Since particulate releases will be part of the
inventory for most, if not all, communities, the Manual includes
guidance for your technical team to identify participate releases and
use the capability of the ISCST to model their dispersion.
What will the community need to keep in mind to
understand the limits and the value of using the
ISCST air dispersion model as a part of the screening
process?
The ISCST model, like all computer models, must simplify the
extremely complex process of the dispersion of chemicals in
community air to make a tool that is practical to use. The modeling
approach used in this Manual, for example, does not take into
account factors that affect air concentrations, such as the daily
Community Air Screenins How-To Manual
135
-------
Chapter 6: Secondary Screen
variations in release that occur from some sources or the reactions
that some chemicals undergo once they are released in the air. In
addition, the Secondary Screen, like the Initial Screen, still uses
overestimates of releases. Perhaps most important, the modeling
results will reflect any uncertainty inherent in the information that
the Partnership has collected in its inventory database and used as
input to the model, such as the stack characteristics and locations of
emission sources.
As a result, the Partnership should view the concentrations estimated
by the ISCST model as only approximate estimates of the actual
concentrations in community air. Studies that have compared ISCST
modeling estimates to measured concentrations have shown that
modeled estimates, depending on the situation, can differ from
measured concentrations by a factor of 2. (Please see the Technical
Guidance section, Chapter 11, for some discussion of and references
for these studies.) Despite its inherent uncertainties and limits, air
dispersion modeling does provide communities with a valuable tool
to help set priorities. Modeling allows a community to estimate
concentrations with enough accuracy to effectively identify the
chemicals that should be the focus for possible community action.
The ability to identify and agree on priorities can be crucial to the
effective use of community resources to improve air quality. Using
modeling to reach agreement on community priorities, like all the
methods and information used in the screening process, depends on
everyone in the Partnership understanding the uncertainties involved
in the screening process and agreeing in advance that the screening
method is reasonable and sufficient to identify community priorities.
This agreement depends, in part, on the recognition that the
alternatives to modeling, such as monitoring, would be significantly
more expensive and time consuming and would very likely result,
given the level of accuracy of modeling, in identifying the same
priorities. Please refer to the discussion of alternate technical
approaches for analyzing air quality in Chapter 2.
Understanding the level of uncertainty inherent in modeling will also
help the Partnership to interpret and explain the results of the
modeling. Modeling uncertainty will be especially important to
remember when reviewing the concentration numbers produced as
the output of the model. Because the model results will be expressed
in the form of numbers with two, three, or more decimal places, such
as 0.156 [.ig/m3, they can look very accurate. They are not that
accurate. In fact, in communicating the results of the modeling to the
136
Community Air Screening How-To Manual
-------
Chapter 6: Secondary Screen
community, the Partnership may want to find a way of expressing the
results that better reflects the uncertainties inherent in the modeling.
And an understanding of the uncertainties inherent in modeled
estimates will encourage the Partnership to consider using its own
judgement in deciding which chemicals to move to the final step of
the screening process. The Partnership may decide to keep a chemical
in the process despite the fact that its estimated concentration is
below the screening level. For example, if the estimate of a chemical's
concentration is close to, but below, the screening level and there are
few chemicals above the screening level, the Partnership could decide,
realizing the uncertainty in the modeled estimate, to keep the
chemical for further review in the Final Screening step. On the other
hand, if there are many chemicals with concentrations significantly
above their screening value, the Partnership may decide to drop a
chemical with a concentration that is above, but close to, its screening
value. Understanding the nature of modeling, and the uncertainties
included in the estimates it produces, will allow the Partnership to
make the kinds of informed judgments that will increase the
effectiveness of the overall screening process. Of course, these
judgments need to be made with the participation and agreement of
the full Partnership committee so that everyone will be in agreement
on any actions that may result from the screening effort.
This may also be a good point to remember that the air dispersion
model estimates air concentrations, not the exposure of members of
the community to these concentrations. Exposure is a measurement
of how much an individual or a community breathes the outdoor air
concentration. Measuring this exposure would require information
on factors such as the amount of time spent outdoors, the years spent
in the community, rates of breathing, etc. Since the methodology
described in this Manual does not include the collection of this
exposure information, the community cannot use the estimated
concentrations to estimate the risk that these chemicals pose to the
community. See the fuller discussion of this issue in the section on
screening-level concentrations in Chapter 5.
How will the Partnership find the technical skills and
resources that will be needed to use the ISCST air
dispersion model?
The Partnership technical team assigned to collect the information
needed for the project and the team assigned to estimate
Community Air Screenins How-To Manual
137
-------
Chapter 6: Secondary Screen
concentrations will work together to complete the Secondary Screen.
The team estimating concentrations will need members with skills in
using air dispersion modeling. Partnership members from colleges
and universities, industry and government technical staff, or retired
community professionals are likely to have the skills needed to use the
ISCST model. This technical team will need access to a computer and
to the ISCST model. The technical team members will need time to
set up and run the model with the information that the Partnership
has collected. If the members of the technical team do not have the
time or the skills to run the air dispersion model themselves, the
Partnership may need to find funding to hire a contractor to run the
model for the community. In this case, a technical team from the
Partnership will probably still be needed to oversee the work of the
contractor.
How will the ISCST model handle the different types
of sources and what new information will be needed
to complete this modeling?
The following section provides a general overview of how the ISCST
air dispersion model will be used to estimate the air concentrations
for the different types of sources in the community. Understanding
these approaches will help to explain the different kinds of
information that will be needed to complete the Secondary Screen.
For the stationary point sources: The location of each of these
sources will be entered into the ISCST model, and the dispersion of
the releases from these facilities will be modeled individually from
their locations in the community. The concentrations resulting from
the releases of each facility will be estimated throughout the
Partnership area.
Information required: For the stationary point sources, the model will
need information on the location of the source, the chemicals
released, the amount of each chemical released, the release
characteristics needed for modeling such as stack height and the
velocity of the release as it leaves the stack, and local meteorological
information.
For the stationary area sources: Since these sources are too
numerous or dispersed to model individually, air concentrations will
be estimated by apportioning the total county-wide emissions to each
census tract in the community and by assuming that the apportioned
emissions are released from five imaginary points (pseudo-points)
located in each census tract. The ISCST air dispersion model will
138
Community Air Screening How-To Manual
-------
Chapter 6: Secondary Screen
estimate the concentrations resulting from the releases from these
pseudo-point sources.
Take, for example, the releases from the heating of all the homes in
the Partnership area. Since there are too many homes to locate and
model individually, the Partnership's technical team will use the
estimated emissions for the entire county and apportion them
appropriately to each of the census tracts in the Partnership area. In
this case, the surrogate or factor used to apportion emissions from
home heating is population. The Partnership will compare the
population in a census tract to the total population in the county and
assign an equal portion of the total county releases to that census
tract. Once the releases have been apportioned to each census tract,
the concentrations that would result from these releases will be
estimated by assuming that the releases come from five imaginary
points spread evenly throughout the census tract. In other words, the
concentrations will be estimated by modeling from five imaginary
points instead of the much larger number of homes actually located
in the census tract. Modeling the concentrations from the five
imaginary points in each census tract will provide an estimate of the
concentrations resulting from the releases from household heating.
This basic modeling approach will be used to estimate the
concentrations from all the types of sources too numerous to model
individually.
Information required: To estimate the concentrations resulting from
the stationary area sources, the Partnership will need census tract
geographic information and census tract centroids, county-wide
estimated releases for each source type, chemicals released,
information needed to apportion releases to each census tract, and
local meteorological information.
For the on-road and non-road mobile sources: For both types of
mobile sources, the technical team will follow the same procedure
used for stationary area sources described above. A proportion of the
county-wide total emissions for the on-road and non-road mobile
sources will be apportioned to each census tract, and concentrations
will be estimated by assuming that the apportioned releases come
from five imaginary point sources and by modeling the
concentrations that would result from these five imaginary points.
Information required: The information needed to complete this task
includes county-wide release data, census tract geographic
information and census tract centroids, a method for apportioning
county-wide release estimates to each census tract, and local
meteorological information.
Community Air Screeniris How-To Manual
139
-------
Chapter 6: Secondary Screen
Detailed guidance to help the team use the ISCST model to estimate
concentrations for each type of source can be found in the Technical
Guidance section of the Manual. The Inventory Team and the team
estimating concentrations can work together to collect the new
information that will be needed. Guidance to help the teams find this
data can also be found in the Technical Guidance section.
The information needed to run the ISCST model in the Secondary
Screen is summarized in Table 6-1.
Table 6-1. Summary of Information Heeded to Run the ISCST Model in the
Secondary Screen
TYPE OF SOURCE
INFORMATION NEEDED
STATIONARY SOURCES
Stationary Point Sources:
All large and small commercial, institutional,
and industrial sources
(sources will be modeled individually)
•Chemicals released
• Release amounts
•Location of source
• Modeling release parameters
• Local meteorological information
Stationary Area Sources:
Residential, building, and other
miscellaneous
sources (sources combined for modeling)
•Chemicals released
•Total county emissions
• Census tract geographic information and
centroids
• Information needed to apportion county
emissions
• Local meteorological information
MOBILE SOURCES
On-Road
•Chemicals released
•Total county emissions
• Census tract geographic information and
centroids
• Information needed to apportion county
emissions
• Local meteorologicalinformation
Non-Road
•Chemicals released
•Total county emissions
• Census tract geographic information and
centroids
• Information needed to apportion county
emissions
• Local meteorologicalinformation
Note: The new information needed to complete the Secondary Screen is highlighted in italics.
140.
Community Air Screening How-To Manual
-------
Chapter 6: Secondary Screen
What are all the steps the Partnership will need to
take to complete the Secondary Screen?
The following is a list of all the steps the Partnership will need to
complete during the Secondary Screen.
Summary of Steps to
Complete the Secondary Screen
Step 1: Appoint a technical team with the skills needed to use
the ISCST model to estimate concentrations.
Step 2: Provide education on air dispersion modeling to the full
Partnership committee so that all members understand
the role and the limits of the ISCST model that will be
used in the Secondary and Final Screening steps.
Step 3: Set the quality control system to check the analysis to
ensure that it follows Partnership guidelines and that it
is accurate and complete.
Step 4: Complete the collection of all the information needed
for running the ISCST model.
Step 5: Choose the locations in the community where the
ISCST air dispersion model will estimate air
concentrations.
Step 6: Acquire or get access to the use of the ISCST model and
a computer to run the model.
Step 7: Set up and use the ISCST air dispersion model to
estimate concentrations.
Step 8: Compare the new concentrations estimated for the
locations identified by the Partnership to the
community screening-level concentrations and identify
those above the screening concentrations.
Step 9: Communicate results to the broader community.
Community Air Screenins How-To Manual
141
-------
Chapter 6: Secondary Screen
Are there any key decisions that the full Partnership
needs to make to ensure that the Secondary Screen
meets community needs?
At this point, most of the decisions needed to ensure that the
screening process meets community needs, such as deciding on the
risk screening level and setting standards for selecting data, have
already been made. Work during the Secondary Screen will continue
to follow the guidelines set by the partnership in the previous step.
For this step, the Partnership will need to identify the locations of
special concern in the community and instruct its technical team to
use the air dispersion model to estimate the concentrations at these
locations.
What should the Partnership consider in choosing
the community locations where the air
concentrations will be estimated?
Working with the broader community, the Partnership may want to
identify locations in the community where information on air
concentrations will be especially important. These can include
locations where community members who may be especially sensitive
to air toxics might be exposed. Schools, playgrounds, sports fields, and
day care facilities could be identified for children, and nursing homes
and assisted-living facilities could be identified for older community
members. Residential areas where community members are
concentrated and residences close to sources of toxics, either
stationary or mobile sources, may also be a concern. Identifying
locations with special concerns and providing information on these
locations to the community will help to ensure that community
questions are answered directly. In addition to estimating
concentrations at specific locations, keep in mind that the ISCST
model will provide information that will allow the Partnership to
identify any area in the community with a concentration above the
community screening level.
The Partnership will need to draw on all of its members to identify
locations in the community that are of special concern. Community
members, local schools, and local public health practitioners should
be especially helpful in this discussion.
Please note that the modeling methods used in this Manual result in
some significant limitations in the ability to estimate the aggregate
concentrations from all sources at specific community locations. It
142
Community Air Screening How-To Manual
-------
Chapter 6: Secondary Screen
will be important for the Partnership to understand and explain these
limits to the broader community, especially following the Final
Screening step, when community priorities have been identified. In
particular, the pseudo-point method used to estimate concentrations
for stationary area sources (e.g., home heating) and for mobile
sources tends to spread the releases evenly across each census tract.
For mobile sources especially, this may not adequately reflect
concentrations at points close to roads or intersections with heavy
traffic. In other words, the concentrations close to mobile sources at
some community locations may be underestimated by the pseudo-
point method. This means that for those community locations close
to mobile sources, the aggregate concentration that results from
combining the mobile source estimates with the stationary point and
area source estimates may also be underestimated. This possibility and
the limits in the ability of the pseudo-point method to identify mobile
source hotspots need to be kept in mind and explained to the broader
community. For the purposes of the Secondary Screen, if the pseudo-
point method used to estimate mobile source chemicals results in
aggregate concentrations that are below screening-level
concentrations, the Partnership may need to consider moving these
chemicals to the Final Screen where a more accurate modeling
method will be an option. In most cases, the pseudo-point method of
estimating mobile sources, despite the fact that it underestimates
concentrations in locations close to mobile sources, will result in
concentrations above community screening levels. Please see a further
discussion of mobile sources in Chapter 7.
How long will it take to complete the air dispersion
modeling using the ISCST model?
The time needed to complete the air dispersion modeling will vary
depending on the number of chemicals and sources that need to be
modeled and the resources that are available to set up and run the
model. If all the information is collected and ready to use, the
Partnership's technical team will spend most of its time setting up the
model with all the information on locations and releases of sources,
locations of concern, and census tract boundaries. In Baltimore, it
took about 40 hours of work to set up the model for the study
neighborhoods and to input all the information for the 29 chemicals
and 36 sources that were modeled in the Secondary Screen for
stationary commercial and industrial sources only. Setting up the
model to add household and mobile sources in Baltimore would have
required additional time, perhaps as much as 40 more hours. Once all
the information was entered into the model, running the model to
Community Air Screenins How-To Manual
143
-------
Chapter 6: Secondary Screen
Training teachers
and students from
local schools or
training residents
would help to
ensure that the
capacity needed
for future updates
of the modeling
will be available in
the community
estimate the concentrations took only several hours. This too may
vary depending on the speed of the computer used.
It is good to know that the investment of time and resources required
to set up and enter the information on sources and their locations
into the model will need to be done only once. All the work done to
set up the model to reflect community details can be saved. Future
community modeling will require only updating the model with any
changes that have occurred since the last modeling.
How could the Partnership carry out the technical
work of the Secondary Screen in a way that helps to
build the long-term capacity of the community to
understand and improve air quality?
The partnership and its technical team may consider developing the
capacity of a community group and/or community individuals to do
the air dispersion modeling needed for the Secondary Screen. Instead
of doing the modeling themselves, technical team members could
train and work with local science teachers and their students, a local
youth organization, or a local group of retired professionals to carry
out the modeling. Training teachers and students from local schools
or training local residents would help to ensure that the capacity
needed for future updates of the modeling will be available in the
community. Providing training for a community group would also
help the Partnership develop the skills needed to communicate the
modeling work to the broader community. Providing schools with the
opportunity to work with the Partnership and use air dispersion
modeling to help answer community questions about local air quality
could create an ideal setting for the teaching of science in
neighborhood schools.
In addition to the skills needed for air dispersion
modeling, what other skills will the Partnership need
to complete the Secondary Screen?
As in the Initial Screen, the Partnership will need to draw on the skills
and resources of most of its members to complete the Secondary
Screening step. In addition to the technical skills needed to run the
ISCST air dispersion model, discussed above, the Partnership will
need the following.
Science education skills: The full Partnership committee will need to
understand how the ISCST air dispersion model works and how it
144.
Community Air Screening How-To Manual
-------
Chapter 6: Secondary Screen
will be used in the Secondary Screen. Committee members with skills
in communicating technical information will be needed to make sure
that all the Partnership members have the information and
understanding they will need to participate fully in oversight of the
technical team's work and in the use and interpretation of the results
of the modeling. Science teachers from local schools, colleges, and
universities, and any technical members of the committee with
experience in communicating technical information, could provide
these skills.
Communication skills: Explaining the Secondary Screen and its
results to the broader community will be an important part of the
Partnership's work during and at the completion of the Secondary
Screen. (See discussion of communication below.) The Partnership
committee will need individuals with the ability to communicate the
work of the Secondary Screen to the community. Community
members, teachers, journalists, or possibly a team that combines
community members with the professional writers could provide
these skills.
Does the Secondary Screen identify the chemicals
and sources that will become the community's
priorities?
Since the air dispersion model in the Secondary Screen still uses
maximum permitted releases, the Secondary Screen is designed, like
the Initial Screen, to overestimate concentrations. While the
Secondary Screen is more accurate and less conservative than the
Initial Screen, it is still intended, except in the case of mobile and
stationary area sources, to overestimate concentrations.
As a result, the actual concentrations of the chemicals identified by
the Secondary Screen are likely to be lower than the estimated
concentrations. This means that the Secondary Screen is not designed
to identify the community priority chemicals. Like the Initial Screen,
the Secondary Screen only identifies chemicals and sources that
deserve further consideration. In the Final Screen, the Partnership will
work to get the best information available to estimate concentrations.
This next and final screening step will identify the chemicals and
sources that will be the community's priorities. Both the Initial and
Secondary Screens are designed to provide a resource-effective
method to eliminate chemicals that are very likely to be at or below
community screening levels so that the resource-intensive effort of
visiting stationary point sources to collect detailed information on
Community Air Screenins How-To Manual
145
-------
Chapter 6: Secondary Screen
Explaining the
work on a regular
basis throughout
the project will
ensure that the
Partnership
develops the
ability to
communicate
effectively with
the community
releases can be focused on only those chemicals that need this detailed
review. The Final Screen, described in the next section provides that
detailed review.
What can the Partnership do to communicate the
results of the Secondary Screen to the broader
community?
As discussed in Chapter 2, it is important to communicate with and
involve the broader community at every stage of the screening
process. The Partnership could take the occasion of the completion of
this phase of its work as an opportunity to develop a press release and
send speakers to community groups to explain the work. Of course, it
will be important to explain that the chemicals identified at this stage
of the work are only candidates for further review and that they may
not have actual concentrations above the screening values. The
Partnership can also take this opportunity to explain that the
chemicals identified in the Secondary Screen will be reviewed in the
Final Screen with the best available information, and the results of
this review will be used to identify the community's priority
chemicals.
Developing educational materials and explaining the work on a
regular basis throughout the project will ensure that the Partnership
develops the ability to communicate effectively with the community
and that the community is aware of and supports the work of the
Partnership. It will also be important to take this opportunity to make
sure that all the sources of the chemicals identified in the Secondary
Screen have been contacted and encouraged to join the Partnership.
146.
Community Air Screening How-To Manual
-------
Overview
Final Screen
What is the purpose of the Final Screen?
The Final Screen is designed to take the chemicals still in the process
after the Secondary Screen and, by collecting and using the best
information on sources that can be collected, develop new and more
accurate estimates of concentrations in community air. With these
newly estimated concentrations, the Final Screen will be used to
identify the chemicals and the sources that will become community
priorities. These are the sources and chemicals that will be evaluated
for possible community action.
How does the Final Screen work?
The Initial and Secondary Screening steps provided an effective
method to find and set aside many of the chemicals that have
concentrations in community air that are at or below the community
screening levels. In the Initial Screen, the Partnership used a
simplified method combining readily available source information
and a simple calculation based on the SCREEN3 air dispersion model
to estimate concentrations. For the chemicals still needing further
review after the Initial Screen, the Secondary Screen used readily
available source information and the ISCST air dispersion model to
get a more accurate estimation of concentrations. With many
chemicals safely set aside by these screening steps, the Partnership will
now focus its resources on a more detailed analysis of the chemicals
still left in the screening process after the Secondary Screen.
All of the chemicals and sources under review in the Final Screen have
been in the screening process from the start. The Final Screen will be
the third time that the concentrations of these chemicals in
community air will be estimated, each time using a more accurate
method. For the Final Screen, the Partnership will review these
chemicals by, once again, using the ISCST air dispersion model, only
this time the Partnership will collect and use the best available source
Analyze
Community Air Screenins How-To Manual
147
-------
Chapter 7: Final Screen
information as input for the model. To get this detailed information,
the Partnership will organize itself to do things such as contact facility
sources, work with transportation planners, or conduct surveys. The
details of this information collection will be discussed below. Based
on this effort, the Final Screen will give the Partnership estimates of
concentrations in community air that are accurate enough and
reliable enough to be used to identify community priorities.
As in the previous screening steps, these newly estimated
concentrations will be compared to the screening-level concentrations
that were developed in the Initial Screen. The chemicals with
concentrations that are still above the community screening levels will
become the community's priorities.
If a priority chemical has more than one source, the ISCST model will
also be used to estimate the contribution that each source makes to
the total concentration. This information will help the Partnership to
target its efforts to the sources making the largest contributions to the
total concentrations of the priority chemicals.
To complete the Final Screening step, the Partnership will be able to
use the screening-level concentrations that were developed in the
Initial Screen as well as all the work done in the Secondary Screen to
set up the ISCST model with the community and source locations. At
this point, the Partnership will only need to collect the best
information on the sources and chemicals still left in the screening
process and rerun the ISCST model using this new information.
What will be the results of the Final Screen?
The Final Screen completes the Partnership's effort to review all the
chemicals released into community air and find those releases that result
in concentrations estimated to be above the community screening levels.
With the completion of this review, the Partnership will have two
important pieces of information. First, the Partnership will have the list of
the chemicals and the sources that will be identified as the community
priorities. All the chemicals whose newly estimated concentrations are
still above the community screening values will become the community
priorities. And second, for each priority chemical, the Partnership will
have an estimate of the contribution that each source makes to the total
concentration. With these two pieces of information, the Partnership will
be able to focus its efforts on the chemicals and the sources that have the
greatest potential to adversely affect the health of members of the
community. These chemicals are the highest priority for efforts to
improve local air quality.
148
Community Air Screening How-To Manual
-------
Chapter 7: Final Screen
What new source information will the model need to
produce the more accurate estimates for the Final
Screenins step?
Up to this point in the screening process, the Partnership has been
using readily available information on the sources and releases in and
around the Partnership area. For the Final Screen, the Partnership will
contact, visit, and observe sources to collect and verify the best
available information. This more accurate information will be used as
input for the ISCST air dispersion modeling. The following is a list of
the kinds of information that the Partnership will collect for each of
the sources releasing the chemicals that are under review in the Final
Screen.
For the Stationary Point Sources
• Release amounts: Instead of using maximum permitted amounts
and other conservative overestimates, the Partnership will collect
and verify estimates or measurements of actual release amounts
from sources.
• Verified stack information: The Partnership will contact facilities
to verify and, if necessary, correct the information on stack
heights and locations collected from available databases for the
Secondary Screen.
• Verified release characteristics: The Partnership will contact
facilities to verify and, if necessary, correct the information on
the release characteristics such as the velocity and temperature of
the releases as they leave the stacks. This information was
collected from available databases for the Secondary Screen.
In addition, the Partnership may want to consider the use of
alternative methods, such as modeling fugitive sources as emissions
released uniformly over a finite area rather than combining all
fugitives into a single stack release. This can be easily accomplished
using the area source modeling option in ISCST and information
from the facility on the dimensions and chemicals released from on-
site stationary fugitive sources.
For the Stationary Area Sources
In most cases, the concentrations developed in the Secondary Screen
will be used again, and no further information on these sources will
need to be collected. The Partnership will determine if any further
refinement of the information used to estimate concentrations in the
Community Air Screenins How-To Manual
149
-------
Chapter 7: Final Screen
Secondary Screen is available. For example, members of the
Partnership may question the accuracy of the information used to
estimate the concentrations due to home heating if the number of
woodstoves with high emissions may have been underestimated. If the
Partnership decides that the information used in the Secondary
Screen could be significantly improved, then efforts to collect better
information can be organized and new concentration estimates
developed based on the refined information.
In addition, if the area source contributions are significant to the
overall analysis, the Partnership may want to consider the use of an
alternative to the pseudo-point modeling method used in the
Secondary Screen. Stationary source releases can be modeled as
emissions released uniformly over the area of the census tract rather
than as combined releases of five pseudo-stacks as done in the
Secondary Screen. If GIS resources are available, this can be
accomplished easily using the area source modeling option in ISCST
and information on census tract boundaries. Information for this
approach is provided in the technical section of the Manual.
For Mobile Oil-Road Sources
At this point the Partnership will need to decide if further modeling
will be necessary to identify mobile on-road chemicals as community
priorities. Given the well-documented risk that these sources present
in urban areas, the pseudo-point method used in the Secondary
Screen may, despite its limitations, be sufficient to establish these
chemicals and sources as community priorities. The Secondary Screen
estimate can also be used to estimate the relative proportion that
mobile sources contribute to the aggregate chemical concentrations in
community air, keeping in mind that, due to the pseudo-point
method used in the modeling, the concentrations at locations close to
roads with heavy traffic may be higher. The Partnership could easily
identify highways and streets with high traffic volume or idling
vehicles by drawing on the residents' knowledge. With this
information, the Partnership may be able to identify mobile sources as
a priority and identify key neighborhoods and streets for special
attention without the further use of air dispersion modeling to refine
the concentration estimates.
Even if the Partnership decides that mobile sources can be identified
as community priorities with no further modeling, to help find
possible solutions the Partnership will need to collect as much
detailed information as possible on the number and types of vehicles
using the roads and highways targeted for possible community action.
150
Community Air Screening How-To Manual
-------
Chapter 7: Final Screen
If the Partnership finds that it needs more refined estimates of
concentrations to develop recommendations or to get the support
needed for actions to reduce exposures to mobile sources, the
Partnership's technical team can use the ISCST model to develop
more accurate estimations of concentrations near heavily traveled
roads. The Partnership could also request monitoring in the areas
most affected by mobile sources to directly measure mobile source
concentrations.
To use the ISCST model to produce more accurate estimates of
mobile on-road source concentrations in the community locations
closest to the streets and highways with the most traffic, the
Partnership's technical team will use information on vehicle miles
traveled for each targeted street and estimate the emissions that will
result from the vehicles using the street by using MOBILE6.2, an
emissions model available from EPA's Office of Transportation and
Air Quality. This model uses information on vehicle miles traveled to
estimate highway emissions. The technical team will then use the
ISCST air dispersion model to predict the dispersion of these
emissions from the community's heavily traveled roadways and
estimate the concentrations that will result in areas close to the
modeled roads. Information for finding detailed guidance for using
MOBILE6.2 and ISCST to estimate mobile on-road concentrations is
provided in the Technical Guidance section of the Manual.
The information required to use MOBILE6.2 and ISCST to develop
more accurate concentration estimates includes vehicle miles traveled,
information on the key community highways and streets, gasoline
formulations used in the area, temperatures, and other inputs.
For Mobile Non-Road Sources
As for non-road mobile sources, the concentrations estimated in the
Secondary Screen will, in most cases, be adequate to determine if
these sources will be targeted as community priorities and to estimate
the contribution of these sources to the aggregate concentration from
all sources. If the Partnership is aware of a local concentration of non-
road sources, such as an airport, a railroad terminal, a port, or even a
large construction site affecting its area, the Partnership may want to
make a special effort to develop a more accurate estimate of the
concentrations resulting from these sources. Methods to estimate
emissions and concentrations from these sources have been
developed. Please see Chapter 12, "Final Screen," in the Technical
Guidance section for references to resources for estimating
concentrations from these sources.
Community Air Screenins How-To Manual
151
-------
Chapter 7: Final Screen
Trucks line up to enter a terminal at the
Port of Oakland
How will the Partnership collect
this new information?
Collecting the information listed above will
require an effort to contact, visit, or observe
the sources releasing the chemicals that are
under review in the Final Screen. Depending
on the chemicals and sources identified by the
Secondary Screen, the Partnership may need to
survey traffic on major roads or contact and
visit both large and small commercial,
industrial, and public facilities. To make these
contacts and collect the information listed
above, it may be helpful for the Partnership to
set up teams and divide up the responsibility
for collecting information on the different
sources. It will help if most of the
representatives from the stationary sources are
already participating in the Partnership. These
members can facilitate the collection of the
information that will be needed from the
facilities they represent. If a facility source is
not represented in the Partnership, the team
will need to contact the source and introduce
the Partnership to collect the information that
will be needed.
Fenix Barbour, a
resident of West
Oakland, monitors
truck traffic along
7th Street in West
Oakland.
Photos on this page
courtesy of Pacific
Institute
152.
Community Air Screenins How-To Manual
-------
Chapter 7: Final Screen
If necessary, collecting more detailed information on the releases from
the on-road mobile sources may require contacting local, regional,
state, and tribal transportation experts and getting their help to
collect the additional information on traffic that will be needed. The
Partnership may also need to mobilize community resources to
conduct traffic surveys if the information needed is not available.
Local schools or community organizations may be able to help with
the collection of this information.
In addition to collecting information, the teams will need to develop a
method for verifying the accuracy of the information that is collected.
For example, the team could review the methods used for estimating
releases from stationary sources to ensure that they are reliable or
review production and chemical use information to ensure that all
releases are accounted for.
The Partnership teams set up to collect the information may be most
effective if they contain a cross section of Partnership members.
Community leaders and local residents will be key to explaining the
work of the Partnership and convincing the facility sources to
cooperate and join in the effort. Technical members of the
Partnership will be needed to help with the collection and verification
of the information. The effort to contact and collect information from
the facility sources reviewed in the Final Screen will provide an
excellent opportunity for the members of the Partnership to get to
know these sources and to strengthen the Partnership.
How will the Partnership complete the modeling for
the Final Screen?
Once the Partnership teams have collected the new and more accurate
information on the sources and releases, the technical team
responsible for modeling will use this information and the ISCST air
dispersion model to more accurately estimate concentrations for the
chemicals under review. As in the Secondary Screen, the model will be
set to estimate air concentrations at the locations designated by the
Partnership. The model will also identify all locations in the
community with concentrations that are estimated to be above the
community screening levels. If the concentration estimates for
stationary area and mobile sources developed in the Secondary Screen
are used for the Final Screen, please remember the limitations to
estimating concentrations at specific community locations, discussed
in the previous chapter, that result from the pseudo-point method
that was used to estimate the concentrations from these sources.
Community Air Screenins How-To Manual
153
-------
Chapter 7: Final Screen
As the priority chemicals are identified, the technical team will also
use the ISCST model to determine the contribution that each source
makes to the total concentration. Guidance to help the technical team
run the ISCST model to estimate concentrations and the contribution
of each source can be found in the Technical Guidance section of the
Manual.
What are all the steps the Partnership will need to
complete the Final Screen?
Please see the following page for a list of all the steps the Partnership
will need to complete during the Final Screen.
Once the Final Screen has been completed and the community's
priority chemicals and sources have been identified, it will be
important to report this information to the community and develop
recommendations for possible actions to reduce exposures. These
important Partnership activities will be discussed in Chapter 8.
What are the key decisions the Partnership will need
to make or monitor to ensure that the screening
continues to meet its needs?
At this point, the oversight role of the Partnership will probably need
to focus on the review and approval of the methods that the teams
will use to collect and verify data. The full Partnership will need to
participate in these decisions since the chemicals identified in this step
will become the community's priorities, and everyone will need to be
confident that the information used to estimate concentrations was
reliable and accurate.
The Partnership may also need to decide on a policy for estimating
concentrations if sources are not willing to provide, and the
Partnership cannot find, the information that it needs to improve the
modeling estimates.
What skills and resources will be needed during the
Final Screening step?
The Partnership will, once again, need to draw on the resources of
most of its members. In addition to the technical skills needed to run
the ISCST air dispersion model, the Partnership will need the
following skills.
154
Community Air Screening How-To Manual
-------
Chapter 7: Final Screen
Summary of Steps to
Complete the Final Screen
Step 1: Provide background education to the full Partnership
on the kinds of information that will be needed to
improve the estimations of releases and education on
the possible methods that the Partnership can use to
verify the accuracy of this information.
Step 2: Agree on the kinds of information that will be collected
for the Final Screen and on the methods that will be
used to verify the accuracy of the information collected.
Step 3: Set up teams and divide responsibilities for contacting
the stationary sources and collecting information on the
mobile sources that release the chemicals reviewed in
the Final Screen.
Step 4: Set the quality control system to check the data
collection and analysis to ensure that it follows
Partnership guidelines and that it is accurate and
complete.
Step 5: Collect information by the best means possible
including, if necessary, visits to facilities, traffic
surveys, etc.
Step 6: Run the ISCST model using new information to develop
new concentration estimates.
Step 7: Compare new estimates to community screening levels
and identify chemicals with concentrations that are still
above the screening levels as the community's priorities.
Step 8: Identify the sources of the priority chemicals and run
the ISCST model to estimate, for each chemical, the
contribution of each source to the total concentration.
Technical skills: To collect and verify the new emissions and source
data, the Partnership will need members familiar with methods used
to estimate releases from various sources and with methods that can
be used to verify release estimates. Members familiar with modeling
and the information used in models will also be necessary to help
determine the kinds of information that the Partnership will collect.
University, industry, and government technical staff and retired
community professionals will have these skills.
Community Air Screenins How-To Manual
155
-------
Chapter 7: Final Screen
Science education skills: To participate in or monitor the collection
and verification of the new information that will be used in the Final
Screen, the full Partnership will need background information and
education on kinds of information used for air dispersion modeling
and on the methods that can be used to verify the accuracy of
information collected from or about sources. Committee members
with skills in communicating technical information will be needed to
provide this training to the full Partnership. Science teachers from
local schools, colleges, and universities, and technical members of the
Partnership with experience in communicating technical information,
should have the skills needed to provide this training.
Communication and partnership skills: Contacting sources,
explaining the Partnership, and encouraging representative of sources
to provide information and join in the Partnership effort to improve
air quality will require communication and partnering skills. Any
member with experience in communication will be able to participate
in this effort.
How can the work of the Final Screen be carried out
in a way that builds the Ions-term capacity of the
community?
As in the previous steps of the screening, the Partnership's technical
team can provide training to local residents, teachers, and students
and help them to run the ISCST model. This approach to the work
may take more time, but it would help to build the long-term capacity
of the community and the Partnership and help to ensure that all the
skills needed for future reviews of community air will be available in
the community.
What are the next steps?
In addition to learning about the sources and releases of the chemicals
in community air and identifying priorities, the purpose of the
Partnership's work is to mobilize the community to reduce risks from
chemical releases. As a result, the Partnership's work does not end
when the results of the Final Screen come in. Once the screening is
completed and priorities have been identified, the Partnership will
take the information learned through the screening process and use it
to inform the broader community, develop recommendations for
possible actions that can be taken to reduce exposures, and mobilize
the community to take action where possible. These next steps will be
discussed in the next chapter.
156
Community Air Screening How-To Manual
-------
Overview
Communicating the
Screening Results and
Developing
Recommendations
What will the Partnership need to do to use the
results of the screening analysis to achieve the
Partnership's goals?
It is important to remember that the technical screening work that
has been the main focus for the Partnership for some time is not an
end in itself. The screening effort and its results are a means designed
to help the Partnership reach its overall goals. The overall goals of the
Partnership were discussed and set at the beginning of the effort, and
the next steps for the Partnership will be determined by these goals.
Partnership goals may include things such as improving local air
quality, or developing a better understanding of local air quality and
local sources of pollution, or building the long-term capacity of the
community to understand and improve local air quality, or some
combination of these or other goals. Whatever goals have been set, to
reach them the Partnership will, almost certainly, need to work with
and mobilize broad sections of the community to make further
progress. As a result, the Partnership's emphasis will now shift from
primarily studying air quality to the task of informing and mobilizing
the community to take actions needed to reach its overall goals.
Mobilize
The Partnership's
emphasis will now
shift from primarily
studying air
quality to the task
of informing and
mobilizing the
community to
take action
Community Air Screenins How-To Manual
157
-------
Chapter 8: Communicating the Screening Results
and Developing Recommendations
Once the screenins analysis is completed, what
steps will the Partnership need to take to reach its
goals?
The following is a list of the steps the Partnership will need to take
once the screening analysis has been completed.
Summary of Steps to
Reach Partnership Goals
Step 1: Prepare a report and communication materials
summarizing the work and the results of the screening
process.
