DRAFT
National Ambient Air Monitoring Strategy
Office of Air Quality Planning and Standards
Research Triangle Park, NC
December 2005
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DISCLAIMER
This document is a work prepared for the United States Government. In no
event shall either the United States Government or Contractor have any
responsibility or liability for any consequences of any use, misuse, inability to
use, or reliance upon the information contained herein, nor does either warrant or
otherwise represent in any way the accuracy, adequacy, efficacy, or applicability
of the contents hereof
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DRAFT
National Ambient Air Monitoring Strategy
Table of Contents
Page
Preface 1
Executive Summary 2
1. Need for a National Ambient Air Monitoring Strategy (NAAMS) 6
1.1 Importance of Ambient Monitoring and Primary Goals 6
1.2 Brief History and Overview of Ambient Air Monitoring in U.S 7
1.2.1 Monitoring Designed to Implement the NAAQS 7
1.2.2 Acid Rain/Deposition Monitoring in Rural Areas 9
1.2.3 Visibility Monitoring 9
1.2.4 Air Toxics Monitoring 10
1.2.5 Trib al Monitoring 11
1.2.6 Research-level and Other Monitoring 11
1.3 Current Air Quality Management Challenges and Opportunities 14
1.4 Identifying the Need for a National Strategy 15
1.5 Strategy Development Steps to Date 16
1.6 Process and Timeline for Continued Development and Implementation of the Strategy.. 18
2. Overview of Strategy 20
2.1 Principles for Design and Management of Ambient Air Monitoring into the Future 21
2.2 Strategy for Urban Areas 23
2.2.1 NCore Multipollutant Sites 23
2.2.2 Rationalization of NAAQS Pollutants Networks 24
2.2.3 Coarse PM 24
2.2.4 PAMS 24
2.2.5 PM Speciation 25
2.2.6 Air Toxics 27
2.2.7 Near Roadway Exposure 28
2.2.8 Homeland Security 28
2.3 Strategy for Rural Areas 28
2.4 Tribal Monitoring 29
2.5 Common Elements Applicable to All Monitoring 30
2.5.1 Quality System 30
2.5.2 Monitoring Technology Development and Transfer 31
2.5.3 Planning and Assessment Processes 32
in
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Table of Contents (cont.)
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2.5.4 Data Access 33
2.5.5 Data Analysis 34
2.5.6 Funding 35
3. Multipollutant Sites in Urban Areas 37
3.1 Introduction and Obj ectives 37
3.2 System Design Attributes 39
3.3 NCore Multipollutant Measurements 41
3.3.1 General Measurement Considerations 41
3.3.2 Measurement Issues 42
3.3.3 Future Multipollutant Measurements 43
3.4 Siting Considerations 43
3.4.1 Guidance for Site Selection and Site Allocation Proposal 44
3.5 Measurement Technology Strategy 47
3.6 Using the NCore Multipollutant Site Approach to Enhance Network Integration 48
4. Other Monitoring in Urban Areas 49
4.1 Streamlined SLT NAAQS Monitoring 49
4.2 Local, Flexible Monitoring Component 50
4.3 Near Roadway Monitoring 50
4.4 RadNet and Homeland Security 51
5. Rural Monitoring 57
5.1 Importance of Maintaining and Enhancing Existing Rural Monitoring Networks 57
5.1.1 NADP 57
5.1.2 CASTNET 59
5.1.3 IMPROVE 60
5.1.4 Additional Rural Monitoring 62
5.1.5 Conclusion on Existing Rural Monitoring 62
5.2 NCore Monitoring: Urban/Rural Connection 62
6. Tribal Monitoring 65
7. Quality System 67
7.1 The Quality System 68
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Table of Contents (cont.)
Page
7.2 Planning Activities 68
7.2.1 Development of Data Quality Objectives (DQO) 68
7.2.2 Move Towards a Performance-Based Measurement Process 69
7.2.3 Regulation Development 69
7.2.4 Using a Graded Approach to QA 71
7.2.5 Guidance Documents 71
7.3 Implementation Activities 71
7.3.1 Training 72
7.3.2 Internal Quality Control Activities 72
7.3.3 Data Validation/Verification 73
7.3.4 Data Certification and Quicker Data Access on AQS 74
7.4 Assessment and Reporting 74
7.4.1 Site Characterizations 74
7.4.2 Performance Evaluations 75
7.4.3 Assessments of Quality Systems and Technical Systems Audits 76
7.4.4 Data Quality Assessments 77
7.4.5 QA Reports 77
7.5 Funding and Resource Issues 77
7.6 Network Assessments 78
8. Monitoring Technology Development and Transfer 81
8.1 Monitoring Technology 83
8.1.1 Measurement Methods for Use at NCore Multipollutant Sites 84
8.1.2 Organic Aerosol Speciation (Not Required) 92
8.1.3 Implementation Products and Deliverables 92
8.1.4 PM Continuous Monitoring Implementation Plan Summary 92
8.2 Data Management Technology 93
9. Implementation Plan 94
9.1 Continued Strategy Development 94
9.2 Rule Changes 97
9.2.1 Network Design and Criteria 98
9.2.2 Changes to the PAMS Network 99
9.2.3 Network Assessments 99
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Table of Contents (cont.)
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9.2.4 Performance-Based Measurement Systems (PBMS) 99
9.2.5 QA Related Changes to 40 CFR Part 58 Appendix A 99
9.3 Funding 100
9.3.1 General Funding Issues 100
9.3.2 Specific Funding Issues 101
9.4 Guidance, Training, and Pilot Efforts 103
9.4.1 New Measurement, QA, and Data Analysis Technologies 104
9.4.2 Network Deployment 106
9.5 Integration of Research Programs into this Strategy 106
9.6 Ongoing Implementation of Major Federal Networks 108
9.6.1 General Implementation Plan for CASTNET Improvements and Opportunities 108
9.6.2 RadNet Implementation Status and Plan 109
9.7 Information Technology Implementation Plans Ill
Appendix A: Acronyms and Terms A-l
Appendix B: 2000 and 2003 Network Assessments B-l
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December 2005
DRAFT
National Ambient Air Monitoring Strategy
Preface
This document presents a National Ambient Air Monitoring Strategy (Strategy). This
version updates a draft version, dated April 2004. This version differs from that earlier draft in a
few substantive ways:
(1) This version does not discuss in as much detail the history and rationale for various
strategic decisions as the April 2004 draft, but those rationales for the most part remain
valid.
(2) This version is broader in scope and includes several areas of ambient monitoring that,
even where mentioned in the April 2004 draft, were not incorporated as primary
elements of the overall national Strategy.
(3) The April 2004 draft categorized monitoring stations in three levels. The three levels
combined were referred to as the National Core Monitoring Network (NCore). This
version of the Strategy dispenses with the three-level concept because it did not
encompass all relevant monitoring efforts. This Strategy refers to the collection of all
ambient air monitoring including research sites, all types of monitoring by states and
Tribes, and all types of ambient monitoring by Federal agencies as the National
Ambient Air Monitoring System (NAAMS).
(4) U.S. Environmental Protection Agency's (EPA) specific strategy with regards to some
topics remains in a formative stage. Thus, in several instances, this version of the
Strategy focuses more on goals than specific strategic plans. EPA anticipates that
further consideration of those topics will occur over the coming year, with a final
version of this Strategy released in early 2007. That final version would include
additional details on the strategies and implementation plans EPA intends to pursue in
those areas.
The documents associated with this Strategy are available at
http://www.epa.gov/ttn/amtic. That website includes earlier drafts of this Strategy as well as this
current December 2005 draft. Note that even after finalizing this Strategy in early 2007, EPA
envisions that it will produce supplements and revisions to this document as conditions evolve,
and EPA adjusts its strategy and implementation plans to address emerging air quality
developments, technology advances, and other implementation issues.
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Executive Summary
Federal agencies, state and local air agencies, and Tribes operate and maintain a wide
variety of ambient monitoring systems across the U.S. Many of these systems now serve
multiple environmental objectives, even though they may have been sited originally for a more
limited purpose. Over time, regardless of whether the original objective remains or diminishes in
importance, air quality management developments may warrant rethinking how best to use the
monitoring system for other environmental and air program objectives. One important element
of this Strategy is to recognize all of the different types of monitoring and all of the various
environmental and other program purposes they serve, and then identify ways in which
integration of these monitoring systems may aid in fulfilling those objectives, perhaps with
increased efficiency. Collectively, EPA refers to all of these various monitoring efforts as the
National Ambient Air Monitoring System (NAAMS). This Strategy is designed to outline EPA's
current efforts and future plans to maintain and enhance the NAAMS to meet the nation's air
quality goals and challenges.
In addition, technology advances over time. This includes both the capabilities of the
monitoring hardware and the ability to record, store, disseminate, and analyze the monitoring
data. A second key element of this Strategy is to ensure that our monitoring strategy is flexible
enough to provide incentives for improved monitoring and improved use of the monitoring data.
Finally, EPA has developed a systematic data quality approach over the past several
years. The quality system requirements for most ambient monitoring predates that development.
As such, there is a strong need to reevaluate how agencies should conduct quality assurance and
what minimum requirements are appropriate for regulatory provisions.
This Strategy looks at each of these areas and provides EPA's overall approach for
achieving these objectives through an integrated NAAMS. As shown in Table ES-1, there are a
number of different monitoring programs covered in this Strategy, with various objectives. That
table also indicates the key elements of EPA's current strategy and any specific implementation
plans that EPA has developed. As the information makes clear, there are a number of situations
for which EPA's strategy remains at a formative stage. In those situations, this document
presents the overall objectives and goals and indicates EPA's commitment to continue to pursue
more specific strategies.
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Table ES-1
Overview of December 2005 Draft Monitoring Strategy
Monitoring
Network/Type
Environmental/Program
Objectives
Strategy Components
Implementation
Tasks/Elements
Urban Monitoring for
NAAQS
Use for Attainment/Nonattainment
determinations, designations,
redesignations, classifications, and
maintenance plans
Assess long-term trends
Control strategy development and
model validation
Conduct high-grade research and
methods development at select sites
Support enviromnental justice
analysis, health effects research, and
other special studies
Aid in determining source-receptor
relationships
Public air quality reporting and
forecasting (Air Quality Index)
Reconfigure existing
SLAMS/NAMS, PAMS, and
Speciation (STN) into NCore
multipollutant sites and additional
local scale monitoring sites, with
overall reduction in number of sites
Streamline PAMS
Move to continuous PM monitoring
Enhance QA
Investigate ways to integrate with
CASTNET, National Air Toxics
Trends Stations (NATTS), and other
monitoring networks
Acknowledge data management
systems as inherent part of
monitoring program
Regulatory revisions (proposal
December 2005)
Annual National Program and
Grant Guidance documents
Technical guidance documents
(pending regulatory finalization)
Continue integration discussion
Urban Monitoring for Air
Toxics
Assess potential toxic hot spots to
protect human health
Assess effectiveness of air toxic
control programs
Long-term trends analysis
Support health effects research
Aid in determining source-receptor
relationships
Maintain NATTS
Support existing state and local
program monitoring by continuing to
fund local-scale projects to assess
conditions at local level
Utilize PAMS, IMPROVE, and
CASTNET where possible
Use monitoring data to refine air
quality model-based assessment tools
(e.g.. National Air Toxics
Assessment)
Ongoing development of
ambient monitoring component
of air toxics strategy
(cont.)
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Table ES-1
Overview of December 2005 Draft Monitoring Strategy (cont.)
Monitoring
Network/Type
Environmental/Program
Objectives
Strategy Components
Implementation
Tasks/Elements
Rural Monitoring
Assess atmospheric deposition trends
Assess mercury and other persistent
bioaccumulative toxics (PBT)
deposition
Assess visibility
Ensure protection of PSD increments
Provide information on upwind
ambient conditions vital to NAAQS
strategy development and assessment
Long-term trends analysis
Aid in determining source-receptor
relationships
Aid efforts for regional air quality
model data input and evaluations
Maintain and upgrade CASTNET,
NADP, and IMPROVE as core
elements in national monitoring
framework for acid deposition,
mercury, and visibility
Retain other rural monitoring
generally "as is" (for example, PSD
monitoring) for applicable NAAQS
Use rural monitoring networks to
track rural background ambient
conditions
Seek ways to formally integrate
CASTNET, and maybe other rural
networks, with urban monitoring
networks to enhance ability to
manage current and future air quality
management challenges
Support PBT monitoring
Continue integration
discussions, and issue more
detailed elements of this
component in January 2007
strategy document
Take action on pursuing semi-
continuous monitoring
technology for certain
CASTNET sites
Continue to enhance public
access to CASTNET data
through Data and Maps website
portal
Make regulatory requirements
for PSD monitoring QA
consistent with those for
state/local monitoring
Tribal Monitoring
Assess air quality in Indian country
Contribute to long-term trends
analysis
Respect Tribal autonomy
No requirements to be imposed on
Tribal monitoring; no mandates
linking Tribal air monitoring with
national networks
Continue discussions with
Tribes on mutually beneficial
efforts and encourage
collaboration between Tribal,
Federal, state, and local entities
Update Strategy to reflect
outcome of those discussions
(cont.)
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Table ES-1
Overview of December 2005 Draft Monitoring Strategy (cont.)
Monitoring
Network/Type
Environmental/Program
Objectives
Strategy Components
Implementation
Tasks/Elements
Tribal Monitoring
(cont.)
Continue to rely on EPA Regional
Offices to allocate available Tribal
grant funds
Leverage opportunities that
simultaneously benefit Tribes and the
national network through support for
Tribal monitoring efforts and sharing
of Tribal monitoring data
Explore opportunity for Tribes to
operate rural sites of
national/regional interest
Near Roadway Monitoring
Assess exposure impacts in near
roadway enviromnents
Determine long-term trends
(potentially NAAQS compliance)
Stress importance of near roadway
exposures and further explore what
these exposures mean in terms of
urban NAAQS and toxic air
monitoring networks
Develop and incorporate into
national network as appropriate
Consult with SLTs and other
stakeholders
Issue more detailed elements of
this component in January 2007
strategy document
Homeland Security
Surveillance of terrorist threats from
intentional releases of radiation or
biological agents
Enhance RadNet as vital element of
air program
Support BioWatch
RadNet approach under review
by EPA's Science Advisory
Board; to be incorporated in
overall strategy once approach
and implementation plan
finalized
BioWatch strategy undisclosed
for national security reasons
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1. Need for a National Ambient Air Monitoring Strategy (NAAMS)
1.1 Importance of Ambient Monitoring and Primary Goals
Ambient air monitoring systems are a critical part of the nation's air quality management
program infrastructure. Environmental management officials and other environmental
professionals use the ambient air monitoring data for a wide variety of purposes in managing air
quality. Air quality management involves a cycle of setting standards and objectives, designing
and implementing control strategies, assessing the results of those control strategies, and
measuring progress. Ambient monitoring data have many uses throughout this process, such as
determining compliance with the National Ambient Air Quality Standards (NAAQS);
characterizing air quality and trends; estimating health risks and ecosystem impacts; developing
and evaluating emission control strategies; evaluating source-receptor relationships; providing
data for input to run and evaluate models; and measuring overall progress of air pollution control
programs. Ambient air monitoring data provide accountability for emission strategy progress
through tracking long-term trends of criteria and noncriteria pollutants and their precursors. The
data also form the basis for air quality forecasting and other public air quality reports. They also
can provide valuable information for broader ecosystem impacts.
Federal agencies, state and local agencies, and Tribes have a long history of providing
high quality, credible environmental data. State and local agencies and Tribes (SLTs) have
primary responsibility for urban air monitoring in order to demonstrate that areas attain national
ambient air quality standards (NAAQS). Many SLTs maintain additional monitoring to assess
local air issues and air toxics. In addition, the federal government operates or supports several
networks, such as atmospheric deposition and visibility monitoring networks, that provide data
on specific issues, particularly focused on rural ambient conditions.
The challenge for SLTs and federal agencies is to maintain and improve upon these
valued products despite flat or possibly declining funding. Monitoring programs are subject to
continual changes in SLT, federal, and research priorities. New and revised NAAQS, changing
air quality (e.g., significantly reduced concentrations of some criteria pollutants), and an influx
of scientific findings and technological advancements challenge the response capability of the
nation's networks.
One of the findings that continues to present challenges in air quality management is the
complex nature of air pollution formation and control. To respond to these challenges, EPA and
its partners often need integrated measurements and strategies. The single-pollutant
measurement approach, commonly administered in SLT networks, is not an optimal design for
integrated air quality management approaches. In addition, as many air quality control solutions
move toward large-scale regional, multipollutant control strategies, there is an increasing need
for coordinating urban and rural ambient monitoring networks, given that the changes in regional
background atmospheric conditions that are critical to reducing urban air pollution generally are
observed at the rural monitoring stations. At the same time, ambient air networks need a certain
degree of stability so that EPA and others have consistent, long-term data to detect long-term air
pollution trends.
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Thus, a coordinated national strategy needs to update SLT networks (which largely grew
out of efforts dating back to the 1970s), recognize the importance of other monitoring, such as
atmospheric deposition monitoring, integrate that other monitoring with the SLT networks where
appropriate, and maintain continuity so that an appropriate set of monitors continue to provide
valid comparisons of long-term trends.
Given this backdrop, the overarching goals of this air monitoring strategy are:
(1) To ensure that the existing SLT monitoring networks are reconfigured to be consistent
with the basic environmental and programmatic needs for current environmental
management;
(2) To seek ways to integrate various monitoring networks where opportunities for
integration exist;
(3) To improve the scientific and technical competency of the nation's air monitoring
networks to ensure high quality data; and
(4) To enhance data storage, dissemination, and analyses so that government agencies,
researchers, and the general public have improved access to ambient monitoring data,
both in terms of completeness and timeliness.
In developing a strategy that can meet these objectives, EPA and its partners must
consider resource constraints and look for opportunities to streamline and integrate existing
monitoring resources in a way that maximizes the benefit of the monitoring data collected.
1.2 Brief History and Overview of Ambient Air Monitoring in U.S.
1.2.1 Monitoring Designed to Implement the NAAQS
State and local ambient monitoring stations (SLAMS) and national ambient monitoring
stations (NAMS) represent the majority of all criteria pollutant (SO2, NO2, CO, O3, Pb, PM2.5,
PM10) monitoring across the nation, with over 5,000 monitors at approximately 3,000 sites.
These stations use federal reference or equivalent methods (FRM/FEM) for direct comparison to
the NAAQS, that lead to determining whether areas are listed as in attainment or nonattainment.
NAMS are a subset of SLAMS that are designated as national trends sites and, in some cases,
also serve as the design value sites for an area. The EPA has established a suite of regulations
that specifies the design and measurement requirements for these networks: 40 CFR Part 58
(design and quality assurance); Part 53 (equivalent methods); and Part 50 (reference methods).
The SLAMS and NAMS were developed in the 1970s. In the early 1980s, the networks
began to add PM10 monitors, and then expanded to include PM2.5 monitors, starting in 1999, to
assess attainment with the PM2.5 NAAQS promulgated in 1997. The PM2.5 network consists of
ambient air monitoring sites that make mass or chemical speciation measurements. As of 2005,
there were about 900 FRM/FEM filter-based sites and 540 continuous measurement sites for
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Draft NAAM Strategy
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mass measurements.1 Chemical speciation measurements were made at over 50 trends sites,
about 210 SLT sites were used in support of SLT monitoring objectives (including state
implementation plan (SIP) development), and there were about 110 IMPROVE (Interagency
Monitoring of Protected Visual Environments) sites in Class I visibility protection areas. These
sites collect aerosol samples and analyze the filters for trace elements, major ions, and carbon
fractions. Most of the IMPROVE sites are operated by other federal agencies within the
Department of the Interior (see Section 1.2.3 below). IMPROVE sites support implementation
of the NAAQS by providing data to assess PM2.5 concentrations from rural areas that may impact
urban areas.
The number of monitoring sites for total suspended particulates has declined sharply, as
has the number of sites for other pollutants such as lead, N02, and S02. The number of ozone
and carbon monoxide sites has stayed relatively stable (Figure 1-1). Given the long history of
using these sites, and the changing nature of NAAQS attainment and control strategy issues,
rethinking the design of SLAMS/NAMS is one of the central topics of this Strategy.
In addition to the SLAMS/NAMS networks, the Photochemical Assessment Monitoring
Stations (PAMS) was developed in the 1990s to measure ozone precursors, volatile organic
compounds (VOC), and NOx. The PAMS consists of 75 sites in 25 metropolitan areas that were
classified as serious ozone nonattainment areas. The addition of PAMS in the early- to mid-
1990s was a major addition to the state/local networks, introducing near research grade
measurement technologies to produce continuous data for over 50 VOC compounds during
summer ozone seasons.
Figure 1-1: Growth and decline of criteria pollutant networks.
1 The PM2 5 continuous monitoring network is the only criteria pollutant reported and forecasted nationally on a
year-round basis as part of the Air Quality Index (AQI) ~ see http://airnow.gov.
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1.2.2 Acid Rain/Deposition Monitoring in Rural Areas
The Clean Air Status and Trends Network (CASTNET) originally was designed mostly
to account for progress of strategies targeting major electrical generating utilities throughout the
eastern U.S., which release acid rain precursor emissions, sulfur, and nitrogen oxides. Network
operations are contracted out to private firms funded through Science and Technology (S&T)
funds and managed by EPA's Office of Air and Radiation. CASTNET consists of over 80 sites
located predominantly throughout the East, with greatest site densities in states along the Ohio
River Valley and central Appalachian Mountains (Figure 1-2). Unlike SLAMS/NAMS, most
CASTNET sites are located away from local sources of pollution in order to assess broad,
regional air quality trends.
The National Atmospheric Deposition Program (NADP) comprises three subnetworks:
the National Trends Network (NTN), the Mercury Deposition Network (MDN), and the
Atmospheric Integrated Research Monitoring Network (AIRMoN). NTN collects weekly
samples for hydrogen, sulfate, nitrate, ammonium, chloride, and base cations (such as calcium
and magnesium). NTN provides a long-term, high-quality database that is useful for assessing
the magnitude of the acid rain problem and for determining spatial and temporal trends in the
chemical composition of the atmosphere and the removal of atmospheric compounds as
deposition. The NTN has grown from 22 sites in 1978 to over 200 sites currently. MDN collects
mercury samples, and supports a regional database of the weekly concentrations of total mercury
in precipitation and the seasonal and annual flux of total mercury in wet deposition. Lastly,
AIRMoN was formed for the purpose of studying precipitation chemistry with greater temporal
resolution (precipitation samples are collected daily). The samples are analyzed for the same
constituents as NTN sites. AIRMoN currently operates eight sites, with the full network
expected to grow to about 20-30 wet and dry deposition sites. The AIRMoN sites provide a
research-based foundation for operations of the other deposition monitoring networks (NADP for
wet deposition and CASTNET for dry deposition).
1.2.3 Visibility Monitoring
The Interagency Monitoring of Protected Visual Environments (IMPROVE) program is a
cooperative measurement effort by a steering committee composed of representatives from
Federal and regional-state organizations. The IMPROVE program was established in 1985 to aid
the creation of Federal and state implementation plans for the protection of visibility in Class 1
areas (156 national parks and wilderness areas) as stipulated in the 1977 amendments to the
Clean Air Act (CAA). The IMPROVE network presently comprises 110 monitoring sites. Note
that the IMPROVE sites also provide PM2.5 speciation data, as noted in Section 1.2.1, above.
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CAST NET Site Locations
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1.2.4 Air Toxics Monitoring
Unlike NAAQS pollutants, the Clean Air Act does not require monitoring for air toxics.
Because the primary focus of the air toxics program to date has been on reducing air toxics
emissions by application of available control technology for industrial sources and more
stringent mobile source emission standards, the success of the program so far has been measured
more often by the level of emissions reductions achieved as opposed to measured changes in air
quality. EPA has used air dispersion modeling to estimate the impact of air toxics emissions on
ambient air concentrations of air toxics and, ultimately, on human health.
EPA now has an active national air toxics monitoring program that includes three distinct
monitoring efforts:
National Air Toxics Trends Stations (NATTS);
EPA funded local-scale projects to assess conditions at the local level; and
Existing state and local program monitoring.
The NATTS network is intended to provide long-term monitoring data for certain priority
air toxics across representative areas of the country in order to establish overall trends for these
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pollutants. EPA has established 23 NATTS, 17 of which are in urban areas and six of which are
in rural areas. In the near term, this Strategy documents EPA's commitment to maintain NATTS.
Initial ambient air toxics monitoring pilot studies have shown that across a city
significant variations in pollutant concentrations occur that cannot be characterized by a single
monitoring site. Thus, EPA has incorporated into the national air toxics monitoring strategy
support for local-scale projects consisting of several monitors operated for one to two years.
Many state and local agencies for some years have operated ambient air toxics
monitoring networks in support of their state or local air toxics programs. These can include
monitors to address "hot spots," environmental justice concerns, or citizen complaints. About
250 separate air toxics sites exist at the state and local levels.
In addition to these air toxic-specific monitoring activities, other monitoring programs
primarily intended to address other air pollution concerns incorporate aspects of air toxics
monitoring. EPA's Photochemical Assessment Monitoring Stations (PAMS) collect data on
certain volatile organic compound and carbonyl air toxics, while the IMPROVE and CASTNET
networks collect data on certain air toxics metals. To identify certain air toxics compounds, the
results of some particulate matter monitoring is speciated.
In addition to these existing efforts, EPA has an ongoing effort to develop a strategy for
persistent bioaccumulative toxics (PBT) monitoring, including expanded mercury monitoring.
1.2.5 Tribal Monitoring
Currently, there are well over 100 Tribal air quality programs in various stages of
development across the United States. This is a dramatic increase from only nine programs in
1995. Many of these Tribes currently report data to EPA's Air Quality Subsystem (AQS) from
about 120 monitors in Indian country for several types of pollutants, including PM2.5 and PMio,
ozone, nitrogen and sulfur oxides. Tribes also operate monitors in other national networks such
as CASTNET, IMPROVE and NADP.
EPA's Tribal air policy emphasizes that, as sovereign governments, Tribes set their own
air program goals and determine how monitoring is to be used in achieving these goals. Thus,
EPA's role for Tribal air programs is to help the Tribes understand their air quality problems and
to establish and meet their air quality goals, rather than to set goals or timetables for the Tribes.
1.2.6 Research-level and Other Monitoring
In addition to the monitoring networks described above, there are many additional recent
or ongoing ambient monitoring initiatives that provide valuable data, some of which are
comparable in terms of being a network design and others that are targeted for particular research
or other purposes. There is a wide range of these types of efforts. Some critical examples that
will play a role in this Strategy include:
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PM Supersites. This ambient monitoring research program was designed to characterize
particulate matter, support health effects and exposure research, and conduct methods
testing. The supersites were established through cooperative agreements with
universities and EPA. These sites operated over various periods spanning 1999 to 2005
and conducted a wealth of standard and research grade measurements. Supersites were
designed to address the extremely complicated sampling issues associated with fine
aerosols and constituted an ambitious technology transfer and liaison effort across
research level and routine network operations.
Near Roadway Monitoring Efforts. Research monitoring efforts to characterize the
impacts of mobile sources near roadways are emerging as a key area for ambient air
monitoring development. An estimated 35 million Americans live near four-lane roads,
and EPA and others will need to investigate how to incorporate near roadway conditions
and exposures into NAAQS attainment monitoring. To date, ambient monitoring in these
areas consists of targeted research efforts. For example, the Traffic-Related Exposure
Study (T-REX) has measured concentration gradients along roads, identified intrusion
into nearby buildings, and evaluated air quality and exposure models. As another
example, the Detroit Exposure and Aerosol Research Study (DEARS) has measured
personal exposure and assessed residential proximity to roads and other sources. These
and other research efforts indicate the need to evaluate methods of integrating near
roadway monitoring into NAAQS compliance monitoring network design and siting.
New Source Review Permit Monitoring. The Prevention of Significant Deterioration
(PSD) provisions in the CAA establish permitting requirements for new or modified
major sources located in areas that attain the NAAQS. In general, PSD requires the
classification of all land areas as either class I, II, or III. The Clean Air Act specifies that
certain large, federally owned, publicly accessible lands (generally, National Parks,
Monuments, Forests, and Wilderness Areas exceeding 5,000 acres) must be treated as
Class I areas. The Act classifies all other areas as Class II areas, but states can
redesignate areas as Class I or Class III areas through a process laid out in the Act.
Generally, Class I areas receive the most significant protection from increased air
pollution under the PSD program and Class III areas the lowest. Under the PSD
provisions for Class I areas, a facility owner seeking a permit must demonstrate through
air quality modeling that their facility will not degrade the Class I area's air quality.
Monitoring may be required before construction begins on a new facility to establish
baseline conditions. In addition to monitoring ambient concentration pollutants emitted
from permitted facilities, PSD provisions allow states to require meteorological
monitoring in order to determine whether the permitted source is degrading air quality in
a class I area. Monitoring may continue for as long as the facility is in operation. These
PSD monitoring provisions have contributed to the establishment of many industry-
operated monitoring sites in so called "clean" areas. In addition to meeting the basic
needs of the PSD program those sites have contributed to a greater understanding of
atmospheric processes in general and the transport and fate of certain pollutants in
particular.
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Radiation and Homeland Security Monitoring. Currently, RadNet is the nation's only
comprehensive radiation monitoring network, with more than 200 sampling stations
located throughout the United States. The network is multi-media and provides broad
geographical coverage as well as coverage of many major population centers. For air
monitoring, RadNet samples twice per week at 59 locations. In addition to RadNet, there
are other radiation monitoring programs in the U.S. The Department of Homeland
Security's (DHS) Environmental Measurements Laboratory operates the Surface Air
Sampling Program (SASP). This global air particulate monitoring network is comprised
of approximately 41 active sampling stations worldwide. In addition, DHS operates a
global precipitation monitoring network with 45 U.S. sampling locations.
The Department of Energy (DOE) Los Alamos National Laboratory, in cooperation with
EPA, operates the Neighborhood Environmental Watch Network (NEWNET). This
network measures gamma radiation exposure rate, humidity, barometric pressure, wind
speed, and wind direction using real-time monitoring devices with satellite uplink at
locations in Alaska and New Mexico. The majority of the sampling sites are located in
New Mexico in support of efforts at Los Alamos National Laboratory.
In the United States, DOE has research and development responsibility for monitoring
and verification of the Comprehensive Test Ban Treaty (CTBT). In support of the CTBT,
which was signed by President Clinton in September 1996, an International Monitoring
System and National Data Center has been developed. The monitoring system consists of
a worldwide network of seismic, hydro-acoustic, infrasonic, and radionuclide monitoring
stations that provide near-real-time data to the National Data Center. There are 80
radionuclide monitoring stations worldwide. Eleven radionuclide monitoring stations are
operated by the United States.
