[Federal Register Volume 61, Number 241 (Friday, December 13, 1996)]
[Proposed Rules]
[Pages 65764-65778]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-31343]
[[Page 65763]]
_______________________________________________________________________
Part V
Environmental Protection Agency
_______________________________________________________________________
40 CFR Part 51
Implementation of New or Revised Ozone and Particulate Matter (PM)
National Ambient Air Quality Standards (NAAQS) and Regional Haze
Regulations; Proposed Rule
Federal Register / Vol. 61, No. 241 / Friday, December 13, 1996 /
Proposed Rules
[[Page 65764]]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 51
[FRL-5661-5]
RIN 2060-AF34
Implementation of New or Revised Ozone and Particulate Matter
(PM) National Ambient Air Quality Standards (NAAQS) and Regional Haze
Regulations
AGENCY: Environmental Protection Agency (EPA).
ACTION: Advance notice of proposed rulemaking (ANPR).
-----------------------------------------------------------------------
SUMMARY: The EPA is providing advance notice of key issues for
consideration in the development of new or revised policies and/or
regulations to implement revised NAAQS for ozone and PM, and
development of a regional haze program. The EPA is under court order to
issue a proposed decision on whether to retain or revise the PM NAAQS
by November 29, 1996, and to issue a final rulemaking for PM by June
29, 1997. The Agency anticipates following the same schedule for the
ozone standard and also intends to propose a regional haze program in
mid-1997. If revised NAAQS replace existing NAAQS, there would be a
period of time to phase in new requirements while continuing to address
the requirements of the current programs. Further, ozone, PM and
regional haze are products of interrelated chemical conversions in the
atmosphere, and new approaches will be needed to identify and
characterize affected areas and to assign planning, management and
control responsibilities. This could lead to integrated implementation
policies for ozone, PM and regional haze control programs. This ANPR
provides a broad scientific and policy perspective on these issues and
addresses implementation issues that have been identified, such as the
need for regional strategies, and is a continuation of the advisory
process first announced on September 11, 1995 (60 FR 47171) and further
explained by the Agency on June 12, 1996 (61 FR 29719). Through today's
action, the Agency is providing a brief discussion of a broad range of
options, principles and questions related to each of these key issues.
The options/principles/questions in this ANPR were designed to provide
sufficient background information to stimulate public interest and
comments and are not intended to indicate preferences or decisions by
the EPA. By publishing this information at this time, the EPA is
providing more time for the public to develop input and comments than
would occur following the publication of the subsequent regulatory
notices for the implementation strategies and regional haze program. An
explanation and structure of the Federal Advisory Committee Act (FACA)
Subcommittee is provided in SUPPLEMENTARY INFORMATION. Applicable terms
and definitions are provided in the Appendix.
DATES: Written comments on this proposal must be received by February
18, 1997.
ADDRESSES: Comments. Comments should be submitted (in duplicate if
possible) to the Air and Radiation Docket and Information Center, 401 M
Street, SW, Washington, DC 20460, Attention Docket Number A-95-38.
Docket. The public docket for this action is available for public
inspection and copying between 8:00 a.m. and 4:00 p.m., Monday through
Friday, at the Air and Radiation Docket and Information Center (6102),
Attention Docket A-95-38, South Conference Center, Room 4, 401 M
Street, SW, Washington, DC 20460. A reasonable fee for copying may be
charged.
FOR FURTHER INFORMATION CONTACT: For general FACA Subcommittee
questions and comments, contact Ms. Denise Gerth, U.S. EPA, MD-15,
Research Triangle Park, NC 27711, telephone (919) 541-5550. For
specific questions and comments on the ANPR, contact Ms. Sharon
Reinders, U.S. EPA, MD-15, Research Triangle Park, NC 27711, telephone
(919) 541-5284.