Step 2: Develop, if possible, feasible recommendations for
possible actions the community can take to effectively
reduce exposures to the priority chemicals and sources.
Step 3: Communicate the results and the recommendations to
the broader community.
Step 4: Expand the Partnership so that it has all the resources
necessary to mobilize the community to take actions
that will improve local air quality.
What skills, resources, and organization will the
Partnership need to prepare a summary report,
develop recommendations, and communicate the
results and recommendations to the broader
community?
All the members of the Partnership will need to contribute their time
and skills to move the Partnership's work from study to action. Skills
needed will include the following.
Communication skills: Preparing the summary report and
communicating the report and recommendations to the broader
community will require a broad range of communication skills, from
writing and art to presentations. A good understanding of
community questions and views on air quality will also be essential to
good communication. Partnership members who know the
158
Community Air Screenins How-To Manual
-------
Chapter 8: Communicating the Screening Results
and Developing Recommendations
community can team up with members who have experience in
writing and communicating to explain the results of the screening
and the recommendations. Teachers, reporters, students, technical
staff with experience in communication, and community members
and leaders can provide these skills.
Community leadership and organizational skills: Using the
screening results and recommendations to organize and mobilize the
community to take action will require leadership and organizational
skills from all sectors of the community. Business leaders will be
needed to mobilize their colleagues to carry out recommendations
relating to business. Similarly, community, church, and school leaders
will be needed to organize and mobilize the community to address
other community priorities and sources. Community and business
leaders who are members of the Partnership will have these skills, and
additional leaders can be recruited to the effort as the work
progresses.
Technical and research skills: Developing recommendations for
reducing exposures to priority chemicals and sources may require a
broad range of technical skills. Recommendations, depending on the
chemicals and sources, could include things such as changes in
chemical uses in industrial processes or in community households.
Technical staff from local industry and business or from their trade
associations, government technical and pollution prevention staff, and
college and university staff will have the technical background and
skill to develop recommendations. Research skills will also be
important to help find technologies and approaches that have been
developed and used by the similar pollution sources in other
communities.
Creativity: Finding effective and practical ways to reduce exposures
will probably require the Partnership and community to come up
with some new and creative approaches. The work to improve air
quality at the local level is new, so there are not a lot of ready-made
solutions for the Partnership to use. The Partnership will need to
encourage and draw on all of its members to find the solutions it will
need.
Community Air Screenins How-To Manual
159
-------
Chapter 8: Communicating the Screening Results
and Developing Recommendations
How will a report summarizing the work and the
results of the screening analysis support the
Partnership's efforts to inform and mobilize the
community to take action?
A written report summarizing the work done to study community air
and to identity the chemicals and sources that will be community
priorities will be a tool for the Partnership to use to build the
consensus in the community that will be needed to take action. Many
members of the community will not have the opportunity to
participate directly in the work of the Partnership. The report will be
key to providing these members of the community with all the
information that they will need to understand and join in the work to
improve local air quality. This information and the open, thorough,
and objective screening method that the Partnership used to identify
the priority chemicals and sources will provide the basis for building a
consensus in the community on a plan for improving air quality. A
clear presentation of the limits of the information in the report will
also ensure that community members understand the information
and can place it in context with other information. With all sectors of
the community united and mobilized around a plan for possible
action, the community will have the best possible chance of achieving
its goals. As the saying goes, "Where there's a will, there's a way," and
the Partnership's report will be key to creating the "will" in all sectors
of the community.
The development of a report summarizing the results of the screening
will also be a key opportunity for the Partnership to build the
community's capacity to understand and improve local air quality.
The Partnership can use the community's interest in the priority
chemicals and sources as an opportunity to share the background
information on air quality that the community will need to
participate fully in the work to improve air quality. To accomplish
this, the report will need to be written in a clear and understandable
fashion. Some methods the Partnership might use to help ensure that
the report communicates effectively will be discussed in the next
section.
To meet the needs of the community, the Partnership will probably
need to produce several different versions of its report, including a
short summary in the form of a press release, a short summary
designed to be widely distributed and read by almost everyone in the
community, and a longer report of the work of the Partnership for
those in the community who will be interested in a detailed account
160.
Community Air Screening How-To Manual
-------
Chapter 8: Communicatins the Screening Results
and Developing Recommendations
of the work. All of these versions will help to build the broad
consensus that will be needed to take possible action.
While a written summary report of the Partnership's work will be
crucial, it is important to remember that this report will not be the
only means the Partnership will use to communicate the work it has
done. To reach its goals, the Partnership will need to use a variety of
different means to communicate with the broader community. A
discussion of how the Partnership might conduct a broad campaign
to communicate the results of the screening and the
recommendations it has developed is discussed below.
What methods can the Partnership use to develop a
report for the community that effectively summarizes
the results of the screening process?
Developing and maintaining a consensus as the work progresses in
the Partnership, and communicating with and getting input from the
community at each stage of the screening analysis, are the most
effective ways to prepare the Partnership to write a final report that
can effectively communicate the work to the community. If the
Partnership has communicated consistently with the community
throughout the screening work, it will have the experience needed to
effectively communicate the results of the analysis.
Once the screening analysis is complete, the first step in developing a
summary report will be to thoroughly discuss the results of the
screening and what they mean for the community in the full
Partnership committee. Before starting to write a report, the
Partnership should reach a consensus on all the key points that will be
made in the summary. This consensus in the Partnership will provide
the basis for beginning work on the report. The time needed for the
Partnership to reach a consensus on the key points of the report will
depend in part on the amount of time the Partnership took to clarify
its thinking at each stage of the work.
An effective report will directly address the concerns of the
community. The community will look to the report for answers to
their questions and concerns about local air quality. Understanding
these questions and concerns, and addressing them directly, will be
key to developing an effective report. The screening analysis will
probably not answer all community questions, and it will be
important for the report to point out which community questions
can and can't be answered with the work that the Partnership has
done. Once again, practice at communicating the work of the
Community Air Screenins How-To Manual
161
-------
Chapter 8: Communicating the Screening Results
and Developing Recommendations
Partnership and paying attention to community input are the best
ways to prepare for understanding and addressing community
questions and concerns.
To help with drafting its summary report, the Partnership team that is
given responsibility for drafting the summary report may want to
involve community members, both residents and business
representatives, who have not participated in the previous work of the
Partnership. Their participation would help to ensure that the report
is written in a form that is understandable to everyone in the
community and not just those who have participated in the
Partnership's work.
Once the Partnership has agreed on the form for the summary of its
work, either a written summary of the main points or a draft version
of the full report, it would be helpful for members of the Partnership
to practice presenting these ideas to small groups in the community.
This will give the Partnership a chance to identify any questions that
have not been addressed or areas that need better explanation. Input
from these small meetings can then be used to complete the final
report.
It will also be important for the Partnership, even after it has prepared
and presented its final report to the community, to remain open to
input from the community and to be willing to address important
community issues that may have been missed.
Why should the Partnership consider working on
developing recommendations for reducing the
exposures to the priority chemicals and sources?
Developing and presenting recommendations for potential actions
that can be taken to reduce exposures as soon as the priority
chemicals and sources are identified will help to ensure that the
community gets a quick start on its effort to improve community air
quality. In addition, presenting possible solutions side by side with the
priorities identified by the screening process may help to relieve
community concerns and channel community energies into the
efforts that will be needed to address those concerns. If facility sources
are identified as community priorities, developing recommendations
for reducing exposures will also give these facilities an opportunity to
demonstrate their willingness to work with the community to address
concerns and improve air quality.
162
Community Air Screening How-To Manual
-------
Chapter 8: Communicatins the Screening Results
and Developing Recommendations
Should the results of the screening analysis and the
recommendations for addressing the priority
chemicals and sources be communicated to the
community at the same time?
Each Partnership will have to determine the most effective way to
develop recommendations and communicate the results of the
screening for their community. The following are considerations to
keep in mind while planning this work. First, the Partnership will
probably want to communicate the results of the screening to the
community as soon as a clear summary can be written. To delay in
communicating the results could contradict the Partnership's goal of
informing the community and possibly undermine the community's
trust in the Partnership. If the Partnership delays releasing the results
of the screening so that it has time to develop recommendations, the
community may feel as though important information has been kept
from them, especially if there are actions the community members
could take immediately to reduce risks. And, given the broad nature
of the Partnership, the community is certain to learn about the results
of the screening even if the Partnership delays its report while it
develops recommendations.
Once the Partnership reports the results of the screening process to
the community, it should make every effort to develop feasible
recommendations for addressing the priority chemicals as soon as
possible. Presenting recommendations for possible actions that can be
taken to reduce risks from priority chemicals and sources as soon as
possible will help to alleviate community concerns and shorten the
time needed to reach the goal of improving air quality. Any long delay
between the identification of the priority chemicals and the actions to
address them is likely to increase community concerns.
It may be possible to identify in advance some chemicals that are
likely to be priorities, and the Partnership, if it has sufficient
resources, could organize a team to begin developing
recommendations even before the screening analysis is completed.
Mobile source chemicals with high concentrations throughout the
nation could, for example, be selected for early work to develop
recommendations. On the other hand, some chemicals will not be
obvious priorities and, once they are identified, may require
considerable time for the Partnership and community to develop an
effective and practical plan to reduce exposures.
Community Air Screenins How-To Manual
163
-------
Chapter 8: Communicating the Screening Results
and Developing Recommendations
As an illustration, the following is an example of a plan the
Partnership could adopt to try to meet community needs at this stage
of its work: As soon as the results of the screening are in, the
Partnership develops a clear written report summarizing the results.
The Partnership distributes this report to the local press and the
community along with an announcement letting the community
know that the Partnership will be working on ideas for addressing the
priority chemicals and sources and that there will be open community
meetings in a month to discuss both the results and the
recommendations for addressing the concerns. The Partnership then
spends a month working to identify as many effective and practical
recommendations as possible. Chemicals and sources that need
additional time and community input to develop effective plans for
action are also identified, and further work to develop a plan for
reducing risks for these chemicals and sources are included in the
recommendations. At the community meeting following this month's
work, the Partnership presents the results and the preliminary
recommendations for action as the beginning of a major effort to
communicate with and mobilize the community.
What should the Partnership consider to develop
recommendations and to decide which ones should
be implemented?
To develop and choose recommendations for implementation, the
Partnership will need to carefully discuss all options to find the ones
that best match community goals. The Partnership may, for example,
have more recommendations than can be implemented at once with
available resources. In this case, the recommendations will need to be
prioritized and ranked in terms of their ability to achieve community
goals. It will be especially important at this point for the Partnership
to take time to review the discussion of goals held at the beginning of
the Partnership's work and to clarify and update these goals so that
they reflect everyone's current thinking. Once the goals of the
Partnership and community have been clarified, recommendations
can be discussed with these goals in mind. For example, if the
Partnership's goals are to reduce risk from air toxics, improve
community health, and build community capacity, then in order to
develop and choose among recommendations, the Partnership will
need to consider things such as the following: the amount of risk
reduction that a recommendation will achieve in comparison to other
recommendations, the cost and the time it will take to implement a
recommendation, and the contribution of a recommendation or a
combination of recommendations to strengthening the Partnership
164
Community Air Screening How-To Manual
-------
Chapter 8: Communicatins the Screening Results
and Developing Recommendations
and building the enthusiasm of all sectors of the community to
contribute to risk reductions. Partnerships may also want to consider
community perceptions of risk and the relationship of the
recommendations to these perceptions.
The relationship of the recommendations to other community goals
should also be considered. For example, it will be important for the
Partnership to take time to consider the impact of work to improve
air quality on the other ongoing efforts to improve community health.
This will enable the Partnership to design the work to improve air
quality in a way that complements and supports the other work to
improve community health. In most cases, this work to coordinate
with other community efforts will result in more effective work to
improve air quality. In some cases, especially in communities with
limited resources, a partnership may decide, based on the information
obtained from the screening analysis, that other community concerns,
such as contaminated food or drinking water, are more pressing
concerns for the community. As a result, they may delay
implementation of the recommendations on air toxics until these
risks are addressed.
Finally, although the goal of the screening exercise is to identify
community priorities so that effective efforts to reduce risk can be
started, in some cases a Partnership decision to recommend further
study of the priority chemicals and sources may be warranted. For
example, the Partnership may decide to seek assistance for a
monitoring study to verify the results of the modeling. This may be
necessary to resolve any doubts in the Partnership about the data used
for modeling or the accuracy of the modeling. The Partnership could
also decide to begin reduction actions based on the modeling results
and carry out a monitoring study at the same time. Or the
Partnership could decide to request assistance from state or federal
agencies to conduct a more in-depth exposure investigation of the
priority chemicals so that information on risk can be used to help
make decisions on recommendations and possible actions.
What should the Partnership consider to develop
recommendations for each of the priority sources
and chemicals?
To do the work to develop recommendations for each of the priority
chemicals and sources, the Partnership may need to organize a team
for each source or source type. The members of the teams that
collected information on the priority sources for the Final Screen will
be good candidates for membership on these teams since they will
Community Air Screenins How-To Manual
165
-------
Chapter 8: Communicating the Screening Results
and Developing Recommendations
JeffAigeldinger calibrates
a painter's spray gun and
offers advice during a site
visit to an auto refinishing
shop. Best practice
information for auto
refinishing shops was
developed by EPA's
Design for Environment
Program
already be familiar with the sources. For example, the Partnership
might organize teams to develop recommendations for mobile
sources, for auto body shops, for households, for a refinery, for an
incinerator, etc. The following is a list of suggestions for these teams
to consider in their work to develop recommendations.
Relying on the community, residents, and businesses to find
practical solutions: Whatever the chemical or source of concern, to
find solutions that will work and can be implemented, the Partnership
will need to rely on those affected to help develop the
recommendations. Businesses and residents who understand and
support the goals of the Partnership will have the best chance of
finding ways to change business practices and community habits. The
Partnership may need to recruit new members to help with the
development of recommendations for reducing emissions of the
priority chemicals. Representatives of all the major sources, if they are
not already members of the Partnership, should be recruited to
participate in the effort to find solutions.
Looking for models and benchmarks: In addition to drawing on its
members and the community for ideas on reducing emissions and
exposures, the Partnership should also look for information on efforts
to address similar chemicals and sources that have been present in
other communities. Successful programs and technologies may have
been developed that the Partnership can adopt or learn from.
Businesses in other communities that have developed model emission
reduction programs can be used as benchmarks and as a source for
ideas. Similarly, successful community efforts to address mobile and
household sources can be a source for ideas.
Using a pollution prevention approach to address the priorities:
When possible, the Partnership should look for pollution prevention
opportunities in the recommendations it develops. Pollution
prevention focuses on reducing the release of pollutants by limiting or
eliminating the use of toxics at the source, instead of looking for ways
to control the releases and exposures that result once the toxics are
used. Pollution prevention solutions eliminate the need for ongoing
management and reduce the possibility of exposure from accidental
releases. In addition, many businesses have found that pollution
prevention can help to cut costs.
Applying for funding: As a part of its plans, the Partnership may also
need to consider applying for funding to support its work. There are a
variety of funding sources designed to support community efforts to
reduce emissions, and the Partnership, based on the work it has done
166.
Community Air Screening How-To Manual
-------
Chapter 8: Communicating the Screening Results
and Developing Recommendations
to set priorities and mobilize local resources, will be in an excellent
position to quality for this funding. To take advantage of current and
future funding opportunities, the Partnership may need to organize
training to build the capacity of the community to apply for funding.
Some members of the Partnership should be able to provide this
training or know where it can be found.
Providing incentives: It will also be important for the Partnership to
include in its recommendations ways to provide incentives to
businesses and residents for reducing emissions. In the long term, the
incentive of building a healthy and sustainable community will have
the most impact, but finding ways, in the short term, to recognize and
reward efforts to support community goals can be very effective.
Developing community "green" or "clean" business, household, or
school recognition programs may be very helpful. Models for
developing these kinds of incentive programs are available.
Using enforcement as an option: While, in most cases, the potential
actions required to meet community goals will go beyond regulatory
requirements and require voluntary efforts, if there are violations of
environmental regulations and the Partnership cannot convince a
business to join in community efforts, the Partnership
recommendation may call on its government partners to use their
enforcement authority to address community concerns.
Partnering with nearby communities: In the cases where the
Partnership will need to address sources that have regional impacts,
such as mobile sources or large facilities, the Partnership may find
that it needs to join with other nearby communities to develop a plan
that can effectively reduce emissions. Because of the need to consult
with other communities, recommendations to address these concerns
will probably take longer to develop and implement. Despite the time
required, the Partnership is likely to find that some of the
community's key concerns can only be addressed by reaching beyond
its own borders and working with other communities.
Developing both long- and short-term recommendations:
Combining recommendations that can produce results in a short
amount of time with recommendations that will take longer to
develop and implement may help to sustain community involvement.
Making and publicizing short-term accomplishments will build
community confidence and enthusiasm and help to maintain the
efforts that will be needed to address larger or more complex
concerns. For example, changing to low-sulfur fuel for local buses,
getting facilities to commit to early reductions in emissions, or
Community Air Screenins How-To Manual
167
-------
Chapter 8: Communicating the Screening Results
and Developing Recommendations
All the members
of the Partnership
will need to be
involved in the
effort to
communicate
with the
community
working with local retailers to reduce household chemical use can
produce measurable results in a year or less, while the planning and
work for longer-term projects, which may take two or more years, can
be developed, such as redirecting truck traffic or developing and
providing pollution prevention training to small local businesses.
Recommending pollution prevention and emission reductions as
community standard for chemical use: In addition to the key task of
developing recommendations to address the community's priority
chemicals and sources, the Partnership should consider developing a
general recommendation and incentive program that encourages
continuous emission reductions and pollution prevention for all
chemicals used in the community. This is especially important given
the limited information that is available to communities to conduct
screening exercises. As the Partnership learned, many chemicals do
not have adequate testing data, and new testing may discover
additional hazards for even well-tested chemicals. In light of these
uncertainties, a recommendation that supports and encourages a
continuous commitment to reductions and pollution prevention for
all community chemicals would complement the specific
recommendations developed for the priority chemicals.
Please see Appendix G for a list of resources and programs for
pollution prevention and emissions reduction.
How can the Partnership organize a campaign to
effectively communicate the results and
recommendations and mobilize the community to
potentially take action?
Once the summary report and preliminary recommendations have
been developed, the Partnership will probably need to focus for a time
on a major effort to communicate this information and mobilize the
community to take potential action. All the members of the
Partnership will need to be involved in this effort to communicate
with the community.
To develop an effective outreach campaign, it will be important
for the Partnership to clarify its goals and message so that all the
members of the Partnership are speaking with one voice in
the community. Goals for the outreach might include mobilizing the
community to take some possible action or actions, improving
the community's understanding of local air quality, and recruiting
volunteers to implement the next steps of the Partnership's work. The
Partnership should also agree on the key points from the screening
168.
Community Air Screening How-To Manual
-------
Chapter 8: Communicatins the Screening Results
and Developing Recommendations
analysis and the summary report that it wants to stress and prepare
presentation materials summarizing the goals and message that
everyone in the Partnership can use. The Partnership will also need to
plan to discuss and respond to any input that the community
provides during the course of the outreach.
With a common understanding of the message and goals, the
Partnership can organize small outreach teams or assign individuals
to represent the Partnership in local media and to speak to
community organizations such as block clubs, PTAs, business
organizations, schools, and churches. Teams or individuals can also
meet with key community leaders and with key stakeholders outside
the community. Combining Partnership members from different
sectors of the community on the same outreach team will improve the
effectiveness of the outreach and provide an excellent opportunity for
strengthening the Partnership. The Partnership may also want to
organize its own public community meetings to communicate with
and mobilize the community for the next steps.
Will the Partnership be able to find the community
resources that will be needed to develop and
implement the recommendations for improving air
quality?
The campaign to communicate the results of the screening and the
recommendations to the community will provide an excellent
opportunity for the Partnership to recruit the resources it will need
to reach its goals. The communication effort to explain the priority
chemicals and sources and the work done to identify them will
help to develop community interest in local air quality. The
recommendations for changes that can improve air quality will also
be sure to attract the attention of the community, especially those
directly affected by any proposed changes. Small businesses that are
the focus of a recommendation will be encouraged to participate by
the prospect of getting help finding the resources and information
that they need to protect their workers and neighbors. Residents will
actively help with measures designed to improve community health
by reducing exposures from the use of household chemicals or from
mobile sources.
The Partnership itself and its work will also serve as an incentive for
greater community participation. As the outreach campaign unfolds
and teams from the Partnership meet with groups throughout the
The campaign to
communicate the
results of the
screening and the
recommenda tions
to the community
will provide an
excellent
opportunity for
the Partnership to
recruit the
resources it will
need to meet its
goals
Community Air Screenins How-To Manual
.169
-------
Chapter 8: Communicating the Screening Results
and Developing Recommendations
Partnership area, the community will learn about the successful
completion of the screening work and see a first-hand demonstration
of the community's ability to work together to get things done. The
Partnership's successes may be the most effective encouragement for
broader community participation.
The Partnership's switch from a focus on understanding air quality to
possible actions to improve air quality will also bolster participation.
Efforts focused on making concrete measurable improvements in
community air will attract many community members who were not
interested in the more analytical aspects of the Partnership's work.
Overall, the opportunity that the Partnership offers for the
community to focus on the chemicals and sources that have the
greatest potential to adversely affect the health of community
members and to make real improvements in community air will
ensure the participation needed to move forward. To make sure that
the new community volunteers do not waste their time, the
Partnership will need to set up and organize new committees or other
forms of organization prepared to focus on the implementation of the
recommendations. These new committees will become the center of
Partnership activity as the Partnership shifts to the work to improve
air quality.
What can the Partnership do to ensure that the
community's work to improve air quality will
continue in the future?
At some point the Partnership will need to take time to consider and
plan for the long-term work that will be needed to monitor and
continue to improve local air quality. The work to develop and
implement recommendations will also take time and planning, and
long-term goals may need to be set for this work. Plans for updating
the Emission Source Inventory database annually and plans for the
next thorough screening of local air quality will need to be
considered. The ability to sustain the work in the long term will also
require the Partnership to plan for long-term funding and for the
maintenance of some form of organization to support the work. The
shape of the organization the Partnership will take will differ from
community to community depending, in part, on the Partnership's
relationship to other organizations in the community. The
Partnership will also need to think about developing the leadership
and providing the training that the community will need to carry on
170
Community Air Screening How-To Manual
-------
Chapter 8: Communicatins the Screening Results
and Developing Recommendations
this work in the future. Keep in mind that the best way to ensure the
long-term viability of the work may be to take advantage of the
current work to improve air quality as an opportunity to build
community capacity. Special training for community leaders and for
local teachers could also be set up on a regular basis. For example, the
Partnership could help teachers incorporate the science and
knowledge needed to understand local air quality in the curricula of
local schools so mat the community's students are prepared with the
background they will need to continue and to lead the work.
What can the Partnership do to share its experiences
with other communities?
Communities across the nation are working to understand and
improve local air quality. All of these local community efforts would
benefit immensely if communities found ways to share their
experiences and learn from each other. Sharing of information will
also help to identify the air quality problems where the joint action of
many communities and governments might be helpful or necessary.
To share information with other communities, the Partnership will
need to assign one of its teams to take on this responsibility and
provide them with the resources they will need. Setting up an Internet
site for the Partnership and making all Partnership reports, decision
documents, and outreach materials available on the web site would be
an effective way to make the Partnership's experiences accessible to
other communities. Including regular summaries of lessons learned
on the web site would be especially useful. And an opportunity, such
as a partnership with a local school with video training capacity to
record the community's experiences in a video documentary, would
be an excellent way to share experiences with other communities.
In addition, national meetings can be organized to bring communities
together to share their experiences. If possible, the Partnership should
plan to send members to participate in these meetings. At some point,
the Partnership may want to take the lead to facilitate the sharing of
information. For example, a Partnership committee working on
developing a recommendation for a particular source may find it
useful to organize a national conference call with other communities
working on the same concern. As work at the local level develops,
additional opportunities for exchanging information will develop.
Local community
efforts would
benefit immensely
if communities
found ways to
share their
experiences and
learn from each
other
Community Air Screenins How-To Manual
.171
-------
172
Community Air Screening How-To Manual
-------
Technical
Guidance
Building the Emission
Source Inventory
This section describes the procedure the Partnership's
Emission Source Inventory Technical Team will use to set
up the Emission Source Inventory database needed for
the screening process. It includes the software and
hardware requirements, a description of the information
to be collected, a list of the steps that need to be
completed to set up the database and collect the
information, and detailed suggestions to help the
technical team carry out each task. The information in
this section is based on experiences of the Baltimore
Community Environmental Partnership and on the
comments received during the review of the technical
report summarizing these experiences (refer to
Baltimore Community Environmental Partnership Air
Committee Technical Report, EPA 744-R-00-005, April
2000).
What is the overall goal for the technical
team?
Chapter 4 of the Overview provides a general
introduction to and background information for
building the Emission Source Inventory. The overall goal
for the technical team is to set up the Emission Source
Inventory database and enter information needed to
complete the Initial, Secondary, and Final Screening
steps. A flow chart showing the overall procedure for
developing the emission source inventory is shown in
Figure 9-1.
The technical team begins the process of building the
Emission Source Inventory database by collecting and
entering release and location data for all the stationary
and mobile sources in the study area. Information on
background and relevant monitored concentrations are
also entered in the database at this time. Detailed
guidance for setting up the Emission Source Inventory
database, identifying and locating sources, collecting
release information, and collecting background and
relevant monitored concentrations is provided in this
section of the Technical Guidance. The process of
collecting information about emission sources and
entering this information into the database continues
through the Final Screening step. At each step of the
screening process, the Emission Source Technical Team
will collect the additional information that will be
needed to estimate ambient air concentrations. Guidance
for collecting the additional information that will be
needed for each step of the screening process is provided
in subsequent sections of the Technical Guidance.
What software and hardware will the
Partnership use to store the emission
source information needed for the
screening process?
The software needed to create the source inventory
database can be either a spreadsheet program (e.g., Lotus
or Excel) or a database management program (e.g.,
dBase or Oracle). A database program may be preferable
if your study area includes a large number of emission
sources and chemicals, but in most cases a spreadsheet
program will be sufficient. The software program is used
to store, organize, and manipulate the data collected by
the Partnership. The software must be able to query, sort,
and perform mathematical manipulations. In addition,
the software must also be able to export selected
information from the Emission Source Inventory
database for further analysis using air dispersion
modeling software during the Secondary and Final
Screening steps.
The hardware requirements include a personal
computer, modem, and printer. The computer will need
appropriate processor speed, random access memory
(RAM), and hard disk space to run the spreadsheet or
database software and the air dispersion modeling
software. In addition, an Internet service provider (ISP)
connection will need to be established to enable the
Partnership to send and receive e-mail, perform Internet
searches, and download data from various federal, state,
and local government web sites.
Community Air Screenins How-To Manual
173
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
Partnership selects Emission Source Technical Team to
develop the Emission Source Inventory.
Create data input screens and data tables for the
Emission Source Inventory database.
Collect and enter release and location data for all stationary and mobile sources.
Collect and enter background and monitored concentration information.
Consider collecting the additional
information needed to perform
the Initial, Secondary, and Final
Screening step, if it is available.
Collect and enter data needed to use
SCREENS model to complete the Initial Screen.
Collect and enter data needed to use
ISCST3 model to complete the Secondary Screen.
Collect and enter data needed for more accurate estimation using
ISCST3 model to complete the Final Screen.
Figure 9-1.
Overall Procedure for Developing Emission Source Inventory
174
Community Air Screening How-To Manual
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
What information will be collected and
entered into the database to begin
developing the Emission Source
Inventory?
Once the Partnership has defined the boundaries of the
study area, data on source locations and releases are
collected and entered into the Emission Source
Inventory database. Keep in mind that emission sources
outside the study area may also have an impact on air
quality within the study area and, therefore,
consideration should be given to including these sources
in the Emission Source Inventory. Chapter 4 of the
Overview describes the procedure for defining the
boundaries of the study area. The goal is to capture
information on as many chemicals and emission sources
as possible in the study area. The technical team will
need to collect information from several databases or
information sources maintained by different government
agencies. Each of these databases and data sources
contains information on selected chemicals. Many of the
same chemicals will be in all the data sources, but some
chemicals will be found in one database but not in other
databases. The Partnership will use all available data
sources to collect information on as many chemicals
released in its area as possible. Detailed guidance for
accessing this information is provided below.
Table 9-1 summarizes the information that needs to be
collected for each source type prior to the Initial Screen.
The focus at this point is to collect release and location
information for all sources, as well as background and
relevant monitored concentration data. But, if additional
information needed for the Initial, Secondary, and Final
Screens is readily available, then consideration should be
given to collecting this information too.
During the Initial and Secondary Screening steps, the
Partnership will be using readily available release data
based on maximum permitted release amounts as inputs
for the look-up table and the ISCST model, respectively.
If the release data available to a community Partnership
have only estimated actual release amounts and not
maximum permitted release amounts for stationary
sources, the Partnership will need to increase these
release estimates, possibly multiplying the release
amount by a factor agreed on by the Partnership, to
ensure that the Initial and Secondary Screens are
conservative. For example, release estimates taken from
the TRI database are estimated actual releases, not
maximum permitted releases, so the Partnership's
technical team will need to increase these amounts to
ensure that the Initial and Secondary Screens are
conservative. For the Final Screening step, the
Partnership will have the resources to contact each of the
remaining stationary sources to obtain actual release
data.
A table summarizing the information needed to
complete all of the screening steps is provided at the end
of the Overview section for "Building the Emission
Source Inventory," Chapter 4. The decision to collect
additional information needed to complete the
Secondary and Final Screening steps should take into
account the fact that the Partnership will not know in
advance which chemicals will be identified for further
screening during each step of the process. For example,
detailed information about the temperature of the gases
released from stationary point sources (i.e., stacks) is
needed to estimate concentrations during the Final
Screen. But collecting this information for all the stack
releases in the Emission Source Inventory would be a
waste of time, since the information will only be needed
for the small number of chemicals left after the
Secondary Screen is completed.
Despite the fact that the Inventory Technical Team will
need to wait until the screening results are complete to
know which chemicals will remain in the screening
process, it is important for the Partnership to know all
the data that will be needed to complete the screening.
Understanding what the data requirements are allows the
Partnership to take advantage of easy opportunities to
collect information as they arise. For example, if the
detailed information on releases needed for the Final
Screen is present in the same database used to collect the
information on the amount of releases, and if the
information is in a form that will allow it to be
transferred electronically into the Emission Source
Inventory, then detailed information on all the chemicals
can be collected from the beginning with minimal effort.
Community Air Screenins How-To Manual
175
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
Table 9-1.
Information Collected for Emission Source Inventory Prior to Initial Screen
TYPES OF SOURCES
INFORMATION TO BE COLLECTED
PRIOR TO THE INITIAL SCREEN
Stationary Point Sources:
All large and small commercial, industrial, and publicly owned
facility sources (sources will be modeled individually)
•Sourceswith individual release information available
•Facility name
•Facility location
•Chemical released
• CAS number
•Emission rate
•Sources with individual release information not available
(sources will need to be estimated)
•Facilityname, location, chemical released
• Emission factor and business activity measure or county-wide
release amount used to estimate emission rate (Ib/yr)
Stationary Area Sources:
• Household, small office building, and other miscellaneous
sources (sources will be combined for modeling)
•County name
•Chemical released
• CAS number
• Emission rate (Ib/yr) on a county-wide basis
Mobile Sources:
• On-road: All trucks, buses, cars, and any other street or
highway vehicle
• Non-road: Trains, airplanes, ships, construction equipment,
lawn equipment
•County name
•Chemical released
•CAS number
• Emission rate (Ib/yr) on a county-wide basis
Background Sources:
• Releases that are not the result of current human activity,
including both natural and past human sources
•Chemical name
• CAS number
• National background concentration measurement (ng/m3)
Monitored Concentrations:
•Chemical name
•Annual average concentration
176.
Community Air Screening How-To Manual
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
What are the steps the Partnership will
need to complete to set up the Emission
Source Inventory and collect the
information needed for the Initial Screen?
The following list of tasks will need to be completed by
the Partnership to set up the emission source inventory
prior to the Initial Screen:
Step 1: Set up quality assurance/quality control
(QA/QC) procedures for data collection
and entry
Step 2: Set up an Emission Source Inventory database
to incorporate information needed for the
screening process
Step 3: Identify and collect location information for
all stationary point sources in the study area
Step 4: Collect emission rate information for
stationary point sources when release
information is available for each
individual source
Step 5: Estimate emission rates for stationary point
sources when release information is not
available for each individual source
Step 6: Identify and collect emission information
for stationary area sources (sources combined
for modeling)
Step 7: Collect information on mobile source
emissions
Step 8: Collect information on background
concentrations
Step 9: Collect information on relevant monitored
concentrations
How will the Partnership carry out these
steps?
Step 1: Guidance for setting up QA/QC procedures
for data collection and entry
Quality assurance and quality control are important
considerations for all work performed during the air
screening process. The overall quality control objective is
to collect well-documented data with known quality.
This objective involves establishing and meeting goals for
precision, completeness, and representativeness. The
conclusions and recommendations made by the
Partnership may potentially be used to justify changes
for emission sources in the study area. Therefore, the
information gathered and used to create the source
inventory database must be accurate, complete, and
defensible. The Partnership is responsible for reviewing
the data collected by the Partnership on each facility in
the study area and for deciding whether the data are of
appropriate quality for inclusion in the source inventory
database.
To ensure the accuracy of the work when building the
source inventory database, all information gathered by
the Partnership about the facilities should be
documented. By documenting the information collected
from the emitting facilities, the Partnership will be able
to identify where and when a particular value was
obtained (e.g., facility records, permits, and telephone
conversations). Forms should be created to document
telephone conversation, facility visits, and other data
collection efforts. Notes and other hard copies of data
obtained from the facilities should be filed in a manner
that allows for easy retrieval for future reference.
Data collected from the facilities should be recorded on
predesigned data entry forms that are printed out and
filled in by hand or electronically. The forms should be
designed to ensure that a consistent set of information is
collected from each emission source during the Initial,
Secondary, and Final Screening steps. This minimizes the
potential for data gaps and helps to ensure that all
needed information about a given emission source is
obtained.
The Emission Source Inventory is used to store the data
collected by the Partnership. This information will be
used throughout the screening process. Therefore, it is
important that the information be as accurate and
comprehensive as possible. The following QA/QC
procedures should be put into place by the Partnership
to help ensure the integrity of the database.
Community Air Screenins How-To Manual
177
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
Quality control for data entry is an important
consideration. Data on air emissions collected by the
Partnership should be entered accurately into the
database. There is the potential for data entry errors to
occur when transcribing information from notes, facility
records, and permitting forms, and when importing data
from existing databases. Therefore, procedures should be
put into place to compare the data entered into the
emission source inventory with the original source of the
data. This can be accomplished by comparing the entries
in the database with the information recorded on the
data entry forms. A more stringent quality control
procedure involves entering the data into two separate
databases and comparing the fields in each database to
see if there are discrepancies. Differences between the
two databases can then be examined, a decision made as
to which values are correct, and appropriate changes
made.
Quality control for mathematical manipulations
includes checking the calculations used to convert
emission rates to ambient air concentrations.
In addition, it involves checks to ensure that
consistent units are used when comparing ambient air
concentration values to screening-level concentration
values. Emissions data are provided in different units
(e.g., tons, pounds, grams) and for a variety of time
periods (e.g., per year, day, hour), and the emissions
data may be reported as a rate of emission (e.g., tons/
year, pounds/year, grams/hour). The Partnership should
be sure to work with consistent units of measure. The
mathematics used to convert from one unit of measure
to another should be checked for accuracy.
As a part of its quality control, the Partnership will need
to pay special attention that releases from sources are not
entered into the inventory database more than once.
Since emissions data are collected from a variety of
sources, there is the potential for information to be
collected about the same emission source from more
than one source. If the same releases are recorded in
more than one database, the Partnership's Inventory
Team should only use the information from the database
with the best quality and most appropriate data for
screening. It is also possible that some releases may have
been entered more than once in the same database by
error. If there are multiple releases of the same chemical
from the same facility, the Inventory Team may want to
check to be sure that they are actually different releases
and not multiple entries for the same release. Checking
to make sure that the release amounts entered into the
Partnership's database are not the result of counting the
same release more than once will be a key part of the
Partnership's quality control work.