Some states also perform environmental radiation monitoring. For example, the Illinois
Emergency Management Agency's Division of Nuclear Safety operates a system
comprised of gamma dose rate monitoring devices and air particulate sampling at
approximately 60 sites. The program, however, is basically directed at in-state nuclear
power plants. Similarly, other radiation monitoring systems in the country focus on
facility and site monitoring and special studies monitoring. RadNet remains the only
comprehensive national environmental ambient radiation monitoring network that
focuses on major population centers and broad geographical areas.
In addition to radiation monitoring, EPA has partnered with several other federal
agencies in the establishment and operation of the BioWatch network. Details about this
network are not provided due to national security; however, the system may be described
as a network to monitor for biological material in largely urban areas. In addition, the
federal government conducts additional biological monitoring at various defense
installations.
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1.3 Current Air Quality Management Challenges and Opportunities
Dramatic and mostly positive changes in air quality have been observed over the last two
decades, despite increasing population, vehicle usage, and productivity. Most criteria pollutant
measurements read well below national standards (see Figure 1-3).
As Figure 1-3 shows, control measures adopted under the CAA and state and local laws
have generally solved the widespread, elevated levels of lead and gaseous criteria pollutants.
However, current and future problems in particulate matter, ozone, and air toxics damage
continue to challenge air programs.
ฆ 100%+ of NAAQS
ฆ 80 -100% of NAAQS
~ 60 - 80% of NAAQS
ฆ < 60% of NAAQS
Figure 1-3. Number of monitors measuring values relative to the National
Ambient Air Quality Standards based on AIRS data through 1999. Great progress
has been made in reducing ambient concentrations of most criteria measurements.
Ozone and PM2.5 dominate the nonattainment picture on a national scale.
Many of the key air quality management challenges were outlined recently in a major
National Academy of Sciences (NAS) report: Air Quality Management in United States (2004).
These include:
Meeting new standards for ozone, particulate matter, and regional haze;
Understanding and addressing the human health risks from exposure to air toxics;
Responding to evidence that there may be no identifiable threshold exposure below
which harmful effects cease to occur for some pollutants;
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Mitigating pollution effects that may disproportionately occur in minority and low-
income communities;
Understanding and protecting ecosystems affected by air pollution;
Understanding and addressing multistate and international transport of pollutants; and
Adapting the air quality management system to a changing climate.
Among the NAS recommendations to address those challenges were enhancing
assessments of air quality and health, ecosystem monitoring, and exposure assessment.
Reconfiguring existing monitoring networks can reflect our progress in reducing many forms of
air pollution and incorporate new scientific findings and technologies to address the remaining
challenges. This Strategy is one prong of working to implement those recommendations by
coordinating ambient monitoring efforts and looking for ways to strengthen, update, and link
together existing monitoring systems.
1.4 Identifying the Need for a National Strategy
As EPA looks at the air quality management challenges ahead, it is clear that a national
strategy to maintain effective ambient monitoring systems is a vital component of meeting those
challenges. The Strategy needs to address the following types of gaps, inefficiencies, and
overlaps:
The existing NAAQS compliance networks, SLAMS/NAMS, need to be reconfigured to
emphasize persistent attainment problems, such as 03 and PM2.5 (and the proposed new
PMio-2.5 standard). In part, this will require shifting resources currently being expended
on NAAQS attainment problems that largely have been addressed (such as CO, lead,
NO2, and SO2). While reducing the overall number of NAAQS-oriented sites for these
pollutants, the national networks need to maintain adequate sites for these pollutants to
address other objectives such as long-term trends analysis, photochemical reaction
evaluations, inputs for regional modeling efforts, and a variety of other purposes.
The existing networks need to move toward enhanced data collection by incorporating
continuous and multipollutant measurements where possible.
The importance of rural background monitoring for evaluating long range transport,
cross-border flux concerns, NAAQS control strategies (such as the 2005 Clean Air
Interstate Rule and Clean Air Mercury Rule), and long-term NAAQS trends needs to be
recognized. EPA must seek opportunities for better integrating non-NAAQS networks,
such as IMPROVE and CASTNET, with NAAQS monitoring networks.
The linkages between ambient air monitoring and ecosystem impacts need to be
recognized. These ecosystem impacts can include acid, nitrogen, and mercury
deposition, and ecosystem impacts of elevated ozone levels. These linkages are
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important not only for developing general ecosystem protection strategies, but also for
evaluating secondary NAAQS established under the Clean Air Act to protect the public
welfare.
The quality system and other technical requirements for monitors need to be
performance-based, which ensures high quality data but allows for technological
advances in monitor design and components.
Storage and dissemination of the full range of ambient data that SLTs and EPA collect
needs to be improved. This will enhance the usefulness of the data for modeling, other
research, and general public access.
1.5 Strategy Development Steps to Date
A National Monitoring Steering Committee (NMSC) was developed to provide oversight
and guidance to develop this Strategy.2 The NMSC included representatives from SLTs and
EPA's Office of Air Quality Planning and Standards (OAQPS), Office of Research and
Development (ORD), and Regional Offices. This NMSC structure reflected both the partnership
across EPA and its major grantees as well as an intent to limit participation initially to focus on a
manageable subset of clients and increase probability for progress. With input from the NMSC,
EPA released a series of draft Strategy materials. This December 2005 draft updates an earlier
April 2004 draft, which in turn was a combination of work on a series of earlier draft documents.
This update reflects input from other EPA offices, such as Office of Atmospheric Programs and
Office of Transportation and Air Quality, so that this draft Strategy reflects an Office of Air and
Radiation-wide position, and addresses the full array of critical national ambient air monitoring
components.
In addition, EPA has been conducting national assessments of the criteria pollutant
monitoring networks. An assessment was conducted in 2000 to catalyze subsequent regional
level assessments. A copy of the FY 2000 national assessment can be found on the Web at:
www.epa.gov/ttn/amtic/netamap. This assessment established weighting parameters to
determine relative "value" of individual sites. The weighting factors included concentration
level, site representation of area and population, and error uncertainty created by site removal. In
addition, the assessment evaluated site redundancy. The national assessment calculated error
uncertainty by modeling (i.e., interpolating between measurement sites) surface concentrations
with and without a specific monitor. The difference reflects the error uncertainty (Figure 1-4).
Areas of low uncertainty (e.g., less than five ppb error difference for ozone) suggest that removal
of a monitor would not compromise the ability to estimate air quality in the region of that
monitor as nearby stations would provide adequate acceptable predictions.
2 The NMSC has evolved into the present National Ambient Air Monitoring Steering Committee.
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Base east wont writes ill site Error surges after site rsmcnraS
Figure 1-4: Surface depiction of estimated absolute errors (right) in ozone
concentrations produced by removing existing monitors on a site by site basis, relative to
base case (left). Areas showing low errors (<5 ppb) suggest neighboring monitors could
accurately predict ozone in area of a removed site. Areas of high error suggest necessity
to retain existing monitors and perhaps increase monitoring.
The key findings of the national network assessment were as follows:
Investment Needs: New monitoring efforts are needed to support new air quality
challenges, including monitoring for air toxics and new technology for criteria pollutants
and precursor species. Air toxics have emerged as a top public health concern in many
parts of the country, and a national air toxics monitoring network is currently under
development under special funding for air toxics monitoring. New technology, especially
continuous measurement methods for pollutants, such as fine particles, are needed to
provide more complete, reliable, and timely air quality information, and to relieve the
burden of manual sampling. Resources and guidance are needed for this activity.
Divestment Opportunities: To make more efficient use of existing monitoring
resources and to help pay for (and justify additional resources) the new monitoring
initiatives noted above, opportunities exist to reduce existing monitors. Two areas of
potential divestment are suggested. First, many historical criteria pollutant monitoring
networks have achieved their objective and demonstrated that there are no national (and,
in most cases, regional) air quality problems for certain pollutants, including PMi0, SO2,
NO2, CO, and Pb. A substantial reduction in the number of monitors for these pollutants
should be considered. (Flowever, considerations need to be made to retain a certain
number of trace level monitors especially for SO2 and CO, because of their utility as
tracers for certain sources of emissions and for model performance evaluation.) As part
of this adjustment, it may be desirable to relocate some of these sites to rural areas to
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provide regional air quality data. Second, there are many monitoring sites with only one
(or a few) pollutants. To the extent possible, sites should be combined to form
multipollutant monitoring stations. Any resource savings from such divestments must
remain in the monitoring program for identified investment needs. In addition, a
reasonable period of time will be required to smoothly transition from established to new
monitoring activities.
It should be noted that this type of network assessment produces recommendations on
removing or relocating samplers based largely on technical merit. In some instances,
these recommendations may be in conflict with existing policy or other needs. For
example, a recommendation that an ozone monitor be discontinued in a "nonattainment"
county due to redundancy of neighboring sampling sites raises interesting
policy/technical issues. These and other issues require attention in concert with technical
recommendations developed through assessments. It should not be assumed that policy
should override a technical recommendation, nor should technical approach override
existing policy. Rather, reasonable solutions can be achieved on a case-by-case basis.
See Section 3.4 for further discussion of siting approaches under this Strategy.
Importance of Regional Input: The national analyses were intended to provide broad
directional information about potential network changes. Regional/local analyses are a
critical complement to the national analyses, and are necessary to develop specific
monitoring site recommendations. See Section 2.5.3 for further discussion of the
regional assessment process.
In 2005, EPA conducted an assessment specifically focused on the PM25 speciation
monitoring network. In consultation with STAPPA/ALAPCO, EPA evaluated these sites to
determine which might be shutdown so as to provide resources for future monitoring needs.
EPA ranked the sites according to their overall information value. The ranking was based on
several factors, including whether the site was in a nonattainment area and whether other sites
were nearby. There was general agreement that many of the sites should be shutdown once FY
2005 funding had run out. Other sites were identified as high value sites, particularly with regard
to the PM2.5 NAAQS program. In the case of these sites, EPA evaluated each in developing FY
2006 Regional funding allocations for continued operation and maintenance of speciation sites.
In doing so, the Agency balanced filter-based PM25 speciation against other uses of PM25
funding, such as FRM site operations, filter analysis, starting up additional precursor gas sites,
and starting up continuous speciation sites.
1.6 Process and Timeline for Continued Development and Implementation of the
Strategy
This draft Strategy reflects EPA's emerging position on the appropriate elements of a
national approach to ambient monitoring improvement and implementation. In some areas, the
Strategy indicates that further discussion and input is needed to develop the Strategy into specific
objectives and plans. EPA's goal is to obtain further input through comments and information
from the proposed revisions to the monitoring regulations being proposed in December 2005, to
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continue to work on topics where this draft indicates further analysis and strategy development is
needed, and to complete a final document by January 2007.
The final document will remain a living document that EPA and its partners can evaluate
and update on an ongoing basis. During this process, EPA will continue to work with the
National Ambient Air Monitoring Steering Committee, as well as other entities where leveraging
and common interest opportunities exist. EPA anticipates that this process will involve input
from discussions with the North American Research Strategy for Tropospheric Ozone
(NARSTO), the Committee for Environment and Natural Resources (CENR), and other
stakeholders.
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2. Overview of Strategy
This Strategy has a number of different elements, not all of which apply to all forms of
ambient air monitoring. The major impetus behind this Strategy is EPA's recognition that the
monitoring historically undertaken to determine NAAQS compliance needs to be significantly
reconfigured and updated to meet the challenges facing air quality management in the U.S. At
the same time, EPA recognizes that other ambient monitoring networks and programs, including
some that are just now coming into development, play a vital role in responding to those
challenges as well, and that continued maintenance, and in places enhancement, of those
networks is an important element of a national monitoring strategy. Finally, EPA also realizes
that while these various monitoring programs may have developed initially to provide data for
different objectives, there are synergies and needs between those objectives that provide
opportunities to integrate some of these systems.
Thus, this Strategy has three main elements:
In place of the current SLAMS/NAMS networks, implement the NCore multipollutant
sites and streamline the number of single pollutant sites (still called SLAMS) that are
designed principally to assess NAAQS compliance and long-term NAAQS trends.
Maintain and enhance where necessary other existing monitoring programs so they meet
their environmental objectives effectively and efficiently.
Identify and pursue opportunities for integrating monitoring networks and programs
where synergies exist.
In addition to these primary elements, the Strategy includes several secondary elements
as well:
Encourage quality system enhancements.
Update outdated technology and streamline requirements to encourage technology
innovations over time.
Promote data management, access, and analysis tools to maximize agency, research, and
public use of the data collected.
Ensure adequate resources to implement all necessary elements of the Strategy and take
on other elements of the Strategy in a way that is consistent with available resources.
These primary and secondary elements of the Strategy are laid out in the following
sections, after briefly reviewing high level operating principles that govern development and
implementation of this Strategy.
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2.1 Principles for Design and Management of Ambient Air Monitoring into the
Future
The maintenance of effective ambient monitoring networks involves no single EPA
office or other entity, but a wide range of groups. These groups can have different objectives for
ambient monitoring, different funding, and other constraints. The following operating principles
reflect the important partnership elements across EPA and its grantee organizations that must be
recognized in embracing the goal and objectives of the Strategy:
Partnership. Consensus building is used to corroborate strategic planning elements
among EPA, SLTs, and other partners.
Flexibility by Balancing National and Local Needs. Network design, including
divestment and investment decisions, must achieve a balance between prescription
(consistency) and flexibility to accommodate national and local monitoring objectives.
Although localized issues are "national" issues, and nationally consistent data bases serve
SLT agency interests, allowances must be made for differing needs arising from both
perspectives.
Effective Interfacing with Science. An emphasis should be placed on more active
engagement with the scientific community, recognizing the important role science plays
in network design and technology and the role of networks in assisting scientific research.
The perspective that a clear demarcation exists between science-oriented and Agency-
based monitoring is counterproductive to the larger goal of improving air monitoring.
Zero Sum Resource Assumptions. This Strategy is not a vehicle to promote adding
significant resources for air measurements as a whole, although it does not preclude EPA
or state/local agencies from seeking additional resources. The Strategy assumes
relatively stable but flat projected spending for air monitoring activities. This level
resource assumption requires a reduction in current efforts to accommodate new
monitoring needs. This reduction would occur through the types of divestments
discussed in Section 1.5. Given those savings, the Strategy includes modest resource
proposals to act as a catalyst for enhancing the use of updated technology. EPA believes
these resource proposals represent an insignificant fraction of current monitoring
resources. Furthermore, the Strategy intends to retain the basic infrastructure and
operational stability of existing agencies. Reallocation implies shifts to different
pollutant measurements and technologies. Significant resource shifts across geographical
regimes and agencies should be made only to remedy obvious long-term disparities
between programs where the programmatic needs no longer support such disparities.
Data Analysis and Interpretation. Too often, large data collection programs sacrifice data
analysis tasks because of a lack of protected or dedicated analysis resources, available
guidance and expertise, or declining project interest. Networks will operate more
efficiently when periodic active analyses are performed that identify strengths and
weaknesses and provide more dynamic direction for modifications. A good example has
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been established by the emerging air toxics program, which set aside significant
resources for analysis of historical and new pilot city data prior to large scale network
deployment.
Consistent with these overall partnering principles, the NMSC recommended several key
changes for inclusion in this Strategy. These changes will allow for more efficient collection and
universal use of air quality data, and greater flexibility in air monitoring to meet the challenges
of the 21st Century in ways that meet both national and local monitoring needs. The key
recommendations were:
The networks need to produce data more closely aligned with current challenges by:
including a greater level of multipollutant monitoring sites in representative urban
and rural areas across the nation;
expanding use of advanced, continuously operating instruments and new
information transfer technologies;
integrating emerging hazardous air pollutant (HAP) measurements into
mainstream monitoring networks; and
supporting advanced research level stations.
A new national monitoring network design should accommodate these recommendations
and the major demands of air monitoring networks, such as:
trend determinations;
reporting to the public;
assessing the effectiveness of emission reduction strategies;
assessing source-receptor relationships;
providing data for health assessments and NAAQS review; and
determinations of attainment and nonattainment status.
Existing monitoring regulations require modification and promulgation by EPA to
accommodate recommended network changes.
Flexibility must be maintained and even increased for SLTs to address local and area-
specific issues including, for example, environmental justice concerns, episodic PM and
ozone events, and "local" or hot spot air toxics concerns.
Periodic assessments of air monitoring networks must be performed to determine if the
existing network structure is optimally meeting national and local objectives. The current
national review of the networks indicates that many criteria pollutant measurements (e.g.,
nitrogen and sulfur dioxides, carbon monoxide, PMio) are providing only limited value,
which present opportunities to realign air monitoring resources in more relevant areas.
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Such assessments and network decisions are best addressed through regional level
evaluations.
The network modifications should be conducted within current resource allocations used
to support monitoring (e.g., with respect to staffing). However, there need to be modest
investments in new equipment to upgrade monitoring systems to meet new priorities and
accommodate advanced technologies.
Recommendations for network changes should engage the public.
EPA has in large part used these recommendations as a framework for fashioning this
Strategy. The remaining parts of this Section 2 describe the major elements of the Strategy.
2.2 Strategy for Urban Areas
2.2.1 NCore Multipollutant Sites
Urban monitoring systems need to build on the current air monitoring networks, but also
incorporate changes to address new directions in air monitoring and to begin filling measurement
and technological gaps that have accumulated over the years. This Strategy emphasizes
multipollutant sites, continuous monitoring methods, and important pollutants previously not
included in SLAMS/NAMS, such as ammonia and reactive nitrogen compounds (NOy). When
completed, this modified network will meet a number of important needs: improved data flow
and timely reporting to the public; NAAQS compliance determinations; support for
development of emissions strategies; improved accountability for control programs; and support
for scientific and health-based studies.
Structurally, the central component of this Strategy will be a network of National Core
(NCore) multipollutant monitoring sites. Monitors at NCore multipollutant sites will measure
particles (PM2.5, speciated PM2.5, PM10-2.5), O3, SO2, CO, nitrogen oxides (N0/N02/N0y), and
basic meteorology. Monitors for all the gases except for O3 would be more sensitive than
standard FRM/FEM monitors, so they could accurately report concentrations that are well below
the respective NAAQS but that can be important in the formation of 03 and PM. EPA expects
that each state would have from one to three NCore sites, and EPA will collaborate on site
selection with states individually and through multistate organizations. The objective is to locate
sites in broadly representative urban (about 55 sites) and rural (about 20 sites) locations
throughout the country to help characterize regional and urban patterns of air pollution. In many
cases, states likely will collocate these new stations with PAMS sites already measuring O3
precursors and/or NATTS sites measuring air toxics. By combining these monitoring programs
at a single location, EPA and its partners can maximize the multipollutant information available.
This greatly enhances the foundation for future health studies and NAAQS revisions.
The NCore multipollutant stations are part of an overall strategy to integrate multiple
monitoring networks and measurements, including research grade and SLAMS sites. Research
grade sites would provide complex, research-grade monitoring data for special studies; see
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Section 9.5 for further discussion. The SLAMS monitors would provide NAAQS comparisons
and other data needs of monitoring agencies. The number and placement of SLAMS monitors
would vary according to the pollutant, population, and level of air quality problem. See Section
4 for further discussion.
2.2.2 Rationalization of NAAQS Pollutants Networks
In shifting to the new framework outlined in Section 2.2.1, EPA and its partners will seek
to continue to assess existing monitoring, reduce monitoring where no longer needed to assure
NAAQS attainment or meet other policy needs (such as trends analysis), and move to continuous
monitoring where possible. The key efforts in this area include:
A significant reduction in the number of sites, especially for pollutants such as lead that
no longer pose widespread air quality problems in the U.S.; and
The regulatory changes proposed in December 2005, which will provide the regulatory
framework necessary to restructure the existing SLAMS/NAMS networks, harmonize
quality assurance requirements, and provide additional changes necessary to implement
elements of this Strategy.
The efforts will ensure that the NAAQS monitoring networks focus resources on the most
pressing needs and continue to modernize technology in ways that will enhance use of the data
and timely access to the data. In addition, these changes need to take into account the possibility
of more stringent NAAQS being established in the future, especially for PM2.5
2.2.3 Coarse PM
The proposed regulations EPA is releasing will address monitoring for the proposed new
PMio-2.5 NAAQS. Based on public comments, EPA will finalize those regulations, and it
expects to incorporate the specific elements for this Strategy in a final version of this document
scheduled to be released in January 2007.
2.2.4 PAMS
Consistent with the NCore multipollutant objectives, the PAMS sites already provide
reasonably comprehensive data pertinent to ozone air pollution in non-attainment areas classified
as serious, severe, or extreme. There are four types of PAMS sites, but the primary focus of the
new urban monitoring strategy will promote the continued use of Type 2 PAMS sites: those
areas where maximum ozone precursor emissions are expected. As shown in Table 2-1, the
primary changes to PAMS would include:
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The number of required PAMS sites would be reduced. Only one Type 2 site would be
required per area regardless of population and Type 4 sites would not be required. Only
one Type 1 or one Type 3 site would be required per area.
The requirements for speciated VOC measurements would be reduced. Speciated VOC
measurements would only be required at Type 2 sites and one other site (either Type 1 or
Type 3) per PAMS area.
Carbonyl sampling would only be required in areas classified as serious or above for the
8-hour 03 standard.
N02/NOx monitors would only be required at Type 2 sites.
NOy will be required at one site per PAMS area (either Type 1 or Type 3).
Trace level CO would be required at Type 2 sites.
Table 2-1
Proposed New Minimum Requirements for PAMS Sites
Measurement
Where Required
Sample Frequency (except upper air
meteorology)
Speciated VOC
Two sites per area; one must be at a
Type 2 site
During PAMS monitoring periods:
- hourly auto GC
- 8 3-lir canisters
- 1 morning, 1 afternoon canister plus
continuous NMHC measurement
NOx
All type 2 sites
Hourly during ozone season
NOy
One site per area, either at Type 1 or
Type 3 site
Hourly during ozone season
CO (ppb level)
All sites
Hourly during ozone season
Ozone
All sites
Hourly during ozone season
Surface met
All sites
Hourly during ozone season
Upper air met
One site in PAMS area
Sample frequency must be approved as part
of the PAMS Network Description
2.2.5 PM Speciation
As of 2005, PM2.5 chemical speciation measurements are collected at approximately 50
Speciation Trend Network (STN), about 210 SLAMS, and 110 IMPROVE Class I area sites
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(Figure 2-1).3 The majority of these sites collect aerosol samples over 24 hours every third day
on filters that are analyzed for trace elements, major ions (sulfates, nitrates, and ammonium), and
organic and elemental carbon fractions. As part of this Strategy, EPA is moving toward a
cheaper shipping method and a single method for analyzing carbon from samples from all of
these sites. Both of these shifts should reduce costs associated with existing speciation
measurements.
Figure 2-1: PM2.5 Monitoring Sites, Including Chemical Speciation Sites
In addition, under the new urban monitoring strategy, continuous or semi-continuous
speciation monitors will provide the ability for monitoring networks to deliver data with a high
temporal resolution so that the atmosphere can be characterized on a time scale relevant to how it
changes and how people are exposed under dynamic processes. Initially, the strategy will not
require states to operate continuous speciation samplers, with the exception of 22 National Air
Toxics Trend Stations (NATTS). These NATTS locations use the Aethalometer instrument to
measure black carbon. Nevertheless, EPA's strategy is that there should be a gradual evolution
of continuous sampler operations at NCore multipollutant sites. EPA is committed to supporting
a 10-site continuous speciation network, including carbon, sulfate, and nitrate. This network
evolved from early discussions with the health effects community related to a series of
recommendations forwarded by the National Academy of Sciences in the late 1990s and
continued by CASAC. EPA will continue to take a cautious approach toward continuous
speciation monitoring, based largely on findings from the Supersites and other programs
indicating mixed performance across a variety of monitors.
3 The 250 SLAMS sites currently use either of two sampling and speciation analysis protocols, one the same as the
STN sites and the other the same as the IMPROVE Class I area sites.
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2.2.6 Air Toxics
In 1999, EPA began designing a national ambient air toxics monitoring network. As set
out in the July 2004 National Monitoring Strategy Air Toxics Component, EPA is developing a
national air toxics program that increases the role of ambient monitoring in support of efforts to
reduce human exposure and health risks from air toxics. The primary objectives of ambient air
toxics monitoring include (1) to discern trends and account for program progress by measuring
key air toxics in representative locations to provide a basic measure of air quality differences
across cities and regions, and over time in specific areas; (2) to support exposure assessments by
providing ambient concentration levels for comparison with personal measurements; and (3) to
provide basic grounding for models used for exposure assessments, development of emission
control strategies, and related assessments of program effectiveness.
This Strategy includes four elements of a national air toxics monitoring program:
National Air Toxics Trends Stations (NATTS);
EPA funded local-scale projects to assess conditions at the local level;
Existing state and local program monitoring; and
Long-range strategy development to address PBT monitoring within existing resource
constraints.
The NATTS network is intended to provide long-term monitoring data for certain priority
air toxics across representative areas of the country in order to establish overall trends for these
pollutants. As of January 2004, EPA had established 23 NATTS in 22 cities. In the near-term,
this Strategy documents EPA's commitment to maintain NATTS. EPA intends to review with
stakeholders the list of pollutants monitored at NATTS sites.
In FY 2004, EPA selected 16 local-scale project proposals for grant awards totaling $6.2
million. For FY 2005, EPA solicited bids for $6.3 million in grant funds. EPA works with SLTs
to define the goals and priorities for this monitoring. In FY 2005, EPA reduced the emphasis on
community-scale assessments and increased the emphasis on source characterization and
monitoring methods development. Under this Strategy, EPA anticipates continued funding for
these types of local-scale projects, and a continued dialogue with SLTs on the appropriate
priorities for these efforts.
Many state and local agencies for some years have operated ambient air toxics
monitoring networks in support of their state or local air toxics programs. EPA has assisted
these monitoring efforts since 1997 by providing laboratory analysis of air toxics samples
collected by state and local agency monitors. In FYs 2003 and 2004, EPA re-directed $6.5
million in Section 105 grant funding from criteria pollutant monitoring to air toxics monitoring,
and anticipates maintaining this approach under this Strategy in the future.
In the area of PBT monitoring, EPA currently has been developing a draft strategy that
has not been implemented to date because of resource constraints. Within those constraints, EPA
remains committed to developing further monitoring of PBTs. At this time, EPA's primary focus
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will be to work towards a mercury network that can provide ambient concentration and
meteorological data for estimating dry deposition (see also Section 2.3, below).
2.2.7 Near Roadway Exposure
Monitoring near roadways has, to date, been limited to research-level monitoring. As the
national air monitoring network matures, it is vital that monitoring near roadways continue and
that EPA and others evaluate strategies for incorporating this monitoring into the other
components of the NAAMS as a means of determining health risks and impacts on urban
attainment. EPA fully intends to consult with SLT and other stakeholders in developing the near
roadway component of the Strategy, and issuing more detailed elements of this component of the
Strategy in January 2007.
2.2.8 Homeland Security
EPA has an ongoing implementation plan to enhance RadNet, with a focus on homeland security
concerns. The planned approach to enhancing RadNet is currently being reviewed by EPA's
Science Advisory Board. After the approach and implementation plan are finalized, those
elements will be incorporated into this overall Strategy. In addition, EPA has partnered with
several other federal agencies in the establishment and operation of the BioWatch network. The
network is used to monitor the air for biological material in largely urban areas.
Greater details about this network are unavailable in this Strategy because of national security
reasons.
2.3 Strategy for Rural Areas
EPA has a multi-prong strategy for rural monitoring networks, including CASTNET,
NADP, IMPROVE, and smaller scale rural programs (such as specific PSD monitoring sites):
(1) Recognize that these existing systems represent a core element in our national
monitoring framework that is vital to assessing progress in the program areas for which
they were created (such as atmospheric deposition and visibility). Based on that
recognition, maintain their ability to continue that function and upgrade equipment and
data dissemination as necessary.
(2) Use these systems to track rural background ambient conditions in support of regional
control strategies aimed at reducing long range PM2.5 and ozone transport, including the
2005 Clean Air Interstate Rule (CAIR). This objective has emerged in recent years as
an important rationale for continued support to these systems, in addition to their other
primary purposes (including tracking atmospheric deposition, trends, and visibility).
Data from these systems are important to understand both in terms of identifying
solutions to urban NAAQS attainment problems and tracking progress of regional
control strategies in reducing background ambient concentrations of PM2.5 and ozone.
(3) Identify opportunities to use these systems for integrated ecosystem assessments.
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(4) Consistent with items (2) and (3), seek ways to formally integrate these systems with
the urban monitoring networks where such integration would enhance our ability to
manage current and future air quality management challenges. From a technology
standpoint, integration includes measuring the same constituents on the same time scale,
and using similar, if not the same, methods. In addition, integration includes
coordinating the management infrastructure so that decisions about network
modifications and other issues are coordinated, both internally at EPA and externally
with EPA's partners.
(5) Strengthen existing mercury monitoring to assess the long term effectiveness of
strategies to reduce mercury exposure, including CAIR and the 2005 Clean Air Mercury
Rule (CAMR).
At this time, much of the implementation of this strategy either is static (because the
systems generally are operating smoothly as they are presently established) or is at an early
discussion stage (in terms of system integration plans). In some cases, however, there are short-
term plans for actions needed to implement this strategy. For example, EPA is pursuing hourly
gas and particle measurement systems and trace gas analyzers at select CASTNET sites. In
addition, EPA has recently been expanding public access to CASTNET data by enhancing the
Data and Maps website portal at www.epa.gov/airmarkets. EPA will continue to pursue these
short-term, ongoing improvements. In addition, EPA will engage in dialogue to seek further
system integration opportunities. The final 2007 Strategy document will incorporate additional
details on the integration strategy and the corresponding implementation plans. Finally, EPA
will stay committed to maintaining the ability of these monitoring programs to support both their
original core mission and the analysis of regional control strategies and trends.
For mercury monitoring, EPA has proposed a collaboration with the NADP to design and
implement an ambient, speciated mercury monitoring network for temporally and spatially
characterizing total mercury concentrations in the atmosphere. The MDN provides the
beginning of a network which currently measures wet deposition. However, an enhanced
mercury network will be necessary to assess progress under CAIR and CAMR. The network
EPA is proposing in collaboration with the NADP would begin to fill the national data gap in dry
ambient mercury compounds by initiating a core federal component of a broader, spatially
representative mercury monitoring network in the United States. The goals in filling this gap are
to better understand atmospheric mercury and to track its fate. EPA believes that it is important
to build on the successes of the existing long-term monitoring infrastructure. The Agency hopes
that using an existing and successful long-term multi-stakeholder model, like NADP, as a
foundation for long-term mercury monitoring will encourage other agencies and states to join the
effort.