SUPPLEMENTARY INFORMATION: The following communications and outreach
mechanisms have been established:
Overview information--A World Wide Web (WWW) site has been
developed for overview information on the NAAQS and the ozone/PM/
regional haze FACA process. The Uniform Resource Location (URL) for the
home page of the web site is http://www.epa.gov/oar/faca/
Detailed and technical information--Available on the O3/PM/RH
Bulletin Board on the Office of Air Quality Planning and Standards
(OAQPS) Technology Transfer Network (TTN), which is a collection of
electronic bulletin board systems operated by OAQPS containing
information about a wide variety of air pollution topics. The O3/PM/RH
Bulletin Board contains separate areas for each of the FACA
Subcommittee's five work groups and includes meeting materials, issue
papers, as well as general areas with information about the process,
participants, etc. The TTN can be accessed by any of the following
three methods:
--By modem; the dial-in number is (919) 541-5742. Communications
software should be set with the following parameters: 8 Data Bits, No
Parity, 1 Stop Bit (8-N-1) 14,400 bps (or less).
--Full Duplex.
--ANSI or VT-100 Terminal Emulation.
The TTN is available on the WWW site at the following URL: http://
ttnwww.rtpnc.epa.gov. The TTN can also be accessed on the Internet
using File Transfer Protocol (FTP); the FTP address is
ttnftp.rtpnc.epa.gov. The TTN Helpline is (919) 541-5384.
I. Purpose and Objectives
This ANPR outlines policy and technical implementation issues and
identifies a broad range of options/principles/questions for each issue
associated with the potential revision of the ozone and PM NAAQS and
with the development of a regional haze program. Although the proposals
to change the ozone and PM NAAQS have been made, the possibility that
such changes may be promulgated necessitates this advance notice, as
well as the ongoing implementation discussions under the FACA discussed
elsewhere in this notice. The alternative approach of waiting until
possible standard revisions are actually promulgated would, in the
Agency's judgement, cause inevitable delays and disruptions in
national, State and local efforts to achieve clean, healthy air,
especially those related to attainment of the NAAQS for ozone. The
ozone and PM NAAQS proposals are scheduled for publication in December
1996 with final action scheduled for mid-1997. The EPA intends to
propose a regional haze program in mid-1997.
In advance of these actions, the EPA published an ANPR entitled,
National Ambient Air Quality Standards for Ozone and Particulate
Matter, on June 12, 1996 (61 FR 29719) which announced the Agency's
plans to propose decisions on whether to retain or revise the ozone and
PM NAAQS. That ANPR also described the FACA process and the
Subcommittee for Ozone, PM and Regional Haze Implementation Programs
(Subcommittee). The Subcommittee is composed of 60 representatives from
State, local and tribal organizations; environmental groups, industry
and trade groups (including small business representatives),
consultants; academic/scientific communities; and Federal agencies. The
organization of the Subcommittee includes a Coordination
[[Page 65765]]
Group and four work groups: (1) Base Programs Analyses and Policies
Work Group, (2) National and Regional Strategies Work Group, (3)
Science and Technical Support Work Group, and (4) Communications and
Outreach Work Group. The Subcommittee was established under the Clean
Air Act Advisory Committee (CAAAC) to provide advice and
recommendations to the EPA on developing new, integrated approaches for
implementing potential revised NAAQS for ozone and PM, as well as for
implementing a new regional haze reduction program. Through this
process, EPA is engaging in communications with segments of society
that may be affected by the implementation of NAAQS and the regional
haze program. This announcement is a further attempt to invite
stakeholders to participate in the implementation development process,
to assure that their concerns will be addressed and their options
assessed, and, ultimately increase the effectiveness of NAAQS
implementation strategies and the regional haze program.
The implementation issues described in this ANPR form the basis of
the Subcommittee's deliberations and for the most part were developed
through the various work groups and the Coordination Group. The
presentation of these issues and corresponding options/principles/
questions is designed primarily to provide advance notice for the
public who are not directly involved in the FACA process. Interested
readers are directed to EPA's TTN and WWW site for an up-to-date status
of the work groups' and Subcommittee's deliberations on these issues.