Integrity and defensibility of the database are very
important because the information in the Emission
Source Inventory will be used by the Partnership as a
basis for making decisions about air quality in the study
area. The Partnership should provide the opportunity
for independent review of the information in the
Emission Source Inventory. For example, facilities in the
study area should be given the opportunity to review and
comment on the accuracy of the data. Data reports that
summarize information contained in the source
inventory database can also be generated electronically
and can be checked for accuracy by the facilities.
A particular chemical may be known by a variety of
names (e.g., methylene chloride is also called
dichloromethane). For consistency, it is best to use the
Chemical Abstracts Service (CAS) registry number in the
Emission Source Inventory. The CAS number is
provided in the format xxxxx-xx-x. The number is
unique for each chemical and allows efficient searching
on computerized databases. The CAS number entries
should be checked to ensure that the correct number is
used.
Step 2: Guidance for setting up the Emission Source
Inventory database to incorporate
information needed for the screening process
The Emission Source Inventory database will be set up to
store the information shown on Table 9-1 in preparation
for conducting the Initial Screen. This information is
collected by the Partnership for the purpose of
identifying as many sources of air emissions as possible
(i.e., stationary point sources, stationary area sources,
mobile sources, and background and relevant monitored
concentrations) within the study area. The database will
subsequently be updated during the Initial, Secondary,
and Final Screens to include more detailed and accurate
information about the chemical emissions that affect the
study area.
Figure 9-2 shows an example template for a spreadsheet
that can be used to begin developing the emission
source inventory. Column A is the Emission Source Type
(i.e., stationary point, stationary area, background
concentrations, and relevant monitored concentrations).
Column B is the Facility or County Name and is used to
identify the source of the emission. Column C is the
178.
Community Air Screening How-To Manual
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
Chemical Name and is used to identify the chemical that
is being released. Column D is the Chemical Abstract
Service (CAS) registry number (CAS Number). Column
E is the Annual Emission Rate of the chemical from the
source in units of pounds per year. Emission rate
information is collected at the time for stationary point
sources, stationary area sources, and mobile sources.
Column F is the Measured Ambient Air Concentration
(i.e., monitored concentrations) in units of [^g/m3.
Column G is the Background Source Concentration in
units of [ig/m3.
Step 3: Guidance for identifying and collecting
location information for all stationary point
sources in the study area
As the first step in collecting the information needed for
the screening process, the technical team will need to
identify all the stationary point sources of air toxics in
the Partnership study area. As discussed in the Overview,
the boundaries of the area to be studied will be
determined by the Partnership. In many cases, use of ZIP
codes to define the boundaries of the study area will
make it easier to obtain applicable records for the
emission sources contained in the existing databases.
The technical team will not need to collect location
information for the stationary area sources in the
Partnership area. These sources, such as household
heating or consumer product use, are too numerous or
irregular to locate individually. The following is a list of
the stationary sources that will be treated as area sources
and will not require location information. Any stationary
source in the Partnership area that does not belong to
one of these area source categories will need to be
identified, located, and handled as a point source.
E3 Microsoft Excel - Source lnventory.xls
fjle Edit View Insert Format lools Data Window Help Adobe PDF
Prompt T
10 . B I U
Type 5 qi.-^hen h;i help •* _ fl X
B % * _ - <3» - A , »
5 IS * .
JB -r ;J6
1
2
3
4
5
S
B
Facility or
County Name
7
_§_
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Mi' 4
> w [\Template / Area S
C
Chemical Name
ources / Mobile Sources / Bac
D
CAS Number
B 1 F
Annual
Emission Rate
(Ibs/yr)
Measured
Ambient Air
Concentration
(ug/m3)
3
Background
Source
Concentration
(ug/m3)
H
1
J
^^^^^^^=
Ki"
— '
(ground /Point/ l<| UIP"
Ready
MUM
Figure 9-2.
Template for Emission Source Inventory Database
Community Air Screenins How-To Manual
.179
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
Stationary sources that will be handled as area sources
include:
• Agricultural production
• Asphalt paving: Cutback asphalt
• Consumer products usage
• Gasoline distribution Stage 1
• Industrial boilers: Distillate oil
• Institutional/commercial heating (all types)
• Natural gas transmissions and storage
• Non-industrial asphalt roofing
• Pesticide application
• Residential heating (all types)
• Residential heat (wood)
• Structure fires
• Surface coatings: Architectural
• Surface coatings: Industrial maintenance
• Surface coatings: Traffic markings
The state and national air toxics databases can be used to
identify many stationary point sources in the study area,
but in some areas stationary point sources may be
included in databases as part of an area source, so the
location of individual facilities and their emission rates
will not be available. The technical team, working with
the Partnership, will need to examine the available
databases to determine which of the stationary point
sources in their study area are handled as part of an area
source or were missed as point sources. These stationary
point sources need to be identified and located to ensure
that all stationary point sources are included. For
example, the databases covering some areas do not
identify dry-cleaning facilities as stationary point
sources. In these databases, releases from dry-cleaners
are included in the area source database as a county-wide
total release estimate from all dry-cleaners. Because the
dry-cleaning facilities are combined to produce a
county-wide estimate, the names and locations of the
individual dry-cleaning facilities are not included in the
database. In these situations, the technical team will need
to rely on community and local business members to
help identify and locate these sources. If the study area is
not too large, committee members may know of all
existing stationary point sources. For larger areas, the
technical team may need to organize an on-the-ground
survey to find and identify all sources. Available business
databases may also be used to identify any business
sources that mav not be included in the State or national
air toxics database. For example, the Dunn and
Bradstreet database lists all businesses by ZIP code, SIC
code, and address, and this information can be used to
help identify potential point sources not identified in the
state and local databases. By combining all the
approaches described above and relying on the work and
knowledge of all the members of the Partnership, the
technical team will be able to identify all stationary point
sources of air toxics in the study area. Collecting or
estimating release information for these sources will be
discussed in the next steps.
To ensure that all sources are identified and located
properly, the Partnership may find it useful to develop a
map, either using CIS or hard copy, to show all sources
and their locations. This will help the community and
business members of the Partnership identify the sources
and add ones that may be missing. A map locating all
stationary point sources, major roadways, and major
non-road mobile sources will also be useful as an
educational tool for meetings with the broader
community.
Step 4: Guidance for collecting release information
for stationary point source emissions when
release information is available in existing
databases for each individual source
Figure 9-3 shows the procedure for adding stationary
point source emissions data when release information is
available for each individual source to the Emission
Source Inventory. The information required is the
facility name, facility location, chemical name, CAS
number, and emission rate (in units of pounds per year).
There are three places that can be used as starting points
to collect this information: (1) state and local source
inventories, (2) National Emissions Inventory (NEI)
database, and (3) Toxics Release Inventory (TRI)
database. The procedure for obtaining information from
each source follows. The Partnership will supplement
this information with the knowledge of community
residents and businesses and, if necessary, with surveys,
to ensure that all facility sources in the community are
identified.
State and Local Emission Source Inventories
The primary sources the Partnership should use for
information about stationary point source emissions
data are state and local inventories. State and local
government authorities are responsible for permitting
180
Community Air Screening How-To Manual
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
air releases, and they maintain databases containing
information about local sources and their releases. These
databases and associated files contain information on the
chemicals regulated by state and local legislation. The
amount and kind of information collected will vary
depending on the requirements of the local authority, hi
some cases, the information may be obtained from the
Internet. For example, a listing of selected state and local
agencies providing emissions data can be found on the
Internet at http://www.epa.gov/ttn/chief/
related.html#state.
Personnel from local government staff, members of
environmental organizations, and university staff will be
familiar with the contents of state and local databases. A
representative from the state who is already familiar with
the state and local databases will likely be a member of
the Partnership and the Emission Source Inventory
Technical Team. This person would be a good choice for
taking the lead in acquiring information from the state
and local databases. Staff in the air permitting office in
the state or local government will be familiar with
sources of emissions data within the study area and how
they can be accessed.
Obtain most current HAP (and other chemical)
emission rate data from state and local databases
Obtain HAP emission rate data from NEI database
(if data are not available from
state and local agency sources)
Supplement emission rate data with
TRI release data for other chemicals
Enter information into
Emission Source Inventory database
Figure 9-3.
Procedure for Adding Stationary Point Source
Emissions Data to the Emissions Source Inventory
(when release information IS available for each
individual source)
National Emissions Inventory (NEI) Database
Information about the NEI database and instructions for
downloading the data files for each state are provided at
http://www.epa.gOV//ttn/chief/net/1999inveiitory.html.
The Zip file for the NEI point source files decompress to
a single data file with the naming convention
xx99ptfinal.mdb. For example, the Maryland data file
would be called MD99ptfinal.mdb. The file contains a
total of nine data tables that can be viewed and
manipulated using Microsoft Access. The nine tables are
identified as follows:
1. tblPointCE
2. tblPointEM
3. tblPointEP
4. tblPointER
5. tblPointEU
6. tblPointPE
7. tblPointSI
8. tblPointTR
9. tblRecordCount
Only selected information from these tables is needed to
begin development of the Emission Source Inventory.
The required NEI information for stationary point
sources, along with the corresponding data elements to
be extracted from the point source data tables listed
above, are provided in Table 9-2. Microsoft Access is used
to extract the data from the NEI point source data files
by setting up the query design view screen as shown in
Figure 9-4. Initially only three of the eight data tables
(i.e., tblPointSI, tblPointEM, and tblPointER) are
needed. Figure 9-4 shows how to relate these tables and
shows the structure to be used for the query.
Information is obtained by searching for release rate
information about the facilities located within a specific
county. This is accomplished by selecting records
containing the county name or the names of the facilities
located within the study area using the field
tblPointSI-> strFacilityName. Once the query has been
run, the resulting information shown on Table 9-2 is
imported into the Emission Source Inventory. To obtain
the estimated annual emission rate, it is necessary to
combine data from three separate fields in the
tblPointEM table (i.e., dblEmissionNumericValue,
strEmissionUnitNumerator, strEmissionType) and, in
some cases, to convert the units for the resulting
emission rate to pounds per year. The field
strEmissionType in the tblPointEM table refers to
Community Air Screeniris How-To Manual
181
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
emission type that was reported. The emission types
include actual annual, average daily, average hourly,
maximum allowable annual, maximum annual,
maximum daily, maximum hourly, and potential annual
emissions. Figure 9-5 shows an example of the Emission
Source Inventory database with sample stationary point
source data entered.
Toxics Release Inventory (TRI) Database
The Toxics Release Inventory (TRI) is a publicly available
EPA database that contains information on toxic
chemical releases and other waste management activities
reported annually by certain covered industry groups as
well as federal facilities. TRI contains information about
toxic chemicals used, manufactured, stored, treated,
transported, or released into the environment.
Information about TRI is available on the EPA Internet
site at http://www.epa.gov/tri.
TRI can be used to supplement information on HAP
emissions that were obtained from the state and local
source inventories and from NEI. TRI contains data on
the releases of more than 600 designated toxic chemicals
to air, water, and land. The list of chemicals can be
downloaded as a PDF file from http://www.epa.gOv//tri/
chemical/hemlist2001.pdf.
TRI lists releases for more than 600 chemicals, while NEI
lists the releases for only 188 hazardous air pollutants
(HAPs) (shown in Appendix E). However, because
facilities must exceed a certain emission threshold before
reporting releases, certain releases and facilities may not
be available in TRI that may be contained in other
resources. TRI also is only applicable for facilities that
fall under the predefined Standard Industrial
Classification (SIC) codes. The SIC codes that are
covered by TRI are available at http://www.epa.gov/
triinter/report/siccode.htm.
TRI data can be obtained from several sources described
Microsoft Access - [Point Source Info : Select Query]
File Edit View Insert Query Tools Window Help
' y <53 of
- liniix
Type a question for help T _ ff x
- i?f --x m -M - a _
strSitelD
strBlankField
strEmissionReleasePointlD
strEmissionReleasePointType flB
strEmissionUnitID
strProcessID
strPollutantCode
strBlankField
<
V
Field;
Table;
Sort:
Show;
Criteria;
or;
Ready
strFacilityName "
tblPointSI
Ascending
I
<
strPollutantCode
tblPointEM
Ascending
0
strEmissionType
tblPointEM
Ascending
0
dblEmissionNumeric'
tblPointEM
0
strEmissionUnitNum
tblPointEM
0
strEmissionUnitDei "
tblPointEM =
0
v
>
NUM
182
Figure 9-4.
Microsoft Access Query Design View Screen for NEI Point Sources
Community Air Screening How-To Manual
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
at http://www.epa.gov/triinter/tridata/index.htm.
TRI Explorer provides fast and easy access to the TRI
data to identify facilities and chemical releases that
warrant further study and analysis. The site provides
user-definable reports to obtain information on releases.
Public Data Releases are available at http://www.epa.gov/
triinter/tridata/index.htm#pdr.
The annual TRI Public Data Release includes a general
overview of that year's TRI data and information on
trends, state fact sheets that provide a brief summary of
the TRI data by state, and downloadable data files
containing TRI reports submitted for the reporting year.
TRI State Data Files and documentation describing the
contents of the files are available at http://www.epa.gov/
triinter/tridata//state_data_files.htm.
The TRI State Data Files are sets of files containing all
data submitted to the Toxic Chemical Release Inventory
by facilities located in a selected state for a specific year.
The data has been extracted from the Toxics Release
Inventory System (TRIS).
The state files are downloaded as executable files with the
format xx.exe, where xx is the state abbreviation (e.g., the
Maryland file would be called MD.exe). Three text files
are created after executing the xx.exe file: (1)
xx_Stl.TXT, (2) xx_St2.TXT, and (3) xx_St3.TXT. Only
selected information from file xx_Stl.TXT is needed to
begin development of the Emission Source Inventory.
The required information about stationary point sources
to be included in the Emission Source Inventory, along
with the corresponding data elements to be extracted
from the TRI xx_Stl.TXT point source file, are provided
in Table 9-3.
Step 5: Guidance for estimating emission rates for
stationary point sources when release
information is not available for each
individual source
Sometimes release information for a stationary point
source cannot be found in state and local databases.
There are two ways in which this could happen. Either a
facility located in the study area may, for some reason,
not be included in the stationary point source database
even though other facilities of its type are included, or
the databases handle facilities of this type as an area
source, and information on releases is available, but only
as a county-wide total for all facilities of the same type
and not for each facility. Since emissions rates for these
individual stationary point source facilities are not
available in either of these cases, the technical team will
need to estimate these releases.
The most accurate way to estimate emissions for a facility
uses emission factors and source-specific use
Table 9-2.
Required Data Elements for Emission Source Inventory from NEI Point Source Files
EMISSION SOURCE INVENTORY DATABASE FIELD
TABLE AND FIELD NAME FROM NEI POINT SOURCE DATA FILE
Facility or County Name
tbIPointSI -> strFacilityName
Facility Location
tbIPointSI -> strLocationAddress
tblPointSI->strCity
tbIPointSI ->strState
tbIPointSI ->strZipCode
Chemical Name
The NEI point source files contain information on the CAS
number but do not have a field for the chemical name.
The Partnership will need to look up the chemical name
associated with the CAS number and enter that information.
CAS Number
tblPointEM -> strPollutantCode
Estimated Annual Emission Rate (pounds/year)
tblPointEM -> dblEmissionNumericValue
tblPointEM -> strEmissionUnitNumerator
tblPointEM -> strEmissionType
Community Air Screenins How-To Manual
.183
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
E3 Microsoft Excel - Source lnvenlory.xls
IgJ File Edit View Insert Format Tools Data Window Help Adobe PDF
"T "^ * .»- Prompt ,
A31 - £
B/U
A
Emission
Source
1 Type
2 .Stationary Point
3 Stationary Point
4 Stationary Point
5 Stationary Point
6 Stationary Point
7 Stationary Point
8 Stationary Point
9 Stationary Point
10 Stationary Point
11 Stationary Point
12 Stationary Point
13 Stationary Point
14 Stationary Point
15 Stationary Point
16 Stationary Point
17 Stationary Point
18 Stationary Point
19 Stationary Point
20 Stationary Point
21 Stationary Point
22 Stationary Point
23 Stationary Point
24 Stationary Point
25 Stationary Point
26 Stationary Point
27
28
29
30
M < > w \ Template / Area Sources
Ready
B C
Facility or
D
County Name Facility Location Chemical Name
1 HOUR CLEANER
A A I CORPORATION - INDUSTRY LANE
A A I CORPORATION - INDUSTRY LANE
A A I CORPORATION - INDUSTRY LANE
AGNIHOTRA PRINTERS
AGNIHOTRA PRINTERS
ALLIED SIGNAL AEROSPACE COMP
ALLIED SIGNAL AEROSPACE COMP
ALLSTATE LEASING
AMERICAN YEAST
ART LITHO COMPANY
ASHLAND CLEANERS
BALTIMORE SPICE
BARTON COTTON
BARTON COTTON
BARTON COTTON
BEL AIR CLEANERS
BELL.BOB CHEVROLET
BETHLEHEM STEEL
BETTER ENGINEERING
BETTER ENGINEERING
BLUE CIRCLE /ATLANTIC CEMENT, INC
SCHULMBERGER MALCO
SIEMS RENTAL & SALES CO.
SIEMS RENTAL & SALES CO.
/ Mobile Sources / Background XP<*t/ | <
^^^••^^^^^^^^^^^^^^^^^H
TETRACHLOROETHYLENE
ETHYLBENZENE
Styrene
ACROLEIN
ETHYLENE GLYCOL
N-HEXANE
TOLUENE
TOLUENE
ETHYLBENZENE
ACETALDEHYDE
ETHYLENE GLYCOL
TETRACHLOROETHYLENE
ETHYLENE OXIDE
METHYL ISOBUTYL KETONE
1.1.1-TRICHLOROETHANE
CHLOROMETHANE
TETRACHLOROETHYLENE
ETHYLBENZENE
MANGANESE
TOLUENE
TOLUENE-2.4-DIISOCYANATE
MERCURY
METHYL ETHYL KETONE
METHANOL
METHYL ETHYL KETONE
^^^^^^^^^^^^^^^^^^H
E
CAS Number
'127184
'100414
'100425
'107028
'107211
'110543
'108883
'108883
'100414
75070
'107211
'127184
75218
'108101
7155S
74873
'127184
'100414
7439965
'108883
•584849
7439976
78933
67561
78933
I
F —
Annual
Emission Rate
(Ibs/yr)
8.00E-HJ2
5.34E-01
1.42E-01
1 .65E+00
7.00E-03
9.63E-03
9.00E-02
1 .75E+02
1 .20E-01
4.60E-H33
1 .78E-CO
2.00E-KH
4.80E+02
2.00E-K)1
1.76E+01
1 .57E-04
1 ,62E-t03
B.OOE+01
1.14E+04
2.00E-02
9.70E-04
1.30E-06
8.20E-01
1 .OOE-02
2.00E+01
w
Hl~
MUM
" "liS&SM -ajase Paint Shop Pro, fcJ^ENVJWSteOMMQ.... E3 Microsoft Excel -Soar... ^ ^•'•''S.jB'"-* f"^' i&®«M
Figure 9-5.
Sample Stationary Point Source Data in Emission Source Inventory Database
Table 9-3.
Required Data Elements for Emission Source Inventory from TRI Point Source Files
EMISSION SOURCE INVENTORY DATABASE FIELD
FILE AND FIELD NAME FROM TRI POINT SOURCE DATA FILE
Facility or County Name
xxSt1.txt -> Facility Name
Facility Location
xx_St1.txt -> Facility Street
xx_St1.txt -> Facility City
xx_St1.txt -> Facility State
xx_St1.txt -> Facility ZIP Code
Chemical Name
xxStltxt -> Chemical Name
CAS Number
xx St1.txt -> CAS Number
Estimated Annual Emission Rate (pounds/year)
xx_St1 .txt -> Total Stack Air Emissions
or
xx_St1 .txt -> Total Fugitive Air Emissions
Note: The TRI database reports the emission rate in units of pounds per year.
I O^ • Community Air Screening How-To Manual
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
information (i.e., bottom-up approach). This bottom-up
approach is recommended if sufficient resources are
available to collect source-specific information. As a less
resource-in tensive alternative to the bottom-up
approach, information about individual stationary point
source emissions may be developed using a surrogate,
such as percent of population, to apportion the county-
wide emissions to each facility (i.e., top-down approach).
Examples of procedures for developing emission
estimates using the top-down and bottom-up
approaches are discussed below.
Dry-Cleaner Example
The Partnership determines that there are four dry-
cleaners (i.e., dry-cleaner A, B, C, and D) located in the
study area. Information is not available about emissions
from each of the individual dry-cleaners, but an
aggregate county-wide estimate for the emissions from
all the dry-cleaners in the county is available. The
Partnership can proceed with developing emissions on a
per facility basis using either a top-down or bottom-up
approach. Figure 9-6 shows the procedure for adding
stationary point source emissions data to the Emission
Bottom-Up Approach
Identify source categories
(using NEI list) that can be converted
into individual sources
Obtain emission factors
for each stationary source category
Collect source-specific use information
(e.g., activity rate)
for each source category
Estimate emission rate using emission
factors and source-specific use information
Top-Down Approach
Obtain county-wide source HAP
(and other chemical) emission rate data
from NEI database
Check with state and local agencies for
latest HAP (and other chemical)
emission rate data to supplement NEI data
ate
Apportion county-wide emission rate
data to study area
Identify a surrogate distribution to apportion
emission rate data (e.g., land use, census
tract information, population distribution
data, employment statistics) and apportion
the county-wide emission rate data
using the surrogate
Estimate emission rate using emission factors and source-specific use information
Figure 9-6.
Procedure for Adding Stationary Point Source Emissions Data to Emission Source Inventory
(when release information IS HOT available for each individual source)
Community Air Screenins How-To Manual
.185
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
Source Inventory, using the bottom-up and top-down
approaches, when release information is not available for
each individual source.
Bottom-Up Approach
The Compilation of Air Pollutant Emission Factors (AP-
42, Vol. 1, 5th ed. Stationary and Area Sources, January,
1995) provides emission factors for activities that
generate air emissions. The compilation of emission
factors can be found on-line at http://www.epa.gov/ttn/
chief/ap42/.
Table 9-4 shows emission factors from AP-42 for dry-
cleaning operations. The emission factor for dry-
cleaners is defined as the number of pounds of
tetrachloroethylene emitted per 100 pounds of clothing
cleaned. As shown on the table, approximately 27.5
pounds of tetrachloroethylene will be emitted to clean
100 pounds of clothing.
Once the emission factors for the dry-cleaning
operations have been obtained, the Partnership calls the
various dry-cleaners in the study area to find out how
many pounds of clothing are washed at each facility per
year. The product of the emission factor and the number
of pounds of clothing cleaned at each dry-cleaner per
year provides the emission rate for tetrachloroethylene in
pounds per year. Table 9-5 shows the estimated emission
rates for each of the four dry-cleaners.
Top-Down Approach
Using the procedure described in step 5 for obtaining
information from the NEI area source database about
tetrachloroethylene dry-cleaners, the Partnership
determines that 41.04 tons of tetrachloroethylene are
released each year in the county that encompasses the
study area. Using a surrogate, the emission rate for the
county is apportioned to the study area. There are many
surrogates that the Partnership can use to apportion
emissions data using the top-down approach. Two
examples of surrogates that can be used for the top-
down approach for this example are provided below.
Apportioning Based on Number of Facilities (county
vs. study area)
Using economic census data as a surrogate, the
Partnership finds that 107 businesses fall under NAICS
code 81232 (i.e., dry-cleaning and laundry services) and
35 businesses fall under NAICS code 81231 (i.e., coin-
operated laundries and dry-cleaners). The total of these
two categories is 107 + 35 = 142 dry-cleaning businesses
in the county. Using the following calculation, the
Partnership can apportion the county-wide emission
rate of 41.04 tons/year to each of the four dry-cleaners:
41.04tons/yrx2,000lb/ton = 578.03 Ib/year tetrachloroethylene
142 facilities in county released per dry-cleaner
Table 9-4.
Emission Factors for Dry-Cleaning Operations
OPERATION
EMISSION FACTOR*
(POUNDS/100 LB)
Washer/Dryer/Still/Muck Cooker
Filter Disposal
16.4
Still Residue Disposal
1.6
Miscellaneous Emissions
1.5
Total
27.5
*77?e emission factor is defined as the pounds of
tetrachloroethylene per 100 pounds of clothes cleaned.
Source: Compilation of Air Pollutant Emission Factors, AP-42,
Vol. 1, 5th ed. Stationary and Area Sources, January 1995.
186.
Community Air Screening How-To Manual
Table 9-5.
Emission Rate Estimate
for Dry-Cleaning Operations
CLOTHES TREATED/YR EMISSION RATE
DRY-CLEANER (POUNDS) (POUNDS/YR)
Dry-Cleaner A
Dry-Cleaner B
Dry-Cleaner C
Dry-Cleaner D
2,000
2,400
1,600
1,300
550
660
440
357.5
Note: The emission rate is calculated by multiplying the total
emission factor (i.e., 27.5 lb/100 Ib) from Table 9-4 by the
pounds of clothes treated per year for each dry-cleaner.
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
Apportioning Based on Population (county vs. study
area)
Using census tract data as a surrogate, the Partnership
finds that the total population in the county is 692,134.
The census tract data also show that the population in
the study area is 17,012. These data show that 17.012/
692,134 (i.e., 2.46%) of the population in the county are
in the study area. Using this percentage as a surrogate,
the Partnership can apportion the county-wide emission
rate of 41.04 tons/year to each of the four dry-cleaners
using the following calculation:
41.04 tons/yr x 2.000 Ib/ton x (2.46/100) = 504.79 Ib/year
dry cleaner tetrachloroethylene
released/dry cleaner
Step 6: Guidance for collecting information needed
for stationary area source emissions (sources
that will be combined for modeling)
Figure 9-7 shows the procedure for adding stationary
area source emissions data to the Emission Source
Inventory. Stationary area source emissions are defined
as county-wide emission rates that cannot be converted
Obtain county-wide source HAP
(and other chemical) emission rate data
from NEI database
(refer to list of source categories that
are recommended to be
modeled as combined area source)
into individual point sources using one of the methods
described in step 4. These sources cannot be turned into
point sources because they are too numerous or irregular
for point source modeling. The technical team will find
and enter the county-wide emissions total for each area
source category in to the Emission Source Inventory
database.
Emissions Data for Emission Source Inventory
As discussed in step 3 above, using the categories
established in the National Toxics Inventory, the
following will be treated as stationary area sources:
• Agricultural production
• Asphalt paving: Cutback asphalt
• Consumer products usage
• Gasoline distribution Stage 1
• Industrial boilers: Distillate oil
• Institutional/commercial heating (all types)
• Natural gas transmissions and storage
• Non-industrial asphalt roofing
• Pesticide application
• Residential heating (all types)
• Residential heat (wood)
• Structure fires
• Surface coatings: Architectural
• Surface coatings: Industrial maintenance
• Surface coatings: Traffic markings
Check with state and local agencies for
latest HAP (and other chemical)
emission rate data to supplement NEI data
Enter information into
Emission Source Inventory database
Figure 9-7.
Procedure for Adding Stationary Area Source
Community Air Screenins How-To Manual
187
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
Table 9-6.
Data Elements in the 1996 NEI Area Source State
Data Files
DATA ELEMENT
DESCRIPTION
Revision Indicator
0 = Original from May 1999
A = New record added by
state/trade association
RA = Revised record added by
state/trade association
Inventory Year
Baseline year for inventory
State FIPS
2-digit Federal Information
Processing Standards state code
County FIPS
3-digit FIPS county code
County Name
Name that corresponds to
3-digit FIPS county code
Area Source Category Name
I source category name
SIC Code
Source category Standard
Industrial Classification code
(when applicable)
EPA MACTID
Source category Maximum
Achievable Control Technology
code (when applicable)
Pollutant CAS
Unique pollutant Chemical
Abstracts Service number
Pollutant Name
common name
Hazardous air pollutant
Emissions
Emissions estimate at
county level
Emission Units
Units for county
emissions estimate
SCC
Source category Source
Classification Code
AMS
Source category Area and Mobile
Source code
Source Type
Source classification
(e.g., area source)
The primary source of stationary area source emissions
data is the NEI. The information obtained from NEI will
be supplemented with information on HAPs and other
chemical emissions obtained from state and local
inventories. The area source files consist of a single
standard ASCII comma-delimited format file for each
state that can be imported into database or spreadsheet
programs. A listing of the data elements contained in the
state data files are provided on Table 9-6. The Area
Source Category Name field contains the name of the
area source category.
The required information about stationary area sources
to be included in the Emission Source Inventory, along
with the corresponding data elements to be extracted
from the NEI area source data file, are provided in Table
9-7. Figure 9-8 shows an example of the Emission Source
Inventory with sample stationary area source data
entered.
The Partnership should check to make sure that all the
sources listed in the NEI area source data file are
included in the source inventory, either by being
converted to a point source or by being treated as a
stationary area source.
Table 9-7.
Required Data Elements for Emission Source
Inventory from NEI Area Source Files
EMISSION SOURCE
INVENTORY
DATABASE FIELD
Facility or County Name
Name of Chemical Released
CAS Number
FIELD NAME FROM
NEI AREA SOURCE
DATA FILE
County name
Pollutant name
Pollutant CAS
Annual Emission Rate (pounds/year) Emissions (refer to note)
Note: The emission rate provided in the NEI area source data file
may need to be converted to units of pounds per year. The value
of the emission is provided in the field labeled Emissions, and
the unit for the emission is provided in the field labeled
Emission Units.
188.
Community Air Screening How-To Manual
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
0 Microsoft Excel *
Sj File Edit View
D a: y sj &
T T; * , .»-
A35
A
Source lnventory.xls
Insert Format Tools Data
a *y * ^ >i \ Templat
Ready
IQggi^H
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
Window Help Adobe PDF
"> * ^, Z - £i " Arial
C
Chemical Name
Acetamide
Acetonitrile
Acrylamide
Acrylic Acid
Acrylonitrile
Allyl Chloride
Aniline
Antimony & Compounds
Benzotrichloride
Benzyl Chloride
Biphenyl
Bis(chloromethyl) Ether
Captan
Carbaryl
Carbon Disulfide
Carbon Tetrachloride
Carbonyl Sulfide
Catechol
Chlordane
Chlorine
Chloroacetic Acid
Chlorobenzene
Chloroform
Chloromethyl Methyl Ether
Chloroprene
3 \flrea Sources^ Mobile Sources /Background /Point/
>
F G . H —
Measured Background Estimatec —
Ambient Air Source Ambient A
Concentration Concentration Concentrati
(ug/m3) (ug/m3) (ug/m3)
T
i >\r
MUM
Figure 9-8.
Example Stationary Area Source Data
Community Air Screenins How-To Manual
189
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
Step 7: Guidance for collecting information on
mobile source emissions
Figure 9-9 shows the procedure for adding mobile source
emission data to the Emission Source Inventory. The
technical team will find and enter county-wide mobile
source emission category totals in the Emission Source
Inventory database.
The primary source of mobile source emissions data is
NEI. The information on mobile source emissions from
NEI will be supplemented with information obtained
from state and local inventories. The mobile source files
consist of a single standard ASCII comma-delimited
format file for each state that can be imported into
database or spreadsheet programs. A listing of data
elements contained in the state data files are provided in
Table 9-8.
The on-road vehicle population is characterized into
seven individual vehicle type categories in NEI. They are:
• Light duty gasoline-powered vehicles (LDGV),
• Light duty gasoline-powered trucks up to 6,000 Ibs
gross vehicle weight (LDGT1),
• Light duty gasoline-powered trucks from 6,000 to
8,500 Ibs gross vehicle weight (LDGT2),
• Heavy duty gasoline-powered vehicles (HDGV),
• Motorcycles (MC),
Obtain county-wide source emission rate data
for on-road and non-road mobile sources from
the NEI database
Check with state and local agencies for
emission rate data to supplement NEI data
Enter information into
Emission Source Inventory database
Figure 9-9.
Procedure for Adding Mobile Source Emissions
Data to Emission Source Inventory
190
• Light duty diesel-powered vehicles (LDDV), and
• Heavy duty diesel-powered vehicles (HDDV).
LDGTl and LDGT2 have been combined into an LDGT
category. For some pollutants, the MC category was
combined with other vehicle types such as LDGV or
HDGV, depending upon the specificity of the data used
to estimate the emissions.
The non-road mobile source category in the NEI
includes vehicles and equipment that normally are not
Table 9-8.
Data Elements in the 1996 NEI Mobile Source
State Data Files
DATA ELEMENT
DESCRIPTION
Revision Indicator
"0" indicates EFIG- or
QMS-developed estimates
Start Date
End Date
Country FIPS
State FIPS
County FIPS
County Name
Beginning time for
inventory year
Ending time for
inventory year
FIPS country code
2 -digit FIPS state code
3-digit FIPS county code
Name that corresponds to
3-digit FIPS county code
Mobile Source Category Name Description of AMS code
Pollutant CAS
Unique NEI pollutant code
number (CAS number if
available)
Pollutant Name
Hazardous air pollutant
common name
Emissions
Emissions estimate at
county level
Emission Units
Units for county
emissions estimate
Emission
Actual annual air emissions
Source Type
Mobile
Community Air Screening How-To Manual
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
operated on public roads to provide transportation. This
includes categories such as lawn and garden equipment,
agricultural equipment, logging equipment, construction
equipment, airport service vehicles, aircraft, locomotives,
or commercial marine vessels, and recreational
equipment including recreational marine equipment.
Gasoline-powered non-road vehicles and equipment can
be characterized into two individual engine-type
categories, specifically 2- and 4-stroke engines. To
estimate the metallic pollutant emissions in this
inventory, the 2- and 4-stroke engine-type categories are
combined into one category called gasoline engines.
The required information about mobile sources to be
included in the Emission Source Inventory, along with
the corresponding data elements to be extracted from
the NEI mobile source data file, are provided in Table
9-9. Figure 9-10 shows an example of the Emission
Source Inventory with sample mobile source data
entered.
Table 9-9.
Required Data Elements for Emission Source
Inventory from NEI Mobile Source Files
EMISSION SOURCE INVENTORY FIELD NAME FROM NEI AREA
DATABASE FIELD SOURCE DATA FILE
Facility or County Name
County name
Mobile Source Category
Mobile source category name
Name of Chemical Released Pollutant name
CAS Number or Unique Pollutant CAS
NEI Pollutant Code Number
Annual Emission Rate
(pounds/year)
Emissions (refer to note)
Note: The emission rate provided in the NEI mobile source data file may
needtobe converted to units of pounds per year. The value of the
emission is provided in the field labeled Emissions, and the unit for the
emission is provided in the field labeled Emission Units.
- Source lnventory.xls
IS) Fie Edit MEW Insert Format Tools DaSa Window Help Adobe PDF
D E* y B & & V- X * - <4 Z - 2| » Arid
• . e x
9 _ - A - A , »
A
Emission Source
1 Type
2 Mobile Offroad
3 Mobile Onroad
4 Mobile Onroad
5 Mobile Onroad
6 Mobile Offroad
7 Mobile Offroad
8 Mobile Offroad
9 Mobile Offroad
10 Mobile Offroad
11 Mobile Onroad
12 Mobile Onroad
13 Mobile Onroad
14 Mobile Onroad
15 Mobile Onroad
16 Mobile Onroad
17 Mobile Offroad
18 Mobile Onroad
19 Mobile Offroad
20 Mobile Onroad
21 Mobile Onroad
22 Mobile Offroad
23 Mobile Onroad
24 Mobile Onroad
25 Mobile Offroad
26 Mobile Offroad
27
28
29
B
C
D
Facility or County
Name
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
l< * * H \ Template / Area Sources
Moble Source Category
Railroads-Diesel
Light Duty Diesel Vehicles (LDDV)
Light Duty Diesel Trucks (LDDT)
Light Duty Diesel Trucks (LDDT)
Railroads-Diesel
All Off-highway Vehicle: Gasoline, 4-Slroke
Railroads-Diesel
Railroads-Diesel
Raiiroads-Dtesel
Light Duty Diesel Trucks (LDDT)
Light Duty Diesel Trucks (LDDT)
Light Duty Diesel Trucks (LDDT)
Heavy Duty Diesel Vehicles (HDDV)
Light Duty Diesel Trucks (LDDT)
Heavy Duty Diesel Vehicles (HDDV)
Raiiroads-Dtesel
Light Duty Diesel Vehicles (LDDV)
Railroads-Diesel
Light Duty Diesel Trucks (LOOT)
Heavy Duty Diesel Vehicles (HDDV)
All Off-highway Vehicle: Gasoline, 4-Stroke
Light Duty Diesel Trucks (LDDT)
Light Duty Diesel Trucks (LDDT)
Railroads-Diesel
Railroads-Diesel
VMobile Sources/ Background /Point /
Chemical Name
Manganese & Compounds
7-PAH
Chromium & Compounds
Arsenic & Compounds (inorganic including arsine)
Manganese & Compounds
vlercury & Compounds
vtanganese & Compounds
Manganese & Compounds
Manganese & Compounds
vlercury & Compounds
N ckel & Compounds
Manganese & Compounds
Arsenic & Compounds (inorganic including arsine)
Manganese & Compounds
Arsenic & Compounds (inorganic including arsine)
Manganese & Compounds
7-PAH
Chromium & Compounds
Manganese & Compounds
Arsenic & Compounds (inorganic including arsine)
vlercury & Compounds
Chromium & Compounds
Arsenic & Compounds (inorganic including arsine)
vlanganese & Compounds
Manganese & Compounds
E
CAS
Number or
NTI
Pollutant
Code
60355
75058
79061
79107
107131
107051
62533
7440360
98077
100447
92524
542B81
133062
63252
75150
56235
463581
120B09
57749
7782505
79118
108907
67663
107302
128998
I
F —
—
Annual
Emission Rate
(Ibs/yr)
7.61 E-03
7.62E-03
7.64E-03
764E-03
7.67E-03
7.71 E-03
7.73E-03
7.74E-03
7.77E-03
7.77E-03
777E-03
7.78E-03
778E-03
7.85E-03
785E-03
786E-03
7.87E-03
792E-03
8.01 E-03
8 01 E-03
8.02E-03
8.04E-03
8.04E-03
8.05E-03
8.05E-03
T
>ir~
Ready
1 vv-jasc paint Shop Prp
m J:\ENV_WS\COWflO-.