2.4 Tribal Monitoring
In the 1990 Clean Air Act, Congress recognized EPA's obligation to work with the Tribes
in addressing air quality in Indian country. Promulgation of the Tribal Authority Rule (TAR) in
1998 provided Tribes with the leverage to begin assessing the air quality on Tribal lands. Tribal
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nations generally are seeking to expand ambient air monitoring efforts, and it is generally
recognized that there exists substantial need for Tribal air monitoring support. At the same time,
nothing in this national Strategy imposes requirements on Tribal monitoring or mandates
linkages of Tribal air monitoring with national networks.
The national networks clearly can benefit from Tribal participation by gaining additional
monitoring sites in those areas where Tribes participate in the national network. Tribes share a
spectrum of technical issues with states, since pollutant transport and meteorological systems
ignore political boundaries. Accordingly, any measurement contribution from Tribal efforts
should be viewed as an asset to a larger integrated national need for air quality measurements,
and Tribes should perceive some level of ownership of air quality data collected in non-Tribal
lands that has relevance to Tribal air quality issues. Tribal participation can benefit all parties as
opportunities exist for Tribes to operate NCore multipollutant sites, particularly in rural areas
where there remain significant spatial gaps in monitoring. There are many rural tribal airsheds
that could be considered pristine and therefore excellent candidates for background monitoring
sites, potentially filling in important gaps in the nation's network. Under this Strategy, Tribes
will be given fair consideration for hosting sites of national interest, and the associated funding.
These comments should not be perceived as suggesting that the Tribal monitoring priority
is or shall be to foster a connection to national networks. Monitoring priorities must be based on
Tribal decisions, which in many cases involve developing a better characterization of local
exposure to air pollutants, and involve funding separate from funds that would be used to host
national network sites. The linkage to national programs should be perceived as leveraging
opportunities that simultaneously benefit Tribes and the national network.
2.5 Common Elements Applicable to All Monitoring
2.5.1 Quality System
Quality assurance is a major component of the air monitoring programs. The goal of this
Strategy is that all of the ambient monitoring networks in the NAAMS produce high quality data
that maximize the usefulness and confidence in the monitoring results. The specific steps for
implementing a quality system for the NAAMS include:
Move toward a performance-based measurement process with specified data quality
objectives;
Minimize start-up problems with a phased implementation approach;
Provide a reasonable estimate of the costs associated with QA programs;
Develop certification and/or accreditation programs;
Develop generic quality assurance program plans (QAPPs);
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Accelerate data review and certification programs for quicker data access into the
national air quality data system (AQS);
Eliminate redundancies in performance evaluation programs;
Develop appropriate data quality assessment tools (e.g., software); and
Streamline regulations, and more specifically identify those actions that should be
mandated through regulation and that should be recommended through guidance.
Both regulatory changes and necessary guidance will be developed as separate actions to
accommodate the implementation of the Strategy. Additional actions that will have to be part of
the implementation plan for this Strategy's approach to a monitoring quality system include:
the development of standard operating procedures (SOPs) to accompany the employment
of new instrumentation; and
appropriate requirements for the infrastructure necessary to accommodate monitoring
sites (e.g., so that sufficient space, power, access, etc, are included in site designs).
2.5.2 Monitoring Technology Development and Transfer
The explosion of computer and communications technologies over the past 15 years
presents significant opportunities for air quality monitoring networks. The potential for
improving monitoring methods; monitoring support capabilities such as computer controlled
instrument calibrations and quality assurance functions; and information transfer (i.e., getting
data quickly to the public) is greater now that at any time in the past. Yet, some components of
our monitoring networks are still functioning under more manual and time consuming regimes.
EPA, working with its state and local partners, has established a Technology Working
Group to examine the prospects for incorporating new technologies and making
recommendations as to the best ways to embrace these. The focus is in three key areas:
Moving toward continuous PM monitors in place of the more cumbersome, labor-
intensive filter-based methods;
Encouraging the utilization of new technologies to measure a more robust suite of
pollutants, such as reactive nitrogen compounds (NOy); and
Fostering the utilization of advanced information transfer technologies (e.g., replacing
antiquated phone communication telemetry systems with internet-based, radio, and
satellite communications media).
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There are several recognized impediments in moving forward in these areas:
Regulations that support the "old" way of doing things need to be revised to reflect the
current technological environment;
Special funding needs to be identified to invest in the equipment capital costs of replacing
older monitors and data transfer systems;
Investments in staff training are needed to ensure that EPA and SLT staff will be able to
operate and maintain the new equipment; and
In some cases, currently available instrumentation has not been demonstrated to operate
successfully without extensive operator oversight and maintenance.
In addressing these impediments, regulation changes are in progress as part of this
Strategy, and funding/training issues will be addressed as part of the implementation plan (see
Section 9 for an outline of an initial implementation plan).
2.5.3 Planning and Assessment Processes
State and local agencies typically conduct an annual network review, and recommend
changes to their networks. As a result, the networks are ever-changing to meet more current
needs. However, for many years there was no concerted effort to take a critical look at our
monitoring sites and determine if there were redundancies and inefficiencies in network designs.
Furthermore, our networks have traditionally been laid out in overlapping fashion, such as an
ozone network, a carbon monoxide network, a PMio and PM2.5 network, an atmospheric
deposition network, a visibility network, and so forth.
In 2000, EPA commissioned a national assessment of the SLAMS/NAMS networks, with
considerations for population, pollutant concentrations, pollutant deviations from the NAAQS,
pollutant estimation uncertainty, and the area represented by each site. Based on this national
assessment, it was determined that substantial reductions in monitors could be made for
pollutants that are no longer violating national air standards on a widespread basis, namely lead,
sulfur dioxide, nitrogen dioxide, and PMio, with the caveat that the measurement of some
pollutants, such as sulfur dioxide, may be useful as source tracers even though ambient levels
may be low. Even for those pollutants of greatest national concern, ozone and PM2.5, sufficient
redundancy was found to suggest reductions of 5 to 20% of our monitors without seriously
compromising the information from our monitors.
With this as a backdrop, each of the 10 EPA Regional Offices was charged with
conducting regional assessments of the SLAMS/NAMS networks. This process began in early
2001, and this Strategy reflects many of the findings of these assessments and the 2000 national
assessment. As part of EPA's commitment to maintaining this Strategy as a living document,
EPA intends to continue the assessment process, with regional assessments targeted to occur on a
five year cycle basis. EPA also is developing standardized guidelines for these assessments.
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The procedures for previous regional assessments were not standardized. Even though
differences in air quality, population, monitoring density, and other factors necessitate some
varying approaches in evaluating networks, generalized guidelines are needed to avoid
unwarranted regional inconsistencies. A Subcommittee of CASAC (Clean Air Science Advisory
Committee) met in July 2003 and recommended that regional assessment guidelines be
developed, and in response, definitive guidelines will be in place for subsequent regional
assessments.
The network assessment process, too, is a collaborative effort between EPA and the
SLTs. While some factors for network changes may be developed from statistical evaluations,
there are also local policy considerations that have a bearing on decisions to change monitors.
Ultimately, the combined efforts among national, regional, and local perspectives and needs will
result in an optimized realignment of air monitoring networks that remains responsive to the
many objectives for conducting the monitoring.
In summary, network assessment is not a new process. State and local agencies
historically have conducted annual network evaluations, and changes to monitoring networks
have been undertaken and reported as part of this process. However, periodically, it is necessary
to take a more holistic review on a multi-level basis: national, regional, and local. As part of
this Strategy, EPA intends to conduct a multi-level network assessment every five years.
The primary objectives of the network assessments are to ensure that the right parameters
are being measured in the right locations, and that network costs are kept at a minimum. Some
of the related secondary objectives include the following:
Identify new data needs and associated technologies;
Increase multipollutant sites versus single pollutant sites;
Increase network coverage;
Reduce network redundancy;
Preserve important trends sites; and
Reduce manual methods in favor of continuous methods.
2.5.4 Data Access
A primary objective of this Strategy is to enhance access to ambient monitoring data.
Within resource constraints, EPA's ongoing approach will be to make available more timely and
effective data than is currently available. EPA already is addressing these issues with a variety
of approaches emerging from a long range "Data Warehouse" OAQPS planning effort as well
inter office collaboration with the Agency's Office of Environmental Information (OEI). Several
pilot projects to gauge the usefulness of new data products and access methods are being
launched as part of these efforts. For instance, EPA's air quality data system (AQS) was taken
off-line for several days so that a "static" copy of the data could be made available, at the request
of a community of EPA research grant recipients.
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Another effort is underway to make all measured (versus reduced) data in AQS available
on demand, allowing a customer to extract a data file based on his or her selection of geographic
area, time frame, and pollutants of interest. A subsequent addition of the more timely AIRNow
data (including quality assurance caveats) would provide an exponential enhancement in data
delivery.
Another goal is to make detailed air quality data summaries available to anyone at any
time by offering a variety of self-service tools to access the data. Currently web pages exist
allowing querying of annual summary information, and air quality professionals can access any
data in the system. The relevant databases and tools are being upgraded to enable public
availability of daily summary information through internet access. The timeliness of this
information also will improve as EPA reduces the time necessary to process data before making
it available to the public and its external partners.
Finally, the collaboration with OEI offers the longer range potential to merge multimedia
data sets that could be used, for instance, to support ecosystem assessments. EPA will continue
to examine those responsibilities and to broaden its outreach efforts beyond traditional SLT
partners to key consumer communities, such as academia, public health organizations, and the
private sector, to ensure delivery of effective products and services.
2.5.5 Data Analysis
This Strategy emphasizes that an effective monitoring program must include an
appropriate analysis and interpretation component. Without that component, the value of
collecting the monitoring data is diminished. The CASAC Subcommittee criticized EPA's lack
of organized archival processes, as well as access to and analysis of air quality data. By allotting
resources annually to data analysis and interpretation, sufficient funding would be available to
make adequate use of the data, enhance information transfer, and provide a higher order of
quality control and network assessment that emerges from data reviews and analysis. A
specified resource allotment would require an integrated perspective across pollutant categories
and could serve as a catalyst for numerous local and other specific, topic-based analyses.
EPA notes that a portion of funds currently allocated to the PAMS network will become
available as EPA scales back PAMS requirements. As part of this Strategy, EPA has proposed to
set aside some of the PAMS-related funds to conduct data analysis. Ideally, this funding should
be combined with additional data analysis resources set aside for air toxics and PM2.5 EPA will
be discussing this proposal with SLTs in more detail, for possible implementation in FY 2007 or
later. A steering group of SLTs and EPA participants could establish a plan for this analysis that
can include an allocation of these resources to SLTs or to other analytical groups.
Some examples of additional data analysis capacity building are included in the
implementation plan in Section 9.
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2.5.6 Funding
A fundamental objective of this Strategy is to maintain adequate funding for all elements
in this Strategy, including NAAQS-oriented networks, rural-oriented networks such as
IMPROVE and CASTNET, and other initiatives such as development of near roadway
monitoring sites. Of critical importance in the near-term is ensuring adequate funding for the
quality systems in all monitoring programs. The timeframe that is anticipated for full
implementation of NCore multipollutant and other modified urban monitoring sites will dictate
the resources needed on a year to year basis to implement the QA activities at Headquarters/EPA
Regions/SLTs. In addition, QA activities need to be intimately tied to the monitoring process, so
that costs for the quality system increase/decrease commensurately with monitoring costs.
Resource and funding related action items include:
Providing a reasonable estimate of the "cost of QA" - Identify quality system
elements for a "typical" SLT monitoring organization and provide an estimate of the
costs of an adequate quality system. Use these estimates to provide a percentage of
monitoring costs that typically should be allocated by a monitoring agency to the
implementation of a quality system. The QA Strategy Workgroup developed a
questionnaire that could be distributed to SLTs in order to get a reasonable handle on
these costs. Similar procedures could be developed for EPA Regions and Headquarters.
Ensuring SLT funds are available for QA training - EPA provides regular and
continuing training on many aspects of air programs. It is important to include QA
training as part of the overall training program.
Automating quality control procedures - There are a number of implementation
activities that are still being performed manually by some monitoring organizations (i.e.,
zero/span and precision checks) that can be automated. The technology section addresses
the aspects of increasing awareness of this technology and moving to more automated
systems. However, an initial expenditure of capital for both equipment and training will
be required to ensure the achievement of this modernization.
Providing contractual support - EPA will provide a mechanism to allow SLTs to tap
into statistical expertise for development of data quality objectives, data quality
assessments, and other statistically-related assessments.
Responsibility and Funding for Quality Assurance Performance Evaluations
Currently, STAG funds pay for the PM2.5 Performance Evaluation Program and NATTS
Proficiency Test Program but not the NATTS field component, PM2.5 speciation
program, or the National Performance Audit Program. Quality assurance is especially
critical as EPA and its partners undertake new monitoring approaches, such as increased
use of continuous monitors. Accordingly, this Strategy focuses on ensuring that quality
assurance performance evaluations are adequately funded and conducted in a consistent
manner. To ensure this result, EPA will propose rule revisions that provide for holding
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back STAG funds where SLTs rely on EPA conducted evaluations or for obtaining EPA
certification of data comparability for audit services not provided by EPA.
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3. Multipollutant Sites in Urban Areas
3.1 Introduction and Objectives
The modified urban area network outlined in this Strategy is both a repackaging and an
enhancement of existing networks. The reconfiguration of the networks reflects their
multifaceted roles. While these networks are critical in assessing NAAQS attainment, they also
can complement more specific applications, such as intensive field campaigns to understand
atmospheric process dynamics, or personal and indoor measurements to assess human exposure.
To produce a more integrated and multipollutant approach to air monitoring, this Strategy
outlines changes in nomenclature for existing networks, reconfiguring the allocation of
monitoring sites within the networks, and additional new measurements to foster a multipollutant
measurement approach. Such measurements would replace existing ones that either do not have
the measurement sensitivity attendant with current atmospheric concentrations or have reached a
point of strongly diminished value.
These changes provide an opportunity to address new directions in monitoring and begin
to fill measurement and technological gaps that have accumulated in the networks. The Strategy
recognizes that there are both nationally and locally oriented objectives in monitoring that
require different design approaches despite the best attempts at leveraging resources and
maximizing versatility of monitoring stations. The Strategy takes a proactive approach in
addressing national needs that often had to make the most of available data sources, regardless of
their design basis. The Strategy addresses the following objectives:
Timely reporting of data to public by supporting AIRNow, air quality forecasting, and
other public reporting mechanisms;
Support for development of emission strategies through air quality model evaluation and
other observational methods;
Accountability of emission strategy progress through tracking long-term trends of criteria
and non-criteria pollutants and their precursors;
Support for long-term health assessments that contribute to ongoing reviews of the
NAAQS;
Compliance through establishing nonattainment/attainment areas through comparison
with the NAAQS;
Support to scientific studies ranging across technological, health, and atmospheric
process disciplines; and
Support to ecosystem assessments recognizing that national air quality networks benefit
ecosystem assessments and, in turn, benefit from data specifically designed to address
ecosystem analyses.
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All of these objectives are equally valued, a departure from an historical emphasis on
NAAQS attainment compliance. This is not meant to imply that EPA is committing to a
research grade network, as the measurements generally are produced through routine operations
conducted by most monitoring organizations. The underlying philosophy adopted in the new
monitoring system is that regulatory assessments are strengthened through a more
comprehensive measurement approach that is well integrated with scientific applications. In
turn, science and research efforts become more focused and effective because of the integration
with the regulatory program perspective.
The new network system provides a basic group of data that are needed to support a
broad spectrum of objectives and analyses (Table 3-1). It is important to point out that, by itself,
this new system cannot meet all of the data requirements for most assessments. It will always be
necessary to expand the specific spatial, temporal and compositional parameters suited for a
particular analysis. Accordingly, it is appropriate to view this new system as a main trunk of
information upon which the necessary branching of specific monitoring needs can be grafted.
The design assumes that pollutant measurements inherently serve multiple data needs and,
therefore, that network efficiencies are enhanced through collocating measurements. There is a
tension between designing for a specific data objective and taking a more holistic design
approach that risks a dilution of attention toward a specific need. Such caution must be
acknowledged in communicating the limitations of a nationally designed network and
recognizing the equal importance of local and other program-specific monitoring efforts that
branch off from the core design.
Table 3-1
Relationships Across New Monitoring System Measurement Types and
Data Objectives
Objective
Monitor Types
(Primary/Secondary
Purpose)
Example Analyses/Rationale
Public reporting (continuous PM and ozone)
Local sites (primary)
NCore sites (secondary)
direct reporting through AIRNow
Emission strategy development (trace gases,
PM2 5 speciation, VOCs)
NCore sites (primary)
model evaluation, source
apportionment and other
observational models
Assessing effectiveness of emission reductions
and AQ trends (trace gases, PM2 s speciation
VOCs)
NCore sites (primary)
Local sites (secondary)
time series comparisons to
emissions projections
Support health assessments and NAAQS
reviews (trace gases, 03, PM (mass and
species))
NCore sites (primary)
Research and local sites
(secondary)
ambient input to exposure models;
direct association analyses
(cont.)
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Table 3-1
Relationships Across New Monitoring System Measurement Types and
Data Objectives (cont.)
Objective
Monitor Types
(Primary/Secondary
Purpose)
Example Analyses/Rationale
Compliance (NAAQS comparisons) (PM25,
PMi 0-2.5. ozone)
Local sites (primary)
NCore sites (secondary)
point and spatial field comparisons
to NAAQS
Science support (all pollutants)
Research sites (primary)
NCore sites (secondary)
methods evaluation, size
distribution analyses, diagnostic
analysis (model processes, particle
formation)
Ecosystem assessment (NOy, HN03, NH3, 03)
NCore sites
mass balance analysis, deposition
calculations
3.2 System Design Attributes
Given the NCore multipollutant site data objectives, there are several basic design
attributes for the NCore sites:
Collocated multipollutant measurements. Air pollution phenomena across ozone,
particulate matter, other criteria pollutants, and air toxics. From an emissions source
perspective, multiple pollutants or their precursors are released simultaneously (e.g., a
combustion plume with nitrogen, carbon, hydrocarbon, mercury, sulfur gases, and
particulate matter). Meteorological processes that shape pollutant movement,
atmospheric transformations, and removal act on all pollutants. Numerous
chemical/physical interactions underlie the dynamics of particle and ozone formation and
the adherence of air toxics on surfaces of particles. Yet, the current monitoring
infrastructure is developed on a style pollutant basis.
The overwhelming programmatic and scientific interactions across pollutants demand a
movement toward integrated air quality management. Collocated air monitoring will
benefit health assessments, emissions strategy development, and monitoring. Health
studies with access to multipollutant data will be better positioned to identify
confounding effects of different pollutants, particularly when a variety of concentration,
composition, and population types are included. Air quality models and source
attribution methods used for strategy development also will benefit from a multipollutant
approach. Modelers will be able to perform more robust evaluations by checking
performance on several variables to ensure the model produces results for correct reasons
and not through compensating errors. Just as emission sources are characterized by a
multiplicity of pollutant releases, related source apportionment models yield more
conclusive results from use of multipollutant measurements. Multipollutant
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measurements also streamline monitoring operations and offer increased diagnostic
capabilities to improve instrument performance.
In addition, in moving aggressively to integrate continuous PM (e.g., both mass and
speciation) monitors in the network, it is important to retain a number of collocated filter
and continuous instruments, as the relationships between these methods are subject to
future changes brought on by modifications of aerosol composition. For example,
assuming proportionally greater sulfur reductions from nitrogen reductions, nitrate will
replace sulfate as the major inorganic component, and aerosol sampling losses because of
volatility may increase at different rates depending on instrument type.
As it is not possible with constrained resources to measure everything everywhere, a
natural conflict arises between the relative value of spatial richness and multiple
parameters at fewer locations. This Strategy assumes that there is a geometric increase in
value gained from combining measurements at a single location, rather than spreading
out single measurements in a very rich spatial context.
Emphasis on continuously operating instruments. Continuous systems allow for
immediate data delivery through state-of-the art telemetry transfer and support reporting
mechanisms such as AIRNow, and critical support for a variety of public health and
monitoring agencies charged with informing the public on air quality. Continuous data
add considerable insight to health assessments and address a variety of averaging times,
source apportionment studies that relate impacts to direct emission sources, and air
quality models that need to perform adequately over a variety of time scales to increase
confidence in projected emissions control scenarios.
Diversity of "representative" locations across urban (large and medium size cities) and
rural (characterize background and transport corridors) areas. National level health
assessments and air quality model evaluations require data representative of broad urban
(e.g., 5 to 40 km) and regional/rural (> 50 km) spatial scales. Long-term epidemiological
studies that support review of national ambient air quality standards benefit from a
variety of airshed characteristics across different population regimes. The basic urban air
monitoring networks must include sites in locations that allow EPA to develop a
representative report card on air quality across the nation, a report that can delineate
differences among geographic and climatological regions. Although "high"
concentration levels will characterize many urban areas, it is important to include cities
that also experience less elevated pollution levels or differing mixtures of pollutants for
more statistically robust assessments. It also is important to characterize rural/regional
environments to understand background conditions, transport corridors, regional-urban
dynamics, and influences of global transport. These design issues are discussed further in
Section 5, which addresses rural monitoring.
These various design attributes differ from historical approaches that emphasized
maximum concentration locations, often dependent on a particular pollutant. Those perspectives
remain valid from a local perspective and need to be addressed through elements of local, single
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pollutant-focused measurement sites, as well as through local discretionary monitoring
conducted outside the scope of the basic urban monitoring networks.
3.3 NCore Multipollutant Measurements
3.3.1 General Measurement Considerations
The approximate total number of NCore multipollutant sites (75), as well as the number
of proposed measurements reflect a modest recommendation for balancing total network growth
while introducing manageable network realignment. Site locations will be based on design
criteria that also balance technical needs with practical considerations, such as leveraging
established sites and maintaining geographic equity. The network is to be phased in over several
years after promulgation of the applicable regulatory revisions.
The minimum recommended measurements (Table 3-2) include continuous gaseous SO2,
CO, NOx and NOy, and ozone (O3) measurements, and continuous PM2.5 and PM10-2.5
measurements. PM10-2.5 measurements have been included in anticipation that EPA will
promulgate a new PM NAAQS that includes requirements for measuring PM10.2.5. In addition,
the inclusion of PM10-2.5 as part of multipollutant measurements will support health studies and
emission strategy development. Additional parameters include filter-based PM2.5 (with FRMs),
PM2.5 speciation, and basic meteorological parameters, including temperature, relative humidity,
wind speed, and direction. In addition, integrated nitric acid and ammonia samples will be
collected, although the methods and sampling frequency remain under consideration at this time.
Although these parameters include most criteria pollutants except nitrogen dioxide [NO2]
and lead [Pb], they are not chosen for compliance purposes. Instead, they represent a robust set
of indicators that support multiple objectives, including accountability, health assessments, and
emissions strategy development (e.g., air quality model evaluation, source apportionment, and
numerous observational model applications). In most cases, these minimum measurements will
be accompanied by existing measurements. For example, aerosol sulfate from the speciation
program combined with gaseous SO2 provides valuable insight into air mass aging and
transformation dynamics.
The monitoring for most of these parameters will be conducted using near continuous
monitors, with reporting at 1-hour intervals or less. The continuous PM measurements are not
expected to use FRM monitors, given that no PM2.5 continuous monitor currently has
equivalency status. As a peripheral benefit, the presence of collocated integrated and in-situ
continuous aerosol methods will provide a continuing reference check for the performance of
continuous instruments and will address some of the network collocation requirements to meet
Regional Equivalency (see Section 8). Collocation with FRMs is an important component of the
PM2.5 continuous implementation strategy, as the relationship between FRMs and continuous
monitors drives the integration of these systems. These relationships will vary in time and place
as a function of aerosol composition (e.g., gradual evolution of a more volatile aerosol in the
East as carbon and nitrate fractions increase relative to more stable sulfate fraction).
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3.3.2 Measurement Issues
The philosophy for the NCore multipollutant measurements is to use commercially
available, reasonably priced continuous instruments that are not considered research grade or
laboratory bench operations. Admittedly, the list of new measurements includes trace gases that
pose challenges. Although these measurements may not be viewed as classic research level
operations, they nevertheless will require a level of attention not typically associated with routine
monitoring. EPA has included trace gas measurements in these multipollutant sites, because
they are of such national importance and need to be adequately characterized in the ambient
atmosphere. EPA expects that some of the additional burdens for conducting these
measurements will be offset by the efficiencies gained from locating multiple instruments and
enhancing the Information Transfer Technology capabilities, such as frequent zero baseline
adjustments, at monitoring platforms. EPA continues to consider ammonia and nitric acid
monitoring methods and sampling frequency issues, in part to ensure that the resources needed to
monitor those constituents are reasonable. These technology issues are discussed further in
Section 8, below.
Table 3-2
NCore Parameter List
Measurements
Comments
PM2 5 speciation
Organic and elemental carbon, major ions and trace metals (24 hour
average; every 3rd day)
PM2 5 FRM mass
typically 24 lir. average every 3rd day
continuous PM2 5 mass
1 hour reporting interval for all cont. species
continuous PM< 10-2.5) mass
in anticipation of PM,i0-25) standard
ozone (03)
all gases through cont. monitors (except HN03 and NH3)
carbon monoxide (CO)
capable of trace levels (low ppb and below) where needed
sulfur dioxide (S02)
capable of trace levels (low ppb and below) where needed
nitrogen oxide (NO)
capable of trace levels (low ppb and below) where needed
total reactive nitrogen (NOy)
capable of trace levels (low ppb and below) where needed
ammonia (NH3)
currently under consideration
nitric acid (HN03)
currently under consideration
surface meteorology
wind speed and direction, temperature, pressure, RH
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3.3.3 Future Multipollutant Measurements
The minimum recommended NCore multipollutant measurements reflect a balance across
a constrained resource pool, available monitoring technologies, and desired measurements.
Consideration should be given to introducing additional measurements at selected sites in the
future. Examples of nationally important measurements that support multiple objectives include
true nitrogen dioxide and continuous measurements of nitric acid, ammonia gases, and particle
size distributions. Consideration also should be given to routine particle size distribution
measurements at selected locations. As multipollutant stations, EPA and its partners should
over-design these sites in terms of space and power consumption with the expectation of
additional future measurements. Such over-design also will encourage collaboration between
research scientists and government agencies, given that the NCore sites should accommodate
periodic visits from health and atmospheric scientists who may conduct specialized intensive
sampling.
3.4 Siting Considerations
The siting goal for NCore multipollutant sites is to produce a sample of representative
measurement stations to service multiple objectives. Siting criteria include:
Collectively
Approximately 75 locations that are predominantly urban, with 10-20 rural/regional
sites.
Urban: a cross section of urban cities, emphasizing major areas with a population
greater than 1 million. Also include a mix of large (0.5 to 1.0 million) and medium
(0.25 to 0.5 million) cities with geographically and pollutant diverse locations
suitable as reference sites for long-term epidemiological studies.
Rural: capturing important transport corridors, including national, continental, and
intercontinental scales, and regionally representative background conditions. In
addition, some sites should allow for characterizing urban-regional coupling (e.g.,
how much additional aerosol does the urban environment add to a larger regional
mix).
Individual site basis
"representative" locations not impacted by unique local sources (urban sites, 5-40 km;
rural sites, greater than 50 km), which is important for using the data in air quality
modeling development and validation.
leverage with existing sites where practical, such as the speciation, air toxics, PAMS,
and CASTNET trends sites.
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consistency with collective criteria (i.e., does the selected site add holistic network
value).
logistical practicality.
3.4.1 Guidance for Site Selection and Site Allocation Proposal
a. Broad-based Technical Guidance. The NCore multipollutant network design is
initiated by considering a cross-section of urban locations to support long-term epidemiological
studies, with subsequent addition of rural/regional locations to support national air quality
modeling evaluation and emissions strategy accountability assessments, followed by a practical
mapping of these general locations with existing sites, and finally an equitable and objective
allocation scheme. This sequential approach is captured in Figure 3-2. This procedure provides
a modest, objective basis on which to judge the adequacy of the site allocation process (see
below).
Figure 1: Population-based Air Quality Regions
Current/Planned
Urban & Rural PM 25 Speciation Networks
Rural background, transport
(internal, global)
Figure 3-2: National maps providing initial broad scale siting guidance for NCore
multipollutant sites. The maps include recommendations based on supporting long-
term health assessments (top left) that emphasize an aggregate of representative
cities and air quality mode evaluations that rely on rural background and transport
locations (top right). Existing site locations in most cases will be used for NCore
siting (bottom).
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b. Site Allocation Process. The allocation scheme (summarized in Table 3-3) is based
largely on historical and political considerations (e.g., one NCore site per state) that distributes
monitoring resources based on a combination of population and geography, which in broad terms
is consistent with several technical design aspects. Technical guidance sets a framework for
assessing the development of NCore multipollutant sites, while the allocation scheme provides a
process for facilitating implementation. This allocation scheme provides a sweeping range of
metropolitan areas. Clearly, the allocation must be flexible enough to ensure that sites add
meaningful value and avoid redundancies. Suspected shortcomings in the proposed allocation
scheme that need to be reconciled include, for example, a lack of rural locations in California,
lightly populated Western states that may not provide a meaningful rural location, multiple
Florida locations with generally moderate air quality due to marine influences, and possible
redundant locations along the East Coast and Midwest. To ensure that the collective national
siting criteria are followed, NCore sites will require approval by the EPA Administrator (or
delegate). An NCore network design committee will be constituted to review site locations and
facilitate site selection approval.
Table 3-3
Proposed NCore Multipollutant Site Allocations
Total
Major
Cities
> 1.0 M
Large Cities
0.5 -1.0 M
Medium
Cities
0.25 - 0.5 M
Rural
1 per state minimum
50
TBD
TBD
TBD
TBD
added 2 in most populated states
(NY, CA, TX, Fl)
8
TBD
TBD
TBD
TBD
added 1 in each second tier populated
states(OH, IL, PA, MI, NC)
5
TBD
TBD
TBD
TBD
additional rural sites
12
TBD
TBD
TBD
TBD
total
75
32
13
10
20
Note: allocation does not cover every major, large, medium sized city in United States; states lacking
cities greater than a 250,000 population can provide rural coverage
c. Process for Input into Specific Site Locations. The number of sites and their
distribution portrayed in Table 3-3 is only a first approximation that requires added input and
consideration to reach decisions on actual site locations. Site locations will be influenced by a
combination of logistics associated with SLT capabilities and existing infrastructures, and input
from SLTs and the health effects/exposure, atmospheric sciences, and ecosystem assessment
communities. OAQPS and the Regional Offices will serve largely as facilitators for this siting
effort. EPA Regional Offices will work with their states (including local agencies and Tribes)
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and RPOs to provide initial suggestions based on logistics and design considerations with which
the states and Regional Offices are most familiar. EPA OAQPS will solicit input from the
research community through a combination of existing committee and organization structures,
workshops and meetings. There likely will be some iteration and negotiation involved in this
outreach effort. The multi-year phased approach for implementation will allow for the necessary
outreach and adjustments to start the NCore multipollutant approach on the right track.
d. Design Concerns. Inevitably, there will be spatial coverage gaps given the limited
number (75) of NCore sites. This concern is balanced by the expectation that these sites are only
minimum recommendations that serve as models for additional network modifications. This
concept is similar to the PM2.5 speciation program, where the majority of state SIP sites operate
similarly to the National trend sites.