This includes work group issue papers with options and, where
appropriate, draft recommendations.
While the EPA is interested in considering new and innovative
approaches to implementation, it is imperative to ensure that momentum
is maintained in the current implementation programs, and that current
programs and efforts such as the Ozone Transport Assessment Group
(OTAG) continue in order to protect public health and welfare. As a
consequence, the Subcommittee is providing recommendations to EPA
regarding the development of an interim implementation policy (IIP),
which was published in December 1996. The IIP will provide EPA's
guidance to the State and local agencies on appropriate actions during
the transitional period of time between any revision of the NAAQS and
the development of new integrated implementation strategies. This is
especially important since it is expected that any new NAAQS will be at
least as stringent as the current NAAQS, and reductions in emissions to
achieve the current NAAQS will be beneficial in achieving the revised
NAAQS. While the IIP will provide guidance during the transition
period, EPA will also develop implementation strategies for the
potential new ozone/PM/regional haze programs.
The final integrated implementation programs for ozone, PM and
regional haze are being developed in two phases. In Phase I, the air
quality management framework issues will be addressed (proposal--mid-
1997). Phase II will focus on more detailed control strategy
development (proposal--mid-1998). These phases are described in more
detail in subparagraph IV.
II. Scientific and Technical Discussion
The following discussion relies on the Scientific and Technical
Support Work Group of the FACA Subcommittee. This group is developing a
draft conceptual model framing our current scientific understanding of
ozone, fine particles and haze, the associated gaps and uncertainties,
and based on the technical basis and issues underlying the integration
of regulatory programs for ozone, fine particles and regional haze, and
the specification of geographic scales required for air quality
management. This conceptual model provides a technical basis for the
Subcommittee's deliberations of these issues. This document is
undergoing further review prior to acceptance by the CAAAC. Regarding
the rationality of integration, the initial response of the Science and
Technical Support Work Group was a qualified yes, given the regional
nature of the pollutants (i.e., regionalization), spatial patterns of
air quality indices, precursors, sources, atmospheric chemistry and
meteorological processes which affect more than one pollutant, and
control options. The following discussion focuses on the relationships
between ozone and fine particles, given the close linkage between fine
particle levels and regional haze (the widespread impairment of
visibility in every direction, mostly attributed to fine particle light
scattering and absorption), with the following assumptions:
--Understanding the emission sources and atmospheric processes which
are responsible for elevated air pollutant levels requires an
examination of urban and regional geographical scales;
--Ozone and fine particles may exhibit similar spatial patterns,
although the frequency (and importance) of concurrent patterns is not
well understood;
--Many of the emission precursors (and sources of precursors) to ozone,
fine particles and regional haze are the same;
--Many of the atmospheric processes (chemistry and meteorology)
affecting ozone, fine particles, and regional haze are the same; and
--Several critically-important information gaps exist which create very
difficult challenges for air quality management of these pollutants.
A. Interacting Spatial Scales of Emissions, Atmospheric Processes and
Air Quality Indices
As explained in greater detail below, there are a variety of
emissions that are precursors to elevated levels of ozone, fine
particles, and regional haze and of sources to these emissions.
Historically, attempts at air quality management of these problems
focused on local sources in the context of an anonymous background term
quantifying imported air quality. The evolution in our understanding of
the spatial and temporal scales of the effects on ozone, fine
particles, and regional haze of the emissions from all sources has,
however, spawned the recognition of the need for a larger geographical
perspective. This larger geographical perspective, which considers
individual sources over regional, as well as local scales, is needed to
support quantitative analysis of the relative contribution of the
various source types and of their emission types (species) that
contribute to nonattainment levels and regional haze. The need for an
altered perspective has been recognized by the establishment of the
Ozone Transport Commission (OTC), the OTAG, and the Grand Canyon
Visibility Transport Commission (GCVTC).