Figure 9-10.
Sample Mobile Source Data in Emission Source Inventory Database
Community Air Screenins How-To Manual
191
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
Step 8: Guidance for collecting in forma tion on
background concentrations
Background concentrations are releases that are not
the result of current human activity, including both
natural and past human sources. Figure 9-11 shows the
procedure for adding background concentration data to
the Emission Source Inventory. The primary sources of
background concentrations data are from state and local
emission inventories and the National Air Toxics
Assessment (NATA). Information about the NATA
program is located at http//www.epa.gov.ttnatwO 1 /nata/.
The NATA program provides background
concentrations based on monitored values identified in
the Cumulative Exposure Project (1990 study that
estimated nationwide ambient concentrations of air
toxics). Based on the study, the nationwide background
concentration values developed for 13 toxic air
pollutants are shown on Table 9-10 and are also available
at http://www.epa.gov/ttnatw01/nata/haptbl.html.
The available data used by NATA are insufficient to
address geographic variations in background, and the
background concentrations are assumed to be constant
across all census tracts. For pollutants whose background
concentration values could not be identified in the
technical literature, the background concentrations are
assumed to be zero. Therefore, this may result in
underestimation of outdoor concentrations for some
toxic ail' pollutants. There is also some concern that, in
certain circumstances, there is the potential for double
counting. The Partnership should review the NATA data
along with other emission data to determine whether the
background concentration data are already accounted
for by other emission data contained in the Emission
Source Inventory.
Background concentration data tables are available for
each state (on a county-wide basis) in Excel or PDF file
format at http://www.epa.gov.ttn/atw/nata/tablcoc.html.
Scroll down the web page to the section labeled
Download a State Summary Table and select your state.
The background concentration data files are available in
Excel spreadsheet and PDF file formats. The required
information about stationary area sources to be included
Check with state and local agencies
for background HAP concentrations
If data are not available, use the
National Air Toxics Assessment
(NATA) data (i.e., 23 chemicals)
Enter information into
Emission Source Inventory database
Figure 9-11.
Procedure for Adding Background Concentration
Data to Emission Source Inventory
192
Table 9-10.
National Air Toxics Assessment Background
Concentration Estimates
BACKGROUND
POLLUTANT
Benzene
Carbon tetrachloride
Chloroform
Dioxins/furans
(toxicity equivalents)
Ethylene dibromide
Ethylene dichloride
Formaldehyde
Hexachlorobenzene
Mercury compounds
Methylene chloride
Polychlorinated biphenyls
Perchloroethylene
(tetrachloroethylene)
Trichloroethylene
CONCENTRATION (|.ig/m3)
0.48
0.88
0.083
0.000000015
0.0077
0.061
0.25
0.000093
0.0015
0.15
0.00038
0.14
0.081
Community Air Screening How-To Manual
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
in the Emission Source Inventory, along with the
corresponding data elements to be extracted from the
NATA background concentration data tables, are
provided in Table 9-11. Figure 9-12 shows an example of
the Emission Source Inventory with sample background
concentration data entered.
Step 9: Guidance for collecting information on
monitored concentrations
This methodology encourages the use of ambient air
monitoring data over concentrations estimated by
modeling. However, when considering how to use
monitoring data, it is very important to understand the
goals of the monitoring program collecting the data and
the limitations in the spatial and temporal coverage of
the data. For example, a program designed to determine
the average concentrations of air pollutants across a city
might not be an appropriate surrogate for the
concentration of that pollutant at the fenceline of a
facility that emits it.
Table 9-11.
Required Data Elements for Emission Source
Inventory from NATA State Background
Concentration Tables
EMISSION SOURCE
INVENTORY DATABASE
FIELD
FIELD NAME FROM NATA
STATE BACKGROUND
CONCENTRATION TABLE
Facility or County Name
County
Chemical Name
Pollutant
CAS Number
The Partnership will need to
assign a CAS number to the
chemical name because it is
not provided in the NATA
tables.
Estimated Ambient Air
Concentration (ng/m3)
Estimated background
Several things should be considered when deciding
whether or not to use monitoring data over estimated
airborne pollutant concentrations.
• Does a monitoring network exist for the pollutants
of interest and what are the averaging times of
concern?
• Has the monitoring network been designed to locate
points of maximum concentrations, average, other?
• Do the data set and analysis allow the impact of the
most important individual sources to be identified if
more than one source or emission point is involved?
• Is at least one full year of valid ambient data
available ?
These questions are intended to help in making the
decision whether to use monitoring data, modeling data,
or both in the methodology. It is recommended that this
discussion take place and the decision on the usefulness
of available monitoring data be made prior to entering
the data into the database (emissions inventory).
The procedure for adding monitored concentration data
to the Emission Source Inventory is shown in
Figure 9-13. The primary source the Partnership should
use for information about monitored concentration data
are state and local inventories. It is important to ensure
that the inventory is set up so that monitoring data are
clearly identified as such and cannot be mistaken for
estimated concentration values derived from modeling.
As discussed under step 3, state and local government
authorities are responsible for permitting air releases and
maintaining databases that contain information about
local sources and their releases. These databases and
associated files may contain monitored concentration
data for the chemicals regulated by state and local
legislation.
The Partnership can also obtain monitoring data from
the AIRData website located at http://www.epa.gov/aiiV
data/aqsdb.html.
The AIRData web site contains ambient concentrations
of pollutants in outdoor air that are measured at more
than 4,000 monitoring stations owned and operated
mainly by state environmental agencies. They forward
the hourly or daily measurements of pollutant
concentration to EPAs database, and EPA computes a
yearly summary for each monitoring station (maximum
value, average value, number of measurements, etc.).
AIRData has the yearly summary values only, and not
the individual hourly or daily measurements.
Community Air Screenins How-To Manual
193
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
What is the next step after the Inventory
Team has completed the first step of
collecting information for the Emission
Source Inventory database?
Information contained in the Emission Source Inventory
can be summarized and displayed in a variety of ways
that would be useful for the Partnership. Use of
summary tables and figures helps to present large
amounts of data in a form that can be readily
understood. Examples include:
• Figure or map showing the study area with the
major emission sources located
• Table showing the emission sources that were
included and those not included in the study
• Table showing the chemicals that will be studied
during the Initial, Secondary, and Final Screening
steps
S Microsoft Excel - Source lnventory.xls
fjte Edit View Insert Format Tools Data Window Help Adobe PDF
" - "S l! ,
A35
The goal for the Partnership, prior to starting the Initial
Screen, will be to include as many chemicals and sources
as possible in its inventory. The full Partnership
committee should take part in reviewing the data in the
Emission Source Inventory to ensure that the
information is accurate and complete. The residents
located in the study area can also assist in quality control
of the source inventory by reviewing the database to
make sure that all potential sources of emissions have
been identified. Members of the Partnership can check
the database through an on-the-ground check of the
study area or by relying on the residents' knowledge of
local facilities and their locations. Community residents
and local businesses will be in the best position to judge
the accuracy of the inventory database. Please see
Chapter 8 in the Overview for suggestions on presenting
the information in the inventory to the broader
community.
Type a question for heto
1
2
3
4
5
6
7
B
9
10
11
12
13
14
15
16
17
18
19
22
23
24
25
26
27
28
29
30.
A
Emission Source Type
Background Concentration
Background Concentration
Background Concentration
Background Concentration
Background Concentration
Background Concentration
Background Concentration
Background Concentration
Background Concentration
Background Concentration
Background Concentration
B C
Facility or County
Name
Baltimore
Chemical Name
Benzene
Baltimore Carbon Tetrachloride
D
CAS Number
71-43-2
56-23-5
Baltimore Cloroform 87-66-3
Baltimore
Ethylene Dibromide 106-93-4
Baltimore Ethylene Dichloride
Baltimore Formaldehyde
Baltimore
Hexachlorobenzene
Baltimore Methylene Chloride
Baltimore
Baltimore
Baltimore
Perchloroethylene
Polychlorinated Biphenyls
Trichloroethylene
M < » H :\ Template / Area S
Ready
P^HMi^^H^^MMB^^^^H
uurces yt Mobile Sources X
•^^•^^^M^M^^^
Background /Point/ J
107-06-2
50-00-0
118-74-1
75-09-2
127-18-4
1336-36-3
79-01-6
AJ
E
Annual
Emission Rate
(Ibs/yr)
F G H —
Measured
Ambient Air
Concentration
(ug/m3)
Background
Source
Concentration
(ug/m3)
4.BOE-01
Uiim.it. —
Ambient
Concentra
m. P m ;
8.BOE-01
B.30E-02
7.70E-03
E10E-02
2.50E-01
9.30E-05
1.50E-01
1.40E-01
3.BOE-04
8.10E-02
I
^_
Mr'
MUM
.Start v-' Jasc Paint shop Pro S» J:\ENV_OPS\COMMO... E3 Microsoft Excel -Sour... ^ Corel WordPoifect- [... + f" - '-',,„ IO;11AM
194
Figure 9-12.
Sample Background Concentration Data in Emission Source Inventory Database
Community Air Screenins How-To Manual
-------
Chapter 9: Building the Emission Source Inventory
• Technical Guidance
Check with state and local agencies for
monitored HAP emission concentrations
Supplement with monitoring data
from AIRData
Enter information in
Emission Source Inventory database
Figure 9-13.
Procedure for Adding Monitored Concentration
Data to Emission Source Inventory
Community Air Screenins How-To Manual
.195
-------
196
Community Air Screening How-To Manual
-------
Technical
Guidance
Initial Screen
This section describes the steps the Initial Screen
Technical Team can take to complete the Initial Screen. If
resources are available, it is recommended that two
technical teams be set up, one for estimating
concentrations and one for developing screening
concentrations. This will save time since these tasks can
move forward simultaneously. Flow charts showing a
summary of the steps for completing the Initial Screen
are shown in Figure 10-1 and Figure 10-2. Figure 10-1
shows how to estimate ambient air concentrations for
the chemicals in the Emission Source Inventory that will
be reviewed in the Initial Screen. Figure 10-2 shows how
to calculate the screening-level concentrations that will
be used to identify community priorities.
Estimating
Concentrations
Which of the sources will have their
concentrations estimated in the Initial
Screen?
During the Initial Screen ambient air concentrations for
stationary point sources (with a receptor distance equal
to or greater than 15 meters) and stationary area sources
will be estimated. Releases from stationary point sources
with a receptor distance less than 15 meters will not be
reviewed in the Initial Screen but will be kept for review
during the Secondary Screen. Mobile source emissions
also will not be reviewed in the Initial Screen but will be
kept for review during the Secondary Screen. Releases of
mobile source chemicals from stationary point and area
sources will also be reviewed in the Secondary Screen.
How will the technical team estimate
these concentrations?
The technical team will use a look-up table, or a simple
conversion factor, to convert emission rate information
contained in the Emission Source Inventory to ambient
air concentrations for each stationary point source and
stationary area source. The estimated ambient air
concentrations emitted from each stationary point
source and stationary area source are added to the
background concentrations contained in the Emission
Source Inventory to obtain a total ambient air
concentration for each chemical. The Partnership will
then compare the total aggregate concentration for each
chemical to the screening-level concentration to
determine whether to keep the chemical for further
analysis in the Secondary Screen.
How were the look-up table and the
conversion factor developed and where
can the technical team find a detailed
description of the SCREENS air dispersion
model?
The look-up table and the conversion factor were
developed using the SCREENS air dispersion model. The
look-up table was developed by running the SCREEN3
model using the input parameters shown in Table 10-1.
The stack height and receptor distance values were
varied prior to each of the modeling runs. The resulting
look-up table is shown on Table 10-2. The Partnership
can use the look-up table to estimate ambient air
concentration by multiplying the emission rate (in Ib/yr)
by the unitized annual average concentration for the
applicable stack height and receptor distance.
The conversion factor, 6.55 E-03 ^ig/m3 per Ib/yr, was
developed by calculating the 95th percentile value from
the look-up table. The estimated ambient air
concentration is obtained by multiplying the emission
rate (in Ib/yr) by the conversion factor.
Community Air Screenins How-To Manual
197
-------
Chapter 10: Initial Screen
• Technical Guidance
Step 1
Set up QA/QC procedures for data collection and entry and for calculations.
Step 2
Collect information on release type, stack height, and receptor distance for
stationary point sources. (If the technical team has limited resources and chooses
to use the conversion factor to estimate concentrations, skip this step.)
Step 3
Identify all the sources that are less than 15 meters from the nearest
community exposure, and hold all the chemicals emitted from these sources
for review in the Secondary Screen. They will not be reviewed in the Initial Screen.
Step 4
Identify all chemicals for mobile sources and hold these chemicals for review
in the Secondary Screen. They will not be reviewed in the Initial Screen.
StepS
or each chemical and for each of the stationary point sources releasing the
chemical, estimate the concentration using the look-up table or conversion
factor method. Add all the concentrations to get a total point source concentration.
Step 6
For each chemical released from stationary area sources, add the county-wide
releases from all the area sources and estimate the concentration
using the conversion factor.
Step 7
For each chemical, obtain the background concentration, if any.
Step 8 ^|r
For each chemical, add the total stationary point source concentration,
the total stationary area source concentration, and the background concentration,
to obtain the total concentration from all sources.
Figure 10-1.
Procedure for Initial Screen
198.
Community Air Screening How-To Manual
-------
Chapter 10: Initial Screen
• Technical Guidance
Step 1 - Set Community Risk Screening-Level Assumption Values
Cancer (C):
Risk screening level expressed as a statement of probability, e.g., 1E-06(1 x 10"°orl in 1 million).
Non-Cancer (N-C) Effects:
Risk screening level expressed as a ratio of exposure level to
hazard (toxicity) level or a hazard quotient (HQ), e.g., HQ = 1.
Step 2 - Decide on Toxicity Information Hierarchy
Technical team explains criteria for ranking sources of toxicity information that it will use to develop
screening-level concentrations and presents a proposal for ranking sources to the Partnership for
approval or modification.
Partnership decides on a method to rank the sources of information to guide the technical team.
Step 3 - Calculate an Air Exposure Screening-Level Concentration (SLC)
Cancer (C) SLC |ig/m3 =
RSL
where:
RSL = Cancer risk screening level (e.g., 1 .OE-06)
UR = Chemical-specific inhalation unit risk estimate (per
Non-Cancer (N-C) SLC |i9/m3 = SHQ * RfC * 100 |ig/mg
where:
SHQ = Screening hazard quotient (e.g., 1 .0)
RfC = Chemical-specific inhalation reference concentration (
Figure 10-2.
Steps for Developing a Screening-Level Concentration
Community Air Screenins How-To Manual
.199
-------
Chapter 10: Initial Screen
• Technical Guidance
The conversion factor was selected by using a
combination of stack height and distance to receptor
that would give a concentration higher than 95% of
all other combinations of stack height and receptor
distance. This conversion factor is intended to be
conservative enough that if it is used as a default value
by a community that does not know stack heights and
receptor distances, the concentration estimated will most
likely be higher than would be estimated using measured
stack heights and receptor distances. The conversion
factor is intended to provide a level of protection in the
Initial Screen when exact values for stack height and
receptor distance are not known.
Detailed information on the SCREENS model can be
found in the SCREENS user's guide. The user's guide can
be downloaded from the EPA web site at http://
www.epa.gov/scram001/userg/screen/screen3d.pdf.
Table 10-1.
SCREENS Input Parameters Used to Generate
Initial Screen Look-Up Table
SCREEN3
MODEL
PARAMETERS
Emission
source type
Emission rate
Stack height
Stack diameter
VALUE
point
1g/s
variable
0.15m
SCREENS
MODEL
PARAMETERS
Receptor height
Landscape type
Meteorological
conditions
Building
down wash
VALUE
0
urban
general
full
meteorology
No
Stack gas 2 m/s
exit velocity
Terrain calculation No
Exit gas 293 K
temperature
Receptor distance variable
Ambient 293 K
temperature
Which method, the look-up table or the
conversion factor, will the Partnership use
to estimate concentrations?
The decision to use the look-up table or the conversion
factor to estimate ambient air concentrations is based on
the resources available to the technical team. The look-
up table is the recommended method for estimating
concentrations, but if the team's resources are limited,
then the conversion factor can be used instead. To use
the look-up table, the technical team will need to have
information on stack height and distance to receptor for
each source. If the resources the Partnership has
allocated to this project are limited, and stack heights
and receptor distance values are not easily obtained, the
Partnership may elect to use the conversion factor
instead to estimate ambient air concentrations.
The conversion factor will conservatively estimate
ambient air concentrations approximately 95% of the
tune, as long as the study area contains a diverse array of
stack heights and receptor distances. However, in certain
situations (approximately 5% of the time), use of the
conversion factor may underestimate the ambient air
concentration for a chemical. This would occur, for
example, if all of the sources in the study area have stack
heights of 3 meters and all of the receptors are less than
50 meters from these sources. On the other hand, if all of
the sources have a stack height of 30 meters and all of the
receptors are greater than 50 meters from these sources,
use of the conversion factor would overestimate the
ambient air concentration for a chemical.
Use of the look-up table will typically result in lower
concentration estimates than would be obtained using
the conversion factor. Therefore, use of the look-up table
is likely to screen out more chemicals during the Initial
Screen and reduce the number of chemicals kept for
further study in the Secondary Screen. Another
advantage of this approach is that because of the work
required for the Partnership to collect information about
the stack height and distance to receptor needed to use
the look-up table, there is a better chance that sources
that are less than 15 meters to the closest receptor will be
identified for closer review in the Secondary Screen.
200
Community Air Screening How-To Manual
-------
Chapter 10: Initial Screen
• Technical Guidance
Table 10-2.
Look-Up Table. Unitized Annual Average Concentration at Different Distances from a Stack
per Ib/year)
,?t?c,k Distance to Receptor
Height
(m) 15m 20m 50m 100m 200m 300m 400m 500m
3 1.59E-02 1.55E-02 1.04E-02 3.97E-03 1.19E-03 5.78E-04 3.50E-04 2.39E-04
5.63E-03 7.05E-03 5.42E-03 3.33E-03 1.13E-03 5.64E-04 3.45E-04 2.37E-04
8 1.05E-03 2.20E-03 2.93E-03 2.23E-03 1.01E-03 5.33E-04 3.33E-04 2.31 E-04
10 2.35E-04 9.51 E-04 1.94E-03 1.57E-03 9.12E-04 5.08E-04 3.23E-04 2.26E-04
20 1.70E-09 1.08E-06 4.05E-04 4.59E-04 3.37E-04 2.79E-04 2.06E-04 1.55E-04
30 - - 6.98E-05 2.10E-04 1.76E-04 1.30E-04 1.22E-04 1.04E-04
40 - - 6.34E-06 1.02E-04 1.02E-04 8.53E-05 6.49E-05 6.49E-05
50 - - 3.00E-07 4.79E-05 7.03E-05 6.08E-05 4.94E-05 3.81 E-05
75 ... 3.74E-06 2.95E-05 2.95E-05 2.54E-05 2.36E-05
100 - - - 1.11E-07 1.28E-05 1.63E-05 1.59E-05 1.41 E-05
Community Air Screeniris How-To Manual
.201
-------
Chapter 10: Initial Screen
• Technical Guidance
How will the Partnership collect the
information needed to use the look-up
table?
The Initial Screen Technical Team will work with and
rely on the Partnership's Inventory Team and the
community to collect information on stack height and
distance to closest receptor for all stationary point
sources. The work that the Inventory Team has done to
collect release and location information for all stationary
point sources to begin the Partnership's Emission Source
Inventory database will provide a good foundation for
collecting the information that will be needed for the
Initial Screen. See step 2 below for more details.
What are the steps that the technical
team will need to complete to estimate
concentrations for the Initial Screen?
Step 1: Set up QA/QC procedures for data collection
and entry and for calculations.
Step 2: Collect information on release type, stack
height, and receptor distance for stationary
point sources. (If the technical team has
limited resources and chooses to use the
conversion factor to estimate concentrations,
skip this step.)
Step 3: Identify all the sources that are less than 15
meters from the nearest community exposure,
and hold all the chemicals emitted from these
sources for review in the Secondary Screen.
They will not be reviewed in the Initial Screen.
Step 4: Identify all chemicals for mobile sources and
hold these chemicals for review in the
Secondary Screen. They will not be reviewed in
the Initial Screen.
Step 5: For each chemical and for each of the
stationary point sources releasing the chemical,
estimate the concentration using the look-up
table or conversion factor method. Add all the
concentrations to get a total point source
concentration.
Step 6: For each chemical released from stationary
area sources, add the county-wide releases
from all the area sources and estimate the
concentration using the conversion factor.
Step 7: For each chemical, obtain the background
concentration, if any.
Step 8: For each chemical, add the total stationary
point source concentration, the total stationary
area source concentration, and the background
concentration to obtain the total concentration
from all sources.
How will the Partnership carry out these
steps?
Step 1: Set up QA/QC procedures for data collection
and entry and for calculations.
See discussion of QA/QC procedures in Chapter 9 of the
Technical Guidance section of the Manual.
Step 2: Collect information on release type, stack
height, and receptor distance for stationary
point sources, (If the technical team has
limited resources and chooses to use the
conversion factor to estimate concentrations,
skip this step.)
The technical team needs to collect and enter
information about release type, stack height, and
receptor distance into the Emission Source Inventory for
each stationary point source. Three additional fields
need to be added to the Emission Source Inventory
database: (1) Release Type (stack or fugitive), (2) Stack
Height (meters), and (3) Distance to Receptor (meters)
to store this information.
Stationary point sources are designated as being either a
stack or fugitive release type. The fugitive release type
designation applies only to stationary point source
emissions that are not released from stacks, vents, ducts,
pipes, or other kind of confined stream. The Inventory
Team can rely on the technical expertise of its members
or on site visits to determine if the releases from a
stationary point source are stack or fugitive.
Stack height information for stationary point sources
can be obtained from the National Emission Inventory
(NEI) database. Table 10-3 shows the appropriate NEI
data table and field name to obtain the required stack
height information for stationary point sources. Some
sources handled as point sources in this Manual may be
treated as area sources in the NEI database and will not
be included in the NEI point source database. (Methods
for turning the area sources into point sources and
202
Community Air Screening How-To Manual
-------
Chapter 10: Initial Screen
• Technical Guidance
Table 10-3.
Required Data for Emission Source Inventory from
HEI Point Source Files
EMISSION SOURCE
INVENTORY
DATABASE FIELD
TABLE AND FIELD NAME FROM NEI
POINT SOURCE DATA FILE
Stack Height
tblPointER->sngStackHeight
estimating an emission rate for each of these sources
were provided in Chapter 9.) Since they are not included
in the NEI point source database, stack height
information will not be available from NEI. The
technical teams will need to collect or estimate stack
height information for each of these sources. Fugitive
stationary point source emissions are assigned a default
stack height value of three meters in the Emission Source
Inventory.
Information about the distance to the nearest receptor
can be obtained from a variety of sources, including
small-scale maps, desktop mapping software,
community members, and businesses, or, if necessary,
the technical team can organize site visits to collect this
information.
Step 3: Identify all the sources that are less than 15
meters from the nearest community
exposure, and remove all the chemicals
emitted from tliese sources from the review.
These chemicals will be reviewed in the
Secondary Screen.
Stationary point sources, and associated chemicals, with
receptor distances that are closer than 15 meters will be
passed to the Secondary Screen for review. If the look-up
table is used to estimate concentrations, the information
about the distance to receptor for each source was
collected and added to the Emission Source Inventory
during step 2. If the conversion factor is used to estimate
concentrations, the Inventory Team will need to
determine which sources are closer than 15 meters to the
nearest community exposure.
Step 4: Remove all the chemicals from mobile
sources. These chemicals will also be
reviewed in the Secondary Screen.
Mobile source emissions will not be reviewed in the
Initial Screen but will be kept for review during the
Table 10-4.
Mobile Source Chemicals to Be Passed to the
Secondary Screen
CHEMICAL NAME
1,3-Butadiene
Acetaldehyde
Acrolein
Arsenic compounds
Benzene
Beryllium compounds
Cadmium compounds
Chromium compounds
Dioxins/Furans as 2,3,7,8-TCDD TEQs
Ethyl benzene
Formaldehyde
Lead compounds
Manganese compounds
Mercury compounds
Methyl tertiary butyl ether (MTBE)
n-Hexane
Nickel compounds
Polycyclic organic matter (POM) as 7-Polycyclic
aromatic hydrocarbon (PAH)
Polycyclic organic matter (POM) as 16-Polycyclic aromatic
hydrocarbon (PAH)
Priopionaldehyde
Styrene
Toluene
Xylene
Source: Table 2. Mobile Source HAPs in the 1996 A/77, page 10,
athtto://www.eDa.aov/ttn/chief/nti/ntioao1.Ddf.
Community Air Screenins How-To Manual
.203
-------
Chapter 10: Initial Screen
• Technical Guidance
Secondary Screen. A list of the mobile source chemicals
is shown in Table 10-4. If any of the mobile source
chemicals shown in Table 10-4 are released from either
stationary point sources or stationary area sources then
these releases will also be passed to the Secondary Screen
for review.
Step 5: For each chemical and for each of the
stationary point sources releasing the
chemical, estimate the concentration using
the look-up table or conversion factor
method. Add all the concentrations to get a
total point source concentration.
For stationary point sources when the stack height and
the distance to the receptor is known, the look-up table
is used to estimate the ambient air concentration. This
is accomplished by selecting the appropriate row on the
table for the stack height and the appropriate column for
the receptor distance and obtaining the corresponding
unitized annual average concentration (in units of ^ig/m3
per Ib/yr). Then, the estimated ambient air
concentration is obtained by multiplying the emission
rate (in units of Ibs/yr) by the unitized annual average
concentration for the applicable stack height and
receptor distance. For fugitive releases, a default value of
3 meters is used for the stack height. This process is
repeated to estimate the concentration of each record in
the Emission Source Inventory that contains stack
height, receptor distance, and emission rate information.
When the stack height and distance to receptor are not
known for a stationary point source, or if there are
insufficient Partnership resources available to collect this
information, the conversion factor of 6.55 E-03 [ig/m3
per Ib/yr can be used to estimate the ambient air
concentrations. The estimated ambient air concentration
is obtained by multiplying the emission rate (in units of
Ibs/yr) by the conversion factor.
The estimated ambient air concentrations are entered
into the Estimated Ambient Air Concentration field in
the Emission Source Inventory. For stationary point
sources, a separate value for the estimated ambient air
concentration (obtained using the look-up table or the
conversion factor) will be entered into the Estimated
Ambient Air Concentration field in the Emission Source
Inventory for each chemical. Add all the concentrations
to get a total point source concentration for each
chemical.
Step 6: For each chemical released from stationary
area sources, add tlie county-wide releases
from all the area sources and estimate the
concentration using the conversion factor.
To estimate the ambient air concentrations for stationary
area sources, the conversion factor of 6.55 E-03 ^ig/m3
per Ib/yr is used. The emission rates for a given chemical
are summed for all of the stationary area sources. Then
the estimated ambient air concentration is obtained by
multiplying the sum of all the emission rates (in units of
Ibs/yr) for each chemical by the conversion factor. The
estimated ambient air concentrations are entered into
the Estimated Ambient Air Concentration field in the
emission source inventory for each chemical.
Step 7: For each chemical, obtain the background
concentration, if any.
Background concentrations for chemicals in the study
area have been collected and entered into the Emission
Source Inventory by the Partnership prior to the Initial
Screening step. However, additional relevant monitoring
data may be collected and entered.
Step 8: For each chemical, add the total stationary
point source concentration, the total
stationary area source concentration, and the
background concentration, to obtain the
total concentration from all sources.
Add the total stationary point source concentration
(step 4), the total stationary area source concentration
(step 5), and the background concentration (step 6) to
obtain the total concentration from all sources. The total
ambient air concentration is then compared to the
screening-level concentration for each chemical.
Guidance for developing screening-level concentrations
is provided below.
204
Community Air Screening How-To Manual
-------
Chapter 10: Initial Screen
• Technical Guidance
Developing
Screening-Level
Concentrations
How will the Screening-Level
Concentration Technical Team work with
the Partnership to set the screening-level
concentrations?
To ensure that estimates of screening-level
concentrations are consistent with the goals and values
of the Partnership, the technical team will need to work
closely with the overall Partnership to complete its work.
Decisions on the risk screening level and sources of
toxicity information need to be made, as described in
the Overview, by the full Partnership committee. The
technical team will help to provide the Partnership with
the information and background that it will need to
make these decisions. Once the full Partnership
committee has made the necessary decisions, the
technical team will calculate an air exposure screening-
level concentration for each community chemical.
What steps will the technical team need
to complete to develop screening-level
concentrations for the Partnership?
The technical team will, in general, assist the Partnership
in providing the education that its members will need to
participate fully in decisions that the Partnership will
need to make to ensure that the work to set screening-
level concentrations meets its goals and values. In
particular, the Screening-Level Concentration Technical
Team will need to complete the following steps:
Step 1: Provide assistance and background education
to help the Partnership decide on the risk
screening levels that it will use to identify the
community's priority chemicals that will be
evaluated for possible community action.
Step 2: Explain criteria for ranking sources of toxicity
information that the Partnership will use to
develop its screening-level concentrations.
Present a proposal for ranking sources to the
Partnership for approval or modification to
help the Partnership decide on a method to
rank the sources of information to guide the
technical team. See the Overview for a
discussion of the choice of toxicity sources.
Appendix H provides additional information
on types and sources of toxicity values needed
to complete this step.
Step 3: Once the Partnership has decided on risk
screening levels and on a plan for accessing
toxicity information, develop air exposure
screening-level concentrations for the
Partnership and store them in the Partnership
database for the Partnership to use. Appendix I
provides detailed instructions for calculating
screening-level concentrations.
Figure 10-2 summarizes these steps. Steps 1 and 2 of
Figure 10-2 list the risk screening level concentration
assumptions and toxicity information hierarchy that are
required. Step 3 of Figure 10-2 provides the math-
ematical relationships the technical team can use to
calculate screening-level concentrations, one for each of
the two types of long-term toxicity potentially associated
with each chemical. For detailed information and
guidance for each of these steps, see the appendices listed
above.
What are the next steps after the
technical team has developed screening-
level concentrations for the Partnership?
The technical team will enter a screening-level
concentration for each community chemical into the
Partnership's inventory database. It will provide the
Partnership with a complete description of the method
and information used to develop screening-level
concentrations so that the Partnership and community
can understand all of the assumptions and information
that were included in calculations for each of its
screening-level concentration values. The Partnership
may want to develop an indication of the level of
uncertainty for each screening-level concentration value
to summarize the quality of the information used to
develop the screening-level concentrations. Then,
working together, the technical team that estimated the
chemical concentrations in community air and the
Screening-Level Concentration Technical Team will
develop a report for the Partnership that summarizes
results from comparing community chemical screening-
level concentrations to the estimated ambient air
Community Air Screenins How-To Manual
205
-------
Chapter 10: Initial Screen
• Technical Guidance
concentrations. The Partnership will use results of these
comparisons to identify chemicals that may need further
analysis in the next step of the screening process.
206.
Community Air Screening How-To Manual
-------
Technical
Guidance
Secondary Screen
What is the overall goal for the technical
team?
The goal of the Secondary Screening process is to (1)
provide a more refined estimate of the ambient chemical
concentrations for chemicals remaining after the Initial
Screening process, and (2) assess chemicals released from
mobile sources. The results of the Secondary Screening
process will be compared to the same screening-level
concentrations developed during the Initial Screen to
identify those chemicals that require further review in
the Final Screen. A flow chart summarizing the steps
for completing the Secondary Screen is shown in
Figure 11-1.
How will the technical team estimate
concentrations?
The technical team will estimate chemical
concentrations by using the Industrial Source Complex
Short Term (ISCST) model. This model conforms with
EPA's Guideline on Air Quality Models (Revised) and
allows the technical team to model emissions from a
wide range of sources, employing the straight-line,
steady-state Gaussian plume equation to estimate
ambient concentration values. The ability of the
mathematical approach used by ISCST, given
accurate input data, to accurately estimate airborne
concentrations of a chemical has been investigated in
several studies. In one extensive investigation (EPA 1982.
Evaluation of Rural Air Quality Simulation Models. EPA-
450/4-83-003), estimated concentrations of SO, around
a power plant derived using the same algorithms that
ISCST uses were compared to actual measured
concentrations over a two-year period. Comparison of
the 25 highest estimated values and the 25 highest
measured values indicated overprediction. Estimated
values were generally within a factor of 2 of those
measured. Prediction accuracy from one location to
another within the receptor grid was variable. Results for
different meteorological conditions indicated that the
model tended to shift to underprediction as wind speed
increased. Accuracy was also influenced by atmospheric
stability conditions. For class A and B (unstable
atmospheric conditions) the model overpredicted,
while for class E and F (stable) the model
underpredicted. There was a general trend toward
model underprediction as the averaging period
increased (i.e., 1-hour, 3-hour, 24-hour).
Why not use NATA's national-scale
assessment of 33 air pollutants?
As a part of EPAs National Air Toxics Assessment
(NATA), EPA has conducted a national-scale assessment
of 33 air pollutants. This assessment used the ASPEN air
dispersion model to estimate air concentrations for these
33 pollutants for each census tract in the nation. These
concentrations are available on the web at
http://www.eoa.gov/ttnatw01/nata.
Stationary area and mobile source concentrations were
estimated for the national-scale assessment using the
pseudo-point method similar to the one recommended
in this Manual. Since the methods used in the national-
scale assessment and this Manual are similar, the
possibility of saving Partnership resources by using
the readily available national-scale assessment
concentrations needs to be considered. This Manual
recommends that the Partnership do its own estimation
of stationary area sources and mobile sources using the
pseudo-point method for three reasons. First, while
access to the census tract concentrations for 33 air
pollutants is available, the concentrations for each source
category type may not be easily available. For example,
the national-scale assessment concentrations for area
sources may include some sources that are categorized as
point sources in this Manual. As a result, using the area
source concentrations from the national-scale
assessment would result in double counting of some
sources. Second, the national-scale assessment is
conducted once every three years, so the Partnership may
have access through its state partner to more current
release information for its modeling. And third, the
national scale assessment estimated concentrations for
only 33 chemicals and the Partnership's inventory may
have mobile or stationary area source chemicals that are
not included in this list of 33 chemicals.
Community Air Screenins How-To Manual
.207
-------
Chapter 11: Secondary Screen
• Technical Guidance
Step 1
Institute a QA/QC process to ensure
accuracy of team work.
Step 2
Set up a model grid for community targets.
Step 3
Collect meteorological data.
Step 4
Determine which pollutants of interest are
released as particulates and collect
information for wet and dry particulate
deposition modeling, if necessary.
StepS
Step 6
Collect necessary information for
stationary point sources.