Also, although the proposed allocation scheme is based largely on population and
existing EPA Regions, the intention is to set the basic design goal and allow for regional
flexibility to choose the most appropriate and practical locations. This type of flexibility is
necessary to ensure that the siting decision process takes into account the needs of the multiple
environmental and program objectives for the monitoring. For example, long-term
epidemiological studies are best served by obtaining data from a cross-section of different cities
with varying climates, source configurations, and air quality characteristics. Air quality model
evaluations require similar locations, as well as proportionately more information on rural and
background locations (along with vertical characterization of the atmosphere, which is beyond
the scope of NCore multipollutant monitoring). Siting for accountability purposes benefits from
"representative" locations. Often, this factor may favor obtaining information from rural
locations more so than urban locations, given the difficulty of separating source signals in urban
environments. For example, nitrogen in urban locations is dominated by mobile sources,
whereas in selected rural locations, such as CASTNET sites, the emission signals from major
utility sources are less affected by area-wide sources.
e. Accurate Site Characterization Data. In using ambient data for modeling and
assessments, EPA promotes the use of spatial analysis techniques to resolve the spatial gradients
based on point measurements. For that reason, it is important to have an accurate
characterization of the spatial representativeness of monitoring sites. Under this Strategy, the
NCore multipollutant sites are intended to represent relatively broad spatial scales. Accordingly,
these sites will require a dedicated effort to characterize their spatial representativeness. A key
element of future network assessments should be a technically sound analysis through modeling
or other means that establishes the average (as well as some indication of variance as driven by
topography and meteorology) of spatial representation of a monitoring site.
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3.5 Measurement Technology Strategy
The minimum measurements required at NCore multipollutant sites require the
implementation of some advanced continuous and semi-continuous measurement technologies.
With the exception of trace level CO, SO2. and NOy, these measurements can be made using
methods that are currently available in 40 CFR and the QA guidance provided in the QA
Handbook, http://www.epa.gov/ttn/amtic/qabook.html. Trace level CO, SO2. and NOy will
require the development of additional technical guidance to allow implementation of continuous
monitoring. The following provides an outline of the implementation strategy by measurement
type needed.
Filter-based FRM PM2.5 Mass and Ozone. Approved FRM and FEMs will be used to
implement the procedures described in 40 CFR Part 50, Appendices D and L.
Continuous PM!f/PM 10-2.5'- EPA is proposing regulatory requirements to measure
PM10-2.5 to support implementation of emerging PM NAAQS. Forthcoming guidance on
PM10-2.5 monitors will provide the basis for implementation. PM10-2.5 will be phased in
during the latter stages of the NCore network.
Continuous PM2.5 Mass: These methods will be implemented through the strategy
outlined in the "Continuous Monitoring Implementation Plan." These methods may
include, but are not limited to, TEOMs, beta attenuation monitors (BAM), beta gauges,
and nephelometers.
Basic Surface Meteorology . Temperature, relative humidity, wind speed, and wind
direction measurements will be obtained through a variety of methods described in the
guidance provided in "Meteorological Monitoring Guidance for Regulatory Modeling
Applications," EPA-454/R-99-005, February 2000
(http://www.epa.gov/scram001/guidance/met/mmgrma.pdf). These methods include, but
are not limited to, anemometers, wind vanes, resistance temperature detectors, and
hygrometers.
Total Reactive Oxides of Nitrogen (NO J: NOy measurement methods will be based on
the technical guidance prepared for PAMS in June of 2000. This guidance lacks
calibration procedures that include difficult-to-convert organic nitrate compounds (e.g.,
n-propylnitrate) to provide a more stringent test of converter efficiency. Implementation
of NOy monitoring methods will require an update to the existing PAMS guidance to
incorporate new calibration procedures.
Continuous, trace level CO. Commercially available, non-dispersive infrared (NDIR)
monitors that include modifications to enhance performance and offer "high-sensitivity"
options to meet the requirements of monitoring non-urban air will be implemented. The
principal constraints on lower detection limits of these devices are water vapor
interference and background drift. These limitations can be reduced by drying the sample
air and frequent chemical zeroing of the baseline. Currently, these modifications are
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done manually by the user. Prior to implementation, technical guidance will be
developed that will include a detailed description of the interferences and limitations, and
how to address them to obtain trace level measurements.
Continuous trace level SO2. Measurements of SO2 suffer similar issues with sensitivity
in rural areas as CO. Technical guidance will be developed prior to implementation of
trace level SO2 measurements.
Direct NO2. Measurement methods will be incorporated as the measurement technology
advances and is commercially available. EPA's Office of Research and Development is
currently evaluating prototype instruments.
Integrated nitric acid and ammonia. While both of these constituents will be monitored
at NCore sites, the specifics on the methods and sampling frequency for these two gases
will be determined after EPA establishes appropriate data quality objectives for these
monitors. See Section 8.1.1, below, for further discussion of the possible methods and
other technology issues for these monitors.
3.6 Using the NCore Multipollutant Site Approach to Enhance Network
Integration
Initial reviews of the monitoring strategy have suggested the need for greater integration
into areas that extend beyond the traditional roles of routine networks operated by SLTs. More
specifically, CASAC and CENR have advocated for greater attention to ecosystem assessment
support, coordination with intensive process oriented field campaigns, consideration of sites
dedicated to inter-continental pollutant transport, and a linkage to a wealth of satellite data.
Sections 4 through 6 below, look more closely at other monitoring networks in the urban, rural,
and Indian Country areas, and suggest some of the ways in which this Strategy can foster
integration and cooperation between those monitoring resources.
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4. Other Monitoring in Urban Areas
4.1 Streamlined SLT NAAQS Monitoring
In addition to the NCore multipollutant sites, SLTs will continue to operate additional
sites designed for NAAQS compliance and local issues. These sites are much more numerous
than the NCore sites, focus generally on the more important criteria pollutants, augment the
NCore multipollutant site network, and are sometimes referred to as "adjunct sites." Primarily
dedicated to defining needed information for nonattainment areas, many of these sites will
continue to be single pollutant and targeted mainly to PM2.5 and ozone. Such sites will help
define the nonattainment areas and boundaries, monitor in areas with the highest concentrations
and the greatest population exposure, provide information in new growth areas, meet SIP needs,
and evaluate local background conditions. Many of these sites already function as part of the
current SLAMS/NAMS air monitoring program. For other pollutants, this Strategy anticipates a
significant reduction in the number of operating sites (see Table 4-1). Although these sites need
only include one pollutant measurement, this Strategy strongly encourages collocating other
measurements at these sites.
Table 4-1
Potential Reductions in Number of Monitors for Various Pollutants
Pollutant
Operating Number of
Monitors (Approximate)
Long Term Number
(Approximate)
PM10
1,072
0
(except as part of PMi0-2.5)
Carbon Monoxide
445
250
Sulfur Dioxide
465
300
Nitrogen Dioxide
413
50
Lead
184
50
These sites will continue to implement the FRM and FEM (or Network approved
methods as are expected to be developed for regional equivalency of PM2.5 continuous methods)
required for criteria pollutant monitoring and attainment/non-attainment decisions as currently
described in 40 CFR, Part 50. No new monitoring technologies or methods will need to be
developed for implementation. However, siting for this monitoring requires Regional
Administrator approval. Where possible, sites should be optimized for multipollutant purposes,
although multipollutant monitoring is not required. For example, there may be opportunities to
collocate ozone and PM monitors without degrading the network information that is derived
from having separate ozone and PM locations.
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4.2 Local, Flexible Monitoring Component
In addition to the NAAQS monitoring described in Section 4.1, there is also a local,
flexible component to the Strategy. This part recognizes that there are specific local needs that
need to be addressed with air monitoring. Local considerations include such things as addressing
environmental justice concerns, air toxics "hot spots," community concerns, local source
impacts, political considerations, and a host of other elements that can be important on a local
level. EPA will continue to support these efforts. For instance, as part of this Strategy, EPA
remains committed to supporting local-scale toxics monitoring and other local toxics programs
(generally through Section 103 and Section 105 grant funds).
By incorporating this flexible part of the overall monitoring structure, both national and
local needs can be addressed. In many situations, monitoring conducted for local needs can also
be of value from a national perspective. Thus, SLTs are encouraged to utilize available
monitoring funding, after NCore multipollutant and other NAAQS monitoring requirements have
been met, toward local needs.
4.3 Near Roadway Monitoring
Over 1,000 compounds have been identified in exhaust and evaporative emissions from
motor vehicles. These compounds include criteria pollutants and air toxics. Motor vehicle
emissions significantly impact air quality and contribute to national emission inventories for
criteria and air toxic pollutants. Mobile sources account for over 75 percent of national CO
emissions, over 50 percent of national NOx emissions, and over 25 percent of national PM2.5
emissions. For air toxics, mobile sources significantly contribute to air pollutant concentrations
of gaseous and particulate phase compounds. For example, mobile sources emit over 50 percent
of the nation's benzene, toluene, and acetaldehyde. PM air toxic emissions include metals, ions,
and semi-volatile organic compounds.
Given that an estimated 35 million people live within 100 meters of a four-lane roadway,
near roadway exposure from these mobile source emissions is an important concern. It cannot
properly be thought of as either a "hotspot" issue affecting relatively few areas in a city or a
broader component of particulate matter NAAQS attainment issues. Near roadway exposure
may, in fact, emerge as one of the dominant urban air quality issues. Air quality measurements
collected near roads often identify elevated pollutant concentrations at these locations, as well as
pollutant composition and characteristics that differ from those measured at a distance from
roadways.
Elevated pollutant concentrations near roadways may lead to elevated exposures for
populations working or residing near these roads. In addition, these populations may experience
exposures to differing physical and chemical compositions of certain pollutants. The location of
schools near major roads may also result in elevated exposures for children due to potentially
increased concentrations indoors, increased exposures during outdoor activities, or increased
exposures while commuting to school (e.g., walking along roads or riding in a school bus or
passenger vehicle). Mobile sources influence temporal and spatial patterns of regulated gases,
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air toxics, and PM concentrations within urban areas. Since motor vehicle emissions generally
occur near the breathing zone, near roadway populations may be exposed to "fresh" combustion
emissions as well as combustion pollutants "aged" in the atmosphere.
Results from emissions and exposure studies suggest that simple methods of estimating
the contribution of motor vehicle exhaust to exposure likely do not capture the substantial
variability in the chemical and physical characteristics of motor vehicle exhaust that may be
leading to adverse health effects. Comprehensive assessments of exposure will be a critical
factor in identifying which compounds are leading to adverse health effects in the near roadway
environment.
With this background, EPA's Strategy currently involves (1) recognition of the
importance of near roadway exposures, and (2) the need for further exploration of what these
exposures mean for both urban NAAQS-oriented monitoring networks and air toxics networks.
EPA anticipates discussing these issues both internally and with partners and other stakeholders
over the coming months, and then continuing to develop specific elements of a near roadway
monitoring strategy that can be adopted into this overall Strategy document.
4.4 RadNet and Homeland Security
Currently, RadNet is the nation's only comprehensive radiation monitoring network, with
more than 200 sampling stations located throughout the United States. In February of 2001, a
key national monitoring system meeting was held in Montgomery, Alabama, the purpose of
which was to redefine the mission and objectives of the network and to develop an initial
conceptual design to guide the reconfiguration of the network into the future. A significant
outcome of the meeting was the determination and agreement that support of the Agency's
emergency response responsibilities was to be the primary purpose of the network's current and
future radiation monitoring capability. The working mission of the system to be designed, it was
agreed, would be: To monitor radionuclides released into the environment during significant or
major radiological emergencies. Three basic objectives that would support the system's mission
also were defined:
To the extent practicable, maintain readiness to respond to emergencies by collecting
information on ambient levels capable of revealing trends.
Ensure that data generated are timely and are compatible with other sources.
During events, provide credible information to public officials (and the public) that
evaluates the immediate threat and the potential for long-term effects.
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The RadNet planning team not only recognized the linkage between emergency response
and the monitoring network, but considered the relationship of the monitoring network to other
related emergency response assets. In August of 2001, the planning team provided a vision of
the new monitoring system that was developed on the basis of four design goals:
Better Response to Radiological Emergencies
More Flexible Monitoring Capability
More Integrated and Dynamic Network
Meet Needs within Realistic Costs
The terrorist attacks on the United States on September 11, 2001 expedited and strongly
influenced the subsequent planning for updating and expanding RadNet. In January 2002, EPA's
Office of Radiation and Indoor Air (ORIA) began a self-assessment of the existing monitoring
program in light of homeland security concerns, and very early on decided that the air program
could best support homeland security objectives. As a result, the review of the other sampling
networks in RadNet was deferred to a later time, and the air network received full scrutiny in the
system assessment.
The ORIA self-assessment of the RadNet air network identified two major system
weaknesses and three proposals to solve them, as shown in Table 4-2.
Table 4-2
Post-9/11 Weaknesses Discovered in and Solutions Proposed for the RadNet Air
Monitoring Network
Weakness
Proposed Solution
Decision makers need data more
quickly than is currently possible.
Add real-time monitoring capabilities.
Assessing widespread impacts from
an incident that might occur
anywhere in the United States will
require data from more locations
than are currently monitored.
Significantly expand the number of locations with fixed monitors.
Provide the flexibility to augment the fixed locations with
"deployable" monitors that can be either pre-deployed to a location
where there is an increased threat potential (such as a national
political convention, Olympics), or quickly deployed after an
incident to provide higher monitoring density.
Since planning prior to 9/11 had already endorsed the value and appropriateness of
deployable monitors in a new RadNet air monitoring design, and because these monitors could
be implemented more quickly, the first available homeland security funding (late 2001) was
committed to acquiring them. The attention then turned to updating the fixed system. Based on
the findings of the post-9/11 assessment and reinforced by similar findings in the earlier 2001
assessment, ORIA turned its attention to the system of fixed monitors to determine the most
appropriate equipment; to find the most acceptable plan for siting the monitors across the nation;
and to design an electronic capability for delivering verified data (from fixed as well as
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deployable monitors) quickly to decision makers and the public. By 2005, ORIA was able to
purchase an initial order of upgraded fixed station radiation monitors.
The specific objectives and data uses that have guided the development of the RadNet air
monitoring network are shown in Table 4-3. The objectives encompass the fixed monitoring
network augmented by deployable (mobile) monitors operating in either routine or emergency
mode. The objectives and data uses are presented in sequential phases reflecting the
chronological progress of an event and the parallel status of the system from routine, to
emergency, and back to routine.
-------
Table 4-3
Overview of Objectives and Data Uses for the RadNet Air Monitoring Network
Ongoing Operations/
Pre-incident
Early Phase (0-4 days)
Intermediate Phase
(up to 1 year)
Late Phase (after 1 year)
Fixed Monitors
Objectives
Provide baseline data
Maintain system readiness
Provide data to modelers
Develop national impact picture
Provide data to decision makers and
the public
Continue national impact
assessment
Reestablish baseline
Provide data to decision makers
and the public
Determine long-term impact
Monitor baseline trends
Provide data to decision makers and
the public
Data Uses
Pre and post event
comparisons
Provide public information
Adjust model parameters and verify
outputs
Assist decision makers in allocation
of response assets
Identify non-impacted areas
Help determine follow-up
monitoring needs
Verify or assist in modifying
protection action recommendations
Assist in determining if delayed
contamination transport is
occurring
Assure citizens and decision
makers in unaffected areas
Assist in dose reconstruction
Determine short- or long-term
baseline changes from event
Assist in determining if delayed
contamination transport is
occurring
Assure public that conditions are
back to normal
Ensure that recovery efforts are not
causing contamination spread
Verify return to previous baselines
_ , , , .. . (Options: May be Returned to
Deployable Monitors T u t A t- ux
* Laboratories or Remain in Field)
Objectives
Provide baseline data (if
deployed)
Ensure readiness by
conducting regular exercises
Provide data to modelers
Provide data to decision makers and
the public
Assess regional impact
Provide data to decision makers
and the public
Provide continuity of data in
impacted or non-impacted areas
Provide data to decision makers and
the public
Data Uses
Pre- and post- event
comparisons
Provide public information
Adjust model parameters and verify
outputs
Assist in identifying un-impacted
areas
Help determine follow-up
monitoring needs
Verify or assist in modifying
protection action recommendations
Assist in determining if delayed
contamination transport is
occurring
Assure citizens and decision
makers in unaffected areas
Help determine when to relax or
reduce protective actions
Assist in determining if delayed
contamination transport is
occurring
Ensure that recovery efforts are not
causing contamination spread
Note: Objectives and data uses may overlap from one phase to another.
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Currently, the plan for upgrading the RadNet network answers the overarching question
of "What changes should be made to the RadNet air monitoring component to best meet the
current needs for national radiation monitoring?" Instead of targeting just nuclear or radiological
accidents, the mission envisioned in this plan for RadNet now includes homeland security
concerns and the special problems posed by possible intentional releases of radiation to the
nation's environment. The plan proposes new monitoring equipment, more monitoring stations,
more flexible responses to radiological and nuclear emergencies, significantly reduced response
time, and much improved processing and communication of data. The ultimate goal of RadNet
air monitoring is to provide timely, scientifically sound data and information to decision makers
and the public. The plan currently is being reviewed by EPA's Science Advisory Board, and
remains subject to change. However, Table 4-4 provides a snapshot of the draft improvements to
the RadNet air monitoring network currently being considered.
Table 4-4
Main Improvements Proposed for RadNet Air Monitoring Network
Improvement Area
New System
Old System
Number of Stations
180 (approximately) fixed; 40
deployable
59 fixed; 0 deployable
Time for Data Availability
Near-real-time (4-6 lirs)
36 hours minimum (if on alert)
Criteria for National Siting
Population and Geography
Population and Fixed Nuclear
Facility Proximity
Local Siting Criteria
Derived from Title 40 Code of
Federal Regulations (CFR) Part 58
None
Data Dissemination
Central Database with Internet
Access
Hard copy
Meteorological Data
Yes -- deployables
Optional ~ fixed monitors
No
Telemetry
Phone (land line); cell phone;
internet; satellite link
None
Station mobility
40 deployable monitors
(in addition to 180 fixed stations)
None
Data Security
High
None
Operator Dependency
Primarily for air filter changes; no
operator action required for near-
real-time data transmission to
central database to support
emergency response
Completely operator dependent
Gross alpha/beta data
at station location
Gross alpha and beta
Gross beta only
(cont.)
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Table 4-4
Main Improvements Proposed for RadNet Air Monitoring Network (cont.)
Improvement Area
New System
Old System
Gross alpha/beta data
at station location
Gross alpha and beta
Gross beta only
U.S. Population Proximity (see
Section 3.6)
Approximately 60%
Approximately 24%
Frequency of Data Collection
Continuous (hourly data
transmission during routine
conditions) and two air filters per
week for fixed lab analysis
Two air filters per week for fixed lab
analysis
In addition to RadNet, EPA and partner federal agencies have deployed and will continue
to maintain and upgrade the BioWatch network. The goal of this network is to monitor the air
for biological material in largely urban areas. Further details about this network are unavailable
in this Strategy for national security reasons. In addition, the federal government will continue
to undertake biological and other monitoring of various defense installations for security and
surveillance purposes.
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5. Rural Monitoring
5.1 Importance of Maintaining and Enhancing Existing Rural Monitoring
Networks
EPA fully recognizes the importance of such existing rural monitoring networks as
NADP, CASTNET, and IMPROVE for their core objectives of tracking atmospheric deposition
and visibility. In addition, EPA recognizes the importance of these networks in tracking regional
background concentration levels for evaluating the effectiveness of regional control programs
such as CAIR. The current focus of EPA's strategy on reconfiguring the SLAMS and NAMS
networks for urban monitoring in no way diminishes the importance of rural monitoring to this
national Strategy. In fact, the reconfiguration of these networks provides an opportunity to
explore ways to integrate the rural monitoring networks with urban NAAQS-oriented networks.
Such integration must maintain the rural networks' core activities while making optimal use of
the data they produce. What follows is a brief description of these networks, and ongoing
strategic elements to enhance these networks.
5.1.1 NADP
The NADP now comprises several networks: the NTN, the MDN, and AIRMoN. The
NADP was established in 1978 to provide information on geographical patterns and temporal
trends in U.S. precipitation chemistry. A major objective of the program is to characterize
geographical patterns and temporal trends in atmospheric deposition of the United States.
a. National Trends Network. The NTN consists of about 250 long-term wet deposition
monitoring stations across the U.S. These sites are sponsored by cooperating agencies and
organizations that volunteer personnel, equipment, analytical costs, and other resources and
agree to follow the network's standard established procedures. The network involves over 100
organizations, including eight federal agencies, state and local agencies, universities, and private
industries. Five of the stations are located on Tribal lands within the states of Maine, South
Carolina, Michigan, Minnesota, and New York. NADP/NTN criteria and protocols ensure
uniformity in siting, sampling methods, analytical techniques, data handling, and overall network
operation. The NTN involves measurement of hydrogen (acidity as pH), sulfate, nitrate,
ammonium, chloride, and base cations such as calcium and magnesium. The network has one of
the longest multi-site records of precipitation chemistry in the world and has maintained an
effective quality assurance program throughout the years. EPA remains committed to supporting
this monitoring network.
b. Mercury Deposition Network. The MDN was established in 1996 to develop a
regional database on the weekly concentrations of total mercury in precipitation and the seasonal
and annual flux of total mercury in wet deposition. Atmospheric deposition is the prevalent
source of mercury to aquatic ecosystems. The data are used to develop an information database
on spatial and seasonal trends in mercury deposited to surface waters, forested watersheds, and
other sensitive receptors. Mercury is of special concern to state and local governments because
most states now post health advisories for the consumption of gamefish with excessive mercury
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levels. A national network is important to assist these state and local efforts given that most
advisories are issued in areas lacking point sources of mercury, and monitoring for mercury
transport plays an important role. With about 90 sites currently in operation, the MDN has
grown to be the largest network in the United States measuring total mercury in precipitation.
Around 20 state, Federal, and private organizations support the NADP/MDN. The Minnesota
Pollution Control Agency and the Wisconsin Department of Natural Resources are the two
largest participants in the program.
The deposition of atmospheric mercury occurs in wet and dry forms over multiple
geographic scales, with various environmental effects. The MDN provides data on wet mercury
deposition from precipitation. Although MDN is a step in the right direction for mercury
monitoring, a lack of scientific information on the dry mercury components as well as limited
geographic coverage over broader scales provide an insufficient picture of total (wet + dry)
mercury deposition and mercury atmospheric transport. Based on current model estimates, dry
deposition of mercury can be from 0.25 to 3 times the rate of wet deposition, depending on
location. The nation's ability to characterize and detect changes in mercury ambient air
concentrations and deposition rates is severely compromised due to a lack of ambient-air
speciated-mercury measurements needed to estimate dry mercury deposition. Tracking these
changes is an important component of EPA's obligations to assess and account for
implementation of emission control strategies to reduce exposure to mercury, including
promulgation of both CAIR and CAMR in 2005.
Monitoring mercury in the atmosphere is a relatively new concept that presents a number
of scientific assessment challenges. The three mercury compounds which contribute to dry
deposition - reactive gaseous (RGM), particle-bound (PHg), and elemental (Hgฐ) - are currently
not monitored systematically in the U.S. Close to sources that emit RGM and PHg, the impact of
mercury dry deposition can be substantial. Even though the estimated deposition rate of Hgฐ is
small, Hgฐ comprises more than 95 percent of the total mercury in air. Monitoring all three
forms of mercury compounds will enable better understanding of mercury deposition and
tracking of contributions from emission sources within and external to the United States.
EPA is proposing to work collaboratively with the NADP to build a foundation for
detecting future CAIR- and CAMR-driven changes in atmospheric mercury levels and expand
EPA's capacity for atmospheric mercury monitoring, modeling, and assessment. This
collaboration would plan and initiate an ambient-air speciated-mercury monitoring network for
temporally and spatially characterizing mercury concentrations in the atmosphere that will help
to ensure that baseline and long-term information needed to evaluate CAMR and CAIR is high
quality, transparent, and accessible. In addition, the new speciated mercury monitoring network
will provide data necessary to validate and improve existing mercury deposition models. The
EPA's ability to defend the existing models used to estimate mercury deposition is limited due to
the shortage of dry deposition data necessary to ground truth these models. Defensible
predictive air deposition models will be essential for further examination of this issue.
Additional objectives of the proposed speciated mercury monitoring network include:
identifying geographic and temporal variability and trends, characterizing regional and global
transport, and examining emission-source and deposition-ecosystem relationships.
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Initial development through this initiative would facilitate network start-up activities
(e.g., site selection, external quality assurance, and limited instrumentation purchase, installation,
and operation). Additional steps would be required to populate a broad scale network and
sustain operations longer-term. The plans for this mercury network development remain in the
formative stage. EPA anticipates that the final 2007 Strategy document will outline these plans
and EPA's implementation approach in greater detail.
c. Atmospheric Integrated Research Monitoring Network. The National Oceanic and
Atmospheric Administration (NOAA) sponsors the AIRMoN network. AIRMoN brings together
wet and dry deposition components to reveal the causes of observed trends. The AIRMoN-wet
program relies on common field equipment, a single analytical laboratory, and centralized
quality assurance. Daily samples are collected, and samples are analyzed for nitrate, sulfate, and
ammonium. The AIRMoN-dry program relies on a two-tiered approach that infers dry
deposition from air quality, meteorology, and surface observations and directly applies eddy flux
and/or gradient techniques. These methods yield average dry deposition rates to areas, typically
many hundred meters in radius, surrounding observation points. Observation sites are located
within areas that are both spatially homogeneous and representative of the large region.
AIRMoN provides a research-based foundation for operations of NADP and CASTNET.
A part of AIRMoN is dedicated to detecting the benefits of emissions controls mandated by the
Clean Air Act Amendments of 1990, and to quantify these benefits in terms of deposition to
sensitive areas. AIRMoN is designed to quantify the extent to which changes in emissions affect
air quality and deposition at selected locations. AIRMoN sites are to be chosen to optimize the
probability for detecting the change that is sought, and to serve related needs of effects
researchers. Specific sites are (and will be) emphasized, where operations of different observing
arrays can be collocated. Such Collocated Operational Research Establishments ("CORE sites")
will serve two additional distinct purposes: (a) to provide linkages among network programs
operating to address different needs with different protocols and (b) to provide the detailed
measurements necessary to understand important processes. A strong linkage with the emerging
National Environmental Monitoring Framework has been forged. NOAA continues to expand
AIRMoN, which currently includes eight sites, and anticipates a 20-30 site network.
5.1.2 CASTNET
In contrast to the NADP, which (except for the AIRMoN dry deposition sites) measures
wet atmospheric deposition, CASTNET focuses on dry deposition and, more recently, an
additional component to address fine particles and visibility. CASTNET measures ambient
concentrations of gaseous phase pollutants and aerosols (O3, SO2, HNO3, particulate nitrate, and
sulfate and ammonium species), along with meteorological parameters needed to estimate
deposition velocities and dry deposition fluxes of these constituents. CASTNET is the only
broad source of dry deposition data in the country. The data are used to determine relations
among emissions, air quality, and deposition and to provide information necessary to understand
the ecological effects of atmospheric deposition.
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With over a decade of data collected, CASTNET provides critical information necessary
in bench marking and understanding the impact of pollution on the environment and the
effectiveness of pollution management programs. CASTNET was deployed in the 1980s as part
of EPA's National Acid Precipitation Assessment Program (NAPAP). An assessment in the mid-
1990s led to a more optimized and less extensive network. The National Park Service, in
cooperation with EPA, operates 27 of the CASTNET sites.
Currently, EPA and other CASTNET partners are selecting, developing, and evaluating
an automated, semi-continuous monitoring system for routine use in CASTNET. The new
instrument will provide hourly sampling and analysis for a suite of particulate and aerosol
components, and allow for rapid, real-time availability of data. As part of the ongoing
development of this Strategy, EPA also will continue to explore ways to integrate CASTNET
with other networks, including deployment of rural NCore multi-pollutant sites (see Section 5.2,
below).
5.1.3 IMPROVE
The IMPROVE program is a cooperative measurement effort by a steering committee
composed of representatives from Federal and regional-state organizations. The IMPROVE
program was established in 1985 to aid the creation of Federal and state implementation plans
for the protection of visibility in Class 1 areas (156 national parks and wilderness areas) as
stipulated in the 1977 amendments to the Clean Air Act. The program currently consists of 110
aerosol visibility monitoring sites and additional instrumentation that operates according to
IMPROVE protocols. The 110 IMPROVE network monitoring sites were selected to provide
regionally representative coverage and data applicable to all 156 Class I federally protected
areas.4 Additional IMPROVE protocol sites include 65 aerosol samplers, plus transmissometers,
nephelometers, and cameras that fill identified data needs and enhance and fill spatial gaps in the
core IMPROVE network. The first sites began collecting data in 1988, and along with the
IMPROVE network expansion in 2000-01, provide the only long-term record available for
tracking visibility improvement and degradation.
The objectives of IMPROVE are to (1) establish current visibility and aerosol conditions
in mandatory Class 1 areas; (2) identify chemical species and emission sources responsible for
existing manmade visibility impairment; (3) document long-term trends for assessing progress
towards the national visibility goal; and (4) with the enactment of the Regional Haze Rule,
provide regional haze monitoring representing all visibility-protected federal Class 1 areas where
practical.
To fulfill this regulatory objective, the 110 IMPROVE sites collect and analyze every
third day 24-hour duration particle samples at sites chosen to represent the federal Class I areas.
Specifically, the network is set up to collect and process aerosol speciation data that can establish
the five-year averaged baseline and subsequent five-year averages of haze levels for the haziest
4 The Bering Sea Wilderness, on an uninhabited island in the Bering Sea about 200 miles off the Alaska Coast, is
deemed impractical for routine monitoring under the IMPROVE network.
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(worst) and clearest (best) 20% of days for as long as the regional haze rule is in effect (currently
envisioned as a 60-year process).
The IMPROVE network has been generally viewed as an efficient, uniform, and cost-
effective means to generate the required Class I area representative data needed for regional haze
trends tracking. While long-term consistency is the hallmark of a successful trends monitoring
program, a number of issues should be explored that may result in changes to monitoring for
trends tracking over the next 10 years. These include: the degree to which the current
monitoring sites represent the visibility-protected Class I areas, and the advisability of continued
use of filter-based sampling with the current suite of analyses.