Air quality management in the metropolitan statistical area or
consolidated metropolitan statistical area (MSA or CMSA) has worked
well historically to control the local source effect on nonattainment
problems. This is evidenced by the significant decrease in the number
of ozone nonattainment areas over the past decade. As these controls
have reduced emissions and as modeling tools have progressed, the role
of the effect of sources beyond the MSA or CMSA and the varying spatial
scales of air quality indices and atmospheric processes continue to be
investigated and supported by a strong body of scientific evidence:
--The 1991 National Academy of Science (NAS) Report, Rethinking Ozone
in Urban and Regional Scales
[[Page 65766]]
(National Research Council (NRC), 1991);
--The 1993 NAS Report, Protecting Visibility in National Parks and
Wilderness Areas (NRC, 1993);
--The National Acid Precipitation Assessment Program (Trijonis et al.,
1990); and
--The Southern Oxidant Study (Chameides and Cowling, 1995).
Recent analyses based on ambient air monitoring data (Rao, 1995)
and regional acid deposition model air quality modeling (Appleton,
1995) suggest a very broad spatial air pollution region covering the
greater part of the Eastern United States (U.S.). These studies
indicate that, while sources still have their largest influence in the
near field, the zones of potential influence of source regions (e.g.,
an urban city) can under certain conditions extend out hundreds of
kilometers (km) for ozone, fine particles, and regional haze. Moreover,
these scales appear to be similar for ozone and fine particles. In
other words, sources once thought to be remote with respect to
nonattainment levels of ozone, fine particles, and regional haze are
seen as potential contributors to those levels. The analyses suggest
that chemical and meteorological processes which influence pollutant
generation, air mass movement and pollutant removal (e.g., clouds and
precipitation) are key factors in defining regional zones of influence.
When the various nonattainment areas of the Eastern U.S. are surrounded
by even conservative estimates of the zones of influence of these other
sources, what results is a modeling domain that may span the greater
part of the Eastern U.S. Accordingly, efficient air quality management
requires addressing these additional sources, atmospheric processes and
related impacts as scales of interactions over multiple spatial and
temporal frames.
In air quality management practice, the term ``transport'' has been
used in a very broad context beyond the strict meteorological
definition of the term. This broad context includes: (1) The overall
regionalization of both the scale of pollutant distributions and zone
of influence of sources, (2) the interaction (or effect of one area on
another) among local, urban and regional source scales, and (3) meso
and large-scale meteorological phenomena (such as recirculation due to
stagnant high pressure systems and land-sea interactions, large-scale
movement of air masses with fairly uniform motion, and other events
perhaps as simple as widespread elevated temperatures). The prevalence
and importance of biogenic volatile organic compounds (VOC) emissions
(e.g., emissions from trees) in the Eastern U.S. are ``regionwide,'' as
are many other area source emissions such as those emitted by motor
vehicles. All of these regional attributes are enhanced by the
relatively flat and consistent terrain in the East and Midwest,
contrasting the greater topographic and meteorological effects in the
Western U.S., although the West can also experience regional problems.
Several physical and chemical events act together in determining
pollutant concentrations over multiple space and time scales. Moving
air masses carry all chemical species including precursors, fast-
reacting intermediates, and chemical sinks, as well as the specific
pollutant species of interest (e.g., fine particles and ozone). Removal
of pollutants occurs continuously through deposition. Also, the impact
of these pollutants is not simply additive. Ozone (or precursors)
transported from one location can affect ozone levels downwind by
indirectly accelerating atmospheric chemical reactions through the
production of chemical intermediates (e.g., hydroxyl radicals). Clouds
play several roles in modifying concentrations by: (1) Dissolving
soluble gases (e.g., nitric acid, sulfur dioxide (SO2), hydrogen
peroxide) and generating aerosols through aqueous phase reactions, (2)
circulating and venting pollutants to high altitudes where strong winds
promote large horizontal transport, and (3) removing pollutants through
precipitation. Cloud-related dissolution and transport also contribute
to pollutant removal. Vertical air mass movements, or phenomena as
basic as the daily mixed layer growth, affect air concentrations on
various scales. Superimposed on these processes are a variety of
emission sources with their own spatial, temporal and component
(speciation) scales. Depending on location, pollutant and season, one
particular spatial scale (e.g., urban) may (or may not) exert a
dominating influence on air quality relative to another scale (e.g.,
regional). Even in cases where local and urban sources are responsible
for most of the ``local'' air quality, an assessment of the
contribution of distant sources to local air quality is required to
reach such a conclusion. Thus, to avoid the exclusion of potentially
important considerations in air quality analysis, ``regionality'' or
``interacting scales'' is a more descriptive term (than transport)
which encompasses the broader meaning and effects of several complex
interacting phenomena operating over extensive and multiple time and
space scales.