Collect necessary information for stationary area,
on-road mobile, and non-road mobile sources.
Step 7
Set up and run ISCST model to estimate
total concentration from all sources.
Step 8
Add background concentrations
to modeled concentrations.
Step 9
Compare modeled concentrations to
available monitored concentrations.
Figure 11-1.
Procedure for Secondary Screen
Where can the technical team find a
detailed description of the ISCST model?
The most recent version of ISCST can be obtained for
free from EPA's Technology Transfer Network (TIN),
Support Center for Regulatory Air Models (SCRAM)
web site at http://www.epa.gov/ttn/scram,
under the Dispersion Models link. The hardware and
operating system requirements can be found in volume 1
of the user's guide. However, most modern computers
using the Windows operating system can run ISCST.
There are several commercial versions of ISCST that can
be obtained from vendors. These versions of ISCST are
designed to run on Windows operating systems and may
be easier to use and provide more features for the
technical team. These Windows-based programs can
simplify the model setup process, construction of
necessary input files, and interpretation of results. While
the actual savings of resources will differ from case to
case, it will likely increase as the number of emissions
and receptors increase and other advanced options are
selected. However, it should be noted that these versions
of ISCSTcan cost a substantial amount (approximately
$1,250-1,500), and it is left to the Partnership to
determine whether it would be worthwhile to invest in
such software.
The ISCST3 model will also be available for use via the
Internet using the Internet Geographic Exposure
Modeling System (IGEMS), a program under
development by EPA. But a fairly new computer with
high-speed Internet access is needed to run the model.
IGEMS also includes some of the data needed to run the
model and will include GIS and the ability to perform
risk assessment calculations in the near future.
Information on IGEMS can be accessed at http://
www.epa.gov/oppt/exposure/
What additional information will the
technical team need to gather for the
Emission Source Inventory?
Some of the information about the sources in the study
needed to run the ISCST model (i.e., emission rate and
stack height) were collected and entered into the
Emission Source Inventory during the Initial Screen. In
addition, the following new information is needed to run
the ISCST model:
208.
Community Air Screening How-To Manual
-------
Chapter 11: Secondary Screen
• Technical Guidance
• Location of Potential Receptors
• Meteorological Data
• Information for Wet and Dry Particulate Deposition
• Stationary Point Source Parameters
• Information for Modeling Stationary Area and
Mobile Source Emissions
The sections below discuss the various types of
information required to run ISCST and where the
technical team can find this information. The technical
team should consult volume 1 of the ISCST user's guide
on how to format this information so the model can use
it properly. If commercial software is being used, the
technical team should consult the software user support
documents. It is recommended that the technical team
work with the Inventory Team to collect the required
information. The Inventory Team should provide
support to the technical team throughout the process,
providing emissions data and other source-related data
as necessary. This will permit the technical team to focus
on setting up and running the model and avoid potential
duplication of information-gathering efforts.
Location of Potential Receptors
The ISCST data input file requires the technical team to
specify a receptor network. This network can be input
using a Cartesian (grid) network or using a polar
coordinate network, although the Cartesian system
appears to be the method of choice, primarily because it
is compatible with the latitude and longitude or
Universal Transverse Mercator (UTM) coordinates given
for the locations of sources and receptors.
The grid network should be developed to identify both
the sources of chemical emissions and the extent of the
study area. This point of reference will subsequently be
used to describe the locations of all sources and
receptors. The technical team should determine a point
of reference on the grid, also known as the location of
origin in the study area. The technical team should also
identify the locations of sensitive populations (i.e.,
schools, hospitals, nursing homes, residential
communities, etc.) so that concentrations can be
estimated for these sites. The key values that the
technical team should determine for this grid are
• Total length of grid
• Total width of grid
• Spacing along length
• Spacing along width
• Elevation at each grid location (if elevated terrain
or flagpole receptors are considered)
Distance and height entries should be provided in units
of meters. It should be noted that this information is
specific for Cartesian grid networks and that the
technical team should consult volume 1 of the ISCST
user's guide (or commercial software support
documents) for more detailed information on setting up
polar coordinate systems if that system is used.
Meteorological Data
ISCST requires at least one year of hourly meteorological
data contained in a data file formatted to work with the
model. But the technical team should collect five years of
hourly meteorological data to account for year-to-year
variations that have been formatted to work with the
ISCST model. Meteorological data are available for
weather stations located throughout the country, so the
technical team should select a weather station that is
representative of the study area. The technical team must
also determine the anemometer height of the weather
station being used for the meteorological data and
mixing height information. Lastly, the technical team
will have to classify the study area setting as either urban
or rural.
Information for Wet and Dry Particulate Deposition
Modeling
Additional data are required to model the deposition of
participates. This information includes additional
meteorological data as well as information on the
physical characteristics of the particulates being
modeled.
Stationary Point Source Parameters
The technical team will be able to use some of the data
from the Emission Source Inventory collected during the
Initial Screen. However, additional data about the
sources will be required. This additional data will vary,
depending on the type of source being modeled, and are
discussed as follows.
Stationary Point Stack
Information on emission rate (in grams per second) and
stack height (in meters) for each source will have been
collected during the Initial Screen to model stationary
point sources. The Technical Team will need to collect
the following additional information about the sources
Community Air Screeniris How-To Manual
.209
-------
Chapter 11: Secondary Screen
• Technical Guidance
for the Secondary Screen:
• Stack diameter, in meters
• Stack exit velocity, in meters per second
• Stack exit temperature, in degrees Kelvin
• Source location, relative to the origin location, in
meters
Stationary Point Fugitive
Since fugitive emissions are uncontrolled and not
necessarily associated with a stack, the exact location of
the fugitive emissions may or may not be known. For
simplicity's sake, the fugitive emissions of a chemical at
a given facility can be combined and modeled. This
approach is relatively conservative because combining
all fugitive releases into a single point source results in
higher source strength and concentrations than if they
were modeled as an area source, where the same mass of
pollutant was released over a larger area, resulting in a
lower source strength.
For each facility stationary fugitive sources will be
modeled as a stationary point source, with the ISCST
source-specific inputs set to represent no plume rise,
using the following values:
• Stack height: 5 meters
• Stack diameter: 0.001 meters
• Stack exit velocity: 0.001 meters/second
• Stack exit temperature: 298 Kelvin
These parameters are chosen to represent releases
relatively close to the ground that do not rise because of
their elevated temperature or high exit velocity. This
conservative approach is expected to be more protective
than if greater release heights, temperatures, and exit
velocities were chosen.
Information for Modeling Stationary Area and
Mobile Source Emissions
Stationary area and mobile sources are modeled
following a simplified version of the methodology from
EPA Region 6 Regional Air Impact Modeling Initiative
(RAIMI 2001). This method distributes stationary area
and mobile source emissions evenly over the area of the
census tracts in the study area. To use this approach the
technical team will need to apportion county-wide
mobile on-road and non-road mobile and stationary
area source emission rates, collected from National, state,
and local databases, to the census tracts in the study area.
The technical team will then apportion the census tract
emission rates to five pseudo-stack points located in or
near each census tract. The pseudo-stacks will be run in
ISCST as point source emissions. One point will be
located at the center of the census tract, while the
remaining four will be located on the periphery, at the
four different cardinal directions (i.e., North, South,
East, and West). Detailed information for apportioning
county wide emissions and locating pseudo-stack points
are provided in Step 6 below. The following information
will need to be collected for each stationary area and
mobile source (the county wide emission rates that will
be used were collected earlier in screening process):
• Information needed to apportion county wide
emission rates to census tracts
• Emission rate in g/s apportioned to each census
tract
• Location of centroids for census tracts in study area,
relative to origin location, in meters
• Location of remaining four emission points, relative
to origin location, in meters
As with stationary fugitive emissions, stack parameters
will be set to represent no plume rise.
Information on the location of each census tract
centroid in the partnership area and the area of each
census tract can be obtained from the files contained in a
tool called LandView. Land View reflects the
collaborative efforts of the U.S. Environmental
Protection Agency (EPA), the U.S. Census Bureau, the
U.S. Geological Survey (USGS), and the National
Oceanic and Atmospheric Administration (NOAA) to
provide the public ready access to published Federal
spatial and related data and is available for purchase.
More information on its capabilities, availability and cost
is available at: http://landview.census.gov/.
A resource available free to the public is the Census
Bureau's American Fact Finder: http://
factfinder.census.gov/.
This website provides access to much of the census and
employment related information required for use
apportioning county wide emission rates to census
tracts. The IGEMS system being developed by EPA also
includes census data: http://www.epa.gov/oppt/
exposure/.
210.
Community Air Screening How-To Manual
-------
Chapter 11: Secondary Screen
• Technical Guidance
Are there special situations the technical
team will need to consider in designing
its modeling approach?
The technical team will need to initially determine
whether the simplified ISCST modeling approach will be
adequate for estimating the concentrations of pollutants
in their community. To save resources, the simplified
ISCST modeling approach should be used whenever
possible, but in some cases more sophisticated modeling
will be required. For example, if there are tall buildings
near sources of emissions, then the technical team may
want to go beyond the simple approach and consider
building downwash in their modeling. The wind blowing
around a building makes areas of rapid movement that
are greater than if the building was not there. If release of
a pollutant takes place from a roof vent or short stack,
those releases can get caught in the areas of rapid
movement. In the zone nearest the building, called the
cavity zone, plumes can travel without much dilution
and can be brought to the ground intermittently. This
phenomenon can result in higher concentrations of the
pollutant on the side of the building than would be
predicted if the building was not present.
EPA provides guidance on whether building downwash
should be considered when conducting air dispersion
modeling. The decision is based largely on the height of
the stack of concern in relation to the height or width of
nearby buildings. The area of influence of a building is
the lesser value of its height or width. Emissions within
this area may be affected by downwash.
Stacks greater than EPA Good Engineering Practice stack
height are generally not impacted by building effects,
and downwash does not need to be considered for them.
In its example for modeling urban air toxics, EPA used a
65-meter stack height as an upper limit for stacks
potentially impacted by building effects. By referring to
EPA guidance at the following web site, the Partnership
can determine the appropriate stack height cutoff to use:
http://www.epa.gov/scramOO I/guidance/guide/
uatexample.pdf.
The technical team could use a simple approach to help
determine when to consider including downwash in
their modeling using local knowledge. The approach
would be to consider the possibility of including
building downwash for any stack less than 65 meters
high with a building within 30 meters. This is based on
an old "rule of thumb" that a stack next to a building
must be at least 2.5 times the height of the building in
order to avoid downwash of the plume, and on the area-
of-influence guidance discussed above.
In addition to building downwash, unusual terrain can
also change wind patterns that affect dispersion. If the
study area is located in an area with a complex terrain,
then more sophisticated modeling would be needed, for
example, if the study area were located in a valley
surrounded by high lulls on hillsides higher than the
sources of emission. The ISCST3 modeling approach
used in support of the methodology is run without
terrain influences, i.e., flat terrain is assumed. However,
the ISCST3 model can adjust the plume heights by the
receptor elevation above or below the stack base to
account for the effects of elevated and complex terrain.
The ISCST user's guide contains information for
handling terrain.
Where the urban area is in mountainous terrain, terrain
effects are important for sources with stacks. First, the
impact of individual plumes on elevated terrain results
in higher air concentration (through placing the receptor
at the correct higher air concentration and vertical
location within the plume and estimating the impact of
the plume upon intervening terrain). Second, wind
channeling due to terrain can cause higher air
concentrations. The ISCST modeling approach does not
address wind channeling effects other than if these
effects are captured by the available meteorological data.
If the area contains complex terrain features that are
expected to significantly affect the modeled
concentrations, a dispersion model that handles such
situations should be selected from those listed in the EPA
Guideline on Air Quality Models.
Community Air Screenins How-To Manual
.211
-------
Chapter 11: Secondary Screen
• Technical Guidance
What are the steps the technical team will
need to take to complete the work of
estimating concentrations for the
Secondary Screen?
After the technical team has decided whether or not to
consider building downwash and terrain they should
follow these steps to complete the Secondary Screen:
Step 1: Institute a QA/QC process to ensure accuracy
of team work.
Step 2: Set up a model grid for community targets.
Step 3: Collect meteorological data.
Step 4: Determine which pollutants of interest are
released as particulates and collect information
for wet and dry particulate deposition
modeling, if necessary.
Step 5: Collect necessary information for stationary
point sources.
Step 6: Collect necessary information for stationary
area, on-road mobile, and non-road mobile
sources.
Step 7: Run the ISCST model to estimate total
concentrations from all sources using five
years of collected meteorological data.
Step 8: Add background concentrations to model
concentrations.
Step 9: Compare modeled concentrations at the
monitoring site to available monitored
concentrations.
How will the technical team complete
these steps?
Step 1: Institute a QA/QC process to ensure accuracy
of team work.
Refer to the QA/QC section (step 1) in the Technical
Guidance section.
Step 2: Set up a model grid for community targets.
The technical team needs to review the study area and
determine how best to divide up the area to run in
ISCST. Land use/land cover (LULC) maps, topographic
maps, aerial photography, and CIS software are good
sources of information. Elevation data can be obtained
using 90-meter spaced USGS digital elevation data. The
technical team should also identify the locations of
sensitive populations (i.e., schools, hospitals, retirement
communities, etc.) so that specific concentrations can be
modeled for these sites. After surveying the study area,
the technical team should lay out a grid network on a
map of the study area. This will assist the technical team
in determining the length and width of the grid network
and the grid spacing along both axes, and will allow the
technical team to choose a point of origin. Use of UTM
coordinates can make it easier for the technical team to
develop the grid network, as many databases use this to
identify the location of a facility. Multiple receptor grids
can be used to delineate the study area. Discrete receptor
locations can also be entered into ISCST.
The technical team should keep in mind that the finer
the grid spacing, the greater the time needed to run the
ISCST model. The model calculates the sum of the user-
specified hourly or annual average concentrations of a
chemical from all sources defined on the grid, at each
grid node or receptor location specified by the user. As
the number of user-defined receptor sites and/or grid
nodes increase, so do the number of calculations
required to complete the modeling run.
A number of recent efforts to model urban air toxics at
the community level have involved the use of grid
spacing ranging from 100 meters to 1,000 meters. The
use of a finer grid will allow the model to calculate
concentrations at more grid nodes, which are spaced
closer together, and potentially closer to a receptor of
concern.
Step 3: Collect meteorological data
The technical team should collect five years of hourly
meteorological data to account for year-to-year
variations that have been formatted to work with the
ISCST model. These data should include information on
precipitation for use in modeling wet deposition of
particulates. Meteorological data can be obtained from
the National Oceanographic and Atmospheric
Administration (NOAA) National Climatic Data Center
(NCDC) web site at http://lwf.ncdc.noaa.gov/oa/
ncdc.html; EPAs SCRAM web site at http://www.
epa.gov/ttn/scram, under the Meteorological Data link,
the Solar and Meteorological Surface Observation
Network (SAMSON) compact disks, etc.
212
Community Air Screening How-To Manual
-------
Chapter 11: Secondary Screen
• Technical Guidance
Meteorological data are also available for weather
stations located throughout the country. If weather
station data are used, the technical team should select a
weather station that is either located inside the study
area or representative of the study area. Data derived
from these sources must then be run through a
preprocessing program to put the data in the proper data
file format for use with ISCST. Preprocessor programs
are available at EPA's SCRAM web site under the
Meteorological Data link.
The technical team must also determine the anemometer
height of the weather station being used for the
meteorological data. This information is available at the
NCDC web site, under the Weather Station/City link.
Additionally, information on the upper air
meteorological conditions (i.e., mixing height data) for
some states can be obtained from the EPA SCRAM web
site at http://www.epa.gov/scram001/tt24.htmffmbdng.
Mixing height data are also available for a fee from the
National Climatic Data Center web site at http://www.
ncdc.noaa/oancdc.html.
Lastly, the technical team will have to classify the study
area setting as either urban or rural. Section 8.2.8 of
EPA's Guideline on Air Quality Models (Revised) provides
two procedures for determining if a study area is urban
or rural. The more popular method (i.e., Land Use
Procedure) looks at a 3 km circle around the study area.
If 50% or more of the area in this 3 km circle can be
classified as urban, then the study area should be
classified as urban.
Step 4: Determine which pollutants of interest are
released as particulates and collect
information for wet and dry particulate
deposition modeling, if necessary.
Particle deposition is a process in which particulates
emitted from a source come into contact with a surface
by the combined processes of atmospheric turbulence
and gravitational settling. Particle deposition is evaluated
during the Secondary Screen for exposure due to
inhalation only. Emissions to air in the form of particles
subject to deposition behave differently than gases.
Deposition of particles may result in lower concentration
in air at a distant receptor because the particles settle to
the ground as they are carried downwind. This results in
a reduction in exposure at a distant receptor, but may
result in higher particulate concentrations for receptors
near the source. Fugitive dust, mobile sources, metal
smelters, coal-fired utilities, and wood stoves are
examples of sources with particulate emissions.
In step 3, meteorological data were collected for ISCST
modeling. In this step additional data required to model
the deposition of particulates are collected. The technical
team needs to determine if any of the pollutants of
interest are released to air as particulates. If so, then
additional information on the physical characteristics of
the particulates being modeled, such as their size
distribution and settling rates, should be collected. It is
recommended that emissions of metals, including
arsenic, beryllium, cadmium, chromium, lead,
manganese, and nickel, be modeled as particulates.
For specific guidance on how to model deposition refer
to the ISC User's Guide volumes 1 and 2, available
through the Technology Transfer Network Support
Center for Regulatory Air Models (TTN SCRAM), at
http://www.epa.gov/scram001/userg/regmod/isc3vl.pdf
and http://www.epa.gov/scramOO 1/userg/regmod/
isc3v2.pdf.
For general guidance see the Guidance/Support page at
http://www.epa.gov/scram001/tt25.htmffguidance.
For an example of how deposition is modeled see
Example Application of Modeling Toxic Air Pollutants in
Urban Areas available at http://www. epa.gov/scram001/
guidance/guide/ uatexample.pdf.
Step 5: Collect necessary information for stationary
point sources (stack and fugitive).
The technical team will start by using data from the
Emission Source Inventory that were developed for use
in the Initial Screen. It is recommended that the
technical team work with the Inventory Team to collect
the new information that will be needed. The technical
team should then contact state and local agencies to
obtain more detailed information on stack parameters
for stationary point sources. National databases (such as
NEI and TRI) can be used to supplement missing
information. If the required information is still not
available, the technical team may need to contact facility
representatives or use conservative default information.
It may also be necessary to visit the site and make visual
estimates.
Fugitive emissions for each chemical at a facility are
modeled from a single stack with default characteristics
described elsewhere. Each pseudo-stack needs to be
assigned a location on the modeling grid. The technical
team may want to consider the following to choose a
location for the pseudo-stack:
Community Air Screenins How-To Manual
213
-------
Chapter 11: Secondary Screen
• Technical Guidance
• Location of operations at the facility with fugitive
emissions
• Location of sensitive populations
• Direction of prevailing winds
• Distance from operations with fugitive emissions to
fenceline
• Distance from facility fenceline to populated area
Using the grid network developed in step 2, the technical
team should identify the stationary point source (i.e.,
stack location) on the map, and estimate the location of
the point source relative to the origin of the grid
network. Again, using UTM coordinates can make this
step easier for the technical team.
Keep in mind that for stationary sources these new
estimates of concentrations developed by modeling are
still designed to be conservative, that is, overestimates. To
ensure that the Secondary Screen is conservative, the
Partnership and its technical team will still be using the
readily available data on maximum permitted release
amounts as input to the model. If the release data
available to a community Partnership only have
estimated actual release amounts and not maximum
permitted release amounts for stationary sources, the
Partnership will need to increase these release estimates,
possibly multiplying the release amount by a factor
agreed on by the Partnership, to ensure that the
Secondary Screen is conservative. Release estimates taken
from the TR1 database, for example, are estimated actual
releases, not maximum permitted releases, so the
Partnership's technical team will need to increase these
amounts to ensure that the Secondary Screen is
conservative.
Step 6: Collect necessary information for stationary
area, on-road mobile, and non-road mobile
sources.
County-wide emission rate data for on-road mobile,
non-road mobile, and stationary area sources will be
apportioned to census tract emission rates. To estimate
emissions of these types of sources, spatial allocation or
apportioning is used to estimate emissions at a small
geographic scale based on national emissions estimates.
County-wide emission rate data for on-road and non-
road mobile sources can be obtained from state and local
databases. National databases, such as NEI, can also be
used when state and local data are not available. All
stationary area sources will be modeled as point sources,
except those shown on Table 11 -1. It is envisioned that
only a few stationary area source emissions in a
community will not be able to be described as discrete
point sources. Table 11-1 shows the categories that need
to be modeled as area sources, along with suggested
allocation methods.
To model stationary area sources as a point source, the
technical team will define a circle, centered on the
centroid of each census tract. The area of the circle is
equal to the area of the census tract. This is then repeated
for each census tract located within the study area. This
can be done using desktop mapping or CIS software (if
available) and census tract data from the U.S. Census
Bureau. The methodology described here uses pseudo-
points but, if CIS resources are available, there is another
perhaps easier method under development that uses GIS
to define the boundaries of the census tract and model
the emissions as an area source. Check the Community
Assistance Technical Team web page for the availability
of this methodology.
Five pseudo-stack source locations will be positioned
inside each circle: one pseudo-stack source will be placed
at the center of the circle (i.e., centroid of the census
tract), and four pseudo-stack sources will be placed at a
distance of one-half of the radius of the circle at each
cardinal point (i.e., north, south, east, and west). The
technical team will set the ISCST source-specific inputs
to represent no plume rise, as below:
• Stack height: 5 meters
• Stack diameter: 0.001 meters
• Stack exit velocity: 0.001 meters/second
• Stack exit temperature: 298 Kelvin
The technical team will then weight the emissions from
the pseudo-stack points accordingly: one-ninth of the
emissions to the center pseudo-stack source and two-
ninths of the emissions to each of the four surrounding
pseudo-stack sources. Figure 11-2 depicts census tracts
utilizing the pseudo-point source technique.
To allocate emissions, two different methods are
available. One method is to estimate area source
emissions using the 1996 NTI approach. A detailed
discussion of the spatial allocation procedure appears in
the NTI documentation on area sources (http://
www.epa.gov/ttn/chief/emch/spatial/). Keep in mind that
an inventory prepared by a state or local agency using
county-specific data can include more local detail and
assign emissions to the county level more accurately. The
second method is to estimate emissions using the
214
Community Air Screening How-To Manual
-------
Chapter 11: Secondary Screen
• Technical Guidance
approach used for the Cumulative Exposure Project in
1998 (http://www.epa.gov/ttn/atw/urban/appx_b 1 .pdf).
The methods each have advantages and disadvantages.
The advantage of the NTI method is simplicity. The
method uses primarily population and employment
information in its allocation methodology, but it is
limited by the lack of employment at a smaller scale of
resolution. This limitation increases uncertainty
associated with area source emissions estimates. NTI
assumes that the ratio between the total number of
workers in an SIC code for the whole United States and
the number of those workers in a given county is
predictive of the ratio between national-scale emissions
of chemicals in an SIC code and county emissions of
individual chemicals in the SIC code. While this
approach was deemed appropriate for allocation to the
county level, the validity of the extension of this method
to allocate from the county level to the census tract level
has not been evaluated. This uncertainty is further
reason why the Partnership, whenever possible, should
attempt to determine the characteristics and locations of
small and dispersed emissions and model them as point
sources, avoiding most of the assumptions that they
would have to make with area source emissions
estimates.
In order to address the need to provide emissions at a
finer level of resolution (e.g., census tract level), methods
developed for this purpose by EPA in the Cumulative
Exposure Project can also be used. The CEP work
utilized an approach in which emissions were spatially
allocated to the census tract level by using other
geographically distributed surrogates including
population and land use. See Appendix J for more
information on the use of land use/land cover data and
other methods of allocation.
Step 7: Set up and run ISCST model to estimate total
concentration from all sources.
Once the information from steps 2 to 6 has been
collected, it needs to be put into a data input file
formatted for use during ISCST modeling runs. The
input file format is very specific. The technical team
should consult volume 1 of the ISCST user's guide (or
commercial software support documents) to determine
the specific data file format requirements. Figure 11-3
depicts a simplistic ISCST input file.
Each ISCST input file consists of six sections, or
pathways:
• Control (CO) pathway
• Source (SO) pathway
• Receptor (RE) pathway
• Meteorological (ME) pathway
• Terrain grid (TG) pathway
• Output (OU) pathway
Below is a description of each pathway and some of the
default assumptions and inputs that should be used
when conducting modeling for the Secondary Screen.
Control Pathway
The Control pathway directs ISCST to perform specific
types of computations. For the Secondary Screen, the
technical team should use the following constraints:
regulatory default options, concentrations, annual
averaging times, and elevated terrain heights, if required.
The technical team should also use the urban or rural
land use setting defined for the study area.
Source Pathway
The Source pathway contains information on the source
type and emission rate. Some key inputs in this pathway
include:
• Location: developed in steps 5 and 6
• Emission rate: as described in the emissions
inventory
• Source group: ALL
• Stack parameters for fugitive and area source
releases
Building downwash effects will not be incorporated into
the simplified version of the Secondary Screen used in
this Manual.
Receptor Pathway
The Receptor pathway identifies the receptor grid nodes
developed in step 1. These data are used by ISCST as the
locations to compute estimates of air concentrations.
Meteorological Pathway
The Meteorological pathway directs ISCST to the input
file containing the meteorological data. This pathway
also defines the anemometer and mixing height
information.
Community Air Screenins How-To Manual
.215
-------
Chapter 11: Secondary Screen
• Technical Guidance
Table 11-1.
Area Source Categories and Apportioning Methods
SOURCE CATEGORY
NT! APPORTIONING METHOD
CEP APPORTIONING METHOD
Agricultural Production
Not specified
USGS land use categories: "farmland" and
"orchard land," "confined feeding operations,"
"other agricultural land"
Asphalt Paving
County proportion of national
1996 population estimateb
Total miles of all roadway types in each
census tract as reported in TIGER/Line
Consumer Products Usage
1996 population estimateb
County proportion of national
U.S. Census category. 1990 residential population
Gasoline Distribution Stage I
County proportion of national
1996 CBP employment for
SIC code 5171
USGS land use categories: "industrial," plus one-
half of "industrial and commercial complexes" plus
one-third "mixed urban and built up land" plus one-
third "other urban and built up land"
Industrial Boilers: Distillate Oil
County proportion of national
1996 CBP employment for
SICGROUP = IND»
USGS land use categories: "commercial and services,"
plus one-half of "industrial and commercial
complexes" plus one-third "mixed urban and built
up land" plus one-third "other urban and built up land"
Institutional/Commercial Heating
(all types)
County proportion of national
1996 CBP employment for
SICGROUP=COMMa
USGS land use categories: "commercial and services,"
plus one-half of "industrial and commercial complexes"
plus one-third "mixed urban and built up land" plus one-
third "other urban and built up land"
Natural Gas Transmission and Storage
County proportion of national
1996 CBP employment for
SIC code 4920: Gas Production
and Distributiona
USGS land use categories: "industrial," plus one-half of
"industrial and commercial complexes" plus one-third
"mixed urban and built up land" plus one-third "other
urban and built up land"
Non-industrial Asphalt Roofing
Not specified
Sum of USGS land use categories:
"residential" and""commercial land"
Pesticide Application
County proportion of national
1990 PCBEIS agricultural acres
(adjusted for 1996 county
definitions)-
Not specified
Residential Heating (all types)
County proportion of national
1996 population estimate6
U.S. Census category. 1990 residential population
216
Community Air Screening How-To Manual
-------
Chapter 11: Secondary Screen
• Technical Guidance
Table 11-1.
Area Source Categories and Apportioning Methods (continued)
SOURCE CATEGORY
NTI APPORTIONING METHOD
CEP APPORTIONING METHOD
Residential Heating, Wood
Regional proportion of national
1990 residential wood
consumption and county
proportion of regional 1996
population estimateb
Not specified
Structure Fires
County proportion of national
1996 population estimateb
U.S .Census category 1990 residential population
Surface Coatings: Architectural
County proportion of national
1996 population estimateb
USGS land use categories: "industrial/1 plus one-half of
"industrial and commercial complexes" plus one-third
"mixed urban and built up land" plus one-third "other
urban and built up land"
Surface Coatings: Industrial Maintenance
County proportion of national
1996 CBP employment for
SICGROUP=INDa
USGS land use categories: "industrial," plus one-half of
"industrial and commercial complexes" plus one-third
"mixed urban and built up land" plus one-third "other
urban and built up land"
Surface Coatings: Traffic Markings
State proportion of 1996
national disbursements and
county proportion of state
1996 population estimates"
USGS land use categories: "industrial," plus one-half of
industrial and commercial complexes" plus one-third
"mixed urban and built up land" plus one-third "other
"urban and built up land"
County Business Patterns 1996. United States Department of Commerce, Bureau of the Census. CBP-96-1. November 1998.
Estimates of the Population of Counties: Annual Time Series, July 1, 1990, to July 1, 1997 (includes revised April 1, 1990, census
population counts). CO-97-4. Population Estimates Program, Population Division. U.S. Bureau of the Census, Washington, D.C.
The Personal Computer Biogenic Emissions Inventory System (PCBEIS) was developed by EPA and is available at
http://www.epa.gov/ttn/chief/software.html.
Total Disbursements for Highways, All Units of Government -1996. Table HF-2. United States Department of Transportation.
October 1998.
Community Air Screenins How-To Manual
217
-------
Chapter 11: Secondary Screen
• Technical Guidance
Figure 11-2.
Illustration of Pseudo-Point Layout
tlM lICSTt Had*)
I STACKI 1 00 H D 112 11 ? i 1
KTILDBGT STACK! !•:•
IBID STACKS 35 43 16 4£ 3* 37 IS 16 32 92 29 tti 25 50 20 EC
STACtt I* 10 iO **• 3% *9 J» ** « »J « »« 3< )* »k «S
ATACSl 3', 41 J) It n «) li « 0 00 If I* 13 92 .-* it
'""
90XTMTA 940IJ 1M*
IU1IOATA t«»}l mt
HCTM1UC AUAVK riXSt MBMP
«PtS^f "
f/ffurc 11-3.
Example of ISCST Input File Format
Terrain Grid Pathway
The Terrain Grid pathway defines input grid data used in
calculating dry depletion in elevated or complex terrain.
Depending on the decision of the technical team, dry
depletion may or may not be considered.
Output Pathway
The Output pathway directs ISCST to generate outputs
for reviewing, summarizing and plotting the air
modeling results. The technical team should generate
plot files depicting the annual average air concentrations
for each emission source, at each receptor grid node.
Step 8: Include background concentrations in model
concentrations.
Background concentrations are releases that are not the
result of current human activity (including both natural
and past human sources) in the study area and cannot be
attributed to any of the stationary point, stationary area,
or mobile sources that have been identified. During
development of the Emission Source Inventory,
background concentrations were identified for the
various chemicals of concern. These values should be
added to the concentrations developed from ISCST to
estimate the total ambient concentration. The technical
team should assume that the background concentrations
collected in the Emission Source Inventory are uniform
throughout the study area and are the same at each
receptor location.
Step 9: Compare modeled concentrations at
monitoring site to available monitored
concentrations.
If the Partnership has access to relevant monitoring data
for the study area, the technical team should use this data
for comparison purposes with the ISCST model results
for the study area monitoring sites. If the differences
between the monitoring data and the modeled data are
more than an order of magnitude, the technical team
should review the values used during the modeling to
identify the source of the discrepancies.
218
Community Air Screenins How-To Manual
-------
Chapter 111 Secondary Screen
• Technical Guidance
How will the technical team summarize its
work to present to the full Partnership?
As mentioned at the beginning of this chapter, the results
of the Secondary Screen will be used to identify those
chemicals for further review in the Final Screen. As such,
it is important for the technical team to provide results
that support the Partnership's decision to retain or
remove a chemical from consideration. A summary table
should be compiled that lists the following for each of
the analyzed chemicals:
• Name
• Maximum estimated concentration
• Screening-level concentration
• Ratio of maximum estimated concentration to
screening-level concentration
The table should be arranged in descending order of the
ratio of maximum chemical concentration to screening-
level concentration. This type of table should provide the
Partnership with an easy way to prioritize the chemicals
for further analysis in the Final Screen.
The technical team should generate a summary table
depicting the locations of sensitive populations selected
for discrete concentration estimation. The table should
be designed to display:
• Name of the location
• Name of the chemical
• Estimated concentration of the chemical
• Screening-level concentration
• Ratio of the estimated concentration to screening-
level concentration
As with the first table, the chemicals in this table should
be arranged in descending order of the ratio of estimated
chemical concentration to screening-level concentration.
The technical team should also provide the Partnership
with a table that lists the facilities releasing chemicals
whose concentrations exceeded the screening level
concentration. This table will provide the Partnership
with a list of facilities to contact during the process for
refinement of emission data in the Final Screen.
Finally, the technical team should provide the
Partnership with a separate report detailing the technical
team's air modeling approach, assumptions, data, and
results to support the results depicted in the summary
tables. If the Partnership has access to GIS resources,
color-coded maps indicating the range of chemical
concentrations throughout the study area can be
developed.
What should the Partnership do after the
ambient air concentration values have
been estimated from each emission
source?
Once the technical team is confident that there are no
errors in the values they have estimated using the
Secondary Screening approach, the Partnership needs to
compare these estimates to the screening-level
concentration values. Chemicals with concentrations
above the screening level should be forwarded on to the
Final Screen. Those chemicals with concentrations below
the screening level can be set aside because they are
below the community's screening levels.
Community Air Screenins How-To Manual
219
-------
220
Community Air Screening How-To Manual
-------
Technical
Guidance
Final Screen
What is the overall goal for the technical
team?
The goal of the Final Screening process is to develop
more accurate estimates of the ambient concentrations
for chemicals remaining in the process after completion
of the Secondary Screen, using the best information on
sources that can be collected to develop new and more
accurate estimates of concentrations in community air.
With these new estimates, the Final Screen will be used
to identify the chemicals and the sources that will be
priorities for potential community action. A flow chart
showing a summary of the steps for completing the Final
Screen is shown in Figure 12-1.
How will the technical team estimate
concentrations?
As it did in the Secondary Screen, the technical team will
estimate chemical concentrations using the ISCST
model. In addition, the MOBILE6.2 model maybe used
to develop more accurate concentration estimates for
on-road sources.
How will the technical team collect the
new information needed to estimate
concentrations in the Final Screen?
The Partnership will draw on all of its members and
organize special teams to contact, visit, or observe the
sources that are under review in the Final Screen.
This may involve surveying traffic on major roads or
contacting and visiting both large and small commercial,
industrial, and public facilities.
The Partnership teams that are established to collect
the information should contain a cross section of
Partnership members. Community leaders and local
residents will explain the work of the Partnership and
convince facility sources to cooperate and join in the
effort. Technical members of the Partnership will be
needed to help with the collection and verification of
the information. Refer to the Final Screen chapter in the
Overview for a description of the resources needed to
collect the required information.
What new information will be used to
estimate concentrations in the Final
Screen?
The following is a list of the types of information the
Partnership teams will have to collect for each source
under review in the Final Screen.
Stationary Point Sources
Release amounts—Instead of using values obtained from
various databases, the Partnership teams will collect and
verify estimates or measurements of actual released
amounts (e.g., tons/year). For those sources where a top-
down or bottom-up approach was used to develop a
stationary point source emission rate, the Partnership
teams should visit the identified sites to see if the
methods used to make the estimates were appropriate
and investigate whether a better method could have been
used.
Stack parameters—The Partnership teams will contact
the facilities and collect and verify stack dimensions and
locations. If a GPS is available, the Partnership teams
may want to use it to verify emission locations. While at
the facility, the Partnership teams should assess whether
or not the buildings at the facility affect how the stack
releases disperse into the surrounding area. If the
buildings affect a chemical emission, downwash effects
may need to be included in the ISCST modeling runs,
and building dimensions will have to be collected.
Optional fugitive source dimensions for fugitive source
modeling—The dimensions of areas at each facility
where fugitive emissions occur if the technical team
chooses to model fugitive emissions using the ISCST
area source option.
Stationary Area Sources
The concentrations estimated for area sources in the
Secondary Screen will likely be used again as the Final
Screen estimations. The partnership should review the
area source concentrations and determine if any further
work is necessary to refine the estimated concentrations.
This would involve revisiting the assumptions used for
Community Air Screenins How-To Manual
.221
-------
Chapter 12: Final Screen
• Technical Guidance
Step 1
Institute QA/QC process to ensure
accuracy of team work.