The ultimate question for the issue of representativeness is whether the current network
sites adequately represent all of the Class I areas without redundancy. Some of the Class I areas
are large and situated in complex terrains, so that even if a monitoring site represents some
portion of the Class I area, it may not represent conditions in other parts of the same area. On the
other hand, the levels and temporal variations of some of the measured species (e.g. sulfates,
nitrate, and organic carbon) are similar at multiple IMPROVE monitoring sites within a region,
which raises the question of redundancy. However, simple comparisons of data from
neighboring sites could be misleading since sites that currently measure similar concentrations
may not do so under future emissions configurations. IMPROVE is planning to conduct a
network assessment that should be complete early in 2006 to explore these concerns.
Possible changes to the IMPROVE sampling and analysis protocols need to be carefully
tested and considered prior to implementation because of the possibility of introducing artifacts
that would detrimentally impact trends assessments. However it is likely that some changes will
be made over the next ten years. These may result from monitoring technology advancements
(e.g., high-time resolution speciation instrumentation for long-term monitoring application), or
changes in our understanding of atmosphere processes that identify other critical components
that should be monitored (e.g., inclusion of ammonium ion monitoring), or identification of
problems with the current monitoring approach that need to be rectified in order to generate data
of adequate quality. In addition to understanding their impacts on the data trends, any potential
change in the funding and practical consequences of potential changes need to be factored into
all protocol change decisions. The IMPROVE program continually assesses and adjusts protocol
for issues related to data quality, as well as considering the possible application of innovated
technology or changes to characterize additional atmospheric parameters.
In summary, the regional haze rule clearly calls for tracking haze trends via monitoring of
aerosol species at sites representative of the Class I areas over the anticipated 60-year period of
haze reductions as a means to assess the effectiveness of SIP-mandated emissions changes. The
110-site IMPROVE network supplemented by some IMPROVE Protocol sites selected to
represent some of the larger Class I areas currently fills this need. Over the next 10 years this
trends monitoring approach may evolve somewhat (i.e., minor changes in the number of sites
and/or monitoring protocols), but remains necessary for implementation of the regional haze
rule.
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5.1.4 Additional Rural Monitoring
In recent years, additional measurements have been made by a number of organizations
(principally regional planning organizations, or RPOs) to supplement IMPROVE and answer
fundamental questions about particle formation, speciation, transport, and precursors. All of
these studies are tied through collocation, correlation, or method to the foundation provided by
IMPROVE. These measurements are typically more specialized, regionally focused, and
generally have a 1-3 year lifetime. Establishing a longer-term or permanent monitoring network
is difficult for RPOs or states because a stable funding mechanism is not available and the
available funding varies from year to year. The data collected is used in multiple ways, but the
overarching goal of most monitoring programs is to provide information that can be used to
develop more technically sound State and Tribal Implementation Plans (SIPs and TIPs). For
example, data collected from the Midwest RPO urban organic speciation study is being used as
part of a comprehensive source apportionment analysis, which includes comparison with
previous source apportionment studies based on less detailed data. The study data will also be
used in photochemical model evaluation, emission inventory evaluation, and model
development, as well as contributing to the general characterization of organic carbon in urban
environments (sources, concentrations, seasonality) and continued growth of the regional
conceptual model for PM2.5 and haze. All of these analyses are part of a weight-of-evidence
approach to determining the contribution of emissions from states to downwind Class I areas, as
required by 40 CFR 51.308.
5.1.5 Conclusion on Existing Rural Monitoring
This Strategy seeks to foster continued support and enhancement of these networks and
to recognize the valuable contributions of additional monitoring studies conducted through RPOs
and others. Already, EPA and its partners have sought to optimize resources for these systems
by collocating monitors at various sites. In addition, EPA intends to seek ways to integrate these
rural networks with the NAAQS-oriented NCore multipollutant sites and other SLT monitoring
networks. The next two sections explore EPA's initial concepts for this type of integration.
5.2 NCore Monitoring: Urban/Rural Connection
NCore multipollutant measurements represent the mainstream national sites in the urban
monitoring network. The approximate total number of sites (75) as well as proposed
measurements are modest recommendations that attempt to balance total network growth while
introducing a manageable realignment in the networks. Site locations will be based on design
criteria that also balance technical needs with practical considerations, such as leveraging
established sites, and maintaining geographic equity. One element of designing appropriate site
location is the growing importance of capturing rural background conditions to support urban air
quality modeling and strategy development.
The multipollutant sites require diversity of "representative" locations, across urban
(large and medium size cities) and rural (characterize background and transport corridors) areas.
National level health assessments and air quality model evaluations require data representative of
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broad urban (e.g., 5 to 40 km) and regional/rural (> 50 km) spatial scales. Long-term
epidemiological studies that support review of national ambient air quality standards also benefit
from a variety of airshed characteristics across different population regimes. The NCore sites
should be perceived as developing a representative report card on air quality across the nation,
capable of delineating differences among geographic and climatological regions. While "high"
concentration levels will characterize many urban areas, it is important to include cities that also
experience less elevated pollution levels or differing mixtures of pollutants for more statistically
robust assessments. It also is important to characterize rural/regional environments to
understand background conditions, transport corridors, regional-urban dynamics, and influences
of global transport.
A related factor is that air quality modeling domains continue to increase. Throughout
the 1970s and 1980s, localized source oriented dispersion modeling evolved into broader urban
scale modeling (e.g., Urban Airshed Modeling for ozone) to regional approaches in the 1980s
and 1990s (e.g., Regional Oxidant (ROM) and Acid Deposition (RADM) Models to current
national scale approaches (Models 3 - CMAQ) and eventually to routine applications of
continental/global scale models. The movement toward broader spatial scale models coincides
with increased importance of the regional/rural/transport environment on urban conditions. As
peak urban air pollution levels decline, slowly increasing background levels impart greater
relative influence on air quality. Models need to capture these rural attributes to be successful in
providing accurate urban concentrations.
Thus, a starting point to foster integration of networks, such as IMPROVE and
CASTNET, with the NCore site network, will be to look for opportunities to coordinate NCore
siting with existing rural monitoring sites. Numerous issues will arise related to site selection
and measurement needs that will benefit from better communications across networks and
organizations. As part of this Strategy, EPA will seek to engage three separate disciplines
(ecosystems, health, and atmospheric processes) during the NCore siting process. These
disciplines often have different objectives, participants, and perspectives, but often they do share
data needs.
The possible steps taken to assimilate CASTNET measurements into the SLT national
networks also provide an important linkage to the NADP networks: NTN, MDN, and AIRMoN.
For instance, several CASTNET sites share locations with NADP sites. In addition, the MDN
will provide enormous value to the nation as it is the only infrastructure in place to monitor
mercury on a routine basis. EPA has been developing a specific strategy to increase our ability
to characterize PBTs that include mercury, dioxins, and persistent organic pollutants (POPs). In
addition, the promulgation of the Clean Air Mercury Rule in 2005 increases EPA's need to
obtain ambient gaseous measurements, in combination with precipitation and fish tissue mercury
data, to assess the rule's long-term impacts. Currently, gas phase mercury measurements are too
technically demanding and too cost prohibitive to be instituted routinely. However, the linkages
between the MDN and CASTNET, if also then linked into the NCore multipollutant network,
could enhance the ability to evaluate mercury measurements in coordination with a suite of other
pollutant measurements.
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Another area where EPA has identified opportunities for integration is between the
IMPROVE network and the PM2.5 Speciation Trends Network. IMPROVE data from Class I
areas are the key component of the regional haze monitoring strategy, but because these Class I
areas are nationally distributed, and since there is also a relatively widespread incidence of urban
areas (and some regions) which fail to meet the primary health standard for PM2.5 (15 ug/m3
annual average), IMPROVE data have taken on an important added objective of defining both
the fine mass and chemical composition of "regional background" PM2.5. The value of these data
for illuminating PM attainment issues may take on added future importance as EPA is currently
considering revisions to standards which include: a large reduction in the 24-hour primary PM2.5,
a new secondary sub-daily PM2.5 standard (for protecting visibility outside of Class I areas) and
new primary and secondary PM10-2.5 standards (see for example:
http://www.epa.gov/ttn/naaqs/standards/pm/data/pmstaffpaper 20050630.pdf).
The new PM2.5 STN was established in 1999, using methods adapted from (but not
identical to) IMPROVE. STN sites are primarily urban but there are also a number of new rural
speciation sites, many of which employ IMPROVE methods. These include the former
CASTNET "Visibility" sites, a number of state operated "SIP" sites, and several rural and urban
methods comparison sites where IMPROVE and STN sampling is conducted concurrently. The
new rural IMPROVE protocol sites help fill in the national map, enhancing regional coverage in
areas where Class 1 areas are sparse, and this expanded IMPROVE coverage, in turn, defines
regional-scale PM2.5 concentration and composition, enhancing the value of the urban STN data,
by allowing distinction between regional and local species composition and source contributions.
The urban STN data may in turn help identify the nature and location(s) of urban or industrial
sources that contribute to haze in downwind Class I areas, and can also help quantify the spatial
and temporal scales of large regional events (forest fires, dust storms, sulfate or nitrate episodes)
that affect urban and rural sites alike. As EPA moves to implement NCore multipollutant sites
and general (3-6) research-grade sites under this Strategy, EPA will assess the opportunities to
collocate rural NCore sites with IMPROVE sites in Class I areas (or other RPO sites). This kind
of multi-species, highly time-resolved information would provide a valuable complement to
existing routine regional haze monitoring programs.
Finally, recognizing the increasing importance of contributions from global scale
interactions, the network should include an explicit measurement linkage that addresses
international pollutant transport. Such a linkage can be established through integration with PBT
measurements, which often are impacted by global scale transport phenomena, as well as though
Sentinel sites located at key inflow and outflow locations near the coastlines and elsewhere.
EPA anticipates that a fraction of NCore multipollutant resources may be set aside for such
Sentinel sites.
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6. Tribal Monitoring
Currently, there are well over 100 Tribal air quality programs in various stages of
development across the United States. This is a dramatic increase from only nine programs in
1995. Many of these Tribes operate approximately 120 monitors in Indian Country that report to
AQS for several types of NAAQS pollutants, including PM2.5 and PMio (including some
speciation), ozone, nitrogen dioxide, and sulfur oxides. Tribes also operate sites in the
CASTNET, and NADP networks, and there are currently 11 Tribal IMPROVE protocol sites
operating in six different EPA regions. These numbers may increase as Tribes continue to build
the capacity to assess air quality on their respective lands. However, the maintenance and
growth of air quality monitoring also will remain linked to the availability of Tribal grant funds
to support these activities.
Within the context of the national air monitoring strategy set out in this document, it is
critical to note that in working with the Tribes on air monitoring, EPA is not setting a national
strategy for Tribal monitoring. Nevertheless, EPA does not intend to exclude Tribes from the
national air monitoring program as that program develops. It is also important to note at the
outset that EPA believes that Tribal monitoring is important within the broader national ambient
air monitoring strategy. While acknowledging these points, this strategy document does not
attempt to canvas the entire subject of Tribal monitoring. Two guidance documents that are
being developed by EPA in consultation with Tribes will provide considerably more detail on the
subject.
As the Tribes are autonomous, they are not bound by EPA's monitoring rules. However,
monitors in Indian country must be properly sited, use adequate technology, and follow
prescribed QA procedures if a Tribe wants to use data from the monitor to demonstrate NAAQS
attainment or nonattainment.
There is a growing movement in the United States of Tribal organizations taking an
increased interest in ambient air quality issues on Tribal lands. Tribes wishing to examine
ambient air quality issues on their reservations or Tribal lands should have a good working
strategy in place as they decide what their interests and concerns are in the development of their
work plan and program strategy. Tribal entities often decide that the best way to assess the
current air quality situation is through the use of ambient air quality monitors. A strategic
approach to monitoring should incorporate specific planning stages.
Initially, a Tribe will need to work with its EPA regional contacts to begin development
of a work plan that will be required for EPA operational grant funds and used to organize the
direction of the program. This is especially important in the planning phase, as many of the air
monitoring development steps can be incorporated into the work plan objectives and funded by
EPA, which will be committed to providing guidance and technical assistance throughout the
whole process. Note that, given the limited monitoring throughout Tribal lands, EPA believes
that Tribal network assessments similar to the national and regional efforts discussed in Section
2.5.3 are inappropriate for the relatively new Tribal programs, because those assessments
addressed aged and relatively dense monitoring networks.
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The national networks clearly can benefit by gaining additional monitoring sites in those
areas where Tribes participate in the national network. There are many rural Tribal airsheds that
could be considered for rural monitoring sites, potentially filling in important gaps in the national
network. In making determinations for siting rural monitors, EPA is committed to considering
Indian country on an equal basis, such as for CASTNET or a possible new mercury deposition
network. It is also possible that some NCore multipollutant rural stations might best be sited in
Indian country. These comments should not be perceived as suggesting that the Tribal
monitoring priority is fostering a connection to national networks. Monitoring priorities must be
based on Tribal decisions, which in many cases involve developing a better characterization of
local exposure to air pollutants. The linkage to national programs should be perceived as
leveraging opportunities that simultaneously benefit Tribes and the national network.
Another recent development over the past 3 years has been the establishment of the
Tribal Air Monitoring Support (TAMS) Center, which is a unique partnership between Tribes,
the Northern Arizona University Institute for Tribal Environmental Professionals (NAUITEP),
and EPA. Together, Tribal environmental professionals, ITEP, and EPA provide the full range
of air monitoring technical support, including monitoring network design, monitor siting, quality
assurance and quality control, and data analysis and interpretation. The TAMS Center
recognizes the sovereignty and diversity of Indian nations and is designed to build capacity and
empower Tribes to successfully manage their respective programs with equanimity on a national
scale.
Beginning in 2001, Tribes also have been active participants in the RPOs. The RPOs
have provided leadership in establishing needed rural monitoring throughout the central core of
the nation. As active participants in technical planning and monitoring operations of the RPO,
Tribes have been integrated for perhaps the first time in a large scale national monitoring
program. Through this interaction with RPOs, as well as participation in the current NAMS,
Tribes will likely operate some number of NCore multipollutant sites.
Finally, EPA is currently developing two new documents related to tribal air monitoring.
One will address internal EPA processes and goals. The other will provide guidance to Tribes
that are operating air monitoring stations or that are considering doing so.
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7. Quality System
Quality assurance is a major component of an air monitoring program and is necessary
for ensuring the availability of data of sufficient quality to justify investments made in the
program. Any reevaluation of air monitoring networks must include a reassessment of quality
assurance programs. To undertake such a reassessment, in 2000 EPA and individuals
representing state, local, and tribal interests established a Quality Assurance Strategy Workgroup
charged with developing the elements and activities of a quality system for an ambient air
monitoring program. A quality system is a structured and documented system that describes an
organization's policies, objectives, principles, authority, responsibilities, and implementation
plan for ensuring quality in its processes, products, and services. A quality system is a
framework for the organization's required quality assurance and quality control efforts, which are
essential to have confidence in the data collected.
The Quality Assurance Strategy Workgroup developed these key recommendations:
move toward a performance-based measurement process with specified data quality
objectives;
minimize start-up problems with a phased implementation approach;
provide a reasonable estimate of the costs associated with QA programs;
develop certification and/or accreditation programs;
accelerate data review and certification programs for quicker data access into the national
air quality data system (AQS);
eliminate redundancies to improve cost efficiencies;
develop appropriate data quality assessment tools (e.g., software); and
streamline regulations and, more specifically, identify those actions that should be
mandated through regulation and recommended through guidance.
Implementing the Strategy will require changes to the regulations and the development of
guidance. In addition, standard operating procedures (SOPs) to accompany the employment of
new instrumentation will have to be developed, as will appropriate requirements for the
infrastructure necessary to accommodate various sites within the national networks (so that
sufficient space, power, and access are included in site designs).
Any reevaluation of air monitoring networks must include a reassessment of quality
assurance programs. This section addresses the reassessment of these programs, as well as the
need for redeveloping a quality system that is germane, flexible, and responsive to changes in the
monitoring program.
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7.1 The Quality System
The primary requirements or elements for the Ambient Air Monitoring Program quality
system will be described in 40 CFR Part 58, Appendix A, and in guidance format in the second
volume of the QA Handbook for Air Pollution Measurement System. The elements are
identified in Table 7-1.
Table 7-1
QA Element and Activity List
Quality System
Elements
Activities
Planning
Data Quality Objectives
Performance Based Measurement Approach
Regulation Development
Graded approach to QA - QMPs/ QAPPs and SOPs
Guidance Documents
Implementation
Training
Internal Quality Control Activities
Data verification/validation
Data Certification
Assessment/
Reporting
Site Characterizations
Performance Evaluations (NPAP, PEP, Region/SLT Performance audits)
Assessment of Quality Systems & Technical Systems Audits
Data Quality Assessments
QA Reports
7.2 Planning Activities
7.2.1 Development of Data Quality Objectives (DQO)
The Data Quality Objectives (DQO) process is designed to ensure that the data collected
and/or funded by EPA meets the needs of decision makers and data users. The DQO process
establishes the link between the specific end use(s) of the data and the data collection process,
which is important for identifying the quality and quantity of data needed to meet a program's
goals. The result of the DQO process is a series of data quality indicators (e.g., precision, bias,
completeness, detectability) and acceptance requirements (called measurement quality
objectives) for those indicators.
OAQPS will be responsible for developing DQOs for federally mandated data collection
efforts such as the NCore multipollutant objectives. DQOs for other data collection activities
(e.g., non-trends speciation sites) would be the responsibility of other federal agencies and the
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SLTs using the graded approach to QA described later in this section. OAQPS will develop
DQOs on the basis of resource availability and current priorities set by the National Ambient Air
Monitoring Steering Committee; the process should be completed within two years, or at least
prior to full implementation of monitoring for an NCore or other NAAQS pollutant. PM2.5 and
ozone DQOs have already been developed. The precision and bias data quality indicators for
these two pollutants have been included in 40 CFR Part 58, Appendix A. As DQOs are
completed, they are added to the Code of Federal Regulations.
7.2.2 Move Towards a Performance-Based Measurement Process
A performance-based measurement system (PBMS) should be the primary tool for
selection or identification of appropriate methods for ambient air monitoring. The purpose of a
PBMS is to determine "what is needed" rather than "how to do it." Specifically, a PBMS is a set
of processes that specify the data quality needs, mandates, or limitations of a program, and serve
as the criteria for selecting appropriate, cost-effective methods to meet those needs. An
important element of a PBMS is the development of DQOs, which, in turn, help in the
development of federal reference method acceptance criteria (where needed). For example, the
DQOs developed for PM2.5 are now being used to determine the "acceptability" of continuous
PM2 5 monitors. Use of a PBMS helps to underscore the importance of identifying appropriate
data quality indicators and measuring quality objectives, and it will ensure that these are
consistently defined and measured so as to allow for the assessment of data comparability.
a. PBMS for NAAQS comparison objectives. Due to the regulatory requirements for
NAAQS comparisons, instruments used for this purpose will continue to meet the
performance specifications of the Federal Reference and Equivalency Method criteria.
b. PBMS for NCore objectives. Monitoring instruments used for the NCore objectives that
do not serve a dual purpose for comparison to the NAAQS do not necessarily need to
meet FRM/FEM criteria but must meet the minimum data quality requirements
developed through the DQO process that will be defined in the regulations and guidance.
c. PBMS for other non-Federal objectives. SLTs will be responsible for selecting methods
that will meet their data quality requirements for monitoring. The performance-based
approach lends itself to flexibility but will put more responsibility on the SLTs for
developing quality systems that meet their needs. Therefore, there will be a greater
importance and emphasis on QA project plan (QAPP) development.
7.2.3 Regulation Development
The QA Strategy Workgroup reviewed 40 CFR Part 58, Appendix A, in order to
determine what in the Appendix remained relevant to the Ambient Air Quality Monitoring
Program quality system. In addition to restructuring this Appendix for readability, the
Workgroup recommended these changes (see http://www.epa.gov/ttn/amtic/geninfo.htmQ:
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Combine PSD (40 CFR Part 58, Appendix B) into Appendix A. Appendix A and B are
very similar, and the Workgroup believed that these two sections could be combined.
QMP and QAPP approval: Regulatory revisions should provide more explanatory
information on quality management plans (QMPs) and QAPPs and mention that QAPP
approval can occur at the monitoring agency level as long as it is described and approved
in a QMP.
DQOs: OAQPS should have responsibility for providing DQOs for NCore and other
NAAQS objectives.
Graded approach to QA: The regulations should describe this process in order to provide
flexibility.
Quality assurance lead: Monitoring organizations should designate a quality assurance
lead with certain QA responsibilities.
Reporting organization and primary quality assurance organization: The regulations
should define these two terms in order to clarify the organization primarily responsible
for the quality of the data. An additional field in AQS may be necessary to accommodate
this change.
SO2 and NO2 manual audit checks (formerly Sections 3.4.2 and 3.4.3): These sections
should be removed.
Biweekly precision check concentration range: The regulations should change the ranges
to allow for lower concentration checks to be acceptable in cases where the majority of
the data from a site are below the current range requirements.
The regulations should change the PM10 collocation requirement to 15% of routine sites,
similar to PM2.5.
Provide for quarterly data certifications: Because of the emphasis on real-time reporting,
data quality validation and evaluation is occurring earlier in the monitoring process than
in the past. In addition, the QA Reports distributed by OAQPS (i.e., 1999 and 2000
PM2.5 QA Reports) have limited usefulness because the data are not evaluated until after
they are officially certified, typically 6 months after the calendar year in which they were
collected. Certifications could occur sooner, and a proposal for quarterly certifications is
being considered.
Revised Automated Precision and Bias Statistics: Statistics used to estimate precision
and bias should be changed, and should be calculated on a site basis as opposed to a
reporting organization basis, as appropriate. The paper on this approach has been
published for review.
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Based on these recommendations, EPA is proposing revisions to the QA requirements in
Part 58. That proposed rulemaking is expected to be signed in December 2005.
7.2.4 Using a Graded Approach to QA
As with any EPA-funded activity, EPA QA Policy requires monitoring organizations to
develop QMPs and QAPPs. Under the Strategy, the use of air monitoring data will have multiple
applications. Therefore, some monitoring objectives may not call for quality systems and quality
assurance documentation (i.e., QAPPS) to meet the stringent requirements for NAAQS
comparison purposes and may have data quality needs that differ. The revised EPA QA Policy
allows for a graded approach to quality assurance. This approach provides for some flexibility in
the development of QMPs, QAPPs, and DQOs. The Quality Assurance Strategy Workgroup has
developed and supports a graded approach for the Ambient Air Monitoring Program (see
http://www.epa.gov/ttn/amtic/geninfo.htmn.
7.2.5 Guidance Documents
OAQPS will continue to develop guidance documents relevant to federally implemented
monitoring programs. Within the next few years, guidance will be revised or developed for:
a. The QA Handbook. The primary guidance document for the Ambient Air Quality
Monitoring Program Quality System will continue to be the QA Handbook for Air
Pollution Measurement Systems, Volume II, Part 1. The Handbook was revised in 1998,
at which time it was recommended that it be revised at five-year intervals. Although it is
due for an update, EPA has decided to wait until the regulations are promulgated. It is
expected that QA requirements for the NATTS and for a coarse particulate program
(PM10-2.5) will be included in the next revision. Part 2 of the Handbook is used for the
reference and equivalent methods and will also be used for generic technical guidance for
other pollutant monitoring procedures used at NCore and other SLT sites.
b. Generic QAPP. Using the EPA Quality Staff QAPP guidance, OAQPS, in cooperation
with the Institute of Tribal Environmental Professionals (ITEP), is in the process of
planning for the development of a generic ambient air monitoring QAPP software
product that would allow the SLTs to input the appropriate QA information into each
section of their QAPP for their particular monitoring program. In FY 2003, OAQPS
received $50,000 of Tribal initiative funds to start development of this software product.
The final product will be available in September 2006.
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7.3 Implementation Activities
7.3.1 Training
Section 9 contains additional details on training for QA. This section considers the
implementation items related to training.
One way to place more emphasis on training is to establish a national accreditation
process to certify QA personnel. At a minimum, OAQPS will pursue the development of an
accreditation process for the Quality Assurance Lead defined in 40 CFR Part 58, Appendix A.
Although not mandatory, this accreditation process would foster a level of consistency across the
nation. As of April 2003, the EPA Quality Staff meets the criteria for certification established by
the Certified Provider Commission of the International Association for Continuing Education
and Training (IACET) and is authorized to issue Continuing Education Units (CEUs) when EPA
Quality Staff conduct the EPA Quality Systems training courses. EPA will develop a Quality
Assurance Lead accreditation curriculum using the Quality Staff courses and the courses
provided by the Air Pollution Training Institute (APTI). The following training related activities
provide potential opportunities:
Retraining: If capital expenditures are to be made on automating QC activities,
personnel normally performing these activities will have to be trained for alternate
activities. EPA will explore placing increased emphasis on data and network
assessments.
Conduct a poll for training: SLTs should be polled, perhaps through STAPPA/ALAPCO,
to determine what QA related training is needed.
Training at the annual QA conference: Since 2002, OAQPS has facilitated two days of
presentations and training at the annual EPA National Conference on Managing
Environmental Quality Systems. Approximately 30 to 50 SLT representatives have
attended the last four conferences. This conference provides training on a number of
courses that will be required for quality assurance lead certification mentioned above. An
ambient air monitoring QA related course (e.g., APTI courses) could also be taught at the
National Conference. SLT QA leads should be provided opportunities to attend this
meeting.
Develop web-based training programs: Based upon priority training needs, OAQPS will
pursue the use of web-based training courses, in particular, the APTI courses and a
training module related to the QA Handbook for Air Pollution Measurement Systems,
Volume II, Part 1.
7.3.2 Internal Quality Control Activities
The majority of the day-to-day QA activities at the SLT monitoring organizations involve
implementing or assessing quality control information, whether it be zero/span checks,
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collocated precision, or field trip or lab blanks. Each monitoring method has required and
suggested quality control samples that can be used to assess data quality of a phase (i.e.,
sampling) of the measurement system or the total measurement system. These QC checks will
be included in validation templates that will be developed for each of the NCore multipollutant
sites and for other SLT NAAQS-oriented measurements.
Accordingly, the PBMS principal will be used to develop the necessary quality control
samples in the regulations without mandating frequency and acceptance criteria. The CFR
should identify the types of QC samples that will provide assessments of attaining the DQOs. As
the PM2.5 DQO software tool shows, various combinations of uncertainty (i.e., precision, bias)
affect attainment of the data quality objectives. The CFR would be revised to identify the
uncertainties that would need to be measured, as well as the confidence sought in the estimate of
those uncertainties. The SLTs would then be responsible for developing a quality system that
would measure, assess, and control these uncertainties. Thus, SLTs would determine how often
to perform various QC checks, as well as the appropriate acceptance criteria. Using the data in
AQS, OAQPS would also assess data uncertainty to determine if an SLT had developed a quality
system that was "in control." For organizations with fewer QA resources or less experience, the
QA Handbook will continue to provide the suggested acceptance criteria and QC sample
frequencies through the use of the validation templates.
SLTs are strongly encouraged to invest in cutting edge data logging and automated
quality control and assessment technology. This technology would allow for more frequent QC
checks while reducing manpower burdens of site visits, and would provide monitoring personnel
more opportunity for data verification, reduction, and assessments.
7.3.3 Data Validation/Verification
Verification and validation are processes used to ensure that specified requirements (i.e.,
collocated sampling) have been fulfilled and that particular requirements for a specified use (i.e.,
collocated precision acceptable for NAAQS comparison) also have been fulfilled. Improvements
and activities to be implemented in this area include:
a. Developing validation templates. Since the development of the PM2.5 Validation
Template, there has been an interest in developing similar templates for all criteria
pollutants. The Quality Assurance Strategy Workgroup is nearing completion on
validation templates for the remaining criteria pollutants that will be incorporated into the
next version of the QA Handbook. Following the PBMS paradigm, use of the template
will not be considered mandatory but will provide useful guidance for organizations
developing QAPPs. As part of this Strategy, EPA intends to develop similar templates
for other NCore multipollutant measurements.
b. Providing more automated requirements for data review/verification/validation. An
initial capital expenditure on information capture and transfer technologies (e.g., data
loggers, telemetry, automated quality control) for automatic transfer of routine and
quality control information to central facilities should be considered. Included in this
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expenditure would be quality control systems for automating various QC checks, such as
zero/span checks, or bi-weekly precision checks. Various automated data evaluation
processes would be used to provide for more real-time consistent screening and data
verification/validation activities. Real-time data transfer technology would allow
personnel at centralized offices to implement various verification/validation techniques,
identify problems, and take corrective actions in real-time.
7.3.4 Data Certification and Quicker Data Access on AQS
The recent emphasis on real-time reporting of data means that real-time review,
verification, and validation of data have gained importance as well. Given more timely data
assimilation, the schedule for certification of a calendar year's worth of data must be improved
over the current six months following the end of the previous calendar year. Some SLTs have
already automated a majority of the data verification and validation efforts.
7.4 Assessment and Reporting
The following activities describe the various assessment and reporting features of the
quality system.
7.4.1 Site Characterizations
Site characterizations are a type of audit used to assess whether samplers or monitors at
the monitoring site meet the applicable siting criteria for existing monitoring objectives. Siting
criteria have been described for SLAMS, NAMS, and PAMS sites in 40 CFR Part 58, Appendix
E. Siting criteria for NCore multipollutant sites need to be addressed. The on-site visit consists
of physical measurements and observations of such elements as height above ground level,
proper spacing from various instruments, or distance from obstructions and roads. All NCore
sites should undergo complete site characterizations at the start of the program and/or at the start
of site implementation to ensure that the sites are appropriately characterized. As part of the
technical systems audit function, EPA Regions should confirm the site information for all NCore
and other SLT NAAQS-oriented sites every three years. It is also possible during audits that
Environmental Services Assistance Team (ESAT) personnel can perform certain aspects of the
site characterizations. This would allow for more frequent update and confirmation of site
characteristics.
Recommendations and action items for site characterization include:
Setting minimal levels and tracking. The requirements for the frequency of such
characterization would be changed, as necessary. In addition, better tracking of site
information would ensure that adequate site characterizations were being performed.
There is an area in AQS that can be revised for this tracking activity.
Ensuring updates made in AQS. Information such as that obtained from the inspection of
monitors, from sampling equipment added to the site, and from latitude/longitude
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changes could be described in the AQS tracking area noted above. The information
would be deleted once the changes had been confirmed.
Developing and using a site characterization form. A site characterization form (and
possibly software) could be developed and distributed to provide some consistency in
performing site characterizations.
Speeding up approvals for discontinued sites. SLTs submit paperwork for discontinuing
sites, but EPA approvals often take considerable time. OAQPS will review this process
and determine how to expedite the approval process.