The Eastern U.S. differs markedly, topographically and
climatologically, from the West, so any extension to the West based on
Eastern analyses (or vice versa) is not necessarily appropriate
(important differences exist between Northern and Southern regions as
well). The monitoring data and modeling analyses of the GCVTC process
highlight the challenge of identifying and quantifying specific
sources, some at great distances in order to estimate their effects in
Western national parks and wilderness areas. The variations in
topography, meteorology and source distribution across regions require
that area- and case-specific differences be accounted for in any air
management approach. The effects of emission reduction strategies
should be viewed through multiple scales, considering regional and
urban scale consequences (i.e., health and welfare protection).
A few points summarizing ``interacting scales'' and ``regionality''
should be considered in air management practices:
--Air quality modeling and historical monitoring trends have shown that
local air management practices have the greatest influence on near
field concentration impacts.
--Analyses of observations in the Eastern U.S. reveal the existence of
very broad multistate regions (interacting scales approaching linear
scales of 1000 km or more) of elevated pollutant levels and zones of
influence (Rao, 1996).
--Air quality modeling data for the East suggest that similar regions
of influence exist for ozone and fine particles (Dennis, 1996),
although only sparse monitoring data exist to support these
similarities.
--Modeling analyses for the Grand Canyon National Park (and other)
Class 1 areas show that fine particles and precursors causing
visibility impairment episodes are derived from both nearby (less than
50 km) and more distant (up to 1000 km) regions of influence (NRC,
1993; GCVTC, 1996).
--Area and case-specific analyses are required to delineate reasonable
geographic areas for air quality planning purposes because of the wide
regional variations in meteorology, topography and source distribution.
--The use of terms such as ``transport'' or ``background'' inadequately
describes the complex set of emissions, chemistry, meteorological
processes and interacting scales which contribute to the
regionalization of air pollution.
[[Page 65767]]
--Because of broad spatial extents and gradations of interacting scales
ranging from regional down to sub-grid cell scales, an air quality
assessment focusing on a particular scale (e.g., urban) must consider
effects due to interactions across various space and time scales. The
concept of a single MSA/CMSA nonattainment area may be inconsistent
with the spatial and temporal scales for ozone, fine particles and haze
problems.
B. Technical Basis and Considerations for Integrating Ozone, Fine
Particles and Regional Haze Implementation Programs
The technical and scientific rationale for underlying the
integration of ozone, fine particles and regional haze air quality
management practices is based on a mix of empirical observations,
atmospheric processes and practical administrative concerns. While this
discussion focuses on common attributes across pollutant groups, it is
important to recognize and distinguish those attributes where there is
little linkage. Many examples and inferences presented here tend to
reflect what is known about Eastern U.S. air quality issues (e.g.,
ozone) with possibly little relation to Western U.S. phenomena. At the
risk of generalizing (and simplifying) air quality descriptions for
illustrative purposes, recognition that a generalized approach cannot
operate effectively everywhere must be retained. The discussion focuses
on the relationship between ozone and fine particles, with the implicit
assumption that fine particle levels and chemical composition directly
relate to regional visibility impairment, given the strong relationship
between the constituents of fine particles and the manmade portion of
visibility impairment. Regional haze is a widespread, largely uniform
impairment of visibility in every direction over a large area, mostly
due to light scattering from fine particles from multiple sources.