Step 2
Collect, verify, and refine data for
Final Screen modeling.
Step 3
Run the ISCST model to estimate
total concentrations from
all sources using finalized data.
the pseudo-point source methodology during the
Secondary Screen.
If the area source contributions are significant to the
overall analysis, the Partnership may want to consider
the use of an alternative to the pseudo-point modeling
method used in the Secondary Screen. Stationary area
source releases can be modeled as emissions released
uniformly over the area of the census tract rather than
combining the releases into five pseudo-stacks as done in
the Secondary Screen. If GIS resources are available, this
can be accomplished using the area source modeling
option in ISCST and information on census tract
boundaries. The documentation of the method is in
preparation and should be available on this How-To
Manual's wbsite at: http://www.epa.gov/oppt/cahp/
howto.html.
Step 4
Include background concentration
data in modeled concentration.
Step 5
Compare modeled concentrations to
available monitored concentrations.
Step 6
USE ISCST model to estimate source
contributions to total concentrations.
Figure 12-1.
Procedure for Final Screen
Mobile Sources
The Partnership may decide that it has sufficient
information to target mobile sources following the
Secondary Screen. Refer to the discussion of mobile
sources in the Final Screen chapter in the Overview. If
the Partnership decides that more accurate estimations
of mobile sources are necessary, the technical team will
use the MOBILE6.2 model to estimate mobile soource
emissions and ISCST air dispersion model to estimate
concentrations. To run these models, the technical team
will need to collect detailed information on traffic, fuels
used, and the locations of main roadways and
intersections in the Partnership area. Additional
information on significant non-road sources may also be
required. Examples can be found in the following
references:
Stein, B., Walker, D. Cook, R. and Bailey, C. 2003. Link
Based Calculation of Motor Vehicle Air Toxics Emissions
Using MOBILE6.2. EPA Office of Air Quality Planning
and Standards. 12th International Emission Inventory
Conference. April 29-May 1,2003, San Diego, CA.
Thomas, G. and Dudley, M. 2001. Steps in Conducting an
Urban Air Toxics Assessment: Methodology for Converting
Emissions Inventories into Model Ready Input Files.
USEPA Office of Air Quality Planning and Standards.
10th International Emission Inventory Conference. May
1 3,2001, Denver, CO
Kinnee , EJ., Touma, JS, R. Mason, J. Thurmon, A.
Beidler, C. Bailey and R. Cook. 2004. Allocation ofonroad
mobile emissions to road segments for air toxics modeling
in an urban area. Transportation Research Part D:
Transport and Environment. 9(2) 139-150.
222.
Community Air Screening How-To Manual
-------
Chapter 12: Final Screen
• Technical Guidance
Background Concentrations
Background concentrations are releases that are not the
result of current human activity, including both natural
and past human sources The background concentration
of a chemical of interest, if available, will be used the
same way it was in the Secondary Screen. It will be added
to the modeled concentration estimates to get the total
concentration of the chemical.
What are the steps the technical team will
need to take to complete the work of
estimating concentrations for the Final
Screen?
Step 1: Institute QA/QC process to ensure accuracy of
team work.
Step 2: Collect, verify, and refine data for Final Screen
Modeling.
Step 3: Run the ISCST model using finalized data to
estimate total concentrations from all sources.
Step 4: Add background concentrations to modeled
concentrations.
Step 5: Compare modeled concentrations at
monitoring site to available relevant monitored
concentrations.
Step 6: Use the ISCST model to estimate source
contributions to total concentrations for all
chemicals with estimated concentrations
greater than screening-level concentration.
How will the Partnership teams complete
these steps?
Step 1: QA/QC
Refer to the QA/QC section (step 1) in Chapter 9 in the
Technical Guidance section.
Step 2: Collect, verify, and refine data and
methodologies used in Secondary Screen
The technical team will work with the teams organized
by the Partnership to collect the detailed information
that will be needed for the Final Screen. Teams will
contact facility managers and visit stationary point
sources to collect the information that will be needed for
the Final Screen.
If the Partnership decides to refine its mobile source on-
road estimations, a team will work with transportation
department officials to collect the information needed to
run the MOBILE6.2 and ISCST models. For detailed
guidance on mobile source modeling using MOBILE6.2,
the Technical Description of the Toxics Module for
MOBILE6.2 and Guidance on Its Use for Emission
Inventory Preparation (EPA 420-R-02-029, November
2002) can be found at http://www.epa.gov/otaq/models/
mobile2/r02029.pdf.
If there is a significant non-road source or sources in the
Partnership area, such as an airport, railroad yard, port,
or heavy construction site with significant non-road
emissions, the Partnership may decide to refine its non-
road source estimations.
Step 3: Run the ISCST model using finalized data to
estimate total concentrations from all
sources.
Once the information from steps 1 and 2 has been
collected, it needs to be put into a data input file for the
ISCST and/or MOBILE6.2 modeling runs. As mentioned
in the Secondary Screen, the input file format for
modeling are very specific. The Partnership teams should
consult the discussion about ISCST input files in the
Secondary Screen section and volume 1 of the ISCST
user's guide (or commercial software support
documents) to determine the specific data file format
requirements.
Step 4: Add background concentrations to modeled
concentrations.
Background concentrations are levels of chemicals that
occur naturally in the study area and cannot be
attributed to any of the stationary point, stationary area,
or mobile sources that have been identified. In the
development of the Emission Source Inventory,
background concentrations were identified for the
various chemicals of concern. These values should be
added to the concentrations developed from ISCST to
estimate the total ambient concentration. The technical
team should assume that the background concentrations
collected in the emissions inventory are uniform
throughout the study area and are the same at each
receptor location.
Community Air Screenins How-To Manual
223
-------
Chapter 12: Final Screen
• Technical Guidance
Step 5: Compare modeled concentrations at
monitoring sites to available monitored
concen trations.
If the Partnership has access to monitoring data for the
study area, the technical team should use this data for
comparison purposes with the ISCST model results. If
the differences between the monitoring data and the
modeled data are more than an order of magnitude, the
technical team should review the values used during the
modeling to identify the source of the discrepancies.
Step 6: Use ISCST model to estimate source
contributions to total concentrations.
The Partnership has identified a group of chemicals of
concern and dropped other chemicals that are not of
concern using the Secondary Screen. At this stage it is
important to understand the contribution of each source
of a chemical of concern to the concentration of that
chemical from all sources at the receptor points chosen
by the community. With this understanding it will be
possible to identify candidate facilities for future
voluntary emissions reduction efforts as well as the
contribution of mobile and area sources to the
concentrations of concern at the receptor points.
In order to determine individual source contributions to
the total concentration of a chemical at a given receptor,
multiple ISCST runs need to be made, as follows:
• Run ISCST for a single chemical and all sources of
that chemical (stationary point, area, and mobile)
using the best information available as collected in
the Final Screen (e.g., measured or best estimated
emissions, confirmed stack parameters and
locations) and determine the chemical
concentrations at the receptor locations of interest,
including background concentration, if available.
• Edit input files or select options (as applicable) to
model each source of the chemical one at a time and
determine the concentration of the chemical at the
receptor locations of interest. Be sure to treat area
sources and mobile sources as groups of five
pseudo-point sources in each census tract. When
eliminating these sources to determine the
contribution of a single point source of a chemical,
all five pseudo-point sources in each census tract
must be deleted or set to zero emissions.
• Determine the percentage of each source
contribution to the total concentration at the
receptor points of interest by dividing the
concentration from the single source by the total
concentration from all sources determined in step 1.
This can most easily be done by entering the data
into a spreadsheet to carry out the calculations and
save the information. In practice, it may not be
necessary to account for 100% of the total
concentration if it appears that there are only minor
contributions from multiple facilities after greater
than 95% of the emissions have been accounted for.
The Partnership can make this decision if resources
are limited.
When the results of this exercise are interpreted, more
weight should be given to outcomes that indicate that
stationary point sources are significant contributors than
to those indicating that area sources are major
contributors. For the stationary point sources, efforts
have been made to refine the information on the
emissions and stack characteristics as much as possible.
Also, the results of ISCST modeling will be subject to less
uncertainty than for area sources, where the uncertainty
associated with emissions estimation, allocation, and the
use of the pseudo-point source approach should be
considered.
What is the next step after the technical
team has estimated concentrations for
the Final Screen?
Once the Final Screen concentrations have been
estimated, the technical team should prepare a detailed
report for the Partnership comparing estimated
concentrations at each of the targeted community
locations to the Partnership's screening-level
concentrations. It may be helpful to include a ratio
of the estimated concentration to the screening-level
concentrations. For each chemical with a concentration
above its screening level, the Final Screen summary
report should also include a list of sources and their
contribution, expressed as a percentage, to the total
concentration. A graphical illustration of source
contributions, such as a pie or bar chart, maybe helpful.
For the priority chemicals, it may also be helpful for the
report to review and summarize all the information used
to estimate concentrations and to develop the screening-
level concentrations, describing any uncertainties and
the overall level of confidence that the Partnership has in
its analysis. The technical team will present this report to
the full Partnership for discussion and approval and
work with the full Partnership to help communicate the
results of the screening to the community. This report
will complete the technical work of the screening
224
Community Air Screening How-To Manual
-------
Chapter 12: Final Screen
• Technical Guidance
process. The priority chemicals and sources are now
identified and the next steps for the Partnership,
discussed in the final chapter of the Overview, will be to
communicate the results to the community, develop
recommendations for reducing exposures to the priority
chemicals, and mobilize the community to implement
the recommendations. Appendix G includes a list of
resources for risk reduction and pollution prevention.
Community Air Screenins How-To Manual
225
-------
226
Community Air Screening How-To Manual
-------
Glossary
Glossary
Acute exposure: A single exposure to a toxic substance,
which may result in severe biological harm or death.
Acute exposures are usually characterized as lasting no
longer than a day, as compared to longer, continuing
exposure over a period of time.
Air contaminant: Any participate matter, gas, or
combination thereof, other than water vapor not
normally found in air.
Air dispersion model: A computerized set of
mathematical equations that uses emissions and
meteorological information to simulate the behavior and
movement of air pollutants in the atmosphere. The
results of a dispersion model are estimated outdoor
concentrations of individual air pollutants at specified
locations. While air dispersion modeling relies on
modeled estimates and not on actual measurements
taken at monitoring stations, this method of estimating
concentrations has been extensively tested and verified to
provide reliable estimates of the concentrations that
result from chemical releases.
Air pollutant: Any substance in air that could, in high
enough concentration, harm man, other animals,
vegetation, or material. Pollutants may include almost
any natural or artificial composition of matter capable of
being airborne. They may be in the form of solid
particles, liquid droplets, gases, or in combination
thereof. Generally, they fall into two main groups: (1)
those emitted directly from identifiable sources, and (2)
those produced in the air by interaction between two or
more primary pollutants, or by reaction with normal
atmospheric constituents, with or without
photoactivation.
Air pollution: The presence of contaminants or
pollutant substances in the air that interfere with
human health or welfare, or produce other harmful
environmental effects.
Air quality criteria: The levels of pollution and
lengths of exposure above which adverse health and
welfare effects may occur.
Air quality standards: The level of pollutants prescribed
by regulations that are not to be exceeded during a given
time in a defined area.
Air toxics: Also known as toxic air pollutants or
hazardous air pollutants, those pollutants known to
cause or suspected of causing cancer or other serious
health problems. Health concerns may be associated with
both short- and long-term exposures to these pollutants.
Many are known to have respiratory, neurological,
immune, or reproductive effects, particularly for more
susceptible sensitive populations such as children.
Airborne particulates: Total suspended participate
matter found in the atmosphere as solid particles or
liquid droplets. Chemical composition of particulates
varies widely, depending on location and time of year.
Sources of airborne particulates include dust, emissions
from industrial processes, combustion products from the
burning of wood and coal, combustion products
associated with motor vehicle or non-road engine
exhaust, and reactions to gases in the atmosphere.
Ambient: Surrounding, as in the surrounding
environment. In this assessment, ambient air refers to
the air surrounding a person through which pollutants
can be carried.
Ambient air: Any unconfined portion of the
atmosphere; open air, surrounding air.
Ambient air monitoring station: Ambient air
monitoring stations collect air samples on a regular basis
to determine the concentration of chemicals present in
the air. Monitored concentrations are an accurate
measure of concentrations at specific locations.
Background concentration: In this Manual, the
contributions to outdoor air toxics concentrations
resulting from natural sources, persistence in the
environment of emissions from previous years, and
long-range transport from distant sources. Background
concentrations could be levels of pollutants that would
be found even if there had been no recent man-made
emissions. To accurately estimate outdoor
Community Air Screenins How-To Manual
227
-------
Glossary
concentrations, it is necessary to account for the
background concentrations by adding them to the
modeled concentrations. The National Air Toxics
Assessment (NATA) program provides background
concentrations based on monitored values identified in
the Cumulative Exposure Project (CEP). The CEP is a
study that estimated nationwide 1990 ambient
concentrations of air toxics. Based on that study,
nationwide background concentration values for 13
toxic air pollutants were developed. Details for including
these background concentrations in the Emission Source
Inventory can be found in Chapter 9, "Building the
Emission Source Inventory."
Carcinogen: A chemical or physical agent capable of
causing cancer.
CAS registration number: A number assigned by the
Chemical Abstract Service to identify a chemical.
Census tracts: Land areas defined by the U.S. Bureau of
the Census that vary in size but typically contain about
4,000 residents each. Census tracts are usually smaller
than two square miles in cities but are much larger in
rural areas.
Chronic effect: An adverse effect on a human or animal
in which symptoms recur frequently or develop slowly
over a long period of time.
Chronic exposure: Multiple exposures occurring over
an extended period of time or over a significant fraction
of an animal's or human's lifetime (usually seven years to
a lifetime).
Chronic toxicity: The capacity of a substance to cause
long-term poisonous health effects in humans, animals,
fish, and other organisms.
Compliance monitoring: Collection and evaluation of
data, including self-monitoring reports, and verification
to show whether pollutant concentrations and loads
contained in permitted discharges are in compliance
with the limits and conditions specified in the permit.
Concentration: The relative amount of a substance
mixed with another substance. An example is 5 ppm of
carbon monoxide in air or 1 mg/L of iron in water.
Constituents of concern: Specific chemicals that are
identified for evaluation in the site assessment process.
Contaminant: Any physical, chemical, biological, or
radiological substance or matter that has an adverse
effect on air, water, or soil.
Criteria pollutants: Following the 1990 amendments to
the Clean Air Act, a term derived from the requirement
that EPA must describe the characteristics and potential
health and welfare effects of these pollutants.The
amendments required EPA to set National Ambient Air
Quality Standards for certain pollutants known to be
hazardous to human health. EPA has identified and set
standards to protect human health and welfare for six
pollutants: ozone, carbon monoxide, total suspended
participates, sulfur dioxide, lead, and nitrogen oxide. It
is on the basis of these criteria that standards are set or
revised.
Cubic feet per minute (CFM): A measure of the volume
of a substance flowing through air within a fixed period
of time. With regard to indoor air, refers to the amount
of air, in cubic feet, that is exchanged with outdoor air in
one minute, i.e., the air exchange rate.
Cumulative exposure: The sum of exposures of an
organism to a pollutant over a period of time.
Cumulative risk: An analysis, characterization, and
possible quantification of the combined risks to health
or the environment from multiple agents or stressors.
Designated pollutant: An air pollutant that is neither a
criteria nor hazardous pollutant, as described in the
Clean Air Act, but for which new source performance
standards exist. The Clean Air Act does require states to
control these pollutants, which include acid mist, total
reduced sulfur (TRS), and fluorides.
Diesel particulate matter: A mixture of particles that is
a component of diesel exhaust. EPA lists diesel exhaust as
a mobile source air toxic due to the cancer and non-
cancer health effects associated with exposure to whole
diesel exhaust. EPA believes that exposure to whole diesel
exhaust is best described, as many researchers have done
over the years, by diesel particulate concentrations.
Dispersion model: See Air Dispersion Model
Emission Source Inventory: A collection of
information on all the known sources of air emissions
in and around the Partnership area. The Emission
Source Inventory contains all the information on sources
that the Partnership will need to complete all the steps of
the air screening exercise described in this Manual. The
inventory will serve as a permanent community database
that can be updated periodically and used to measure
progress in improving community air quality.
228.
Community Air Screening How-To Manual
-------
Glossary
Emission standard: The maximum amount of air
polluting discharge legally allowed from a single source,
mobile or stationary.
Exposure assessment: Identification of the ways in
which chemicals may reach individuals (e.g., by
breathing); estimation of how much of a chemical an
individual is likely to be exposed to; and estimation of
the number of individuals likely to be exposed.
Fugitive source: Stationary point source releases are
divided into stack and fugitive release types in this
Manual. Examples of stack releases include a release
from a roof vent of a dry-cleaning business and a release
from a large stack like the kind used for most municipal
trash incinerators. Examples of fugitive releases include
emissions from the surface of a treatment pond or from
the nozzles at a gas filling station.
Geographic Information System (GIS): Can be used to
illustrate the sources and their locations in and around
the Partnership area.
Hazard quotient: The ratio of the potential exposure to
the substance and the level at which no adverse effects
are expected. If the hazard quotient is calculated to be
less than 1, then no adverse health effects are expected as
a result of exposure. If the hazard quotient is greater
than 1, then adverse health effects are possible. The
hazard quotient cannot be translated to a probability
that adverse health effects will occur, and it is unlikely to
be proportional to risk. It is especially important to note
that a hazard quotient exceeding 1 does not necessarily
mean that adverse effects will occur.
Hazardous Air Pollutant Exposure Model, Version 4
(HAPEM4): A computer model that has been designed
to estimate inhalation exposure for specified population
groups and air toxics. Through a series of calculation
routines, the model makes use of census data, human
activity patterns, ambient air quality levels, climate data,
and indoor/outdoor concentration relationships to
estimate an expected range of inhalation exposure
concentrations for groups of individuals.
Hazardous air pollutants (HAPs): The 188 air
pollutants that are not covered by ambient air quality
standards but that, as defined in the Clean Air Act, may
present a threat of adverse human health effects or
adverse environmental effects. Such pollutants include
asbestos, beryllium, benzene, coke oven emissions,
mercury, radionuclides, and vinyl chloride. The full list
of HAPs is given in Appendix E.
Heavy metals: Metallic elements with high atomic
weights (e.g., mercury, chromium, cadmium, arsenic,
and lead) that can damage living things at low
concentrations and tend to accumulate in the food
chain.
Human health risk: The likelihood that a given
exposure or series of exposures may have damaged or
will damage the health of individuals.
Inhalation: Breathing. Once inhaled, contaminants can
be deposited in the lungs, taken into the blood, or both.
Inhalation reference dose: An estimate (with
uncertainty spanning perhaps an order of magnitude) of
daily level of inhalation exposure of the human
population (including sensitive subgroups) that is likely
to be without an appreciable risk of adverse effects
during a lifetime.
IRIS: EPA's Integrated Risk Information System, an
electronic database containing the Agency's latest
descriptive and quantitative regulatory information on
chemical constituents.
Industrial Source Complex Short Term (ISCST) air
dispersion model: A widely used model developed by
EPA to estimate the air concentrations that result from
chemical releases.
Local knowledge: The knowledge that members of the
community, including residents and local businesses,
have as a result of living and working in the community.
The local knowledge important to risk-based screening
includes detailed information on local sources and
releases, on ways that community members are exposed
to toxics, and on possible solutions to address the
priorities identified by the screening exercise. Local
knowledge also includes a detailed understanding of the
community values, organization, and resources that will
be needed to effectively mobilize the community to
address local air quality concerns.
Microgram: One millionth of a gram. One gram is
about l/28th of an ounce.
Mobile source: Any non-stationary source of air
pollution such as cars, trucks, motorcycles, buses,
airplanes, and locomotives.
Monitoring: Periodic or continuous surveillance or
testing to determine the level of compliance with
statutory requirements and/or pollutant levels in various
media or in humans, plants, and animals. Monitoring
directly measures what is in the air, either at fixed
Community Air Screeniris How-To Manual
229
-------
Glossary
locations in a community or as the air is breathed by
someone living in the community through personal
monitors worn by community volunteers.
National Air Toxics Assessment (NATA): EPA's ongoing
comprehensive evaluation of air toxics in the United
States. These activities include expanding air toxics
monitoring, improving and periodically updating
emission inventories, improving national- and
local-scale modeling, researching health effects and
exposures to both ambient and indoor air, and
improving assessment tools.
National Ambient Air Quality Standards (NAAQS):
Standards established by EPA that apply for outdoor air
throughout the country.
National Emissions Inventory (NEI): EPA's
compilation of quantitative information concerning the
mass of air toxics emitted into the atmosphere (through
smokestacks, tailpipes, vents, etc.). The NEI provides a
model-ready emissions inventory as part of the National
Air Toxics Assessment required by the Clean Air Act.
Mobile sources—non-road: Mobile sources not found
on roads and highways (e.g., airplanes, trains, lawn
mowers, construction vehicles, farm machinery).
Mobile sources—on-road: Vehicles found on roads and
highways (e.g., cars, trucks, buses).
One in 1 million cancer risk: A risk level of one in 1
million implies a likelihood that up to one person, out of
1 million equally exposed people, would contract cancer
if exposed continuously (24 hours per day) to the
specific concentration over 70 years (an assumed
lifetime). This would be in addition to those cancer cases
that would normally occur in an unexposed population
of 1 million people. Note that this assessment looks at
lifetime cancer risks, which should not be confused with
or compared to annual cancer risk estimates. If you
would like to compare an annual cancer risk estimate
with the results in this assessment, you would need to
multiply that annual estimate by a factor of 70 or
alternatively divide the lifetime risk by a factor of 70.
A one in 1 million lifetime risk to the public in 1996 was
250 cancer cases over a 70-year period.
Organic chemicals/compounds: Naturally occurring
(animal or plant produced) or synthetic substances
containing mainly carbon, hydrogen, nitrogen, and
oxygen.
Order of magnitude: A factor of 10 difference between
two values (e.g., the difference between 0.1 and 1, or 10
and 100 is an order of magnitude).
Peak levels: Levels of airborne pollutant contaminants
much higher than average or occurring for short periods
of time in response to sudden releases.
Plume: A visible or measurable discharge of a
contaminant from a given point of origin, such as a
plume of smoke or the area downwind from a release,
where exposures to the releases can occur and
concentrations can be estimated.
PM 10, PM 2.5: PM 10 is measure of particles in the
atmosphere with a diameter of less than 10 or equal to a
nominal 10 micrometers. PM 2.5 is a measure of smaller
particles in the air. PM 10 has been the pollutant
particulate-level standard against which EPA has been
measuring Clean Air Act compliance. On the basis of
newer scientific findings, the Agency is considering
regulations that will make PM 2.5 the new standard.
Pollutant: Generally, any substance introduced into the
environment that adversely affects the usefulness of a
resource or the health of humans, animals, or
ecosystems..
Population at risk: A population subgroup that is more
likely to be exposed to a chemical, or is more sensitive to
the chemical, than is the general population.
Pseudo point: The artificial point sources given specific
locations that are used in air dispersion modeling to
represent sources of pollution that are too numerous and
disperse to model individually (e.g., home heating,
consumer product use, lawn mower exhaust, etc.).
Pseudo points only exist in the model and they do not
have an actual location in the real world. Pseudo points
are used as a means to estimate the contribution of
dispersed emissions to airborne concentrations of
pollutants. For example, in the modeling
recommendations included in this Manual, to make air
dispersion modeling practical, all the emissions from
multiple home heating systems in a census tract are
combined and modeled as though they are released from
five pseudo points spaced evenly throughout the census
tract.
Quality assurance/quality control (QA/QC): A system
of procedures, checks, audits, and corrective actions to
ensure that all EPA research design and performance,
environmental monitoring and sampling, and other
technical and reporting activities are of the highest
achievable quality.
Reference concentration (RfC): The reference
230.
Community Air Screening How-To Manual
-------
Glossary
concentration is an estimate (with uncertainty spanning
perhaps an order of magnitude) of a continuous
inhalation exposure to the human population (including
sensitive subgroups which include children, asthmatics
and the elderly) that is likely to be without an
appreciable risk of deleterious effects during a lifetime. It
can be derived from various types of human or animal
data, with uncertainty factors generally applied to reflect
limitations of the data used.
Risk: The probability that damage to life, health, and/or
the environment will occur as a result of a given hazard
(such as exposure to a toxic chemical). Some risks can be
measured or estimated in numerical terms (e.g., one
chance in a million).
Risk characterization: The last phase of the risk
assessment process that estimates the potential for
adverse health or ecological effects to occur from
exposure to a stressor and evaluates the uncertainty
involved.
Risk communication: The exchange of information
about health or environmental risks among risk assessors
and managers, the general public, news media, interest
groups, etc.
Route of exposure: The avenue by which a chemical
comes into contact with an organism, e.g., inhalation,
ingestion, dermal contact, injection.
Risk-based screening: Risk-based screening is designed
to identify the chemicals and sources that present the
greatest risk to the community with the minimum
possible expenditure of community resources. Risk
based screening minimizes resources by screening out
low risk chemicals and simplifying the estimation of
exposure to develop relative risk estimates for each
chemical concentration and each source. Because of
these simplifications, risk based screening has
limitations. It can identify chemicals above screening
levels, rank chemicals and sources by risk, and identify
the chemicals and sources with the highest risk, but risk
based screening does not estimate the risks resulting
from releases and sources. And, because risk based
screening does not attempt to estimate risk, it can not be
used to estimate the cumulative risk from all or some of
the chemicals.
Risk screening level: The risk screening level is a level of
risk that the community agrees to use to identify
priorities. This risk level is used to sort through the
concentrations in community air to find those
concentrations that pose a potential risk greater than the
risk screening level. These concentrations and the
sources that contribute to them become the priorities
that will be evaluated for possible community action.
Screening-level concentration: The screening-level
concentration is the air concentration that would result
after a lifetime of exposure in a risk equal to the
screening level of risk chosen by the Partnership. Once
the Partnership has chosen a risk screening level to use
for screening, it will next need to calculate, for each
chemical in community air, the air concentration that
corresponds to the community's risk screening level. The
concentrations in community air estimated for the
Initial Screen will be compared to the screening-level
concentrations.
Stack: A chimney, smokestack, or vertical pipe that
discharges used air.
State, tribal, and local government air permitting
databases: The primary source for government
information on local air sources. State, tribal, or local
government authorities are responsible for permitting
air releases. They maintain databases with information
on local sources and their releases. The amount and kind
of information collected will depend on the local
authority.
Stationary sources: Stationary sources include all the
emission sources that come from fixed locations. This
type of source includes both large and small stationary
sources ranging from large sources such as electric utility
plants, chemical plants, steel mills, oil refineries, and
hazardous waste incinerators to small stationary sources
such as the neighborhood dry-cleaners and auto repair
and refinishing shops. Small stationary sources also
include all the emission sources from homes and small
office buildings, such as wood stoves, gas-fired home
heating, and even household chemical uses.
Stationary area sources: As defined in this Manual, area
sources, also called stationary area sources, include
sources, such as home furnaces and wood stoves that are
too small and ubiquitous in nature to be inventoried as
individual sources. Because these sources are too
numerous to estimate air concentrations individually,
the releases from these sources will be combined
together by type. The Manual defines the list of sources
that will be handled as area sources for risk screening. To
avoid confusion, it is important to note that the
definition of area source used in this Manual differs from
the definition used in EPAs Air Program. Area sources as
defined in the Air Program can include small stationary
Community Air Screeniris How-To Manual
231
-------
Glossary
sources such as dry-cleaners and gas stations. In this
Manual, all small commercial and business sources will
be handled as stationary point sources, and the
concentrations resulting from the releases from these
sources will be estimated individually.
Stationary point sources: Include all the stationary
sources whose concentrations will be estimated
individually. Large and small businesses, from large
chemical facilities and steel mills to the gasoline station
on the neighborhood corner, will be included in this
group. Publicly owned facilities such as incinerators and
water treatment plants will also be put into this group.
Each of these facilities will have the concentrations
resulting from its releases estimated individually.
Toxics Release Inventory (TRI): This EPA database
contains information on air releases of over 600
chemicals from the large facilities across the country.
Toxic substance: A chemical or mixture that can cause
illness, death, disease, or birth defects. The quantities and
exposures necessary to cause these effects can vary
widely. Many toxic substances are pollutants and
contaminants in the environment.
Upper bound: A plausible upper limit to the true value
of a quantity; usually not a true statistical confidence
limit.
Upper-bound lifetime cancer risk: A plausible upper
limit to the true probability that an individual will
contract cancer over a 70-year lifetime as a result of a
given hazard (such as exposure to a toxic chemical). This
risk can be measured or estimated in numerical terms
(e.g., one chance in a hundred).
Unit risk estimate: The upper-bound excess lifetime
cancer risk estimated to result from continuous exposure
to an agent at a concentration of 1 ^ig/m3 in air. The
interpretation of the unit risk estimate would be as
follows: If the unit risk estimate equals 1.5 x 106 per ^g/
m3,1.5 excess tumors are expected to develop per
1,000,000 people exposed daily for a lifetime to 1 [^g of
the chemical in 1 cubic meter of air. Unit risk estimates
are considered upper-bound estimates, meaning they
represent a plausible upper limit to the true value. (Note
that this is usually not a true statistical confidence limit.)
The true risk is likely to be less, but could be greater.
Vehicle miles traveled (VMT): A measure of the extent
of motor vehicle operation; the total number of vehicle
miles traveled within a specific geographic area over a
given period of time.
232.
Community Air Screening How-To Manual
-------
Appendix
Resources for Building a Partnership,
Setting Goals, and Developing a
Communication Plan
The links below provide access to both web-based and
printed resources for building partnerships, setting goals,
and developing a plan for communication. The list of
web sites is a only a sample of the resources that are
available on the Internet. Each of these sources provides
links to additional resources that are available. Please
check the Manual web site for updates to these links.
In addition to resources available on the Internet, local
libraries and librarians are also an excellent source for
information on these topics. Local community
organizations and colleges can also be great resources to
help you get started and build your organization.
EPA and other federal sovernment
resources
Community-Based Environmental Protection
See the tool, resources, and links pages on this site:
http://www.epa.gov/ecocommunity/about.htm
Watershed Information Network
Although focused on watersheds, this site has excellent
resources for getting started with a community project:
http://www.epa.gov/win/ and
http://www.epa.gov/win/start.html
Community Involvement Toolkit
This excellent community resource was developed for
the Superfund program:
http://www.epa.gov/superfund/tools/index.htm
Public Involvement site
For resources see the tools page on this site:
http://www.epa.gov/stakeholders/
Department of Housing and Urban Development
(HUD), Communities site
http://www.hud.gov/community/index.cfm
National Park Service Community Toolbox
http://www.nps.gov/phso/rtcatoolbox/
Other resources
Please note that the following links are not a part of the
EPA.gov domain. These links provide additional
information that may be useful or interesting and are
being provided consistent with the intended purpose of
this EPA document. However, EPA cannot attest to the
accuracy of information provided by these links or any
other linked site. Providing links to a non-EPA web site
does not constitute an endorsement by EPA or any of its
employees of the sponsors of the site or the information
or products presented on the site. Also, be aware that the
privacy protection provided on the epa.gov domain may
not be available at the external link.
Asset Based Community Development Institute
http://www.northwestern.edu/ipr/abcd.html
Center for Collaborative Planning, Resource Library
http://www.connectccp.org/resources/
Civic Practices Network Tools Community
http://www.cpn.org/tools/manuals/community/
index.html
Citizens Handbook, A Guide to Building Community
http://www.vcn.bc.ca/citizenshandbook/
Clean Air Counts, Campaigns for Clean Air and
Development, Metropolitan Chicago
http://www.cleanaircounts.org/
Community Air Screenins How-To Manual
.233
-------
Appendix A: Resources for Building a Partnership, Setting Goals, and
Developing a Communication Plan
Community Campus Partnerships for Health Partnership for Public Health, Resources
http://www.futurehealth.ucsf.edu/ccph.html http://www.partnershipph.org/col3/resc/res index.html
Community Problem Solving, Strategy for a Changing Study Circle Resource Center
World http://www.studycircles.org/index.html
http://www.community problem solving.net/
Sustainable Communities Network
Community Tool Box http ://www.sustainable .org/
http://ctb.ku.edu/
National Civic League
http://www.ncl.org/
Community Visioning and Strategic Planning
Handbook
http://www.ncl.org/publicatioiis/oiiline/
VSPHandbook.pdf
234.
Community Air Screening How-To Manual
-------
Appendix
Examples of Projects Communities Have
Adopted to Improve Air Quality
Examples of the risk reduction activities or options that
have been identified for consideration by community
partnerships in Cleveland, Ohio; St. Louis, Missouri; and
West Oakland, California, can be found at the web sites
provided below. The web site for the Clean Air Counts
program from the metropolitan Chicago area is also
provided as a resource for risk reduction activities.
In addition, for a list of activities that communities are
taking to reduce exposure to diesel exhaust from school
buses see the descriptions of the Clean School Bus
Demonstration Projects at http://www.epa.gov/otaq/
schoolbus/grants 2003.htm.
The web sites listed below do not provide a
comprehensive list of activities that communities have
used to reduce exposures and risks. At the time of the
publication of this Manual, many communities were
completing local assessments and beginning to consider
options for reductions, so many more examples of
reduction activities will be available in the future. As
communities complete their reduction strategies,
descriptions of their plans will be made available on
EPA's Air Toxics Community Assessment and Risk
Reduction Projects Database at
http://yosemite.epa.gov/oar/CommunityAssessment.nsf/
Welcome?OpenForm.
For a list of resources and programs for pollution
prevention and emissions reduction please see
Appendix G.
Please note that the following links are not a part of the
EPA.gov domain. These links provide additional
information that may be useful or interesting and are
being provided consistent with the intended purpose of
this EPA document. However, EPA cannot attest to the
accuracy of information provided by these links or any
other linked site. Providing links to a non-EPA web site
does not constitute an endorsement by EPA or any of its
employees of the sponsors of the site or the information
or products presented on the site. Also, be aware that the
privacy protection provided on the epa.gov domain may
not be available at the external link.
Clean Air Counts, Campaigns for Clean Air and
Development, Metropolitan Chicago
http://www.cleanaircounts.org/
Cleveland Air Toxics Pilot Project
http://www.ohiolung.org/ccacc.htm
St. Louis Community Air Project
http://www.stlcap.org/whatsnew.htm
One of the results of the St. Louis work is a set of
curriculum materials developed by the Missouri
Botanical Gardens. These educational materials are
designed to help learners of all ages understand air toxics
and how they can affect health and what can be done to
reduce air toxics levels. These materials are developed in
five units for kindergarten through ad Lilt learners. These
curriculum materials will be available in the spring of
2004 at http://www.mobot.org/gatewaycenter/.
West Oakland: Report on Reducing Diesel Pollution
httD://www.pacinst.org/diesel/index.html
Community Air Screenins How-To Manual
.235
-------
236
Community Air Screening How-To Manual
-------
Appendix
Resources for Addressing Indoor Air
Exposures and Acute Outdoor Air
Exposures
The following list of resources is not comprehensive.
Please use these resources as a starting point for your
work. Please see Appendix G for risk reduction resources
for indoor air.
Please note that some of the following links are not a
part of the epa.gov domain. These links provide
additional information that maybe useful or interesting
and are being provided consistent with the intended
purpose of this EPA document. However, EPA cannot
attest to the accuracy of information provided by these
links or any other linked site. Providing links to a non-
EPA web site does not constitute an endorsement by EPA
or any of its employees of the sponsors of the site or the
information or products presented on the site. Also, be
aware that the privacy protection provided on the
epa.gov domain may not be available at the external link.