7.4.2 Performance Evaluations
Performance evaluations (PE) are a type of audit in which the quantitative data generated
in a measurement system are obtained independently and compared with routinely obtained data
to evaluate the proficiency of an analyst or laboratory. Performance evaluations are an
obligation of the program agency, but the evaluation is conducted by a separate agency. OAQPS
will offer the following two types of audits. State and local agencies can either defray the
expense through a hold-back of STAG funds, or make arrangements for non-EPA independent
audits. In the latter case, EPA must certify that the independent audit services will provide data
comparable to EPA conducted audits.
National Performance Evaluation Program (NPEP). The NPEP program will service
NCore multipollutant and other SLT NAAQS-oriented sites. The following PE programs will be
included under the NPEP.
PM2 5 Performance Evaluation Program (PEP): This program has been operating since
1999 using the ESAT contractors to collocate FRM PM2.5 instruments at 25% of a
reporting organization's sites. In addition, during PM2.5 audits, EPA will audit speciation
monitors at both Speciation Trends sites and supplemental sites. This additional auditing
will cost approximately $150,000 per year.
National Performance Audit Program (NPAP): NPAP has been operating since 1970 and
is currently being retooled into a through-the-probe audit system implemented by EPA
Regional personnel and/or ESAT personnel currently implementing the PEP. OAQPS
has expended internal capital for the outfitting of five trailers and one vehicle.
Eventually, the PEP and NPAP programs will be combined into a single program. In
addition, OAQPS will evaluate the need for through-the-probe auditing in the NATTS
and may opt to outfit the NPEP laboratories for this activity.
NATTS proficiency tests samples: OAQPS will contract the development and
distribution of quarterly audit samples to the laboratories analyzing NATTS samples.
Details of these audits can be found in the NATTS Strategy document.
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Certification Programs. Certification programs provide independent testing of products
and/or instrumentation and are used to provide a sense of quality and comparability. The
following certification programs (with the exception of protocol gas) will be implemented for
NCore and other sites.
Standard Reference Photometer Program (SRP): The Standard Reference Photometer,
which is used to certify SLT monitoring organizations' ozone primary and transfer
standards, will continue to be implemented through the Office of Radiation and Indoor
Air (ORIA). The SRPs have been updated recently, and the Standard Operating
Procedures have been revised.
PAMS and NATTS gas cylinder certifications: ORIA currently performs gas cylinder
certifications for the PAMS program and is proposing a similar service for certifying
calibration standards for laboratories participating in the NATTS. Details of these audits
can be found in the NATTS Strategy document.
Re-investing in the protocol gas program: ORD for many years implemented a program
that tested gas standards supplied by gas manufacturers to monitoring organizations in
order to ensure some level of quality control over the gas manufacturers. The program
was discontinued in 1997 as part of the ORD divestment. Recently, in the face of market
in-roads by smaller vendors with potentially inferior quality products, some gas
manufacturing vendors have expressed an interest in resurrecting the program.
7.4.3 Assessments of Quality Systems and Technical Systems Audits
The following types of qualitative assessments will be implemented in the National
Ambient Air Monitoring System:
a. Assessments of quality systems. These assessments are systematic, independent, and
documented examinations that use specified criteria to review an organization's quality
system, mainly through the assessment of the organization's adherence to its quality
management plan. Every three years, EPA Quality Staff will assess OAQPS' quality
system, which will, in turn, assess the EPA Regions' quality systems. As part of the
technical system audits described below, the EPA Regions will assess the quality systems
of SLTs. This process should provide feedback on the strengths and weaknesses at all
levels of the Ambient Air Monitoring Program quality system.
b. Technical Systems Audit (TSA). TSA is a thorough, systematic, on-site, qualitative audit
of a system's facilities, equipment, personnel, training, procedures, record keeping, data
validation, data management, and reporting aspects. EPA will continue to require that the
EPA Regions perform a TSA of the primary quality assurance organization once every
three years. The TSA audit checklist, currently in the QA Handbook, will be revised to
reflect new monitoring methods and/or objectives, and to include questions relative to an
organization's quality management plan. An area for tracking audits will be developed
on AQS.
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7.4.4 Data Quality Assessments
A data quality assessment (DQA) is a statistical evaluation of a data set to establish the
extent to which it meets user-defined application requirements (e.g., DQOs). Historically, DQAs
have received little attention in the ambient air monitoring community. There will be more
emphasis on DQAs, however, given the move towards performance-based measurements
systems and DQOs. OAQPS will be responsible for the development of DQAs for all objectives
in which OAQPS has developed DQOs. DQAs will be performed with the same frequency as
priority decisions are made. For example, PM2.5 NAAQS comparisons are made with an
aggregation of three years of data; thus, DQAs for PM2.5 data would be performed once every
three years.
As DQOs are developed for the criteria pollutants, DQA tools will also be made
available, much like has happened with the modified PM2.5 DQO software. The tools are
expected to be integrated into AQS.
7.4.5 QA Reports
QA reports provide a means for distributing information on the Ambient Air Monitoring
Program Quality System. Two general types of reports will be developed at the Federal level.
a. Annual assessments of data quality indicators. OAQPS now offers automated reports
through AQS that provide assessments of the data quality indicators (e.g., precision,
accuracy, bias, and completeness) that are reported to AQS.
b. Interpretive reports. Following the discussion in the data quality assessment section,
above, interpretive QA reports will be developed at the same time as DQA and will
provide a more thorough discussion of the quality system. DQA results would be
included in these interpretive QA Reports.
7.5 Funding and Resource Issues
The expected schedule for full implementation of NCore and other monitoring will
determine the year-to-year resources required to implement the QA activities at EPA
Headquarters, EPA Regional Offices, and SLTs. To ensure that expectations are met, it is
imperative that the resources required to implement this quality system be enumerated and
acknowledged as appropriate. If an agency believes the funds are not appropriate, they should be
adjusted accordingly. In addition, QA activities must be intimately tied to the monitoring
process so that costs for the quality system either increase or decrease commensurate with
monitoring costs. Resource and funding related action items include:
Ensuring SLT funds are available for QA training. EPA provides regular and
continuing training on many aspects of air programs. It is important to include QA
training as part of the overall training program.
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Automating quality control procedures. Some implementation activities that are still
being performed manually by monitoring organizations (i.e., zero/span and precision
checks) could be automated. The technology section that follows discusses how to
increase awareness of this technology and move to more automated systems. However,
this Strategy recognizes that this modernization will require an initial expenditure of
capital for both equipment and training.
Applying STAG resources for EPA Conducted Audits. Currently, STAG funds pay
for the PM2.5 Performance Evaluation Program and NATTS Proficiency Test Program,
but not the NPAP, PM2.5 speciation, or NATTS (field component) programs. Quality
assurance is especially critical as EPA and its partners undertake new monitoring
approaches, such as increased use of continuous monitors. EPA's proposed rule revisions
will provide for a hold back of STAG funds to cover the cost of EPA conducted
evaluations. As discussed above in Section 7.4.2, EPA must certify data comparability
for other organizations that SLTs use to conduct audits.
7.6 Network Assessments
Network assessment is not a new process. State and local agencies historically have
conducted annual network evaluations, and changes to monitoring networks have been
undertaken and reported as part of this process. However, periodically, it is necessary to take a
more holistic review involving national, regional, and local agencies. As part of this Strategy,
EPA expects that a multi-level network assessment be conducted every five years.
The primary objectives of the network assessments are to ensure that the right parameters
are being measured in the right locations, and that network costs are kept at a minimum. Some
of the related secondary objectives include the following:
Identify new data needs and associated technologies;
Increase multipollutant sites vs. single pollutant sites;
Increase network coverage;
Reduce network redundancy;
Preserve important trends sites; and
Reduce manual methods in favor of continuous methods.
Guidance and training materials are needed for these future network assessments to
provide more structure to the assessment process. The guidance must promote greater national
consistency while allowing for flexibility due to the substantial differences among the regions.
OAQPS is currently preparing a Regional Assessment Guideline Document, which will be
complete by the beginning of the next round of network assessments.
With this in mind, the following steps are provided as a preliminary guide for the regional
network assessments, recognizing that further elaboration is forthcoming in the guideline
document currently under preparation:
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Step 1: Description - Each assessment should contain some basic descriptive material of
the region, to include topography, climate, population and trends, and general air quality
conditions. This section should be considered more of a boilerplate section, needing
updating as appropriate for each subsequent assessment.
Step 2: Network History - A description of the network evolution over at least the
previous 10 years is important in helping to establish a sense of changes that have already
been made in response to changing network needs. At a minimum, this description
should depict the total number of monitors in the region by pollutant and by year, either
in graphical or tabular format. At best, this should be accompanied by a detailed table
showing the history of each monitoring site. Then each successive five-year assessment
would simply append the most recent five-year history to the previous summary,
maintaining a continuous record of the monitoring networks.
Step 3: Statistical Analyses - Each assessment should include some level of statistical
analysis. At a minimum, site intercorrelations would help identify redundant sites. Also,
some comparisons to the NAAQS and trend analyses would help determine which sites
are well below the NAAQS and are not trending upward. Such sites, from a purely
statistical standpoint, could be candidates for divestment. Analyses can be more
complex, at the discretion of the Regional Office. Examples include spatial and factor
analyses, as well as innovative approaches using weighting schemes such as those used in
the National Assessment. The more detailed analyses can be used as important tools for
determining the adequacy of existing monitoring sites. Examples of the types of
statistical analyses that should be conducted can be found at
http ://www. epa. gov/ttn/amtic/netamap. html.
Step 4: Situational Analysis - Apart from the statistics, there are a myriad of other
factors that have bearing on network changes. These include, but are not limited to:
Value of maintaining long-term trends;
Closeness to the NAAQS;
Population changes (e.g., new areas of growth);
Existing maintenance plan and SIP requirements;
Sparseness of the existing network;
Special local circumstances (e.g., political factors); and
Needs of the scientific and health communities.
These factors can be considered subjectively, or more objectively by first identifying the
important factors and developing weighting schemes for each factor. The approach
would be at the discretion of the Region.
Step 5: Suggested Changes - Based on both the statistical and situational analyses, each
Regional Office should prepare a recommended list of network changes, by pollutant and
site, applicable to each state. Regional Office staff should engage in one or more
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workshops/meetings with state and local agencies for the purpose of sharing the results of
the initial analyses and explaining the rationale for any suggested changes.
Step 6: Interactive Discussions - State and local agencies should carefully review each
of the changes suggested by the Regional Office. Deviations from the initially
recommended changes are expected, but state and local agencies should present cogent
rationale for the basis of any deviation. It is expected that state and local agencies will
provide back to the Regional Offices their list of network changes, including those that
agree with the Regional Office recommendations and those that differ. There may need
to be one or more meetings between Regional Office staff and state and local agency staff
to refine the changes that must ultimately be approved by the Regional Office.
Step 7: Final Recommendations - Each Regional Office will provide a listing of the
final changes to the air monitoring network within its jurisdiction. These are to be
provided to OAQPS. The final listing should contain the following information:
Parameter changes (additions/removals/relocations);
Site changes (additions/removals/relocations);
A justification statement explaining (briefly) the rationale for the change; and
A timeline for implementation for each change.
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8. Monitoring Technology Development and Transfer
This section of the Strategy focuses on the technologies that EPA, SLTs, and other
partners will use to deliver timely ambient air monitoring data from the National Ambient Air
Monitoring System. During the planning stages of the Strategy, the Technology Workgroup,
with input from the Quality Assurance and Regulatory Review Workgroups, NMSC, CASAC,
and SAMWG, identified three overall needs for technology investments. In addition to the new
investments, the existing infrastructure for programs such as the ozone network will continue to
be employed. Other technologies such as routine CO, S02, and N02 monitoring and filter-based
PM monitors may be reduced depending on network assessments that take into account the new
investments. While other technology investments will likely be made during implementation of
the Strategy, most of those technologies will be supporting one of three major technology needs:
Timely reporting of high quality, highly time-resolved ambient monitoring data;
Collocated characterization of trace levels of CO, S02, NO and NOy; and
Highly time-resolved, spatially rich PM25 data.
The timely reporting of high quality, highly time-resolved ambient monitoring data will
require a coordinated effort to ensure that data management systems are meeting desired
performance needs. These data management systems will need to provide validated data, to the
extent possible, in near real-time to multiple clients within minutes of the ending of a sample
period. To realize full potential of the nation's ambient air monitoring networks, the data
management systems used will need to provide not only efficient processing and validation of
data, but also proper communication of that data in a format appropriate and available to multiple
users. The main impetus for improved data management systems is providing near real-time,
high quality hourly data from all NCore continuous monitors, as well as ozone, trace level CO,
NO, NOy, S02, and PM2 5 continuous data from other sites. By emphasizing the availability of
data in near real-time, the networks will better serve their clients by providing data as episodes
are occurring. This will allow technical and policy staff to better understand the exposure and
interactions of air pollutants in the present atmosphere.
The characterization of trace level gases and PM2 5 in near real-time is part of the
monitoring technologies emphasized in the networks. The use of monitoring technologies in the
networks is generally limited to reference and equivalent methods for gaseous criteria pollutants.
However, for trace gas analyzers of CO, S02, NO, and NOy, instrument manufacturers are
expected to be utilizing their base reference or equivalent methods with modifications to improve
their detection limit, and thus performance, at low concentrations relative to NAAQS levels. For
PM criteria pollutants, EPA is moving toward a base network of reference or equivalent methods
coupled with a larger network of approved continuous PM monitors that meet appropriate data
quality objectives.
The challenge for implementation will be to produce a framework that encourages
widespread adoption of the technologies described in this section, which some agencies already
use. Specific technologies will not be required in most instances; however, the measurement of
select parameters will be required at NCore sites, as appropriate. The concern with requiring
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specific technologies is that over time new technologies will become commercially available,
making existing technologies obsolete. One of the main tenets of the Strategy is adopting
Performance Based Measurement Systems (PBMS). Doing so for each parameter of interest in
the network will allow future technologies to enter the market-place and gain acceptance over
existing technologies if the data demonstrate that they are a better solution for the network. For
parameters of interest that do not have reference methods, the strategy will be to use PBMS
through a DQO process to identify both a relative standard approach to the method and
acceptable error rates.
Despite the need to invest in many areas of the ambient air monitoring program, doing so
indiscriminately may not lead to an improved system. The Technology Workgroup
recommended focusing on the following issues in addressing these concerns:
Making the right choice for a technology: For any one type of technology there may
be several choices to consider. The most cost effective choice right now may be outdated
in a year. Making the right choice requires careful consideration, and even then the
choice may not be optimum.
Transition from current to new technology: Important considerations in the transition
to new technology include downtime in the system and the need for a contingency plan
should the new system fail.
Training of Staff: New technologies may require a higher level of expertise than those
they are replacing.
Technical service: What, if any, service plan would accompany a new technology? The
need for a service plan may affect the true cost of the technology. Another important
consideration is the responsiveness of technical service.
Use of proprietary software: The use of software that is not in the public domain may
arise as an issue.
Ability to transfer to new technologies at a future time: Agencies must carefully
select technologies that do not preclude the selection of newer technologies in the future.
Identification of appropriate technical specifications: Appropriate technical
specifications should be included on purchase requests so that air monitoring agencies
make the right purchase of equipment. This is especially important where technologies
may have similar features, but the lower cost product is actually inferior and leads to
substantial problems to the end user. If purchasing agents are given an appropriate
amount of detail in the technical specifications, they may better avoid selecting the
inferior technology.
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8.1 Monitoring Technology
The advancement in computing and communications technologies over the past fifteen
years has significant implications for air quality monitoring. There is greater potential now than
at any time in the past to improve monitoring methods, monitoring support capabilities, such as
computer controlled instrument calibrations and quality assurance functions, and the transfer of
information to the public. Yet, some components of the monitoring networks continue to
function with less automation, efficiency, and speed than is necessary.
The technologies used in the ambient air monitoring program cover all hardware and
software used in the measurement, calibration, logging, transfer, storage, validation, and
reporting of data. Many of the areas identified are already using state of the art technologies.
For instance, much of the gaseous criteria pollutants are measured using continuous monitors
with automated features for calibration and data output. Other areas such as data transfer are
relying on technologies that may be outmoded or antiquated. Yet, because it operates well and
satisfies the needs of data users, it may not be an opportune area for investment.
Table 8-1 breaks down the major technology areas of the ambient air monitoring program
into individual technology elements, summarizes the state of technology used in a typical
ambient air monitoring program, provides recommendations for each technology element, and
provides a statement of the expected benefit of moving to this element.
Table 8-1
National Monitoring Strategy Technology Implementation Investments
Technology Element
State of Technologies
used in Typical
Program
Recommendations
Expected Benefit
Data Management
Systems - recording of
data from back of
instrument to datalogger
Analog connection.
Move to digital capture of
data. Could be RS232,
Ethernet, Fire Wire, etc.
Allows tracking of instrument
performance beyond just
concentration. Allows for
improved remote
troubleshooting and two way
communication directly to
instrument.
Telemetry systems
Everything from low
baud modems used on
standard telephone lines
to satellite, cable
modem, DSL, and other
high speed internet
systems.
Focus on performance
needs of moving low
interval data very quickly
to support real time
reporting and other data
uses. Choose most optimal
telemetry system
depending on availability
in area of monitoring.
Improves timely reporting of
data. In many cases, there
may actually be a reduced cost
for utilizing broadband over
dial-up modems due to
avoiding long distance
charges.
(cont.)
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Table 8-1
National Monitoring Strategy Technology Implementation Investments (cont.)
Technology Element
State of Technologies
used in Typical
Program
Recommendations
Expected Benefit
Data Validation
Limited range checks are
used on most systems.
Move toward
comprehensive automated
QC systems with graphical
display of data and point
and click validation.
Reduced manual validation.
Automated QC features
improves quality of real-time
reported data.
Data Reporting Format
For AQS reporting, bar
delimited format is used.
For AIRNow reporting,
"Obs" file format is
used.
Move to common "XML"
schema that can serve both
reporting needs.
XML is an open format that
most applications will be able
to read. By utilizing one
format, data analyses tools
that are developed for one
system will be compatible
with both systems.
Gas pollutants - CO, S02,
N02/NOy
Approved Reference and
Equivalent Methods.
Trace gas analyzers that
are also approved as
Reference and Equivalent
Methods.
Allows for tracking of trends
and signals that may be
important. Allows for better
model evaluation.
Gaseous criteria
calibration systems
Mixed - Everything from
fully automated to
manual.
Move all agencies towards
fully automated systems.
Improved data quality.
PM2 5 monitoring
Approximately 1,000
filter-based FRMs and
over 300 PM25
continuous monitors.
Develop hybrid network of
continuous and filter-based
monitoring to reduce
dependency on filter
network and optimize
resources.
Better spatial characterization
of PM2 5 for episodes.
Improved temporal
characterization. Reduced
operating costs.
8.1.1 Measurement Methods for Use at NCore Multipollutant Sites
This section considers the measurement methods to be implemented at NCore sites, with
a focus on the additional measurement methods that are not currently part of the routine
monitoring networks.
When possible, continuous methods should be implemented over manual methods. Most
importantly, continuous methods deliver data with a high temporal resolution so that the
atmosphere can be characterized on a time scale relevant to how it changes and how people are
exposed. In addition, continuous instruments are usually much less resource intensive to operate,
have a higher sample frequency, provide for greater precision due to reduced human
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intervention, are easier to automate with respect to data delivery, and provide data that are easier
to validate.
However, EPA also recognizes that a mix of continuous and integrated (e.g., filter,
canister, cartridge, denuder) systems in the networks will continue to be necessary for three
important reasons:
integrated samples allow for more extensive chemical and physical property analysis in
the laboratory;
due to uneven performance characteristics exhibited by continuous methods, collocated
integrated measurements enable appropriate transformations of continuous data, thereby
improving their quantification attributes (the basis for regional approved continuous
PM2.5 methods); and
retention of integrated methods allows for a smooth transition to new continuous
technologies with minimal compromise on the ability to construct air quality trends
analyses.
Thus, the broad, longer-term goal is to transfer from a network that consists of nearly
80% integrated and 20% continuous methods to one where continuous methods are the dominant
monitoring approach.
The minimum requirements for measurements atNCore sites are as follows:
Continuous PM10-2.5 and PM2.5 mass
Filter-based FRM PM2.5 mass
Continuous, trace level CO, SO2
Ozone
Continuous NO and NOy
Nitric acid and ammonia characterization (methods and sampling frequency remains
under consideration)
Surface meteorology (temperature, relative humidity, wind speed, wind direction)
In addition, SLTs will continue to operate and maintain additional NAAQS-oriented
sites. These sites will be used primarily for PM2.5 and ozone, with continued operation of lead,
CO, SO2, and PM10 sites only as needed.
The principal pieces of these sites are summarized in the following subsections.
a. Trace Gas Monitoring. One of the major areas of investment in the Strategy is for
the use of trace gas analyzers to characterize CO, SO2, NO2 and NOy at NCore monitoring
stations. These analyzers are basically the same instrumentation as approved reference and
equivalent methods; however, modifications have been made to improve the sensitivity of the
measurement. Utilizing trace gas analyzers instead of conventional gas analyzers, agencies can
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not only determine compliance with the NAAQS, they also can provide valid measurements at
much lower detection limits. Providing data at lower detection limits will allow for better
characterization of confounding factors associated with air pollution episodes given the
collocation of trace gas measurements at NCore sites. In addition, improved gas monitoring data
will result in reduced uncertainties in data sets used to model air pollution episodes and will
enhance an array of multiple factor-based source apportionment analyses. The true measurement
objective remains the characterization of actual levels of gases. Thus, in most cases, conversion
to trace gas methods and associated calibration regimes will be necessary given the low levels of
these gases in many "representative" NCore sites. For certain locations in urban areas where the
levels of these gases remain in the more conventional ranges, it will not be necessary to convert
to new trace gas monitors. Such situations will have to be addressed on a case-by-case basis.
The majority of ambient air gas analyzers operating across the United States were
established to compare monitoring data to the NAAQS. Analysis of these data has shown that
the majority of areas in the country are in attainment for the CO, SO2, and NO2 standards. For
NOy, for which there is no NAAQS, measurements are primarily used to characterize total
reactive nitrogen. However, where concentrations of NOy are shown to be below those for the
NAAQS for N02, it is reasonable to assume that the monitor is demonstrating attainment of N02.
b. Ozone Monitoring. The ozone monitoring network is expected to remain one of the
spatially-rich monitoring programs implemented throughout the United States. Although there is
a large network of ozone monitors in the United States, there may be opportunities through
network assessments to make better use of this network. This could potentially involve areas of
technology and planning associated with ozone monitoring identified below:
Realigning monitors: divesting of some redundant urban monitors and relocating them
from the high monitor density urban environment to areas of lower monitor density in
order to detect the spatial gradient of ozone.
Providing enhanced ozone QA, such as increased use of ozone calibrators.
Operating a minimum number of ozone monitors at NCore sites on a year round basis to
provide a better understanding of ozone seasonal differences and interactions with other
pollutants.
c. PM Continuous Mass Monitoring. The Strategy emphasizes PM continuous
methods as a major component. In response to requests from state and local agencies
(specifically through SAMWG) and from the CASAC Subcommittee on PM monitoring, EPA
has developed an ambitious continuous monitoring implementation plan. That plan is being
proposed in the December 2005 regulatory proposal.
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Major features of the PM continuous monitoring strategy include:
Support for a hybrid network of several hundred PM continuous monitors with a lesser
number of FRM samplers;
Use of performance based criteria developed in a DQO process to determine the
acceptability of PM continuous monitors in the individual networks where they are used;
and
Parallel DQO approach for approval and applicability of methods on a national basis.
The goal of the PM continuous monitoring strategy is to have a PM monitoring network
that can meet multiple monitoring objectives at lower cost.
d. Continuous Speciation Monitoring Generally. With continuous or semi-
continuous monitoring, networks can deliver data with a high temporal resolution that allows the
atmosphere to be characterized on a timescale relevant to how it changes and to how people are
exposed under dynamic processes. Excepting the 22 NATTS sites that include Aethalometer
instruments to measure black carbon, sites need not operate continuous speciation samplers.
Nevertheless, continuous sampler operations atNCore multipollutant and comparable sites
should gradually evolve. To this end, EPA is committed to supporting a 10-site continuous
speciation network to include carbon, sulfate, and nitrate. This commitment is rooted in
discussions with the health effects community regarding recommendations made by the National
Academy of Sciences in the late 1990s and continued by CAS AC.
However, given findings from the Supersites and other programs that indicate mixed
performance across a variety of monitors, EPA is cautiously approaching continuous speciation
monitoring. EPA coordinated a pilot study of semi-continuous PM2.5 speciation monitors at five
Speciation Trends Network (STN) sites (see Table 8-2). The pilot study began in 2002. The
goals of the pilot study were to assess the operational characteristics and performance of
continuous carbon, nitrate, and sulfate monitors for routine application at STN sites, to work
with the pilot participants and the vendors to improve the measurement technologies used, and to
evaluate the use of an automated data collection and processing system for real time display and
reporting. Results from this pilot work indicate operational issues with the effectiveness of the
flash volatilization process and/or thermal and catalytic conversion efficiencies. EPA has
worked with instrument vendors to discuss modifications and adjustments to the monitors for
resolving these issues. As the monitoring technologies improve and new technologies are
developed that are adequate for use in routine monitoring networks, EPA plans to support further
expansion of the monitors to a minimum of 10 STN sites.
New research has focused on the application of coupling ion chromatography with
aerosol collection and in parallel with criteria air pollutant sampling to provide complete gaseous
and aerosol species monitoring. These methods may offer the advantage of freedom from
artifacts, but they may also present design and operational challenges with adapting liquid
media-based chemical analysis to routine field monitoring use.
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Table 8-2
Current Continuous Speciation Sites (Urban)
Site Location
Measurements
Deer Park, TX
N03, S04, C
Indianapolis, IN
N03, S04, C
Chicago, IL
N03, so4, c
Phoenix, AZ
N03, SO4, c
Seattle, WA
NO3, so4, c
In addition, RPOs formed to assess regional haze have initiated continuous speciation
monitoring in rural locations (Table 8-3). The typical suite of measurements at these sites
includes:
continuous [hourly] PM2.5
surface meteorology
PM2.5 speciation, trends or IMPROVE or "IMPROVE protocol" 3rd-day filter 24- hour
average measurements for carbon, ions/elements, and PM2.5/PM10
visuals (HazeCam)
continuous sulfate
hourly EC/OC
light scattering [NGN-2 (wet) "IMPROVE-like" nephelometer]
trace level sulfur dioxide
ozone
Table 8-3
Regional Planning Organization (RPO) Sites with a Subset of Continuous
Speciation Monitors
Location
RPO/Site Type
Known or Expected
Measurements Beyond the
Standard Suite
Raleigh, NC (Milbrook)
VISTAS RPO/
suburban scale
standard suite
Look Rock, TN
VISTAS RPO/rural
Great Smokey Mountains NP (Class I)
standard suite
(cont.)
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Table 8-3
Regional Planning Organization (RPO) Sites with a Subset of Continuous
Speciation Monitors (cont.)
Location
RPO/Site Type
Known or Expected
Measurements Beyond the
Standard Suite
Cape Romaine, SC (Near
Charleston, SC)
VISTAS RPO/rural
Cape Romain NWR (Class I area)
Southeast Coastline
standard suite
Frostburg, MD
Mane-VU/MARAMA/rural
Western Maryland
trace CO; NOy; Profiler
Cornwall, CT
Mane-VU RPO/rural
Mohawk Mtn
standard suite
Bar Harbor, ME
Mane-VU RPO/rural
Acadia NP/(Class I)
trace CO
Bondville, IL
Midwest RPO/suburban
continuous ammonia, nitric acid,
nitrous acid, sulfur dioxide
St Louis, MO
Midwest RPO, urban (original EPA
funded supersite)
Sunset Lab continuous carbon
monitor
e. Nitric Acid and Ammonia Monitoring. Both nitric acid and ammonia are important
precursor gases to the major aerosol components nitrate and sulfate. It is important that these
measurements support air quality model and emission inventory evaluations, and that they track
the long-term progress of emission reduction strategies targeting nitrogen species. Beyond their
critical multimedia roles associated with watershed acidification and eutrophication, these
compounds must be measured within the national networks. Specifics on the methods and
sampling frequency for these two gases will be determined after EPA establishes appropriate
DQOs.
(i) Nitric acid. In the past, time-integrated systems for sampling and collecting nitric
acid have been widely used. These systems use either filter packs or a combination of coated
diffusion tubes followed by filter packs for sampling at the monitoring site. The samples are
then transported to a laboratory for analysis. These systems typically collect samples over
several hours and are therefore limited in providing fine temporal concentration resolution. A
major problem associated with nitric acid detection by point monitors is transport through the
system inlet. Studies are needed to identify the best transport tubing for real-time measurements.
EPA will not pursue semi-continuous measurements for nitric acid until the technology reaches a
higher level of maturity and proven reliability. EPA expects research of technology issues to
continue through a variety of federal and other efforts. Some of the technology developments in
this area include:
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Thermal denuders with selective coating, such as tungstic acid, have been used for semi-
continuous monitoring with data resolution of 30 minutes or less. The denuders are
thermally desorbed and measured by a chemiluminescence detector. Several versions of
parallel-operated denuder systems that are coupled to chemiluminescent detectors for
semi-continuous measurement of nitric acid and ammonium nitrate by difference
calculations have been developed. Commercial chemiluminescence monitors for NO
have been modified to design real-time nitric acid detectors using two inlets, one with
only a particle filter and another with a particle filter and a nylon filter. The difference
signal is attributed to nitric acid.
Wet denuders have been developed in which nitric acid is captured in an aqueous system
using diffusion scrubbers or parallel-plate-wetted denuders and then analyzed by ion
chromatographic or colorimetric means. Prototype instruments providing up to 10-
minute resolution at a detection limit of 10 ppb have been field-tested.
Real-time measurement of nitric acid has been possible using chemical ionization mass
spectrometry with detection limits of less than 15 ppt for a one-second sample interval.
Systems employing tunable diode laser absorption spectroscopy and open-path, multi-
pass Fourier transform infrared spectroscopy have been successfully operated for
monitoring nitric acid by interpretation of IR spectra. For nitric acid, the published
detection limits are 4 ppb for the diode laser and lOppb for the Fourier transform
instrument.
(ii) Ammonia Monitoring. Similar to monitoring nitric acid, monitoring ambient
ammonia can be conducted through a variety of time-integrated sampling methods and
continuous, real-time, or near real-time measurements. The most prevalent time-integrated
methods use acid scrubbers such as sulfuric, phosphoric, or boric acid to collect ammonia, which
is then analyzed through ion chromatography. Although these methods are inexpensive and
relatively simple to implement, their limitation is that temporal resolution is dictated by the
sample collection time; thus, the concentrations are not known until after laboratory analysis.
Other time-integrated methods involve the use of gas sorbent detector tubes or passive diffusion
devices or denuders of various designs (annular or honeycomb) coated with boric, oxalic,
phosphorous, and citric acids or sodium bisulfate.