1. Empirical Evidence for Integration
Ozone and PM-10 (particles with an aerodynamic diameter less than
or equal to a nominal 10 micrometers) concentrations in the Eastern
U.S. can exhibit similar spatial patterns during summer time episodes
(Northeast States for Coordinated Air Use Management (NESCAUM), 1995).
Analyses of PM data consistently indicate that fine particles
constitute the majority mass fraction of PM-10 in the summertime East
(EPA, 1996). In combination, these observations qualitatively imply
concurrence of elevated ozone and fine particles. However,
quantification of the similarity and frequency of such events is
severely restricted by a lack of a fine particles data base in the
East. While more data exist in certain Western locations, the episodic
relationships between ozone and PM appears to be more complex than in
the East. For example, a major component of the fine particle problem
in Los Angeles (as well as the San Joaquin Valley, Salt Lake City and
Denver) is wintertime formation of ammonium nitrate, which is not
stable at the high temperatures associated with elevated ozone. High
levels of fine particles in Western nonattainment areas can impair
visibility when high ozone concentrations are not observed.
Nevertheless, ``smog'' events in Los Angeles are almost always
accompanied by impaired visibility, and visibility is directly
associated with fine particle levels. Although some limited empirical
evidence is highly suggestive of area specific concurrent events, other
considerations as described below provide a stronger rationale for the
appropriate level of integration across ozone, fine particles and
regional haze control programs.
2. Emissions and Atmospheric Process Linkages Across Ozone, Fine
Particles and Regional Haze
Several connections exist among ozone, PM and the resulting effect
of visibility impairment. The linkages are based on the existence of
common emission precursors, source categories and atmospheric chemistry
and meteorological processes which affect more than one pollutant. For
example, emissions of oxides of nitrogen (NOX) potentially can
lead to both ozone and fine particle formation. A combustion source
often emits both SO2 (a fine particle precursor) and NOX (an
ozone precursor). The sequence of atmospheric chemistry reactions
underlying ozone formation is in part responsible for fine particle
formation. Similar meteorological processes affect the movement, mixing
and removal of ozone, fine particles and precursors. Some of these
connections are complicated and will be explained more completely in
forthcoming FACA science documents. The following are very brief
descriptions of the connections across pollutant categories.
--Common ``direct'' precursor emissions. Emissions of NOX, VOC and
carbon monoxide (CO) are considered precursors for ozone formation. The
NOX, VOC and sulfur (SOX, mostly as SO2) emissions can
also lead to fine particle formation through ``secondary'' atmospheric
chemical reactions. Both ozone and a substantial fraction (which can
vary greatly with season and location) of fine particles are the result
of secondary formation processes. The major components (which also are
highly variant) of secondary fine particles include sulfates, carbon
(elemental and organic) and nitrates. The fraction of fine particles
due to secondary processes is highly variant in space and time. During
certain conditions (e.g., available ammonia, negligible sulfate, low
temperatures), NOX emissions can lead to fine PM ammonium nitrate
formation. Several directly-emitted organic compounds contribute to
fine particle organic aerosols. These organic compounds may contribute
as ``primary'' organic aerosols, that is, they almost immediately
condense to the aerosol phase during the emissions process or shortly
downstream. Or, certain VOC (e.g., toluene) which exist as gases under
most conditions can undergo atmospheric reactions and transform into
condensible ``secondary'' organic aerosols. Thus, a VOC like toluene
can contribute to both ozone or fine particle formation as a precursor
emission.
--Common source categories. Based on the multiple roles of precursors,
a particular source (natural or anthropogenic) emitting one precursor
(e.g., NOX or VOC) can affect ozone and fine particles, and a
single source emitting multiple precursors (e.g., combustion process
releasing NOX, VOC, CO and SOX) can affect multiple pollutant
source categories. In this case, integration is not dependent on
atmospheric chemical linkages. This commonality among sources should
lead to a more consistent approach in estimating emissions of multiple
precursors within a specific source category. For instance, a
consistent approach needs to be applied for estimating and projecting
both NOX and SOX emissions from a combustion source.