Indoor Air Resources
Indoor Air Quality Home Page
http://www.epa.gov/iaq/
An Introduction to Indoor Air Quality (LAQ)
http://www.epa.gov/iaq/ia-intro.html
The Inside Story: A Guide to Indoor Air Quality
http://www.epa.gov/iaq/pubs/insidest.html
Fact Sheet: Respiratory Health Effects of Passive
Smoking
http://www.epa.gov/smokefree/pubs/etsfs.html
American Lung Association
http://www.lungusa.org/
Community Environmental Health Resource Center
(CEHRC)
http://www.cehrc.org/
California Indoor Air Quality Program
http://www.cal-iaq.org/
Indoor Air Quality Association
http://www.iaqa.org/
Sources for Information on Acute Effects
of Toxic Chemicals
Agency for Toxic Substance and Disease Registry
Minimal Risk Levels for Hazardous Substances
http://www.atsdr.cdc.gov/mrls.html
California Environmental Protection Agency Office of
Environmental Health Hazard Assessment Toxicity
Criteria Database
http://www.oehha.ca.gov/risk/chemicalDB/index.asp
U.S. EPA Integrated Risk Information System (IRIS)
2003
http://www.epa.gov/ngispgm3/iris/subst/index.html
U.S. EPA Office of Air Quality Planning and Standards
Air Toxics Dose-Response Database 2002
http://www.epa.gov/ttn/atw/toxsource/
summaryl20202.html
Technical Background Document to Support
Rulemaking Pursuant to the Clean Air Act - Section
112 (g): Ranking of Pollutants with Respect to Hazard
to Human Health, U.S. Environmental Protection
Agency. 1994. EPA-450/3-92-010, February 1994.
Voluntary Remediation Program (VRP) Risk
Assessment Guidance, Virginia Department of
Environmental Quality (VDEQ). 2000.
Community Air Screenins How-To Manual
.237
-------
238
Community Air Screening How-To Manual
-------
Appendix
Summary of Lessons Learned by the
Baltimore Partnership
Lessons Learned in Baltimore
The work of the Community Environmental Partnership
in Baltimore, Maryland, was a learning experience for all
of the people who participated. The Partnership tried a
lot of new things—some of them worked and some
didn't. A few lessons learned from this work are listed
below. A complete list of lessons learned by the
Baltimore Air Study can be found in the case study at
http://www.epa.gov.opptintr/cahp/case.html.
The following are among the lessons learned:
• Bringing community stakeholders and science
experts together to address community concerns is a
key to success. Both the local knowledge of
community residents and the science and tools of
experts are needed to understand and to find the
most effective ways to improve a local environment.
Developing a dialogue between residents and
experts also helps to build the consensus that will be
needed to take action.
• Don't skimp on the time spent at the beginning of a
project clarifying goals. Make sure all the
participants are clear about their own goals and
communicate them to the other members of the
partnership. Make sure participants are clear about
how the goals set by the partnership relate to their
own goals. If the goals of the project match the
participants' goals, the resources and energy will be
sufficient to sustain the work.
• Building a strong partnership with a full range of
stakeholders and broad community participation is
key to mobilizing the new resources that will be
needed for detailed local assessments and for
implementing local solutions. No single community
group or level of government has the resources to
address local issues, so building a partnership and
learning to work together will be essential. Local
community organizations and local government can
form the core of the partnership, with others outside
the community providing resources not available at
the local level.
Plan for adequate time and resources to build and
sustain the partnership. Working in a broad
partnership using science at the community level
will be a new way of doing business for most of the
participants. Take time to build the trust, develop
the organization, and provide the information and
training that all the participants will need to work
effectively in a partnership.
Once goals for the partnership are clarified, make
sure the partnership has the resources and scope to
meet the goals. For example, if improving the health
of the community is a goal, a broad partnership that
can address all of the important factors affecting
community health will need to be formed. Any
attempt to improve community health by
addressing environmental issues by themselves will
probably not be able to produce results and will lead
to disappointment.
Be prepared to take a step-by-step approach to
building the consensus on environmental issues in
your community. Communities may decide to focus
on their main concerns first and take on other areas
in the future. It will take time to complete a fuller
picture of the local environment that everyone can
agree with.
Be prepared to be creative in solving problems. The
information, analysis tools, and solutions that
communities need to improve their environments
do not come ready-made. Your partnership will
probably have to find ways to collect data and use
and adapt tools designed for other purposes to
answer your questions. If it is broad enough, your
partnership will have the resources to find answers,
but only if it is prepared to be creative. Making
progress at the local level will depend on effective
Community Air Screenins How-To Manual
.239
-------
sharing among communities, so when you develop
new approaches, please share them so that other
communities do not have to reinvent the wheel. If
you have ideas you can share with others, send them
to us and we will post them on this Manual's web
site for others to learn from.
Communicate and involve the broader community
in the work of the partnership on a regular basis.
Regular communication gives the broader
community an opportunity to provide input into
the work of the partnership, participate in
partnership activities, and learn from the work.
Identifying community needs, taking advantage of
community knowledge, and mobilizing the
community to take action all will depend on
maintaining a close and active relationship between
the partnership organization and the community.
Pay attention to the long-term capacity of the
community to address environmental concerns.
Identify areas of community capacity that need
strengthening and organize the work of the
partnership to help build capacity in these areas. In
addition to knowledge and training in
environmental areas, include other issues that will
be important to long-term capacity, such as fund-
raising, organizing, and leadership skills.
Recognize that the work to understand and improve
local environments will take a sustained long-term
effort, and getting to measurable results will take
years. Partnerships should take a long-term
perspective and develop plans accordingly. The
contributions of outside partners may vary
according to their priorities, but those contributions
should be adjusted to fit into the Partnership's plan
for sustaining a long-term effort.
240
Community Air Screening How-To Manual
-------
Appendix
List of Hazardous Air Pollutants (HAPs)
CAS
Number Chemical
75070 Acetaldehyde
60355 Acetamide
75058 Acetonitrile
98862 Acetophenone
53963 2-Acetylaminofluorene
107028 Acrolein
79061 Acrylamide
79107 Acrylic acid
107131 Acrylonitrile
107051 Allyl chloride
92671 4-Aminobiphenyl
62533 Aniline
90040 o-Anisidine
1332214 Asbestos
71432 Benzene
(including benzene from gasoline)
92875 Benzidine
98077 Benzotrichloride
100447 Benzyl chloride
92524 Biphenyl
117817 Bis(2-ethylhexyl)phthalate (DEHP)
CAS
Number Chemical
542881 Bis(chloromethyl)ether
75252 Bromoform
106990 1,3-Butadiene
156627 Calcium cyanamide
105602 Caprolactam
(See Modification)
133062 Captan
63252 Carbaryl
75150 Carbon disulfide
56235 Carbon tetrachloride
463581 Carbonyl sulfide
120809 Catechol
133904 Chloramben
57749 Chlordane
7782505 Chlorine
79118 Chloroacetic acid
532274 2-Chloroacetophenone
108907 Chlorobenzene
510156 Chlorobenzilate
67663 Chloroform
107302 Chloromethyl methyl ether
The original list of Hazardous Air Pollutants can also be found at the EPA Technology Transfer Network Air Toxics
web site:
http//www.epa.gov/ttn/atw/188pols.html
Modifications to the 112(b)l Hazardous Air Pollutants can also be found at the EPA Technology Transfer Network
Air Toxics web site:
http//www. epa.gov/ttn/atwsmod/188pols.html
Community Air Screenins How-To Manual
.241
-------
Appendix E: List of Hazardous Air Pollutants
CAS
Number
126998
1319773
108394
95487
106445
98828
94757
3547044
334883
132649
96128
84742
106467
91941
111444
542756
62737
111422
121697
64675
119904
60117
119937
79447
68122
57147
131113
77781
534521
51285
Chemical
Chloroprene
Cresols/Cresylic acid
(isomers and mixture)
m-Cresol
o-Cresol
p-Cresol
Cumene
2,4-D, salts and esters
DDE
Diazomethane
Dibenzofurans
l,2-Dibromo-3-chloropropane
Dibutylphthalate
l,4-Dichlorobenzene(p)
3,3-Dichlorobenzidene
Dichloroethyl ether
(Bis(2-chloroethyl)ether)
1,3-Dichloropropene
Dichlorvos
Diethanolamine
N,N-Diethyl aniline
( N,N- Dimethylaniline)
Diethyl sulfate
3,3-Dimethoxybenzidine
Dimethyl aminoazobenzene
3,3'-Dimethyl benzidine
Dimethyl carbamoyl chloride
Dimethyl formamide
1 , 1 -Dimethyl hydrazine
Dimethyl phthalate
Dimethyl sulfate
4,6-Dinitro-o-cresol, and salts
2,4-Dinitrophenol
CAS
Number
121142
123911
122667
106898
106887
140885
100414
51796
75003
106934
107062
107211
151564
75218
96457
75343
50000
76448
118741
87683
77474
67721
822060
680319
110543
302012
7647010
Chemical
2 ,4- Dinitrotol uene
1,4-Dioxane ( 1,4-Diethyleneoxide)
1,2- Diphenylhydrazine
Epichlorohydrin
(l-Chloro-2,3-epoxypropane)
1,2-Epoxybutane
Ethyl acrylate
Ethyl benzene
Ethyl carbamate
(Urethane)
Ethyl chloride
(Chloroethane)
Ethylene dibromide
(Dibromoethane)
Ethylene dichloride
(1,2-Dichloroethane)
Ethylene glycol
Ethylene imine
(Aziridine)
Ethylene oxide
Ethylene thiourea
Ethylidene dichloride
(1,1 -Dichloroethane)
Formaldehyde
Heptachlor
Hexachlorobenzene
Hexachlorobuta diene
Hexachlorocyclopentadiene
Hexachloroethane
Hexamethylene- 1 ,6-diisocyanate
Hexamethylphosphoramide
Hexane
Hydrazine
Hydrochloric acid
242.
Community Air Screening How-To Manual
-------
Appendix E: List of Hazardous Air Pollutants
CAS
Number
7664393
7783064
123319
78591
58899
108316
67561
72435
74839
74873
71556
78933
60344
74884
108101
624839
80626
1634044
101144
75092
101688
101779
91203
98953
Chemical
Hydrogen fluoride
(Hydrofluoric acid)
Hydrogen sulfide
(See Modification)
Hydroquinone
Isophorone
Lindane
(allisomers)
Maleic anhydride
Methanol
Methoxychlor
Methyl bromide
( Bromomethane)
Methyl chloride
(Chloromethane)
Methyl chloroform
(1,1,1 -Trichloroethane)
Methyl ethyl ketone
(2-Butanone)
Methyl hydrazine
Methyl iodide
(lodomethane)
Methyl isobutyl ketone
(Hexone)
Methyl isocyanate
Methyl methacrylate
Methyl tertiary butyl ether
4,4-Methylene bis
(2-chloroaniline)
Methylene chloride
( Dichloromethane)
Methylene diphenyl diisocyanate
(MDI)
4,4-Methylenedianiline
Naphthalene
Nitrobenzene
CAS
Number
92933
100027
79469
684935
62759
59892
56382
82688
87865
108952
106503
75445
7803512
7723140
85449
1336363
1120714
57578
123386
114261
78875
75569
75558
91225
106514
100425
96093
1746016
Chemical
4-Nitrobiphenyl
4-Nitrophenol
2-Nitropropane
N-Nitroso-N-methylurea
N-Nitrosodim ethylamine
N-Nitrosomorpholine
Parathion
Pentachloronitrobenzene
(Quintobenzene)
Pentachlorophenol
Phenol
p-Phenylenediamine
Phosgene
Phosphine
Phosphorus
Phthalic anhydride
Polychlorinated biphenyls
(Aroclors)
1,3 -Propane sultone
beta-Propiolactone
Propionaldehyde
Propoxur (Baygon)
Propylene dicMoride
(1,2-Dichloropropane)
Propylene oxide
1,2-Propylenimine
(2-Methyl aziridine)
Quinoline
Quinone
Styrene
Styrene oxide
2,3,7,8-Tetrachlorodibenzo-
p-dioxin
Community Air Screenins How-To Manual
.243
-------
Appendix E: List of Hazardous Air Pollutants
CAS
Number
79345
127184
7550450
108883
95807
584849
95534
8001352
120821
79005
79016
95954
88062
121448
1582098
540841
108054
593602
75014
75354
1330207
108383
95476
106423
0
0
0
0
0
Chemical
1,1,2 ,2 -Tetrachloroethane
Tetrachloroethylene
( Perch] oroethylene )
Titanium tetrachloride
To lu en e
2,4-Toluene diamine
2,4-Toluene diisocyanate
o-Toluidine
Toxaphene
(chlorinated camphene)
1 ,2,4-Trichlorobenzene
1 , 1 ,2 -Trichloroethane
Trichloroethylene
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
Triethylamine
Trifluralin
2,2,4-Trimethylpentane
Vinyl acetate
Vinyl bromide
Vinyl chloride
Vinylidene chloride
(1,1 -Dichloroethylene)
Xylenes
(isomers and mixture)
m-Xylenes
o -Xylenes
p -Xylenes
Antimony compounds
Arsenic compounds
(inorganic including arsine)
Beryllium compounds
Cadmium compounds
Chromium compounds
CAS
Number Chemical
0 Cobalt compounds
0 Coke oven emissions
0 Cyanide Compounds1
0 Glycol ethers2
0 Lead compounds
0 Manganese compounds
0 Mercury compounds
0 Fine mineral fibers3
0 Nickel compounds
0 Polycylic organic matter4
0 RadionucLides (including radon)5
0 Selenium compounds modifications
NOTE: For all listings above that contain the word
"compounds" and for glycol ethers, the following
applies: Unless otherwise specified, these listings
are defined as including any unique chemical
substance that contains the named chemical (i.e.,
antimony, arsenic, etc.) as part of that chemical's
infrastructure.
1. X'CN where X = H' or any other group where a
formal dissociation may occur, for example KCN or
Ca(CN),
2. Includes mono- and di- ethers of ethylene
glycol, di ethylene glycol, and triethylene glycol
R-(OCH,CH,)n -OR' where
n = 1,2, or 3
R = alkyl or aryl groups
R' = R, H, or groups which, when removed, yield
glycol ethers with the structure: R-(OCH,CH)n-
OH. Polymers are excluded from the glycol
category. (See Modification.)
3. Includes mineral fiber emissions from facilities
manufacturing or processing glass, rock, or slag
fibers (or other mineral-derived fibers) of average
diameter 1 micrometer or less.
4. Includes organic compounds with more than
one benzene ring, and a boiling point greater than
or equal to 100 °C.
5. A type of atom that spontaneously undergoes
rarlinartivp rlprsv
244.
Community Air Screening How-To Manual
-------
Appendix E: List of Hazardous Air Pollutants
Modifications to the 112(b)(1) Hazardous
Air Pollutants
Glycol Ethers
On January 12, 1999 (64FR1780), the EPA
proposed to modify the definition of glycol ethers
to exclude surfactant alcohol ethoxylates and their
derivatives (SAED). On August 2,2000
(65FR47342), the EPA published the final action.
This action deletes each individual compound in a
group called the surfactant alcohol ethoxylates and
their derivatives (SAED) from the glycol ethers
category in the list of hazardous air pollutants
(HAP) established by section 112(b)(l) of the
Clean Air- Act (CAA). Under section 112(b)(3)(D)
of the CAA, EPA may delete specific substances
from certain listed categories, including glycol
ethers. To implement this action, EPA is revising
the definition of glycol ethers to exclude the deleted
compounds. This action is also making conforming
changes with respect to designation of hazardous
substances under the Comprehensive
Environmental Response, Compensation, and
Liability Act (CERCLA). These final rules are being
issued by EPA in response to an analysis of
potential exposure and hazards of SAED that was
prepared by the Soap and Detergent Association
(SDA) and submitted to EPA. Based on this
information, EPA has made a final determination
that there are adequate data on the health and
environmental effects of these substances to
determine that emissions, ambient concentrations,
bioaccumulation, or deposition of these substances
may not reasonably be anticipated to cause adverse
human health or environmental effects. All
information associated with this rulemaking is
available at EPAs Air and Radiation Docket and
Information Docket, Room Ml500, U.S.
Environmental Protection Agency, 401 M Street,
SW, Washington, DC 20460. The docket is an
organized and complete file of all the information
considered by the EPA in the development of this
rulemaking. The docketing system is intended to
allow members of the public and industries
involved to readily identify and locate documents
so that they can effectively participate in the
rulemaking process. Along with the proposed and
promulgated standards and their preambles, the
contents of the docket will serve as the record in
the case of judicial review. (See section
307(d)(7)(A) of the CAA.) An index for each
docket, as well as individual items contained within
the dockets, may be obtained by calling (202) 260-
7548 or (202) 260-7549. Alternatively, docket
indexes are available by facsimile, as described on
the Office of Air and Radiation, Docket and
Information Center web site at http://
www.epa.gov/oar/docket. A reasonable fee may be
charged for copying docket materials. A useful
reference for the glycol ether category is linked
below.
Toxics Release Inventory: List of Toxic Chemicals
Within the Glycol Ethers Category (December
2000).
Caprolactam
On July 19, 1993, EPA received a petition from
AUiedSignal, Inc., BASF Corporation, and DSM
Chemicals North America, Inc. to delete
caprolactani (CAS No. 105-60-2) from the
hazardous air pollutant list in Section 112(b)(l), 42
U.S.C., Section 7412(b)(l). A Notice of Receipt was
published (58FR45081, August 26,1993) noting
that the data filed were adequate to support
decision making. After a comprehensive review of
the data submitted, the EPA published a proposal
to delist caprolactam (60FR48081, September 18,
1995). In order to help address public concern,on
March 13, 1995, EPA executed two detailed
agreements with AUiedSignal concerning the Irmo,
South Carolina, manufacturing facility and another
facility located in Chesterfield, Virginia, copies of
which are included in the public docket for this
rulemaking. AUiedSignal agreed that, if
caprolactam was delisted pursuant to the proposal,
AUiedSignal would instaU emissions controls,
which EPA believed would be equivalent to the
controls which would have been required had EPA
issued a standard to control these sources under
Section 112. The agreed emissions controls are
incorporated in federaUy enforceable operating
permits for the affected facilities, and will be in
place years earlier than controls would have
otherwise been required. In addition, AUiedSignal
has agreed to estabUsh a citizen advisory panel
concerning the Irmo faciUty in order to improve
communications with the community and to
ensure that citizens have an ongoing role in
implementation of the agreed emission reductions.
The pubUc requested a pubUc hearing. On
November 28,1995, the EPA published a notice of
Community Air Screenins How-To Manual
245
-------
Appendix E: List of Hazardous Air Pollutants
public hearing and an extention of the comment
period (60FR58589). After considering all public
comments, the EPA published a final rule delisting
caprolactam (61FR30816, June 18,1996). All
information associated with this rulemaking is
located in Docket Number A-94-33 at the Central
Docket Section (A-130), Environmental Protection
Agency, 401 M St. SW., Washington, DC 20460;
phone 202-260-7548, fax 202-260-4400, e-mail
a-and-r-docket@epamail.epa.gov.
The docket includes a complete index to all papers
filed in this docket, a copy of the original petition,
comments submitted, and additional materials
supporting the rule. A reasonable fee may be
charged for copying. The docket may be inspected
in person between 8:00 a.m. and 4:30 p.m. on
weekdays at EPAs Central Docket Section, West
Tower Lobby, Gallery 1, Waterside Mall, 401 M St.,
SW, Washington, DC 20460.
Hydrogen Sulfide
A clerical error led to the inadvertent addition of
hydrogen sulfide to the Section 112(b) list of
Hazardous Air Pollutants. However, a Joint
Resolution to remove hydrogen sulfide from the
Section 112(b)(l) list was passed by the Senate on
August 1, 1991 (Congressional Record page
SI 1799), and the House of Representatives on
November 25,1991 (Congressional Record pages
HI 1217-H11219). The Joint Resolution was
approved by the President on December 4, 1991.
Hydrogen Sulfide is included in Section 112(r) and
is subject to the accidental release provisions. A
study (see citation below) was required under
Section 112(n)(5).
Hydrogen Sulfide Air Emissions Associated with
the Extraction of Oil and Natural Gas,
EPA-453/R-93-045,
NTIS (publication # PB94-131224, $36.50 hard
copy, $17.50 microfiche).
National Technical Information Services (NTIS)
5285 Port Royal Road
Springfield, VA 22161
703-487-4650 800-426-4791
703-487-4807 8:30-5:30 EST M-F
246.
Community Air Screening How-To Manual
-------
Appendix
Air Pollution and Your Health
St. Louis Community Air Project (CAP) knows that your
health and your family's health are important. It is our
goal to reduce the risks to your health by identifying and
reducing air pollutants. This wiH take the cooperation
and hard work of everyone. We all contribute to air
pollution and we can all do something about it. Visit the
St. Louis CAP "What I Can Do" page at http://
www.stlcap.org/whatsnew.htm for more information.
The St. Louis CAP Partnership spent several monthly
meetings learning about health risk and how the U.S.
Environmental Protection Agency calculates cancer and
non-cancer health risks. This education process prepared
the Partnership to address risk issues concerning:
• Duration of Exposure
• Adopting a Target Level of Risk
• Additivity of Cancer Risk
• Data Evaluation of the Monitors
The Risk Development Team, much like the Community
Involvement Team, met outside of the regular monthly
Partnership meeting to work on establishing the project's
health benchmarks. This small group of Partners
developed a list of pros and cons for the different options
and offered recommendations to the full Partnership.
David Shanks made the presentation to the Partneship at
the February 2001 meeting, and the partners discussed
and voted on each recommendation. On every issue the
Team and the full Partnership chose what came to be
known as the "smorgasbord" approach—that is, to
include as much information as possible when our
monitoring data is analyzed. Based on these decisions,
EPA and MDNR developed the official health
benchmarks for the project.
These benchmarks will help the Partnership analyze and
respond to the monitoring data. To learn more about the
recommendations accepted by the Community Air
Project Partnership as well as the methodology adopted
for establishing health benchmarks, please review the
following documents.
St. Louis Community Air Project
Health Benchmark Recommendations
Risk Development Team Recommendations,
presented to and accepted by the Community Air Project
Partnership, Feb. 29,2001.
The CAP Partnership will use the following
recommendations to set health benchmarks for each of
the chemicals we are monitoring. If a chemical we are
monitoring poses a health risk according to our health
benchmark, the Partnership will work with the
community to reduce the risk.
Recommendation Re: Target Level of Cancer Risk
The Risk Development Team recommends a cancer risk
level of 1 in 100,000 as the level of risk that would trigger
additional activities to reduce exposure.*
Options for target level of cancer risk were:
1. lin 1,000,000
2.1 in 100,000 or 10 in 1,000,000
3. 1 in 10,000 or 100 in 1,000,000
The pros of setting the target level at 1 in 100,000 are:
• It is consistent with most U.S. EPA regulatory
programs.
• It allows us to actually estimate the cancer risk for
more compounds. (Technology cannot detect most
air pollutants at a concentration equal to a cancer
risk of lin 1,000,000).
The cons of setting the target level at 1 in 100,000 are:
• It does not represent the most protective level for
human health, which is 1 in 1,000,000.
This is an EPA ranking system that classifies the
likelihood that a chemical causes cancer in humans. The
classification is based on both human and animal
studies. Group A are human carcinogens, Group B are
probable human carcinogens, and Group C are possible
human carcinogens.
Community Air Screenins How-To Manual
247
-------
Appendix F: Air Pollution and Your Health
248
Community Air Screening How-To Manual
-------
Appendix
Examples of Available Risk Reduction and
Pollution Prevention Programs
The resources listed below are only examples of
reduction and pollution prevention programs. A more
comprehensive list of resources is now under
development. Please check the Manual web site for
updates to this resource list.
This list contains resources and programs for addressing
a wide range of environmental issues, not just outdoor
air issues. This more comprehensive list is provided as a
resource for community partnerships that may want to
address more than outdoor air issues.
Please note that some of the following links are not a
part of the epa.gov domain. These links provide
additional information that may be useful or interesting
and are being provided consistent with the intended
purpose of this EPA document. However, EPA cannot
attest to the accuracy of information provided by these
links or any other linked site. Providing links to a non-
EPA web site does not constitute an endorsement by EPA
or any of its employees of the sponsors of the site or the
information or products presented on the site. Also, be
aware that the privacy protection provided on the
epa.gov domain may not be available at the external link.
PROGRAM TYPE
PROGRAM DESCRIPTION
WEB SITE OR POINT OF CONTACT
For Large Identifying Pollution Prevention Opportunities
Businesses and Encourage large chemical, refining, and manufacturing
Public Facilities facilities to institute voluntary pollution prevention
programs. Encourage companies to conduct audits to
identify pollution prevention opportunities. Identify
national industry sector leaders to use as benchmarks
for local companies. Organize a community team with
independent expertise to help facilities identify
pollution prevention opportunities.
http://cfpub.epa.gov/clearinghouse/index.cfm
httD://www.eDa,aov/compliance/assistance/sectors/
http://www.epa.gov/opptintr/p2home/resources/
For Small Design for the Environment Program
Businesses EPA partnership program working with individual
industry sectors to compare and improve the
performance and human health and environmental
risks and costs of existing and alternative products,
processes, and practices. DfE partnership projects
promote integrating cleaner, cheaper, and smarter
solutions into everyday business practices. Partnership
programs include auto refinishing, printing and
publishing, and dry-cleaning businesses.
http://www.epa.gov/dfe/projects/auto/index.htm
http://www.epa.gov/dfe/projects/flexo/index.htm
http://www.epa.gov/dfe/proiects/gravure/index.htm
http://www.epa.gov/dfe/proiects/litho/index.htm
http://www.epa.gov/dfe/proiects/screen/index.htm
http://www.eDa.aov/dfe/Droiects/aarment/index.htm
Community Air Screenins How-To Manual
.249
-------
Appendix G: Examples of Available Risk Reduction and Pollution
Prevention Programs
PROGRAM TYPE
PROGRAM DESCRIPTION
WEB SITE OR POINT OF CONTACT
For Small Environmental Results Program
Businesses An innovative program designed to assist businesses
(continued) to improve their performance and address environmental
problems. In the Environmental Results Program
communities and regulating agencies can combine
resources to educate businesses about their
environmental impacts and obligations, help them to
certify their compliance, and track them to evaluate
their environmental performance.
http://www.epa.gov/permits/masserp.htm
http://www.epa.gov/compliance/incentives/innovations/
proaramresults.html
Green Business Program
Organize a program like the Bay Area Green Business
Program, a partnership of community organizations,
environmental agencies, professional associations,
waste management agencies, and utilities to work
together to recognize and assist businesses that
operate in an environmentally friendly manner.
http://www.abaa.ca.aov/bavarea/enviro/abus/ab.html
Businesses for the Bay
Create a voluntary organization of businesses, like the
Businesses for the Bay organization in the Chesapeake
Bay watershed, committed to helping each other
implement pollution prevention in daily operations
and reduce releases of chemical contaminants and
other wastes to your watershed.
http://www.chesapeakebav.net/b4bav.htm
Stationary Source Pollution Prevention Fact
Sheets for Communities and Small Businesses
Multiple fact sheets on topics such as metal
operations, electroplating, autobody paint shops, and
printers. Includes information designed to help
communities identify pollution prevention and
reduction opportunities for small businesses.
Designed to provide concrete assistance to help small
shops implement easy pollution prevention measures
and reduce releases of air toxics. Fact sheets now in
final production.
Contact Amanda Aldridge at:
aldridge.amanda@epa.gov
For Schools Tools for Schools
Voluntary, easy-to-use resource kit to help schools
identify, remedy, and prevent indoor air quality
problems in a cost-effective manner. Schools
implement a range of specific guidelines emphasizing
reduced pesticide exposure, use, and safe chemical storage,
proper ventilation, and more.
http://www.eoa. aov/iag/schools/
250
Community Air Screening How-To Manual
-------
Appendix G: Examples of Available Risk Reduction and Pollution
Prevention Programs
PROGRAM TYPE
PROGRAM DESCRIPTION
WEB SITE OR POINT OF CONTACT
For Schools Clean School Bus USA
(continued) Brings together partners from business, education,
transportation, and public health organizations to work
to reduce pollution from public school buses. Includes
policies and practices to eliminate unnecessary idling,
retrofit buses with newer control technologies, and
replace older buses.
http://www.eDa.aov/otaa/schoolbus/
For Mobile Voluntary Diesel Retrofit Program
Sources Develop a program to retrofit older diesel engines
with modern emission control technology.
Enlist private and/or public fleets for participation.
http://www.eDa.aov/otaa/retrofit/
Anti-Idling Campaigns
Develop education campaign and administrative
policies to discourage vehicle idling in areas
where people congregate.
Vehicle Engine and Maintenance Campaigns
Sponsor a campaign to encourage proper vehicle
and engine maintenance. Could involve a "tune
your car today" at a local garage, checklists, and
parts giveaways for do-it-yourselfers, etc.
For Community Fish Consumption Surveys and Advisories
Surface Perform surveys to determine whether there should
Waters be more fish/wildlife consumption advisories.
Make advisories widely available to the public by
print, radio, or television in multiple languages with
an emphasis on subpopulations with high expected
consumption.
http://www.eDa.gov/waterscience/fish/
Watershed Protection
A Watershed Protection Approach is a strategy for
effectively protecting and restoring aquatic
ecosystems and protecting human health.
This strategy has as its premise that many water
quality and ecosystem problems are best solved at
the watershed level rather than at the individual
waterbody or discharger level. Major features of a
Watershed Protection Approach are: targeting priority
problems, promoting a high level of stakeholder
involvement, designing integrated solutions that make
use of the expertise and authority of multiple agencies,
and measuring success through monitoring and
other data gathering.
httD://www.eDa.gov/owow/watershed/index2.html
Community Air Screenins How-To Manual
.251
-------
Appendix G: Examples of Available Risk Reduction and Pollution
Prevention Programs
PROGRAM TYPE
PROGRAM DESCRIPTION
WEB SITE OR POINT OF CONTACT
For Community Mercury Reduction in Hospitals
Surface Help hospitals comply with new requirements by
Waters providing information and assistance. Encourage
(continued) hospitals to eliminate mercury sources such as
thermometers. Conduct education programs for
citizens and hospital staff about mercury reduction.
http://www.noharm.ora/mercurv/issue
Household Mercury Thermometer Exchanges
Sponsor a trade-in program that provides citizens
with new, non-toxic thermometers in exchange for
mercury thermometers to reduce risk of mercury
contamination in homes and to reduce the risk of
water contamination and outdoor air pollution due
to improper disposal.
http://www.noharm.ora/mercurv/issue
National Estuary Program
The National Estuary Program is designed to
encourage local communities to take responsibility
for managing their own estuaries. Each NEP is
made up of representatives from federal, state,
and local government agencies responsible for
managing the estuary's resources, as well as
members of the community — citizens, business
leaders, educators, and researchers. These
stakeholders work together to identify problems in
the estuary, develop specific actions to address
those problems, and create and implement a formal
management plan to restore and protect the estuary.
httD://www.eDa.aov/owow/estuaries/about2.htm
Coastal America
Coastal America is a unique partnership of federal
agencies, state and local governments, and private
organizations. The partners work together to protect,
preserve, and restore our nation's coasts.
http://www.coastalamerica.gov/
For Community Develop a Community Campaign using
Homes Home*A*Syst
Home*A*Syst is an environmental risk assessment
guide for the home that helps homeowners identify
risks and take actions to protect health and the
environment. Organize a community education
campaign using the Home*A*Syst program and
materials.
http://www.hud.aov/offices/lead/helDvourself/index.cfm
Radon "Test and Repair" Campaigns
Enlist citizens to test their home for radon and
provide information and assistance to correct the
problem if radon levels are unacceptably high.
http://www.epa.gov/iaa/radon/
252
Community Air Screening How-To Manual
-------
Appendix G: Examples of Available Risk Reduction and Pollution
Prevention Programs
PROGRAM TYPE
PROGRAM DESCRIPTION
WEB SITE OR POINT OF CONTACT
For Community Home Consumer Products Education Campaigns
Homes Educate citizens in practices they can adopt such
(continued) as proper solvent storage, vehicle operation tips,
landscaping and yard-care options to minimize use
of pesticides and polluting equipment, use of lower
toxicity home products, etc.
http://www.epa.gov/oar/oaqps/peg_caa/
pegcaaQ7.html
http:/vww.epa.gov/reg3esd1/gard en/index, htm
http:/www.epa.gov/greenkit/landscape.htm
Low Emission Gas Can Exchanges
Emissions from portable fuel cans present a
significant source of exposure to gaseous toxics such
as benzene, especially if the can is stored inside a
dwelling or attached garage. Encourage citizens to
exchange their old-style containers for new ones
meeting higher standards.
http://www.arb.ca.gov/msprog/spillcon/gascanfs/
gascanfs.htm
Campaign for a Lead Safe America
Protect community children with an education and
testing program to reduce exposure to lead in homes
and soil.
http://www.hud.gov/Qffices/lead/Qutreach/
communitvoutreach.cfm#leadsafehome
Lead in Drinking Water Campaigns
Approximately 20% of human exposure to lead is
attributable to lead in drinking water. Provide
education about ways to reduce exposure to lead in
drinking water.
http://www.eDa.aov/OGWDW/Pubs/lead1.html
National Asthma Public Education and
Prevention Campaigns
Conduct an education campaign in schools and
homes to reduce asthma and to increase the asthma
awareness and asthma triggers.
http://www.epa.aov/asthma/
Integrated Pest Management Programs
Integrated pest management (IPM) uses habitat
modification, biological controls, and chemical
controls. IPM protects people from noxious pests
and toxic pesticides. Conduct a community
Integrated Pest Management (IPM) Education
Campaign.
http://schoolipm.ifas.ufl.edu/
http://www.epa.gov/pesticides/
Household Hazardous Waste Collections
Exposure to hazardous household materials can be
significantly reduced by collecting old and unused
products and disposing of them properly. Conduct
a neighborhood drive to collect pesticides, coolants,
lubricants, solvents, and other hazardous products,
some of which are now banned due to their toxicity.
http://www.epa.gov/epaoswer/non hw/muncpl/hhw.htm
Community Air Screenins How-To Manual
.253
-------
Appendix G: Examples of Available Risk Reduction and Pollution
Prevention Programs
PROGRAM TYPE PROGRAM DESCRIPTION WEB SITE OR POINT OF CONTACT
For Community Smoke-Free Homes and Cars Campaigns http://www.epa.gov/smokefree/index.html
Homes Making homes and cars smoke-free are an easy and
(continued) proven ways to protect nonsmokers from secondhand
smoke exposure. Conduct a smoke-free campaign
using existing materials, including television, radio,
and print public service announcements (PSAs),
smoke-free home brochures, and the toll-free pledge
number, and other materials.
254
Community Air Screening How-To Manual
-------
Appendix
Toxicity Values and
Toxicity Sources: Background
for the Collection of Information to
Calculate Screening-Level Concentrations
Examples of toxicity values for calculating
screening-level concentrations
To complete step 2 of Figure 10-2, the technical team
collects information that describes each community
chemical's potential to cause a long-term, adverse health
effect. Depending on what it learns about what kinds of
long-term adverse health effects each community
chemical may cause, the technical team may have to find
one or, for some chemicals, two types of toxicity values.
If a chemical has a potential to cause cancer, the
technical team needs to find a cancer toxicity value for
the chemical. If a chemical has a potential to cause a
non-cancer, long-term health effect, the technical team
needs to find a non-cancer toxicity value for the
chemical. If a chemical has a potential to cause cancer as
well as some other non-cancer, long-term health effect,
the technical team needs to find both types of toxicity
values for the chemical.
Examples of toxicity values for cancer-causing chemicals
include the cancer potency slope factor (CSF or simply
SF) and the cancer unit risk (UR) estimate.
A cancer potency slope factor provides an estimate of
increased cancer risk from a lifetime exposure to a given
chemical. This estimate is usually derived from a study of
oral exposure to the chemical of interest. The unit of
expression for the oral cancer potency slope factor is a
portion of a population affected per milligram (one-
thousandth of a gram) of chemical per kilogram of body
weight per day.
A cancer unit risk estimate also provides an estimate of
increased cancer risk from a lifetime exposure to a given
chemical. This estimate is usually derived from an
inhalation exposure study. The unit of expression for the
cancer unit risk estimate for inhalation exposure is a
portion of a population affected per microgram (one
millionth of a gram) of chemical per unit (cubic meter)
of air breathed. It describes an increased cancer risk that
may result from continuous inhalation exposure to a
chemical at this air exposure concentration.
The cancer unit risk estimate is the preferred cancer
toxicity value for use in the cancer screening-level
concentration equation in step 3 of Figure 10-2.
Examples of toxicity values for non-cancer-causing
chemicals include the inhalation reference dose, the
reference concentration, the minimal risk level, and the
reference exposure level.