Chemiluminescence monitors are widely used and are perhaps the most popular means of
measuring ambient ammonia concentrations. These monitors do not actually measure ammonia
directly. Instead, they determine the ammonia concentration by difference. To do this, a thermal
converter must oxidize the ammonia to nitric oxide, which is then further oxidized using ozone
to produce nitrogen dioxide, whose luminescence is measured. Two thermal converters
operating at temperatures either oxidize all nitrogen species or all components excluding
ammonia to produce a difference signal to represent the ammonia concentration. However,
because organic nitrogen compounds and nitric acid are known interferences, ammonia specific
scrubbers have been adapted to the monitors to adjust the measurements. These types of
instruments can typically detect ammonia down to approximately 1 ppb.
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Several optical systems have been adapted for use in real-time ammonia monitoring.
These systems include differential optical absorption spectroscopy (DOAS), Fourier transform
infrared spectroscopy (FTIR), tunable diode laser absorption spectroscopy (TDLAS),
photoacoustic spectroscopy, and ion mobility spectroscopy. Several recent research field studies
using photoacoustic spectrometers have monitored ammonia concentrations as low as 0.1 ppb,
with good accuracy over a range from 1 ppb to 3 ppb.
f. Aethalometers. The SAMWG Subcommittee recommended the use of
Aethalometers at every urban site in the NATTS. These instruments were added to the network
to measure black carbon, with the intent of developing an indicator for diesel emissions.
However, EPA recognizes that all mobile sources emit black carbon, and that other potential
urban sources, such as wood combustion, emit it as well. EPA continues to study the
relationship between ambient levels of black carbon and diesel emissions to asses the
effectiveness of this type of indicator monitoring. Technical guidance can be found in the
NATTS document found at http://www.epa.gov/ttn/amtic/airtxfil.html.
Aerosol black carbon is a primary emission from combustion sources. Black carbon is
ubiquitous and absorbs light. It can be found in diesel and gasoline exhaust, and is also emitted
from all incomplete combustion sources together with other species such as toxic and
carcinogenic organic compounds. The Aethalometer is a semi-continuous instrument that
measures black carbon using a continuous filtration and optical transmission technique. The
light attenuation through a sample spot and a blank reference are used to determine light
absorption. The absorption is converted to black carbon using an absorption coefficient. The
single beam Aethalometer (880 nm) is being used for the NATTS. An estimated detection limit
of 0.05 /ig/m3 black carbon for a 5-minute average is expected. Because no black carbon or
elemental carbon particulate standards are available for use in calibrating this monitor, only flow
rate calibration using a NIST-traceable device is possible. Although the Aethalometer will not
specifically measure diesel-related black carbon, it will be used in conjunction with other
supportive information (e.g., meteorology, measurement of other toxic pollutants, and traffic
patterns) to assess the impact of diesel emissions in the NATTS.
g. Deployment of Continuous Speciation Monitors. All of the identified monitoring
technologies, whether under development or commercially available, offer the potential for
providing either real-time or short time-averaged species data. These data will very likely aid the
health effects research and model development communities, which are both in need of highly
temporally-resolved monitoring data. However, given the limited practical field applications of
emerging monitoring technologies, EPA strongly advises that these new systems be collocated
with integrating methods for ensuring comparative assessments and eventual data
transformation. Such technologies should be encouraged for use at NCore multipollutant sites,
where there will be both time-integrated samplers and continuous gaseous monitors. This offers
the ideal opportunity for both comparative assessments and data integration.
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8.1.2 Organic Aerosol Speciation (Not Required)
EPA is working with technical experts in the field of molecular markers for organic
carbon to develop a document on using molecular marker measurements to assess the origin of
carbonaceous particulate matter. This document will be used to help educate and inform SLTs in
the use of molecular markers or tracers for source attribution. The primary focus will be on the
source attribution aspects, with a lesser focus on sampling and analysis. The document will
review the current molecular markers and their sources, strategies to address unknown sources,
new tracer species, the use of tracers in source apportionment modeling, strategies for
atmospheric sampling, considerations for source sampling, and requirements for chemical
analysis.
8.1.3 Implementation Products and Deliverables
Technical method guidance documents will be prepared to guide SLTs in the proper
installation and operation of NOy, and the trace level CO and S02 instruments. This method
guidance will provide information on the setup, installation, configuration, operation and
calibration of these instruments. This guidance is expected to be completed by the end of 2004.
In addition, SOPs that are prepared for EPA's on-site operation of these types of equipment will
be shared with SLT monitoring agencies.
The implementation of new measurement methods will require additional training. It is
expected that training will be provided by EPA, equipment manufacturers, and SLT monitoring
agencies. EPA's ambient methods training program will focus on instrument operations and
procedures. EPA uses a variety of mechanisms for both formal and informal training, including
workshops, satellite and video training, technical assistance, guidance documents, and EPA's
Ambient Monitoring Technology Information Center website at http://www.epa.gov/ttn/amtic/.
A public forum area allowing users to submit questions on monitoring is also available on this
page. The overall monitoring Strategy training implementation program is discussed as part of
the implementation plan outlined in Section 9.
8.1.4 PM Continuous Monitoring Implementation Plan Summary
An enlarged continuous PM monitoring network will improve public data reporting and
mapping, support air pollution studies more fully by providing continuous (i.e., hourly)
particulate measurements, and decrease the resource requirements of operating a large network
of over 900 filter-based reference and equivalent particulate samplers. The continuous
monitoring implementation plan provides recommended directional guidance to move forward in
deploying a valued continuous PM monitoring program operated by SLT governments. The plan
addresses a range of topics, including relationships between continuous and reference
measurements, performance analyses of collocated continuous and filter-based samplers,
recommended performance criteria, regulatory modifications, and identification of outstanding
technical issues and actions to be taken in the near future.
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The continuous monitoring implementation plan proposes a hybrid network of filter-
based and continuous mass samplers. The hybrid network would include a reduced number of
existing FRM samplers for direct comparison to the NAAQS, and continuous samplers that meet
specified performance criteria related to their ability to produce sound comparisons to FRM data.
The plan proposes two approaches for integrating continuous mass monitors to maximize
flexibility: (1) FEMs, and (2) an expanded use of non-designated approved methods identified
as Approved Regional Methods. For FEMs, new equivalency criteria will be derived based upon
a data quality objective exercise that matches the required performance criteria with the needs of
the data. Approved Regional Methods are analogous to the Regional Equivalent Monitors
(REMs) described in the continuous monitoring implementation plan. These monitors will be
approved in individual SLT networks where data quality meets specified criteria. EPA has
proposed criteria for approval of regional methods in the December 2005 regulatory revisions.
Performance criteria for use on a national basis for FEMs have been derived using the
DQO process. The major emphasis of the DQO process was to tie historical equivalency criteria
that use slope, intercept, and correlation with network operation DQOs that use bias and
precision. The major advantage, from a DQO perspective, of using PM2.5 continuous monitors
over filter-based FRMs is that they provide data daily. Many FRM sites operate on sample
frequencies of once every third day or once very sixth day. Having a method that provides a
daily sample will reduce the uncertainty of a decision with the data, as compared to a method on
a lower sample frequency, all other inputs being equal.
8.2 Data Management Technology
Over the last several years, one of the most important emerging uses of ambient
monitoring data has been public reporting of the Air Quality Index (AQI). This effort has
expanded on EPA's AIRNow website from regional-based, near real-time ozone mapping
products that are color coded to the AQI, to a national multipollutant mapping, forecasting, and
data handling system of real-time data. Since ozone and PM2.5 drive the highest reporting of the
AQI in most areas, these two pollutants are the only two parameters currently reported from
AIRNow. While other pollutants such as CO, SO2, NO2, and PM10 may not drive the AQI, they
are still important for forecasters and other data users to understand for model evaluation and
tracking of air pollution episodes. Therefore, this Strategy seeks the following goals for sharing
nationwide data in near real-time:
share all continuous O3, PM2.5, and PM10 data, where available; and
for NCore sites, share all gaseous CO, SO2, NO, and NOy data, and all base
meteorological measurements.
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9. Implementation Plan
The previous sections of this document provided the conceptual and design basis for
moving forward with a national monitoring strategy. This section provides a summary of the
actions that will allow transition from design to implementation. For many pieces of this
Strategy, EPA is still exploring and detailing the design elements, and a specific implementation
plan is premature. Section 9.1 discusses those elements. The implementation plan then
incorporates action oriented components of the Strategy, including regulatory revisions [Section
9.2], grants [Section 9.3], and guidance and training [Section 9.4], Section 9.5 then discusses
research sites, 9.6 discusses RadNet implementation, and Section 9.7 discusses plans for
implementing data capture, access, and analysis.
9.1 Continued Strategy Development
The CASAC Subcommittee's report recommended increasing integration with other
organizations and networks outside of the traditional SLT monitoring programs that are funded
through STAG resources. Opportunities exist to provide and receive reciprocal benefits from
established networks and organizations that are more focused, for example, on ecosystem
welfare or atmospheric processes, as compared to the NAAQS attainment emphasis in the
traditional monitoring networks.
Effective integration practices that enhance network economies and overall value need to
be pursued. However, the limits to full integration also need to be acknowledged. While the
intent to integrate has merit, there is no clear, compelling program necessity for individual
organizations to participate fully. In addition, no significant new funds to support full integration
are available or foreseen at this time. Given this context, it is imperative to proceed along a
fairly proactive pathway with modest and achievable objectives to maximize engagement. The
following actions are designed to facilitate greater network integration, and may serve as a
starting point for a more detailed plan governing integration of these monitoring networks:
Addition of Ecosystem Support as an Air Monitoring Strategy Objective. Consistent
with the CASAC Subcommittee, this Strategy adopts support for ecosystem welfare
assessments as a key objective.
NCore Multipollutant Siting. Numerous issues related to site selection and
measurement needs will arise that will benefit from better communications across
networks and organizations. For simplicity, three disciplines (ecosystems, health, and
atmospheric processes) are separated, as they often are attributed with different
objectives, participants, and perspectives yet share in some instances significant
commonalities in data. Interaction on ecosystem assessment and atmospheric processes
support will be solicited primarily through interactions with the Air Quality Research
Subcommittee (AQRS) of CENR. Similar dialogue on health effects and exposure
research support will utilize EPA's existing relationship with the Health Effects Institute
(HEI). Internally, EPA's health effects, toxicological, and exposure scientists will be
actively engaged in siting discussions. Within EPA, a design team consisting of OAQPS
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and ORD scientists will provide recommendations for siting criteria based on technical
needs associated with national scale model evaluation and data analysis objectives.
Actual siting recommendations are made by State and local agencies in cooperation with
EPA Regional Offices. Approval of these sites are made by the EPA Administrator.
CASTNET. EPA's Office of Air and Radiation manages the CASTNET network, which
provides a conduit to the atmospheric deposition and ecosystem assessment community.
With certain exceptions, there has been only limited coordination between the CASTNET
and the national networks operated by SLTs. Over the last four years, integration with
networks has been supported by the addition of IMPROVE PM2.5 speciation monitors at
eight CASTNET sites. Starting in late 2003, a pilot study was initiated to establish three
advanced monitoring sites at CASTNET locations to test new continuous speciation
technologies and trace gas instruments. These three sites may become rural NCore sites
(or research-grade sites, as discussed in Section 9.5) and also may provide some minimal
technology transfer support. Overall, developing a full strategy to integrate CASTNET
with other national networks is a key area for strategy development in the near-term.
Increased Coordination with National Atmospheric Deposition Program (NADP).
These positive steps taken to assimilate CASTNET measurements into the SLT national
networks provide an important linkage to the NADP networks: NTN, MDN, and
AIRMoN. Several CASTNET sites share locations with NADP sites. In addition, MDN
will provide enormous value to the nation, as it is the only infrastructure in place to
monitor mercury on a routine basis.
Increased Integration with the PBT Monitoring Strategy and Emerging Mercury
Monitoring Needs. EPA has developed a series of recommendations to increase our
ability to characterize persistent and bioaccumulative toxics (PBT) that include mercury,
dioxins, and persistent organic pollutants (POPs). In addition, in 2005 EPA promulgated
CAIR and CAMR. To assess the effectiveness of those rules in reducing mercury, EPA
will need ambient gaseous measurements in combination with precipitation and fish
tissue mercury data. As discussed in Section 5.1.1, EPA has proposed a plan to develop a
dry deposition mercury network.
Allocation of NCore Sites as Sentinel Sites for International Transport. Recognizing
the increasing importance of contributions from global scale interactions, the new
NAAQS-oriented monitoring network should include an explicit measurement linkage
that addresses international pollutant transport. Such a linkage can be established
through integration with PBT measurements, which often are impacted by global scale
transport phenomena, as well as through Sentinel sites located at key inflow and outflow
locations near the coastlines and elsewhere. Some NCore multipollutant sites may be
placed where they can serve as Sentinel sites.
Also, EPA's evolving Strategy in this area will have to consider how best to work with
NOAA and other workgroups on Sentinel sites. These groups can address the technical
issues with an international perspective and would assist in the design and support of
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routinely operating Sentinel stations. The primary objectives of these sites would be
characterizing fluxes of key pollutants into and out of the United States. The NCore
parameter list could serve as a subset, or at least exhibit considerable overlap, of desired
measurements from a transcontinental (and intra-continental) needs perspective.
Increased Communications with Exposure and Health Effects Research Community
and HEI. The PM Supersites program included support for health effects and exposure
research as one of three primary program objectives. Continued efforts must be pursued
to ensure that the networks are responsive to the needs of the health effects research
community. While the NCore multipollutant design is based, in part, on supporting long-
term epidemiological studies, there still needs to be an effective communications
mechanism to increase support to this community. Recent efforts by HEI have
incorporated the national networks as part of their ongoing agenda. EPA and HEI should
continue to pursue opportunities for integration. More specifically, EPA should engage
active researchers in the health effects community, and have a substantive meeting
addressing important locations (e.g., those cities with planned long-term studies), to help
prioritize NCore sites and comment on the parameter list. Additional attention also needs
to be given to the proposed "daily" speciation sites, which EPA intends to evolve into
approximately 10 continuous speciation sites as discussed in Section 8.
CENR/AQRS The AQRS of CENR is a multi-agency (EPA, NO A A, NPS, DOE, DOI,
and USD A) group positioned to foster integration across a variety of air related topics.
The AQRS has, in the past, pursued related inventorying of a variety of monitoring
network efforts and generally is well positioned to offer guidance to EPA on effective
approaches to integration. As of October 2005, AQRS had an ongoing project to develop
a white paper on the status of existing monitoring systems that will include
recommendations for improved use and integration of data from these systems. EPA will
work with AQRS to consider these efforts in ongoing development of this Strategy.
In addition to the issues of integration discussed above, additional issues are fully
expected to develop as the Strategy is implemented. As such issues arise, EPA will engage in
dialogue with the appropriate entities (e.g., SLTs) and the appropriate staff (e.g., monitoring
technical issues, funding issues, policy issues, etc.). EPA will engage in these discussions as
soon as possible after the issues are raised, so that potential implementation delays can be
avoided or at least substantially reduced.
In some cases, these types of issues have already been raised, and EPA has begun the
dialogue process. These include:
Near Roadway Exposures. EPA plans to discuss internally and with external partners
and stakeholders how to address emerging concerns over exposure in near roadway
microenvironments. This implementation plan will need to be updated as a design and
course of action are developed through that process.
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Satellite Monitoring. Satellites present a new technology approach for ambient
monitoring. How best to incorporate this technology into this Strategy is a key
technology issue to address over the next few years.
9.2 Rule Changes
EPA has promulgated three sets of regulations to provide the framework for how SLTs
conduct ambient air quality monitoring: 40 CFR Parts 50, 53, and 58. Part 50 applies to the
NAAQS and the federal reference methods for each pollutant; Part 53 provides air quality
monitoring equipment vendors with the application and testing requirements for federal
reference and equivalency methods; and Part 58 applies to ambient air quality surveillance. Parts
53 and 58 are the primary focus for regulatory changes needed to implement this Strategy.
The regulations only set minimum requirements. State and local agencies can, and are
encouraged to, exceed such minimums. Tribes, as separate sovereign entities, generally are not
required to meet these regulations, unless they want to use monitoring data to document NAAQS
compliance.
Monitoring regulation revisions are needed to remove potential obstacles in implementing
the Strategy and to foster technically creative instrument approaches and measurement systems.
The monitoring regulations remain the most authoritative guide for air agencies and will
ultimately serve as the principal communications tool to convey many of the details of the
Strategy to EPA's partners at the state and local levels. The specific topics targeted for
regulation changes are:
Reconfiguring the traditional NAMS/SLAMS monitoring components with reduced
number of single pollutant sites and adoption of the NCore multipollutant site framework
(40 CFR Part 58);
Establishing new minimum requirements in criteria pollutant monitoring to enable action
on results from the network assessments and the continuous PM monitoring
implementation plan (40 CFR Part 58);
Introducing new provisions for PM2.5 monitoring, including new performance based
criteria for Federal Equivalent Methods (FEMs) (40 CFR Parts 53) and Approved
Regional Methods (ARMs) (40 CFR Part 58);
Revising PAMS monitoring requirements to emphasize accountability as a primary
objective and to reduce non-type-2 sites (40 CFR Part 58);
Restructuring quality assurance requirements (40 CFR Part 58); and
Revising national equivalency specifications for PM2.5 and expected PM10-2.5 that will be
based on updated data quality objectives and structured to accommodate continuous
technologies (40 CFR Part 53).
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The development of these regulatory changes has been an ongoing effort since 2000.
EPA has established a workgroup process between EPA and state and local agencies, as well as
interaction with the NMSC. The workgroup has had many conference calls to identify: (1) those
portions of the regulations needing review and revision; (2) initial suggestions for changes; (3)
key issues and resolution of those issues; and (4) development of and comment on early draft
language. While the final proposed regulation is entirely under EPA's purview, much of the
necessary background effort was done in cooperation with the state and local agencies.
The specifics of the regulatory changes are not included in this document, as the
regulatory process will govern these details. The proposed regulatory revisions will be issued by
EPA in December 2005, with final changes to become effective after promulgation of final rules
that address public comments. The following discussion highlights some of the key areas that
the regulatory action will address.
9.2.1 Network Design and Criteria
Some of the fundamental changes to the regulations are to: remove the references to
NAMS sites; broaden the scope of "SLAMS" to include all state and local monitors except
special purpose monitors; and reconfigure the national monitoring program for NAAQS
compliance around the NCore multipollutant sites and a streamlined set of additional SLT
monitors (primarily for ozone and PM2.5). The revised regulation would establish:
Fundamental monitoring purposes and objectives.
The minimum design criteria, including specific requirements for the number of NCore
sites by State, and the minimum level of multipollutants to be monitored.
Minimum requirements for PM2.5. PM10-2.5, and ozone monitoring.
Minimum requirements for continuous PM2.5 monitors and for PM2.5 background,
transport, and speciation sites.
Requirements to monitor for lead, as part of a national lead trends site assessment, in at
least one location in each of the 10 EPA Regions. A location could be within the largest
CBS A within a Region, or alternatively, at one of the Urban Air Toxics Trends sites
within the Region.
Requirements for other pollutants including carbon monoxide (CO), oxides of nitrogen
(to include total reactive nitrogen gases, NOy), and sulfur dioxide (SO2).
Requirements to leverage other monitoring programs into the NCore site designs. These
could include PAMS, air toxics monitoring sites, and PM2.5 chemical speciation trends
sites.
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9.2.2 Changes to the PAMS Network
Consistent with the multipollutant objectives of NCore sites, the PAMS sites provide
more comprehensive data pertinent to ozone air pollution in non-attainment areas classified as
serious, severe, or extreme. There are four types of PAMS sites, but the primary focus under the
proposed regulations would shift to the Type 2 PAMS sites: those areas where maximum ozone
precursor emissions are expected.
9.2.3 Network Assessments
The proposed regulatory changes will include requirements for a network assessment
every five years. (See Appendix B for a discussion of the current round of network
assessments.) Along with this will be requirements for SLTs to develop a schedule for
implementing the network changes consistent with the findings of the assessment. The final
recommendations would have to be approved by the Regional Administrator prior to actually
making the network changes. Where deemed necessary and appropriate, other network changes
would be permitted in the years between network assessments.
9.2.4 Performance-Based Measurement Systems (PBMS)
As the move toward PBMS occurs, there will need to be some changes to the CFR.
Instruments used for NAAQS comparison purposes will continue to meet performance
specifications of the FRM/FEM criteria. For NCore objectives, instruments serving other
objectives will need to meet minimum data quality requirements developed through the DQO
process, and these will be defined in regulatory changes and guidance. More detailed
discussions are presented in Section 7.
9.2.5 QA Related Changes to 40 CFR Part 58 Appendix A
The following regulatory changes are expected:
Combine Appendices A and B into Appendix A
Process for QMP and QAPP approval
Responsibility for providing DQOs
Graded approach to QA
Quality assurance lead person
Defining a reporting organization and primary quality assurance organization
Removal of SO2 and NO2 manual audit checks
Bi-weekly precision checks - changes in ranges
Provide for quarterly data certifications
Revise automated precision and bias statistics
Responsibility to provide for adequate, independent evaluation audits
These QA elements are described in more detail in Section 7.
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9.3 Funding
Funding for SLT monitoring programs comes from Section 103 and 105 STAG funds.
EPA-led monitoring programs use a variety of EPA funding resources, including Science and
Technology budget funds. Generally, this Strategy implies moving resources from programs of
decreasing value to those of higher value, consistent with the principles presented in Section 1
(respecting the strong partnership across EPA and SLTs, retaining stability for the monitoring
programs, and accommodating SLT flexibility). At this time, the Strategy assumes that
resources will remain level, with no significant decrease in funding to support ambient
monitoring initiatives. This "zero-sum" constraint implies a reconfiguration of monitoring
networks. This approach contrasts with the process of expanding networks significantly with the
deployment of the PAMS and PM2.5 networks throughout the 1990s and early 2000s.
As EPA moves to finalize this Strategy by early 2007, these funding recommendations
will be discussed with SLTs, and the 2007 final Strategy will address these issues based on those
discussions.
9.3.1 General Funding Issues
One method of being able to accommodate improved monitoring with little additional
funding will be to shift from labor-intensive integrated methods toward more technologically
challenging continuous systems with enhanced data transmission and access capabilities.
Attending this shift will be a short-term need for adequate resources devoted to retraining staff,
quality assurance, and data analysis and interpretation.
The early Strategy discussions evoked a concern that any change in the networks,
especially a thinning in monitoring sites, would result in a reduction in resources and serious
degradation of monitoring agencies. This draft Strategy seeks to allay those concerns by
stressing the importance of retaining stable funding as a basic operating principle, and by
emphasizing a reallocation of skill mix (from labor to technical) and measurement approaches.
Retaining a stable funding base for monitoring agencies and Tribes is of paramount importance
among numerous resource concerns. Although many environmental assessment initiatives are
based on short duration (1-3 years) efforts, effective ambient monitoring practice requires a
longer, stable operation that can capture gradual signal changes in atmospheric concentrations
over decades. Those operations must maintain and enhance a substantial infrastructure. Both the
cost effectiveness and technical credibility of monitoring operations are compromised if operated
in a cyclical ramp up, ramp down mode. As implementation of this Strategy occurs, funding and
priority decisions must continuously balance the desire for network responsiveness and
flexibility with maintaining the necessary stable operations needed for long-term ambient
assessments.
Consistent with these goals and operating principles, the final implementation plan may
need to include a variety of funding shifts within the current program structure. These shifts
would require consensus building if there is no explicit pool of new resources. The basic shift of
moving resources from filter-based methods to continuous and trace gas measurements is
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relatively straightforward, although it requires a substantial communications and training effort.
To a lesser degree, there is a concern about the ability to reach consensus on funding sources for
national level quality assurance and data analysis. While the final version of this Strategy
scheduled for January 2007 will include details on these issues, the following discusses the
general concept of funding for QA and data analysis.
Over the course of deploying the PM2.5 network, EPA and states and local agencies
reached agreement on utilizing Section 103 STAG funds to support the PM2.5 performance
evaluation program, the national level quality assurance program enabling EPA to develop
estimates of FRM performance. The rationale for using STAG funds was predicated on the
understanding that such QA was a required element of the program, and it was more efficient to
manage the program nationally through EPA headquarters. Although consensus was reached on
this approach, there always remained an underlying philosophical concern regarding whether
such national QA should be funded through STAG or other EPA resources. From EPA's
perspective, the STAG resources had a track record of stability that is a prerequisite to maintain
support for quality assurance efforts; whereas, the availability of EPA internal resources can be
volatile, as they are subject to a spectrum of changing priorities. This issue is brought to
attention here, as the Strategy is recommending an increase in the portion of STAG resources
used to support QA.
In addition to recommending a stable funding source for QA, the Strategy also
recommends more explicit designation of STAG funds to support data analysis. This approach
follows the model established early in the air toxics monitoring program. The same issues
discussed under QA apply here in an attempt to address an important gap in the monitoring
programs. The actual data analysis may be performed at the state level by state and local
agencies or at a regional/national level. In the latter case, EPA, multistate organizations, and
states would establish the mechanisms and resource commitments for allocating STAG funds to
the analyses. Assuming consensus is generated to dedicate STAG funds to data analysis, a series
of administrative questions remain regarding how such a program is carried out. Possible
scenarios include establishing a management team of SLT/EPA members, or charging EPA or a
multi-state organization with this task, with the possibility of rotational turns for lead
responsibility.
9.3.2 Specific Funding Issues
a. Section 103 versus 105 Funding. Monitoring operations performed by SLTs are
supported by Section 103 and 105 STAG funds. Generally speaking, the use of Section 103
allows for a more efficient tracking of resources, as agencies are not required to match Federal
Grants. The sub units within state and local agencies responsible for conducting monitoring tend
to favor the Section 103 funds, as they clearly are earmarked to support monitoring activities.
Given the overall change implied by the Strategy, it is imperative that a solid base of Section 103
resources serve as a basis for supporting both the stability of monitoring agencies as well as the
needed change in monitoring approaches. Consideration should be given to delineating more
clearly the outputs and outcomes expected to be achieved with Section 105 resources allotted for
monitoring activities to improve accountability.
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b. Training and Guidance. Training and guidance documents will be required for new
types of monitoring instruments, information management technology, and quality assurance
techniques. Details of training and guidance development are found in Section 9.4.
c. PM2.5. Section 103 STAG funds have supported the ongoing operations and
maintenance of the PM2.5 network. The majority of resources have supported PM2.5 FRM
measurements and the collection and analysis of chemical speciation data. The principal
objectives of the FRM measurements and speciation data have been to support designations of
attainment/nonattainment areas, and the development of national emission reduction strategies
and SIPs. In large measure, these objectives have been attained as the Agency has made
designations based on the FRM data collected from 2001 through 2003 (in some cases, 2002-
2004), and has completed most of the technical analyses supporting major national programs
such as CAIR. The SIP technical analyses will be based on the 2000-2002 time frame, attendant
with the base emission inventory and air quality modeling analyses supporting attainment
demonstrations.
As we move beyond this intensive period of analysis focusing on the current state of the
environment, the networks need be more supportive of a longer range vision. The focus of the
networks should evolve toward characterizing the air quality impacts of national air quality
related programs and SIPs (i.e., measuring accountability), providing an infrastructure for public
health advisories (AQI through AIRNow), and supporting health effects and exposure studies
that feed into periodic evaluation of health standards. Accordingly, resources need to be shifted
to assess the progress of implementation plans to ensure that the billions of dollars in resources
required to reduce PM2.5 levels are reaping observable benefits. And, in the event progress is not
being achieved as planned, the networks must be able to support restructuring or "mid course"
corrections over the next ten to twenty years.
Consequently, the funding base needs to be reconfigured consistent with that design,
which will lead to divesting in areas of the current PM2.5 monitoring system that have served
their current primary objective. EPA's implementation approach will be to shift FRM and
speciation program resources to continuous and multipollutant measurement systems. This
proposed resource shift should address most resource requirements to reconfigure the
SLAMS/NAMS networks. The current resources would be redirected to:
add more continuous PM2.5 monitors;
support the NCore multipollutant sites;
enhance the IT infrastructure in the networks and the capital expenditures for hardware
and site improvements to accommodate additional samplers and NCore sites; and
support training and QA needs arising from modification of network operations.
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Note that, as of December 2005, EPA is proposing to revise the PM2.5 NAAQS. If that
proposal is finalized (a final decision is scheduled for September 2006), EPA would have to
reconsider the divestment and change in direction for PM2.5 monitoring.
d. PMio-2.5 monitoring. EPA will be proposing new PM air quality standards that will
include requirements to measure coarse particulate matter [PM10-2.5]. The Agency expects that
new continuous technologies will be used to measure PM10-2.5 with attendant capital, operational,
and training expenses. The bulk of new requested resources should be directed at initial
equipment purchase and training. Divestment in operator time for related programs such as
PM10 should provide an available workforce for PM10-2.5 monitoring. EPA anticipates that the
projected sum of PM10-2.5 and remaining PM10 sampling costs will be equal to or less than the
current PMi0 operational load. There will be recurring non-salaried costs for equipment
repairs/upgrades and laboratory expenses for chemical speciation.
e. Research-grade sites. The CAS AC NAMS Subcommittee and SLTs have advocated
the need for high grade, research level sites to improve our ability to adopt advanced
technologies and interface more effectively with the research community at a practical
applications level. The STAG resources must remain within the SLT entities to provide the
stable workforce for meeting monitoring needs. Less clear is a resource approach to fund these
research sites, which are needed to provide the technology interface with advanced technologies
and the research community. While some capable SLTs will operate sites that may closely
resemble the research sites EPA envisions (e.g., the MANE-VU rural sites), the research
program ideally would provide resources to academic institutions and firms that are leaders in
methods development and associated leaders in analysis of data.
f. PAMS. PAMS requirements have been scaled down to allow for more specific special
studies of interest by local area/region. There has been a wealth of data collected from the
PAMS program, but analysis and interpretation of the data in some cases has been less frequent
and systematic than EPA believes is appropriate. To address this gap and yield value from the
PAMS databases, EPA has already proposed to set aside some of the PAMS-related funds to
conduct data analysis. Ideally, this funding should be combined with additional data analysis
resources set aside for air toxics and PM2.5. EPA will be discussing this proposal with SLTs in
more detail, for possible implementation in FY 2007 or later. A steering group of SLTs and EPA
participants could establish a plan for this analysis that can include an allocation of these
resources to SLTs or to other analytical groups.
g. CASTNET. While CASTNET provides an excellent framework to support EPA's
overall national strategy, a number of technological and measurement upgrades would allow for
CASTNET to provide greater benefits nationally. EPA has directed a one-time $3.5 million
investment of FY 2006 STAG funds into CASTNET.
9.4 Guidance, Training, and Pilot Efforts
Implementation of this Strategy will require guidance and training for state and local
agency staff. The primary areas for these outreach efforts will be to assist with new
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measurement methods, new QA and data analysis approaches, and pilot projects to support
network deployment activities.
9.4.1 New Measurement, QA, and Data Analysis Technologies
The transition to the new network framework including expanded use of continuous
monitors, new QA requirements, and new information technology to support data collection and
analysis creates a significant need for training existing SLT staff. Areas where some type of
training or a transfer of information on the Strategy will be useful include:
Programmatic Issues
Monitoring Strategy - Overall concepts
Network Development/Assessment
Technical Issues
Methods Implementation
Information Technology
QA
The majority of the resources allocated to training and guidance will be directed towards
the technical areas. These areas lend themselves to the following variety of training
mechanisms:
Satellite Broadcasts and Videos (DVDs) - This can provide broad to semi-detailed
information about a topic and is used to provide an initial exposure to the area, concepts
and rationale for the direction or procedure, time line for implementation, and where one
would get more detailed information and training. These formal presentations of the
topic areas may be developed on DVD and distributed through the OAQPS Education
Outreach Group.
Hands-on Sessions - Formal detailed instruction on a particular area.
Guidance Documents - Written guidance providing the necessary detail for an area
when possible and generic guidance and suggestions when more than one alternative
exits.
Vendor - Training that particular vendors of instrumentation or information technology
systems would provide.
Web-based training - Training developed through software that can be posted on the
internet.
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Workshops - National, Regional or local workshops where various training activities
could be presented.
Table 9-5 provides the training mechanisms that can be developed for the programmatic
and technical areas. Specific decisions on which training efforts will be undertaken will depend
on SLT input and available EPA staff and budget resources.
Table 9-5
Training Mechanisms
Area
Training Mechanisms
Satellite
Broadcasts
Hands - On
Guidance
Documents
Vendor
Web
Based
Workshops
Monitoring Strategy
~
~
Network
Development/Assessment
~
~
~
Methods
~
~
~
~
~
Information Technology
~
~
~
~
QA
~
~
~
~
* Information technology and QA training would be incorporated as needed in methods hands-on training activities.
EPA has already distributed a technical assistance document on the precursor gas
monitors that will be part of NCore multipollutant sites. (See Technical Assistance Document
(TAD) for Precursor Gas Measurements in the NCore Multipollutant Monitoring Network.
Version 4. U.S. Environmental Protection Agency. EPA-454/R-05-003. September 2005.
Available at: http://www.epa.gov/ttn/amtic/pretecdoc.html.) EPA also has conducted three
training workshops on these monitors. Additional guidance will be developed and provided on
some other types of monitors with which many SLT staff are currently unfamiliar, and on
network design, site selection, quality assurance, and other topics. While Tribes are not subject
to the requirements of the proposed monitoring amendments, these technical resources will also
be available to them directly from EPA and via grantees, such as the Institute for Tribal
Environmental Professionals and the Tribal Air Monitoring Support Center.
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9.4.2 Network Deployment
Deployment of a full NCore multipollutant network will be phased in over a multi-year
period, preceded by pilot programs to develop practical experience and knowledge of issues.
Three pilot programs were initiated in 2003:
Internal EPA-RTP methods facility. As described above, EPA maintains a monitoring
platform for training and to gain experience with various technologies. Currently, this in-
house facility is focused on trace gas methods and associated operational and quality
assurance issues.
Joint OAQPS-OAP CASTNET pilot study. EPA OAQPS and Office of Atmospheric
Program (OAP) staff are funding a pilot study at three CASTNET sites to explore new
continuous technologies that would complement the existing filter pack techniques and to
leverage the CASTNET infrastructure to establish rural NCore sites. In addition to
testing continuous ion chromatography instrumentation for major aerosol ions, these sites
will be outfitted with NCore trace gas monitors.
NATTS. The NATTS will be adding trace level CO instruments at four locations to
assess the use of CO as potential surrogate for mobile source hazardous air pollutants.
Most of the NATTS will be NCore sites and eventually include CO measurements.
These four sites are being treated as a pilot program to investigate both methodological
issues and the ability to use CO as a surrogate for other measurements. The use of
continuous CO data is attractive from a temporal perspective, as virtually all air toxics
measurements are conducted through integrated techniques.
In addition to these pilot programs, there exist a handful of other studies being conducted
by state and local agencies that will contribute to the knowledge base for addressing issues
associated with trace gas measurements. The lessons learned from these pilot efforts can be
communicated to SLTs and EPA staff as they move forward with NCore site network
deployment.
9.5 Integration of Research Programs into this Strategy
The key element to implementing federal research monitoring efforts as part of this
Strategy will be to coordinate those efforts with a small set (3-6 sites) of national network
research monitoring sites. These national, research-grade sites would include the most
comprehensive list of routine measurements (i.e., the most complete NCore multipollutant site
with PAMS, PM speciation, and air toxics trends), research level measurements with potential
for routine application (e.g., PM size distribution, continuous nitric acid and ammonia, and true
N02), and additional measurements dependent on area specific priorities, available expertise, and
resources. These sites would serve three needs: (1) a comprehensive suite of measurements
providing the most insightful of all routine air monitoring networks; (2) a technology transfer
mechanism to test emerging methods at a few locations with disparate conditions that eventually
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would find more mainstream application;5 and (3) addressing a specific monitoring objective,
such as providing a continental U.S. background or international trans-boundary transport site, or
supporting ambient methods testing.
For implementation purposes, this Strategy calls for establishing three sites initially that
focus on methods and technology transfer in different regions of the United States. These sites
should be in locations that serve a critical spatial need, such as characterizing inflow or outflow
of transcontinental transport, a true background location within the continental United States, or
a major intra-continental transport location (note, however, that the NCore multipollutant sites
may be more appropriate in addressing transport). Candidate locations include previously used
PM Supersites and other well developed platforms capable of accommodating a large footprint
for instruments, with adequate power and security, such as collocation at an agency-operated
NCore site. Consideration should be given to developing a rural-based master site, to ensure that
technologies tested today can meet future conditions as concentration levels continue to decline.
These research sites need not be considered as only fixed sites operating indefinitely at
the same location. A small network of research sites should be instituted as a base component
with stable funding for an indefinite period, recognizing the importance of the dynamic
interaction between research grade and routine monitoring networks. However, it may be more
prudent to view these sites as having a short-term or even a mobile role where, for example,
dedicated, intensive measurements are conducted for a 1-3 year period in a particular location
and perhaps rotated to another location with a built-in period assessment prior to each new
deployment. Such an approach would be compatible with the joint NOAA-EPA proposed urban
collaboration efforts that seek to conduct intensive studies linking sources to human welfare
effects. This short-term siting approach is possible, because, unlike NCore multipollutant sites,
these sites are not established to document long-term trends or provide long-term program
accountability.
There is a clear need for these research sites to support a dedicated testing program. Over
the last ten years, EPA has decreased its level of methods development and testing. Methods
testing now is conducted through a rather loose collection of state sponsored trials (especially
California's Air Resources Board), vendor sponsored initiatives, and miscellaneous research
grants and agreements to universities (e.g., PM Supersites and health centers). These efforts
have been combined with a skeleton level of internal EPA testing. The Supersites program has
fulfilled some of the technology transfer needs, but it was designed to be a short duration
program focused primarily on a broad array of particle characterization issues in addition to
technology testing.
The new research sites would be one component to address this national level weakness.
State agencies cannot continue to be burdened with being "trial" testers of new methods. More
importantly, it is critical not to miss the benefits of greatly enhanced data value that emerging
technologies present.
5 True nitrogen dioxide measurements should be part of routine operations; however, field testing and demonstration
efforts must precede application in routine networks. Consideration for routine applications should be given to other
measurements such as continuous ammonia, nitric acid, and particle size distributions.
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As EPA and SLTs move forward with initial deployment of these research-grade sites,
EPA needs to incorporate the knowledge and perspective of others engaged in research
monitoring initiatives. For example, EPA's Office of Transportation and Air Quality has
identified monitoring near roadways as one of the key urban air challenges. Over the next year,
EPA intends to assess these issues further and develop an implementation plan for moving
toward integration of monitoring near roadways with the core NAAQS urban air monitoring
networks.
One issue EPA faces in the research monitoring area is that there is no assurance that
resources will be available to support advanced monitoring sites that provide a necessary
technology transfer mechanism across the research and applications communities. These sites
begin to address a major weakness inherent in the national networks, which is the ability to
capture adequate environmental measurements relevant to many evolving demands for air
programs. Coordinating near roadway monitoring presents another key opportunity. However,
resources for these measurements should not be extracted from the existing STAG resource pool
because of the need for stable funding to state and local agencies and Tribes. In that regard, it
may be best to site these stations at an NCore multipollutant site and operate the research station
on a cooperative basis. In such situations, the NCore multipollutant site responsibilities would
be assumed by a host agency, and the augmented monitoring to comprise a research-grade site
stature would be assumed by the entity (e.g., EPA or an EPA contractor) responsible for that
specific monitoring. Clearly, for such an arrangement to occur, there would need to be ample
space, power, and security to accommodate both monitoring functions.
9.6 Ongoing Implementation of Major Federal Networks
One priority of this Strategy is to maintain major federal networks, such as CASTNET,
NADP, IMPROVE, and RadNet. In addition to a commitment to maintain those programs, both
CASTNET and RadNet have specific improvements that EPA intends to implement over the
short-term.
9.6.1 General Implementation Plan for CASTNET Improvements and Opportunities
Except for RadNet, CASTNET is the only routinely operating air monitoring network
directly managed by EPA headquarters. CASTNET was designed to assess deposition impacts
associated with major power production facilities located in the midwestern and eastern portions
of the U.S. CASTNET is a model network that successfully tracks national air quality program
progress in the rural Eastern United States, where siting conditions are relatively free of urban
"noise" that can compromise trends analyses. CASTNET has been expanded over time to
include about 30 sites in the western U.S. In addition, CASTNET provides a more science-
oriented approach than some networks, and has taken important strides toward integrating with
other science based networks, including AIRMoN, NADP, and IMPROVE.
To take full advantage of CASTNET, EPA is committed to developing further specific
methods of integrating it with the other national networks (see Section 9.1). In addition, the EPA
intends that the following specific implementation action steps occur under this Strategy:
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A subset of CASTNET sites should be assigned NCore multipollutant status to address
gaps in rural multipollutant monitoring stations.
A subset of CASTNET sites should be elevated to serve as a test bed of special studies
that evaluate emerging technologies that have potential for routine use in network
operations, thus meeting some research site objectives. The focus of such technologies
would be on those measurements (e.g., ammonia, nitric acid, major aerosol ions, and
trace gases) that support accountability and model evaluation analyses. This aspect is
especially important, as the desire to accommodate new technologies must be achieved
carefully and in balance with historical techniques so as to maintain a credible record of
pollutant trends that reflects shifts in atmospheric conditions and not in technologies. In
this area, CASTNET already has embarked on determining the feasibility of a semi-
continuous (hourly) multi-pollutant monitoring system as next generation monitoring
instrumentation to perhaps move beyond the current integrated filter-based methodology.
The pilot systems are capable of measuring both gaseous and particle (SO2, NH3, HNO3,
NH4, S04, N03, and major base cations) constituents with on-line Ion Chromatography
analysis.
The existing contacts and user groups associated with CASTNET should be utilized as a
larger integrating vehicle that promotes greater communication and coordination across
networks focused on ecosystem and public welfare. The NADP-CASTNET sponsored
workshop on ammonia (Washington, D.C., October 2003) provides an example of
bringing together those responsible for managing ecosystem-based and public exposure
networks.
9.6.2 RadNet Implementation Status and Plan
The RadNet project currently is in the early implementation phase. Table 4-5 reflects
major milestones accomplished and status of work in progress as of October 2005.
Table 9-6
Milestones Accomplished and Status of RadNet Air Monitoring Project
Item
Comment
Fixed monitor acquisition
Contract let; prototype received, tested, and installed in Montgomery
National siting of fixed monitors
60 most populated cities15 locations ready to receive; 20 locations with
operator, but site improvements needed
Local siting of fixed monitors
Local siting criteria established
Deployable monitor acquisition
40 deployable monitors built and delivered to ORIA laboratories in
August 2005 (20 to Montgomery, 20 to Las Vegas)
SOPs for monitor operation
Identified and being developed/drafted
(cont.)
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Table 9-6
Milestones Accomplished and Status of RadNet Air Monitoring Project (cont.)
Item
Comment
Quality Assurance Project Plans
Developed for both fixed and deployable monitors
Data repository for receiving and
storing real-time data
Established at NAREL; OEI approved IT security plan for RadNet system
Status of original RadNet non-real-
time monitoring stations
All remain in operation, but some will be replaced by new equipment in
priority order
Although equipment for the fixed and deployable monitors has been purchased,
relationships with potential station operator groups are fairly well established for the first
purchase batch, and the information technology infrastructure is in place for handling real-time
data, the following implementation areas will require careful attention as the project moves
forward:
National sampling/siting plan.
Logistics for emergency distribution and operation of deployable monitors.
Best protocols for distribution/dissemination of verified RadNet data during emergencies.
The effective placement of approximately 180 fixed monitors that provide near-real-time
ambient air radiation data across the United States by Fiscal Year 2012 requires that the working
approach for siting address major population areas, geographical coverage, and the concerns of
partners (states and regions).
The logistics for rapidly and effectively distributing deployable stations during an
emergency can be daunting. Ideally, the stations (as many as 40) should be in place and
transmitting data within two days of the beginning of a major nuclear or radiological event.
Given the realities of not knowing where an event might occur, delivery by someone other than
EPA personnel, i.e., commercial carrier, is likely to add problems and delays. In addition,
securing appropriate operators/set-up and maintenance staff quickly, in the two-day window for
delivery, is another obvious area of potential difficulty and delay. Answering these questions is
and will remain high on the project team's agenda. The exercises that are planned to test the
RadNet air network are expected to help address and suggest solutions for the logistics issues.
Finally, protocols and practices for data dissemination during an emergency will require
ongoing work. Even though the ultimate control of radiation emergency data will reside with the
Department of Homeland Security or the coordinating agency (see the Nuclear Rad Annex to the
Homeland Security National Response Plan), the ways in which this data will be communicated
and the development of protocols to accomplish that are likely to develop and change as
exercises and new knowledge are acquired in the future.
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9.7 Information Technology Implementation Plans
EPA is addressing these issues with a variety of approaches emerging from a long range
"Data Warehouse" OAQPS planning effort as well inter office collaboration with the Office of
Environmental Information (OEI). EPA is in the process of conducting several pilot projects to
gauge the usefulness of new data products and access methods over the short-term planning
horizon (1-5 years). These projects are discussed in Section 2.5.4. The implementation plan for
these activities is to continue to explore pilots and plan possible upgrades. In the 2007 final
Strategy document, EPA anticipates including more specific milestones in this area.
In addition, EPA is at the early scoping stages for evaluating which data analysis
commitments and objectives ought to be minimum elements of this Strategy. There are a
number of examples of data analysis capacity building EPA wants to promote through this
Strategy, and the 2007 Final Strategy will include more details on the plan for implementing this
capacity building. The general types of analysis include:
(i) Regular analysis for status and trends of criteria and air toxics air quality. The
large amount of data being collected in the monitoring networks, along with important
supplementary data (e.g., meteorological, remote sensing, and QA data), will allow air program
managers to adjust ongoing activities/decisions and explore new aspects of air pollution as they
occur. For these data to be useful for managers, they must be analyzed on a regular basis for a
complete set of measures, including detailed characterizations and specific progress or trend
measures. In parallel, and perhaps more importantly, a "tool set" to facilitate analysis should be
developed to deliver data on annual, seasonal, near-term, and real-time bases appropriately for
various air pollutants across various spatial domains. The products would be based on a variety
of techniques, from simple temporal trends to complex spatial interpolation, and would be useful
at the national, regional, state, and local levels. This approach would develop, for the entire air
program, a set of analytical products analogous to those developed for the visibility program
(e.g., VIEWS website http://vista.cira.colostate.edit views developed under the Regional
Planning Organizations). A "dashboard" website would be needed for viewing regular updates
and access to useable products; thus the need for automation of the basic tool set. In addition to
the basic tool set, this approach would expand the tool set to new tools, as special studies
produce operational techniques, and would work to identify unusual air quality events to study or
address in the context of public health tracking.
(ii) Special studies on technical and policy relevant topics. Monitoring and air quality
data (technical and analytical) uncertainties and limitations may affect policy decisions. These
topics should be investigated through special studies that rely on ambient monitoring data.
These studies would include a number of topics. An assessment of major programs (and their
effectiveness), such as the NOx SIP call, the 2005 Clean Air Interstate Rule, and other various
approaches to reduce ozone concentrations, would be undertaken to provide insights into these
programs, with the potential to adjust those programs periodically. An investigation of multiple
pollutants affected by independent control program elements (PM, ozone, air toxics) would
advance the ability to "co-control" pollutants and avoid shifting air quality problems across
programs (e.g., increasing air toxic emissions in response to VOC controls). A thorough study of
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"exceptional" and "natural" events is needed to provide a factual basis for the proper exclusion of
data from program decisions. Along these lines, source attribution studies would be undertaken
to inform regional and specific issue decisions. In addition, studies to evaluate the quality and
uncertainties associated with collected data and special characterization of monitoring sites
would be undertaken, and the collective information would provide a dynamic feedback into
network design.
(iii) Building air quality data analysis tools and capacity. Broadening the capacity for
analyzing air quality data facilitates greater engagement, and adds analytical and quality
assurance power to the entire network measurement and design process. With expanding detail
in monitoring data and the need to understand air quality issues better, analytical tools have
become complicated and complex to use. Techniques such as back trajectory; source
apportionment; and assimilation of satellite, monitoring, and monitoring data have great potential
to advance the ability to understand the progress of the Nation's efforts to address air quality
problems. Guidance is needed for a range of applications including network assessments and
design, emissions inventory and model evaluation, conceptual model building (e.g., genesis and
attributes of air quality problems), and observational models (source attribution and emissions
strategy tools), as well as a spectrum of more direct regulatory problems. As special studies are
completed by EPA, SLT, and regional analysts, there will be a need to develop new operational
tools for the analytical techniques developed within the study. Accordingly, "how-to"
instructions to aid in the use of existing and new tools would be developed and distributed.
Specific special tools would be developed, evaluated and otherwise made available, as the need
arises, to provide the analytical capacity needed to implement air programs. Efforts to bring
knowledge developed within the research communities to practicing analysts would be
undertaken. For example, an annual conference and a virtual homepage for the Nation's air
quality data analysts could be developed to facilitate communication among analysts for
expanded understanding of tools and exchange of ideas on monitoring and data analysis topics.
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Appendix A: Acronyms and Terms
AIRS - Aerometric Information Retrieval System
AIRMoN -Atmospheric Integrated Research
Monitoring Network
ALAPCO - Association of Local Air Pollution
Control Officials
AMTIC - Air Monitoring Technology Information
Center
APTI - Air Pollution Training Institute
AQI - Air Quality Index
AQS - Air Quality (data) System
ARM - Approved Regional Method
BAM - Beta Attenuation Monitor
CAA - (Federal) Clean Air Act
CAC - Correlating Acceptable Continuous (monitor)
CAIR - Clean Air Interstate Rule
CASAC - Clean Air Science Advisory Committee
CASTNET - Clean Air Status and Trends Network
CBSA - Core Based Statistical Area
CENR - Committee for Environment and Natural
Resources
CEU - Continuing Education Unit
CFR - Code of Federal Regulations
CMAQ - Community Model Air Quality (system)
CO - Carbon Monoxide
CRPAQS - Central Valley (California) Regional
Particulate Air Quality Study
CV - Coefficient of Variance
CY - Calendar Year
DC - Direct Current
DHS - Department of Homeland Security
DMC - Data Management Center
DOE - Department of Energy
DOI - Department of Interior
DQA - Data Quality Assessment
DQI - Data Quality Indicator
DQO - Data Quality Objectives
EC - Elemental Carbon
EPA - Environmental Protection Agency
ESAT - Environmental Services Assistance Team
FEM - Federal Equivalent Method
FLM - Federal Land Manager
FRM - Federal Reference Method
FY-Fiscal Year
GAO - General Accounting Office
GC - Gas Chromatograph
GIS - Geographical Information System
HAP - Hazardous Air Pollutants
HEI - Health Effects Institute
IACET - International Association for
Continuing Education and Training
IADN - Interagency Deposition Network
IC - Ion Chromatography
IMPROVE - Interagency Monitoring of
Protected Visual Environments
ITEP - Institute of Tribal Environmental
Professionals
ITT - Information Transfer Technology
K - thousand
M - million
MANE-VU - Mid-Atlantic/Northeast Visibility
Union
MDN - Mercury Deposition Network
NAAMS - National Ambient Air Monitoring
System
NADP - National Atmospheric Deposition
Program
NAAQS - National Ambient Air Quality
Standards
NAMS - National Air Monitoring Stations
NAPAP - National Acid Precipitation Assessment
Program
NARSTO - North American Research Strategy for
Tropospheric Ozone
NAS - National Academy of Science
NASA - National Aeronautics and Space Agency
NATTS - National Air Toxics Trends Stations
NAU - Northern Arizona University
NCore - The National Core Monitoring Network
NMHC - Non-Methane Hydrocarbons
NMSC - National Monitoring Strategy (or
Steering) Committee
NO - Nitric Oxide
N02 Nitrogen Dioxide
NOAA - National Oceanic and Atmospheric
Administration
NOx - Oxides of Nitrogen
NOy - Reactive Nitrogen Compounds
NPEP - National Performance Evaluation Program
NPS - National Parks Service
NTN - National Trends Network
03 - Ozone
OAP - Office of Atmospheric Programs
OAQPS - Office of Air Quality Planning and
Standards
OC - Organic Carbon
OEI - Office of Environmental Information
ORD - Office of Research and Development
ORIA - Office of Radiation and Indoor Air
PAMS - Photochemical Assessment
Measurement Stations
Pb - Lead
PBT - Persistent Bioaccumulative Toxics
PBMS - Performance Based Measurement
System
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PE - Performance Evaluation
PEP - Performance Evaluation Program
PM - Particulate Matter
PMio - Particulate Matter with aerodynamic
diameter less than 10 micrometers
PM2.5 - Particulate Matter with aerodynamic
diameter less than 2.5 micrometers
PM10-2.5 - PMIO minus PM2.5
POP - Persistent Organic pollutants
ppb - parts per billion
PSD - Prevention of Significant Deterioration
QA - Quality Assurance
QAPP - Quality Assurance Program Plan
QC - Quality Control
QMP - Quality Management Plan
RADM - Regional Acid Deposition Model
REM - Regional Equivalent Monitor
RO - EPA Regional Office
ROM - Regional Oxidant Model
RPO - Regional Planning Organization
RTP - Research Triangle Park (North Carolina)
S & T - Science and Technology
SAMWG - Standing Air Monitoring Working
Group
SIP - State Implementation Plan
SLAMS - State and Local Air Monitoring Stations
SLTs - State and Local Agencies and Tribes
S02 - Sulfur Dioxide
SOP - Standard Operating Procedure
SPM - Special Purpose Monitor
SRP - Standard Reference Photometer
SS - Supersite
STAG - State and Tribal Air Grant
STAPPA - State and Territorial Air Pollution
Program Administrators
STN - Speciation Trend Network
Strategy - The National Air Monitoring Strategy
SVOC - Semi-Volatile Organic Compound
TAMS - Tribal Air Monitoring Support (Center)
TAR - Tribal Authority Rule
TBD - To Be Determined
TEOM - Tapered Element Oscillation Monitor
TIP - Tribal Implementation Plan
TNMOC - Total Non-Methane Organic
Compound
TSA - Technical Systems Audits
TSP - Total Suspended Particulates
USB - Universal Serial Bus
VOC - Volatile Organic Compound
XML - Extensible Markup Language
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Appendix B: 2000 and 2003 Network Assessments
A. FY 2000 National Assessment
An example national assessment of the criteria pollutant networks was conducted in 2000
to catalyze subsequent regional level assessments. This assessment considered concentration
level, site representation of area and population, and error uncertainty created by site removal as
weighting parameters used to determine relative "value" of individual sites. The most widely
applied factor inherent in most assessment approaches is related to site redundancy and can be
estimated in a variety of ways. The national assessment calculated error uncertainty by modeling
(i.e., interpolating between measurement sites) surface concentrations with and without a specific
monitor with the difference reflecting uncertainty (Figure B-l). Areas of low uncertainty (e.g.,
less than 5 ppb error difference for ozone) suggest that removal of a monitor would not
compromise the ability to estimate air quality in the region of that monitor as nearby stations
would provide adequate acceptable predictions.
The assessment approach was expanded to include additional weighting factors beyond
error. Typical outputs for ozone networks (Figure B-2) suggest that ozone sites clustered in
urban areas yield less powerful information than sites located in sparsely monitored areas,
especially in high growth regions like the southeast. However, this conclusion is more
applicable to urban areas with more homogeneous conditions. This methodology was applied to
all criteria pollutants with a variety of weighting schemes to provide a resource for more detailed
regionalized assessments.
The key findings of the national network assessment were as follows:
Investment Needs: New monitoring efforts are needed to support new air quality
challenges, including monitoring for air toxics and new technology for criteria pollutants
and precursor species. Air toxics have emerged as a top public health concern in many
parts of the country, and a national air toxics monitoring network is currently under
development under special funding for air toxics monitoring. New technology, especially
continuous measurement methods for pollutants, such as fine particles, are needed to
provide more complete, reliable, and timely air quality information, and to relieve the
burden of manual sampling. Resources and guidance are needed for this activity.
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las# ease ซnง surface all sites Error surface after site removal
Figure B-l: Surface depiction of estimated absolute errors (right) in ozone
concentrations produced by removing existing monitors on a site by site
basis, relative to base case (left). Areas showing low errors (<5 ppb)
suggest neighboring monitors could accurately predict ozone in area of a
removed site. Areas of high error suggest necessity to retain existing
monitors and perhaps increase monitoring.
National example {Aggregate Ranking- Equal Weight
> All five measures are weighed equal at
20% each.
> High 'aggregate value' stations (red) are
located over both urban and rural
segments of the central EUS.
> Low 'value' sites (blue) are inter-
dispersed with high value sites.
> Clusters of low value sites are found
over Florida, Upper Midwest, and the
inland portion of New England.
Relative Weight of Rankings
Ney Standard saaonArei
ConcewaOBn
20*
Figure B-2: Aggregate assessment of 5 evenly weighted factors. Blue
circles and red squares indicate the lowest and highest valued sites,
respectively
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Divestment Opportunities: To make more efficient use of existing monitoring
resources and to help pay for (and justify additional resources) the new monitoring
initiatives noted above, opportunities exist to reduce existing monitors. Two areas of
potential divestment are suggested. First, many historical criteria pollutant monitoring
networks have achieved their objective and demonstrate that there are no national (and, in
most cases, regional) air quality problems for certain pollutants, including PMi0, S02,
NO2, CO and Pb. A substantial reduction in the number of monitors for these pollutants
should be considered. (However, considerations need to be made to retain a certain
number of trace level monitors especially for SO2 and CO because of their utility as
tracers for certain sources of emissions.) As part of this adjustment, it may be desirable
to relocate some of these sites to rural areas to provide regional air quality data. Second,
there are many monitoring sites with only one (or a few) pollutants. To the extent
possible, sites should be combined to form multi-pollutant monitoring stations. Any
resource savings from such divestments must remain in the monitoring program for
identified investment needs. A reasonable period of time is required to smoothly
transition from established to new monitoring activities.
Importance of Regional Input: National analyses provide broad directional information
about potential network changes. Regional/local analyses are a critical complement to
the national analyses, and are necessary to develop specific monitoring site
recommendations. To this end, EPA must allow States and regional organizations
sufficient time (e.g., at least six months) to conduct adequate regional/local analyses.
A copy of the FY 2000 national assessment can be found on the web at:
www.epa.gov/ttn/amtic/netamap.
B. FY 2003 Regional Assessments
Each of the 10 EPA ROs was tasked with performing a regional network assessment in
conjunction with its SLT partners. Although a framework was suggested, each RO undertook
the assessment process differently, ranging from complex statistical functions to subjective site-
by-site considerations. Some ROs have gone through the process of approving SLT network
changes, while other ROs are awaiting finalization of the network assessment process before
approving changes. This lack of consistency points strongly to the need for network assessment
guidance. Such guidance was deemed to be important by the CASAC Subcommittee on
Monitoring at its July 2003 meeting. Because the regional assessment process is so far along at
this point, there will not be a guidance structure in place for this initial round of assessments;
however, a guidance document is now being developed which will help provide national
consistency for subsequent assessments.
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Though not necessarily final, the following summary of recommended network changes
is intended to show the progress made by each of the Regional Offices:
Region 1:
Reductions:
Additions:
Modifications:
Approach:
PMio FRM monitors, CO, and S02
PM2.5 continuous monitors and air toxic monitoring
PM2.5 FRMs to support PM-coarse monitoring
Site-by-site situational analysis
Region 2: Reductions: PM10 and CO
Additions: PM2.5 continuous monitors
Approach: Site-by-site situational analysis
Region 3: Reductions: SO2, NO2, CO, Pb, and PM10
Additions: Yet to be determined
Approach: Optimum network design function using 6 design
considerations
Region 4: Reductions:
Additions:
Approach:
Region 5: Reductions:
Additions:
Approach:
Region 6: Reductions:
Additions:
Relocations:
Approach:
Region 7: Reductions:
Additions:
Relocations:
Approach:
Region 8: Reductions:
Additions:
Approach:
CO, PM10, N02, lead, and S02
Yet to be determined
Statistical spatial analyses with considerations for
population exposure, a real extent of violations, and
sensitivity analyses
Ozone, CO, PM10, PM2.5, lead, CO, SO2, and NO2
Yet to be determined
Statistical analyses for identifying high/low value sites; use
of positive matrix factorization
PM10, PM2.5, CO, SO2, NOx, lead, and ozone
Continuous PM2.5, NOy, and ozone
PM2.5 FRM, S02, PM10 FRM sites
State-by-state changes in consultation with each state
Pb, PM10, CO, and PM2 5
8 hour ozone sites, further additions considered
1 hour ozone sites
Statistical approach and consultation with State/Local
agencies
Yet to be determined
Yet to be determined
Paired correlation rankings; comparisons to NAAQS; input
and feedback from individual states
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Region 9: Reductions:
Additions:
Approach:
Region 10: Reductions:
Additions:
Approach:
Yet to be determined
Yet to be determined
Statistical process similar to national assessment
PMio and PM2.5 FRM monitors, CO, and NO2
Continuous PM2.5 monitors
Correlation analyses; NAAQS comparisons; NCore design
criteria
It should be noted that the above summary represents work-in-progress, but is intended to
provide a sense of the progress and types of approaches being taken by the various EPA Regions.
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