A reference concentration (RfC) is an estimate (with
uncertainty spanning perhaps an order of magnitude) of
continuous level of inhalation exposure of the human
population (including sensitive subgroups) that is likely
to be without an appreciable risk of adverse effects
daring a lifetime. EPA generally applies uncertainty and
modifying factors to NOAELs, LOAELs, or benchmark
concentrations to set RfCs. EPA uses these factors to
account for specified limitations of the available
chemical toxicity information. The inhalation reference
concentration is the preferred non-cancer toxicity value
for use in the non-cancer screening-level concentration
equation in step 3 of Figure 10-2. The unit of expression
for the RfC is milligrams of chemical per cubic meter of
air breathed. The unit of expression for the RfC can be
converted to micrograms of chemical per cubic meter of
air breathed by multiplying the former by 1,000
A minimal risk level (MRL) is an estimate of the daily
human exposure level to a hazardous (toxic) substance
that has a low risk of adverse non-cancer health effects
Community Air Screenins How-To Manual
255
-------
Appendix H: Toxicity Values and Toxicity Sources: Background for the
Collection of Information to Calculate Screenins-Level Concentrations
over a specified duration of exposure. The federal
government's Agency for Toxic Substance and Disease
Registry (ATSDR) calculates MRLs using an approach
similar to the one used by EPA to develop its estimates of
reference concentrations and reference doses. The unit of
expression for an oral MRL is milligrams of chemical per
kilogram of body weight per day. The unit of expression
for an inhalation MRL is parts per million (ppm) of a
chemical in air. As noted above, the RfC is the preferred
non-cancer toxicity value for use in the non-cancer SLC
equation in step 3 of Figure 10-2. To translate from ppm
to units of mg/m3 (per RfC convention), the MRL is
multiplied by the chemical's MW (mg/mMole) divided
by 24.45 (mMole per m3 at 25 "C and 1 atmosphere
pressure).
A long-term (chronic) reference exposure level (REL) is
an airborne chemical concentration that would pose no
significant health risk to individuals indefinitely exposed
to that level. The California Environmental Protection
Agency (CAL/EPA) calculates the REL, using an
approach similar to the one used by EPA to develop
estimates of its reference concentrations. The unit of
expression for a REL is micrograms of chemical per
cubic meter of air breathed. As noted above, the RfC is
the preferred non-cancer toxicity value for use in the
non-cancer SLC equation in step 3 of Figure 10-2.
Deriving inhalation values from oral values
When an inhalation toxicity value is not available for a
chemical of interest, but an oral exposure route value is
available, the Technical Team may want to consider
extrapolation from the oral to an inhalation value. The
Agency considers data from other routes potentially
useful to derivation of an inhalation value only when
respiratory tract effects and/or "first-pass" effects (a
pharmacologic phenomenon) can be ruled out. (See
section 4.1.2, USEPA, 1994. Methods for Deriving
Inhalation Reference Concentrations and Application of
Inhalation Dosimetry.) First-pass effects refer to the
metabolism that can take place in the portal-of-entry
tissue (e.g., the respiratory tract), prior to entry into the
systemic circulation. A first-pass effect can alter the
disposition of the parent and metabolite chemicals,
thereby affecting the magnitude of the dose to remote
target tissues in a route-dependent fashion. In the
absence of data to determine dosimetry via inhalation,
when a chemical is thought to be susceptible to first-pass
effects (e.g., metabolized), or where a potential for
portal-of-entry effects is indicated but not well
characterized (e.g., respiratory toxicity after acute
exposures), then route-to-route extrapolation for
derivation of an RfC or inhalation unit risk (IUR) is
not appropriate.
For chemicals for which respiratory toxicity and first-
pass effects can be ruled out, route-to-route becomes a
possibility. Methods for this extrapolation range in
accuracy and therefore, inherent uncertainty, with the
simplest approach using default absorption values for
each exposure route appropriate to the chemical class in
question. The general equations for the simplest
approach are as follows.
Equation 1. Extrapolation from an oral cancer SF to
an inhalation unit risk (IUR) estimate
IUR (m3/[ig) = CSF (kg-day/mg) * 20 m3 /day * 1/70 kg *
lmg/103 ^g
where:
IUR is an inhalation cancer unit risk estimate for the
chemical
CSF is the oral cancer potency slope factor for a chemical
20 m3 is an assumption of the daily inhalation intake
70 kg is an assumption of the body weight
Equation 2. Extrapolation from an oral RfD to an
inhalation noncancer reference value
Inhalation RtV (mg/m3) = RfD (mg/kg-day) * I/day/
20 m3 * 70 kg
where:
Inhalation RtV is an inhalation version of the oral non-
cancer reference dose estimate for the chemical
RfD is the oral reference dose for a chemical
20 m3 is an assumption of the daily inhalation intake
70 kg is an assumption of the body weight
It is noted that the paired values 700kg and 20 mVday
are standard defaults intended to be protective of
humans. The mean daily inhalation intake, presuming a
variety of activity levels (rest to heavy activity) during a
24-hour period, would be less than 20 m3 for all age
groups. Given the size of other sources of uncertainty in
the route-to-route extrapolation, the small difference
(e.g., 15%) that might be obtained through replacement
of this default pair of values in the equations, with age-
specific body weight and inhalation intake values, is
considered insignificant.
256
Community Air Screening How-To Manual
-------
Appendix H: Toxicity Values and Toxicity Sources: Background for the
Collection of Information to Calculate Screening-Level Concentrations
References for the discussion above can be found on the
web site of EPA's National Center for Environmental
Assessment at http://cfpub.epa.gov/ncea/cfm/
nceapubtopics.cfm?ActType=PublicationTopics.
Sources for chemical toxicity information
The following are sources of chemical toxicity
information and chemical toxicity values. The
accompanying text and source comparison Table H-l
describe each of these sources relative to the types and
quality of information provided. Please see the
discussion of the choice of toxicity information sources
in the Overview section of this Manual.
• EPA's Office of Air Quality Planning and Standards
(OAQPS) Air Toxics Dose-Response Database: http:
//w\vw.epa.gov/ttn/atw/toxsource/summary.html
• EPA's Integrated Risk Information System (IRIS):
http://wvw.epa.gov/ngispgm3/iria/subst/index.html
• EPA's Health Effects Assessment Summary Tables
(HEAST) hard copy prepared by EPA's National
Center for Environmental Assessment (NCEA) for
EPA's Office of Solid Waste and Emergency
Response (OSWER) for use at contaminated work
sites.
• Agency for Toxic Substances and Disease Registry's
(ATSDR) Minimal Risk Levels (MRLs):
http://www.atsdr.cdc.gov/mrls.html
• California's Office of Environmental Health Hazard
Assessment (OEHHA) or CAL/EPA Toxicity Criteria
Database: http://www.oehlia.ca.gov/risk/
chemicallDB/index.asp
• EPA's High Production Volume Toxicity Database :
web site available in the future
OAQPS's Air Toxics Dose-Response Database is a
compilation of toxicity values obtained from multiple
sources both within and outside EPA. EPA uses these
toxicity values in the National Air Toxics Assessment
(NATA), which range from national- to local-scale
applications. Toxicity values in OAQPS Air Toxics Dose-
Response Database include those from IRIS and other
EPA toxicity information databases, as well as those from
ATSDR and CAL/EPA. Toxicity values describe toxic
effects for chemicals for inhalation as well as for other
exposure pathways. Toxicity values in the Air Toxics
Dose-response Database include cancer unit risk
estimates, cancer potency slope factors, RfCs, MRLs, and
RELs.
The Air Toxics Dose-Response Database contains toxicity
information on approximately 190 chemicals and
chemical classes. Some chemicals/classes of chemicals in
the Air Toxics Dose-Response Database may have
toxicity information from more than one source. These
toxicity information sources vary in the methodology
used to develop their toxicity values, in their selection of
sources of information used to develop toxicity values, in
their characterizations of uncertainty, and in their levels
of peer review. The Air Toxics Dose-Response Database
provides a default order of preference (a priority or
hierarchy) for different types of toxicity values when
more than one type of information is available. OAQPS
notes that changes to the hierarchy may be appropriate
on a chemical-by-chemical basis.
EPA's Integrated Risk Information System (IRIS) is a
high-quality, peer reviewed, and frequently updated
chemical toxicity information source. Its ease of
accessibility, chemical search capacity, and more than
500 chemicals currently within its database make it a
good source of toxicity information and toxicity values.
IRIS is EPA's official repository of Agency-wide
consensus chronic human health toxicity information
and toxicity values.
IRIS presents each of its chronic human health toxicity
values for the inhalation exposure pathway as reference
concentrations (RfCs) for non-cancer chemicals and
cancer inhalation unit risk (UR) estimates for cancer
chemicals. EPA updates IRIS monthly to provide
consistent, up-to-date chemical toxicity information.
The Partnership can access information through IRIS's
home page. It can access information on IRIS chemicals
by highlighting and selecting each chemical's name or
CAS number.
EPA's Health Effects Assessment Summary Tables
(HEAST) provide preliminary EPA chemical toxicity
information and toxicity values. The database, prepared
by EPA's National Center for Environmental Assessment
(NCEA), consolidates toxicity information for chemicals
of interest to Superfund, the Resource Conservation and
Recovery Act, and EPA in general. The degree of peer
review the toxicity information undergoes prior to its
entry into HEAST is less than that for information in
IRIS. The HEAST database currently contains toxicity
information for over 500 chemicals. Unless otherwise
stated, EPA considers the toxicity values for the
chemicals in HEAST to be provisional. Although the
information in HEAST has concurrence of individual
Community Air Screenins How-To Manual
.257
-------
Appendix H: Toxicity Values and Toxicity Sources: Background for the
Collection of Information to Calculate Screening-Level Concentrations
Table H-1.
A Comparison of Toxicity Information Sources
NUMBER
OF
SOURCE CHEMICALS
EPA IRIS over 500
EPA 483
HEAST RfC
(non-
cancer)
181
(cancer)
CAL/EPA- 388
Toxicity
Criteria
Database
ATSDR 138
OAQPSAir 188
Toxics Dose-
Dose-
Response
Database
TYPES
OF
DATA
RfD
RfC
SF
UR
RfD
mg/m3
SF
UR
SF
UR
REL
RfC
MRL
SF
UR
REL
RfC
UNITS
mgAg/day
mg/m3
mg/kg/day
ng/L (water)
ng/m3 (air)
mg/kg/day
update
(mg/kg/day) -'
M9/L (oral)
MS/m3
(inhalation)
(mg/kg-day)-1
((xg/m3)-1
M-g/m3
H5/m3
mg/m3
(particles)
ppm (gases)
(mg/kg-day)- '
(ng/m3)-1
M9/m3
ng/m3
UPDATE
LEVEL OF
PEER
FREQUENCY REVIEW
Monthly
Last
was
July
1997
Period-
ically
Period-
ically
Period-
ically
Values have
received
Agency-wide
consensus
Have undergone
some level of
EPA review but
have not
received final
EPA approval
RELs undergo
review by the public
and the Scientific
Review Panel (SRP).
Cancer potency
values were select-
ed from a heirarchy
list of sources.
Rigorous review
process
Internal and
external peer
review
Pulled
toxicity
values from
multiple
sources and
ranked
according
to data
heirarchy
COMMENTS
RfD value is for chronic oral exposure only.
RfC value is for chronic inhalation exposure only.
Slope factor is for oral exposure only.
Unit risk is available for drinking water and
inhalation.
Consisting almost entirely of provisional risk HEAST
assessment information.
Subchronic and chronic RfD values are provided.
Subchronic and chronic RfC values are provided.
Oral and inhalation slope factors are provided.
Oral and inhalation unit risk values are provided.
Oral and inhalation slope factors are provided.
Inhalation unit risk is provided.
Reported RELs are for acute and chronic exposure.
RELs can be used as surrigates for RfC values when
RFCs are not available.
RFC values are provided in chemical summaries.
MRLs were not based on cancer effects.
MRLs were derived using no-observed-adverse-
effect-level / uncertainty factor approach
Chronic, acute, and intermediate MRLs are provided.
MRLs can be used as surrogate for RfC when RfC
values are not available.
Updated on a periodic basis every 3-6 months.
Values are presented in accordance with a default
hierarchy of preferred sources, with preference given
to those reflective of current knowledge, sound
scientific basis, and external peer review. OAQPS
notes that deviation from the default hierarchy may
be appropriate on a chemical-specific basis.
As available and consistent with the default tiered
hierarchy, an EPA or CAL/EPA inhalation unit risk
value, a chronic RfC, REL, or inhalation MRL, and
a chronic RfD or oral MRL are provided.
258
Community Air Screening How-To Manual
-------
Appendix H: Toxicity Values and Toxicity Sources: Background for the
Collection of Information to Calculate Screening-Level Concentrations
EPA Program Offices and is supported by Agency
references, there is not sufficient peer review of the
information for it to be recognized as Agency-wide
consensus information. Like IRIS, the HEAST database
provides chronic non-cancer toxicity values as reference
concentrations (RfCs) and reference dose (RfDs). The
HEAST provides cancer toxicity values as potency slope
factors and unit risk estimates for the inhalation
exposure pathway. HEAST information is currently
available in hard-copy format only. The date of the most
current version of HEAST is July 1997.
The Agency for Toxic Substances and Disease Registry
(ATSDR) within the United States Department of Health
and Human Services provides toxicity information and
non-cancer toxicity values (known as minimal risk levels
or MRLs) for selected chemicals. ATSDR provides its
information for chemicals found on the EPAs Superfund
National Priorities List. ATSDR does not currently
provide cancer toxicity values for cancer-causing
chemicals. Currently ATSDR provides non-cancer
toxicity information and toxicity values (MRLs) for
approximately 150 chemicals or chemical groups. The
MRL is an estimate of a daily human exposure to a
chemical that has a low potential to cause adverse, non-
cancer effects over a specified duration of exposure.
ATSDR sets its MRLs below levels that, based on current
information, might cause adverse, non-cancer human
health effects in the most sensitive of exposed groups.
The ATSDR sets its MRLs for various exposure durations
and exposure pathways. The MRL of most interest to the
Partnership's community air screening-level
concentration setting process is the MRL for chronic
(365 day or longer) exposure durations for the
inhalation exposure pathway.
The method ATSDR uses to develop its MRLs is similar
to the one used by EPA to develop its reference dose
(RfD) and reference concentration (RfC) toxicity values.
Proposed MRLs undergo a comprehensive peer review
process. Four separate groups take part in the MRL
review process. These groups include the Health Effects/
MRL Work Group within ATSDR's Division of
Toxicology; an expert panel of external peer reviewers;
an ATSDR-wide MRL Work Group with participation
from other federal agencies including USEPA; and the
public through the toxicological profile public comment
period. ATSDR updates its MRLs periodically.
The CAL/EPA's (California Environmental Protection
Agency's) Office of Environmental Health Hazard
Assessment (OEHHA) maintains a toxicity information
database. The database contains toxicity values on both
cancer-causing and non-cancer-causing chemicals.
Toxicity values include those that describe cancer
potency slope factors, unit risk values, and chronic
inhalation reference exposure levels (RELs). A chronic
REL is an airborne chemical concentration that would
pose no significant non-cancer health risk to individuals
indefinitely exposed to that level. CAL/EPA bases its
RELs solely on human health considerations from the
best available human and animal toxicity information in
the scientific literature. The California Air Pollution
Control Officers' Association with consultation from
CAL/OEHHA also develops chronic RELs, based on
toxicity values previously established in readily available
toxicity information sources. CAL/EPA's RELs and other
toxicity values support decisions made in CAL/EPA's Ail-
Toxics' "Hot Spots" program.
The CAL/EPA database currently contains toxicity
information and toxicity values on approximately 400
chemicals. CAL/EPA updates its database periodically. As
it should do with each of the other toxicity information
sources, the Partnership should note the dates of latest
update that the CAL/EPA database lists for toxicity
values for community chemicals. There may be more
current toxicity information available. The CAL/EPA
web site provides a search engine that allows its users to
search for toxicity information by chemical name. The
web site provides an option for downloading specific
cancer potency support documentation to view tables
containing the entire database of cancer potency slope
factor and cancer unit risk values. The database also
provides an option of downloading related REL
documentation to view the tables containing the entire
database of RELs as well.
Community Air Screenins How-To Manual
.259
-------
260
Community Air Screening How-To Manual
-------
Appendix
Steps for Calculating a
Screening-Level Concentration
What steps can the technical team follow
to calculate a screening-level
concentration (SLC) value?
Figure 10-2 shows a three-step procedure the SLC
Technical Team can use to calculate an air exposure SLC.
The procedure for completing each of these three steps is
described below. Two examples of SLC calculations are
provided: one for a cancer risk-based SLC (for arsenic
compounds), the other for a non-cancer risk-based SLC
(for acrylic acid). Two alternate procedures are described
in which the technical team might be able to derive an
air exposure SLC when a chemical toxicity value is not
available for one or more of its community chemicals.
Step 1: Set Community Risk Screening-Level
Assumption Values
Set a cancer risk screening level and a non-cancer risk
screening level for chemicals as appropriate, given
their potential toxicities.
Example values: Additional lifetime risk of 1E-06 for a
cancer risk screening level; a hazard quotient of 1 for a
non-cancer risk screening level. See discussion
describing the Partnership's choice of risk screening
levels in the Initial Screen chapter of the Overview
section.
Step 2: Collect Toxicity Information/Values
The Partnership should establish a toxicity information
source hierarchy. The information source hierarchy is
important to the consistency and transparency of the
Partnership's toxicity information collection process.
Collect toxicity information.
There are two types of chemical toxicity values of
interest: one for cancer, the other for non-cancer effects.
The SLC Technical Team uses its cancer toxicity values
(cancer potency slope factors/inhalation cancer unit risk
estimates) to calculate air exposure SLCs for cancer-
causing chemicals. The technical team uses its non-
cancer toxicity values to calculate air exposure SLCs for
non-cancer-causing chemicals. Some chemicals found in
the community will require calculations of both cancer
and non-cancer SLCs. For these chemicals the technical
team collects toxicity values for both cancer and non-
cancer effects.
The technical team uses its toxicity information
hierarchy to identify an order and uses toxicity data
sources and values for its SLC calculations. An example
of such an order of preference for non-cancer toxicity
values would be: (l)RfC (an inhalation reference
concentration), (2) REL (an inhalation reference
exposure level), and (3) MRL (minimal risk level).
Whichever values the Partnership chooses to use, it is
important that the values are current.
Step 3: Calculate an Air Exposure Screening-Level
Concentration
Use values for the cancer risk screening-level
assumption and the cancer toxicity value assumption
to calculate a chemical-specific cancer screening-level
concentration.
Not all chemicals cause cancer. For those that may cause
cancer, the SLC Technical Team calculates cancer
screening-level concentrations. It uses the following
equation and assumption values:
SLC (cancer) [ig/m3 = RSL
UR
where:
RSL = cancer risk screening level (e.g., l.OE-06)
UR = chemical-specific inhalation unit risk estimate (per
Community Air Screenins How-To Manual
.261
-------
Appendix I; Steps for Calculating a Screening-Level Concentration
Use values for the non-cancer risk screening-level
assumption and the non-cancer toxicity value
assumption to calculate a chemical-specific non-
cancer screening-level concentration.
Not all chemicals cause non-cancer, long-term health
effects. For those that may cause non-cancer effects, the
technical team calculates non-cancer screening-level
concentrations (it refers to them as its non-cancer SLCs).
It uses the following equations and assumption values:
SLC (non-cancer) ng/m3= SHQ * RfC * 1000 ng/mg
where:
SHQ = screening hazard quotient (e.g., 1.0)
RfC = Chemical-specific inhalation reference
concentration (mg/m3)
Compare a chemical's cancer SLC value to its non-
cancer SLC value and use the most conservative
(lowest) value as the chemical's air exposure
screening-level concentration.
Not all chemicals will have toxicity values for both
cancer and non-cancer effects. For those chemicals that
have both cancer and non-cancer toxicity values, the
technical team calculates cancer and non-cancer SLCs.
The smaller of the two SLCs represents the more
conservative, more protective screening-level
concentration. This is the air exposure SLC that the
technical team will use to compare to its estimates of
ambient air concentrations for community chemicals.
What are some examples of SLC
calculations?
The following two examples show how the technical
team calculates its air exposure SLCs for cancer (the
arsenic compounds example) and non-cancer (the
acrylic acid example) chemicals. Toxicity values were
found in OAQPS's Air Toxics Dose-Response Database
(http://www.epa.gov/ttn/toxsource summaryl20202.html).
EXAMPLE 1: Arsenic Compounds (cancer SLC example)
SLC (cancer) [.ig/m3 l.OE-06 2.3E-04 ng/m3
4.3E-03 per ng/m3( from IRIS)
EXAMPLE 2: Acrylic acid (non-cancer SLC example)
SLC (non-cancer) j^g/m3 = 1 * l.OE-03 mg/m3
(from IRIS) * 1,000 ng/mg
= 1.0 n/m3
How can the SLC Technical Team calculate
an SLC when toxicity information is not
available?
Before considering the use of the following two alternate
methods to derive SLCs, the technical team should
exhaust all of its sources of toxicity information. Existing
toxicity information for a chemical may not be in one
source but may be available in another. However, if the
technical team does not find the necessary toxicity
information for one or more of its chemicals, it can use
toxicity information for a surrogate chemical or a default
chemical to derive the necessary SLCs.
To the extent possible, a chemical used as a surrogate
should have a similar chemical structure and similar
physical and chemical properties as the chemical of
interest. For example, the Virginia Department of
Environmental Quality recommends pyrene as a
surrogate chemical for phenanthrene and
benzo(g,h,i)pyrene. If either of these latter two chemicals
were a community chemical for which the Partnership
could find no toxicity information, it could use toxicity
values for pyrene to calculate an air exposure SLC for
either chemical. The technical team should make case-
by-case determinations and get Partnership approval for
chemicals to be used as surrogates for toxicity
information.
If the technical team does not find the necessary toxicity
information for one or more of its chemicals or chooses
not to use information on a surrogate chemical, it can
use toxicity information on a chemical it chooses (and
gets Partnership approval) to be its default chemical. The
technical team (Partnership) has at least four options to
make its choice: (1) It can select its default chemical
from among the most toxic of its community chemicals.
(2) It can select its default chemical from among the least
toxic of its community chemicals. (3) It can select its
default chemical from among the moderately toxic of its
community chemicals. Or (4) it can select as its default
chemical a chemical that may not even be among those
identified as community chemicals. The Partnership,
with the advice of its SLC Technical Team, will make the
final choice. The Partnership's choice will be based on
how conservative it wants its air exposure screening-level
concentrations for those community chemicals with
little or no toxicity information.
262.
Community Air Screening How-To Manual
-------
Appendix
Methods for Apportioning County Data
Methods for Apportioning County Data
Land use/land cover (LULC)—determine area of
different land use categories in census tract and study
area. Develop ratio of area of land use category in census
tract to area of land use category in study area. Different
LULC ratios can be used with different sources (e.g.,
using commercial LULC ratio with autobody
refinishing). LULC data for standard 1:250,000 scale
topographic maps can be obtained on the Internet at
http://edc.usgs.gov/geodata under the LULC tab. Users
should consult the online user's guide and the "read me "
file for more information on these files. A user's guide
that explains the structure of the LULC data files can be
obtained at ftp://map.usgs.gov/pub/ti/LULC/lulcguide.
Users with access to GIS software should download files
under the "land_use" heading. These files are in the
geographic information retrieval and analysis system
(GIRAS) format. This format uses arcs and polygons to
define regions on the map.
Otherwise, users should download files in the composite
theme grid (CTG) format under the "grid_cell" heading.
The CTG format uses grid cells to define locations on a
map. The grid cells are actually a regular point sample of
the quad where the center point of each cell is 200
meters from other center points in adjacent cells. The
cells are mapped to the Universal Transverse Mercator
(UTM) projection, oriented in north-south, east-west
directions, and sequenced by row from north to south,
within each row, by column east to west. More
information on these files can be found at the end of this
write-up.
CTG files can be opened in any word-processing
software. The best view seems to occur when the font has
been changed to Courier 10 point, with left and right
margins set to 0.9 inches. These files can be very large
(thousands of pages) and can be complicated to analyze
and manipulate.
Area—ratio of surface area of census tract to surface area
of study area. Area data can be obtained using GIS or
topographic maps.
Population—ratio of population of census tract to
population of study area. Population data can be
obtained from the U.S. Census Bureau.
Population density—ratio of population to area for
census tracts. Sum population densities for entire study
area. Determine ratio of population density for census
tract to population density for study area. Population
density data can be obtained from GIS, topographic
maps, and the U.S. Census Bureau.
Roadway miles—ratio of total roadway miles in census
tract to total roadway miles in study area. For use with
mobile sources. Roadway mileage data can be obtained
from the Department of Transportation, GIS, or
topographic maps.
Composite Theme Grid (CTG) Data File
Format
Digital data from all the overlays of a given quadrangle
also are combined in a raster or grid cell format as a
Composite Theme Grid (CTG) file.
CTG files are sequential and consist of fixed-length
logical records, and with the exception of header records,
all records are of identical internal format, one grid cell
per logical record. The grid cells are actually a regular
point sample. The attribute codes at the center point of
each cell are recorded from each overlay. The points are
oriented to the UTM projection and are usually spaced
200 m apart in both east-west and north-south
directions. The cell records are first ordered in the file by
row from north to south, then within each row, by
column west to east.
Character Composite Theme Grid (CTG)
File Format
A character-formatted (usually ASCII) CTG file consists
of fixed-length 80-character (card image) logical records.
There are two parts to the CTG file, first a header then
cell records. All records, except the last header record
with one text field, consist of fixed-length integer fields;
each integer is coded as digits with leading blanks (i.e.,
Community Air Screenins How-To Manual
.263
-------
Appendix J: Methods for Apportioning County Data
right justified). The first five logical records of the file
comprise the CTG map header. The header is followed
by cell records, one grid cell per 80-character logical
record.
In some cases a CTG file may be released without the
map header contained in the file. In this case all records
in the file are individual grid cell records, and the header
information is supplied as a printed listing.
Character CTG Map Header
Record 1:
Bytes 1-10 = Number of rows;
11-20 = Total number of cells x 2;
21-30 = Number of columns;
31-35 = Meaningless field;
36-40 = Cell size (width and length) in meters;
41-45 = Number of overlays merged;
46-50 = Map type code (see below);
51-55 = Projection zone number;
56-60 = Map projection code (should be "1" for
UTM);
61-70 = Scale of a plot at one mil per cell width;
and
71-80 = Source date of the land use overlay.
Record 2:
Bytes 1-5 =
6-10 =
11-15 =
16-20 =
21-25 =
26-30 =
31-35 =
36-40 =
41-45 =
46-50 =
51-55 =
264.
= Minimum column index;
- Minimum row index;
- Maximum column index;
- Maximum row index;
- Column index for SW control point;
: Row index for SW control point;
- Column index for NW control point;
: Row index for NW control point;
: Column index for NC control point;
: Row index for NC control point;
: Column index for NE control point;
Community Air Screening How-To Manual
56-60 = Row index for NE control point;
61-65 = Column index for SE control point;
66-70 = Row index for SE control point;
71-75 = Column index for SC control point; and
76-80 = Row index for SC control point.
Record 3:
Bytes 1-10 = Latitude of SW control point;
11-20 = Longitude of SW control point;
21-30 = Latitude of NW control point;
31-40 = Longitude of NW control point;
41-50 = Latitude of NC control point;
51-60 = Longitude of NC control point;
61-70 = Latitude of NE control point; and
71-80 = Longitude of NE control point.
Record 4:
Bytes 1-10 = Latitude of SE control point;
11-20 = Longitude of SE control point;
21-30 = Latitude of SC control point;
31-40 = Longitude of SC control point;
41-50 = UTM Easting value of west edge of cells;
51-60 = UTM Northing value of north edge of
cells;
61-70 = File creation date (a Julian date); and
71-80 = Meaningless field.
Record 5:
Bytes 1-64 = Title (text characters); and
65-80 = Blank.
Some further explanation is needed for some of the
elements in the CTG map header:
1. The map type code (in bytes 46-50 of the first
record) indicates which overlays have been included
in the CTG data file. The code is formed by the
addition (in base 10) of the separate GIRAS map type
codes for each of the overlays:
10 = Land Use and Land Cover;
02 = Political units;
-------
Appendix J: Methods for Apportioning County Data
04 = Census county subdivisions and SMSA
tracts;
10 = Hydrologic units;
20 = Federal land ownership; and
40 = State land ownership.
For example, the map type code for a combination of the
first four overlays above would be 17; all six overlays
combined have a map type code of 77.
2. The UTM Easting and Northing values given in
the fourth record (bytes 41-60) are in whole meters
and are values for the west and north edges of the
cells, rather than the center point of the first
(northwest corner) cell. The Easting and Northing
values for a given cell may be calculated thus:
Easting = (XORG CW/2) + (column index)*CW
Northing = (YORG+CW/2) (row index)*CW
where XORG and YORG are the Easting and Northing
values in bytes 41-60 of the fourth header record, and
CW is the cell width in bytes 36-40 of the first header
record.
3. The control points usually define the 1_ x 2_ (for
l:250,000-scale base maps) or 30' x 1_ (for 1:100,000
scale base maps) quadrangle on which the overlay
data are based. The latitude and longitude values are
given as positive integers of the form DDDMMSS,
where DDD is degrees, MM is minutes, and SS is
seconds. West longitude values are given as positive
numbers, increasing in value from east to west. The
row and column values given for the control points
are the indices for the cell whose center point is
closest to the true position of the control point.
CTG Grid Cell Records
Each grid cell logical record of a standard character-
formatted CTG data file is 80 characters in length and
consists of nine decimal integers, right justified (with
leading blanks) within fixed-length fields:
Bytes 1-3 = UTM zone number (this value should be
the same in every record of a given CTG
file); the first byte will always be a blank
for zones in the northern hemisphere;
4-11 = UTM Easting value, in whole meters, for
the sample point of the cell;
12-19 = UTM Northing value, in whole meters,for
the sample point of the cell;
20 = Blank;
21-30 = Land Use and Land Cover attribute code;
31-40 = Political unit (FIPS State/county) code;
41-50 = USGS hydrologic unit code;
51-60 = Census county subdivision or SMSA tract
code;
61-70 = Federal land ownership agency code; and
71-80 = State land ownership code.
If a given overlay category has not been included within
the file, the codes for that category will be zero (0). Since
some misregistration of map overlays occurs, some of
the cells along the edges of the 1:250,000- or 1:100,000
scale quadrangle may have codes for some overlays, but
not others (the "other" codes will be zero). The standard
character CTG data file will have only those cell records
for which at least one of the categories is coded. This
means that, since the 1:250,000 and 1:100,000 scale
quadrangles do not form perfect rectangles in the UTM
projection (lines of latitude curve and lines of longitude
converge), a variable number of cell records will exist for
any given row or column.
Binary CTG Data File Format
Each logical record of a binary CTG file is either 32 or 52
bytes in length. A record consists of eight 32-bit (4 byte)
binary integers in the following order:
Bytes 1-4 = Row index, where 1 is the index of the
northernmost row and index numbers
increase by one for each row moving
south (NOTE, due to a processing error,
CTG files in which the State ownership is
not coded will have all zero row index
numbers; the row index is then a function
of the sequential position of the record
within the file);
5-8 = Column index, where 1 is the index of the
westernmost column and index numbers
increase by one for each column moving
east;
9-12 = Land Use and Land Cover code;
13-16 = Political unit code;
17-20 = Hydrologic unit code;
21-24 = Census county subdivision or SMSA tract
code;
Community Air Screenins How-To Manual
265
-------
Appendix J: Methods for Apportioning County Data
25-28 = Federal land ownership code; Binary CTG Map Header
29-32 = State land ownership code; and The CTG map header associated with a binary CTG data
^o ,-„ XT 11 /i • x ,- i 1 -,- file is stored in a physically separate sequential file. The
33-52 = Null (binary zeros) field, it present. . * ;' ; , . ^ ,
header consists ot six 32-byte logical records. For the
If a given overlay has not been digitized, the codes for first four records, each 32-byte binary record is
that overlay will all be zero. To be sure that a regular grid equivalent to an 80-character CTG map header card
of cells (forming a UTM rectangle) covers the entire base image; each integer in a 5-digit character field is stored in
map quadrangle, a "buffer zone" of cells with all zero a 2-byte binary integer field, and each integer in a 10-
attributes has been included in the binary CTG data file. digit character field is stored in a 4-byte binary integer
field. The fifth card image header record (with text data)
is represented as the fifth and sixth 32-byte binary
records with EBCDIC coded characters (the last 16
characters of the card image record are always blank).
266.
Community Air Screening How-To Manual
-------
Appendix J: Methods for Apportioning County Data
Listing of CTG Map Header Data
COMPOSITE THEME GRID CHARACTER DATA OUTPUT:
C T G B T A RUN: JUNE 3, 1982 TIME 19:23:06
GRID CELL MAP HEADER INFORMATION:
TITLE: LAWRENCE, MO KS 1:250,000 QUAD LU PB CN HU FO SO
FILE CREATION DATE: 81084 TIME 0: 0
MAP TYPE: 77 PROJECTION:! SCALE 1: 7874016 MAP DATE: 1973
NUMBERS OF FILE ELEMENTS:
CATEGORIES CELLS ROWS COLUMNS ZONE WEST & NORTH EDGES:
NUMBER EASTING NORTHING
6 485368 575 884 15 236900 4321100
DUPLICATE POINT TOLERANCE = 0 CELL SIZE IN METERS = 200
MINCOL= 1 MINROW= 1 MAX COL = 884 MAX ROW = 575
CONTROL POINT INFORMATION:
LONGITUDE LATITUDE COL ROW
SOUTHWEST 960000 380000 -1 557
NORTHWEST 960000 390000 17 2
NORTHEAST 940000 390000 883 21
SOUTHEAST 940000 380000 877 576
CHARACTERISTICS OF THE CHARACTER CTG FILE:
THE FILE CONTAINS ONLY GRID CELL (AND NO HEADER) RECORDS.
THE FILE CONSISTS OF 80 CHARACTER RECORDS, ONE GRID CELL PER RECORD.
UTM ZONE, EASTING, AND NORTHING VALUES ARE PART OF EACH CTG DATA RECORD AS THE FIRST
THREE INTEGERS, RIGHT JUSTIFIED IN BYTES 1-3,4-11, AND 12-19.
BYTES 21 80 OF EACH RECORD CONTAIN THE USGS 10 DIGIT INTEGER CODES, RIGHT JUSTIFIED
WITHIN 10 BYTE FIELDS, FROM THE FOLLOWING OVERLAYS, IN ORDER:
LAND USE/LAND COVER, POLITICAL UNIT, HYDROLOGIC UNIT, CENSUS SUBDIVISION/TRACT, FEDERAL
LAND OWNERSHIP, AND STATE LAND OWNERSHIP.
ONLY RECORDS WITH AT LEAST ONE NON ZERO ATTRIBUTE ARE PART OF THE FILE.
(A VARIABLE NUMBER OF RECORDS EXIST FOR A GIVEN ROW OR COLUMN.)
Community Air Screenins How-To Manual
.267
-------
Appendix J: Methods for Apportioning County Data
Sample
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
"Standard" Character-Formatted CTG Data file (without header)
240200
240400
240600
240800
241000
241200
240200
240400
240600
240800
241000
241200
241400
241600
241800
242000
242200
242400
242600
242800
243000
243200
1243400
243600
243800
244000
4321000
4321000
4321000
4321000
4321000
4321000
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
21
21
21
21
21
21
21
21
21
21
21
21
21
21
21
21
21
31
31
31
31
31
31
31
31
31
0
0
0
0
0
0
201971
20197
20197
20197
20197
20197
20197
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0270102
10270102
10270102
10270102
10270102
10270102
10270102
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2099
2099
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2099
2099
2099
2099
2099
2099
2099
2099
2099
2099
0
0
0
0
0
0
0
0
0
0
268.
Community Air Screening How-To Manual
-------
Appendix J: Methods for Apportioning County Data
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
[etc]
244200
244400
244600
244800
245000
245200
245400
245600
245800
246000
246200
246400
246600
246800
247000
247200
247400
247600
247800
248000
248200
240200
240400
240600
240800
241000
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320800
4320600
4320600
4320600
4320600
4320600
31
31
31
31
31
31
31
31
31
31
31
31
21
21
21
21
21
21
21
21
21
21
21
21
21
21
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
20197
20197
20197
20197
20197
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
10270102
10270102
10270102
10270102
10270102
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
20197025
20197025
20197025
20197025
20197025
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2099
2099
2099
2099
2099
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2099
2099
2099
2099
2099
Community Air Screenins How-To Manual
.269
-------
-------
-------
United States Environmental Protection Asency
Washinston, DC 20460
EPA 744-B-04-001
October 2004
------- |