--Interaction of atmospheric chemistry reaction cycles and ``indirect''
precursors. Much of the general atmospheric chemistry involved in ozone
formation can affect fine particle formation, as alluded to above, in
certain instances. For example, ozone is the major initiator of
hydroxyl radicals, a chemical intermediate which converts SO2 and
nitrogen dioxide (NO2) to more oxidized sulfate (e.g., sulfuric
acid) and nitrate (nitric acid) forms. Both sulfates and nitrates can
contribute to fine particle formation. Clearly, a linkage between ozone
and fine
[[Page 65768]]
particles exists through the role of ozone in generating hydroxyl
radicals. Note that this linkage between ozone and fine particles is at
the process level and does not require coexisting ``high'' ozone and
fine particle levels. Many other important linkages involving oxidizing
chemical species (radicals and peroxides) exist within the NOX,
VOC, SOX, ozone chemistry system. A correct characterization of
the basic ozone chemistry and the associated linkages among the
precursors is needed to predict the affect of changing emissions on air
quality indices. Consequently, the predictive air quality models used
to assess ozone and fine particle impacts should include a basic core
set of atmospheric chemical reactions (i.e., a gas phase ozone
chemistry mechanism).
Because of their common atmospheric chemical linkages, many
precursors associated with one pollutant might be considered as an
``indirect'' precursor for another pollutant as well. Virtually all
precursor emissions (NOX, SOX, VOC, CO) undergo initial
attack by hydroxyl radicals and participate in the general cycling of
various chemical intermediate species. Therefore, precursors that
typically may not be associated with a particular secondary pollutant,
such as the effect of VOC on either sulfate or nitrate, indirectly
participate through their roles in atmospheric chemistry. In this
general context, the term precursor does not imply a positive effect on
an associated secondary species as the emission precursor may only
share in certain atmospheric chemical processes without leading to
increases in a secondary pollutant. Multiple possibilities exist. For
example, NOX, which affects the cycling of hydroxyl radicals
(which convert SOX to sulfate), could act indirectly as a sulfate
particle precursor. The majority of VOC species that do not transform
into organic aerosols could nevertheless be fine particle precursors
through their general role (i.e., cycling of radicals) in atmospheric
chemistry. Nitrogen oxides could serve as indirect precursors for
aerosol sulfate formation. This ``universal'' pool of precursors does
not imply that reductions of any specific precursor lead to reductions
of every pollutant. Just as reductions in NOX potentially can
raise local ozone levels, a reduction of a fine particle precursor
possibly can increase ozone or increase a different fine particle
component (e.g., SOX reductions leading to increased ammonium
nitrate, or NOX reductions increasing sulfate formation). These
examples are some of several conceivable indirect precursor
relationships. Many other relationships with similarly unknown degrees
of effect exist. Thus, integrated implementation is far from a
straightforward exercise. Complex air quality simulation models (in
combination with simpler models and receptor/observational methods)
which include approximations of these process linkages will need to be
exercised to account for the multiple nonlinearities and positive and
negative feedbacks. This complexity demands that high quality emission
inventories, technically credible models, and spatially and temporally
representative monitoring data will be needed in predicting pollutant
concentrations and control strategies.
3. Integrating Control Strategy Development Through an Air Quality
Modeling Approach
What does integration mean from an implementation perspective?
Given the complex mechanisms for and linkages between ozone and fine
particle formation, the formulation of control strategies should
acknowledge the need to optimize control options; control of one
precursor might affect both ozone and fine particles or might be
detrimental for one or both. For example, one might start with ozone
management strategies being developed as part of ongoing urban and
regional planning efforts and attempt to quantify the future impact on
secondary aerosols. On the other hand, because NOX controls might
increase ozone levels in certain localized urban areas or because
SO2 reductions might lead to increased concentrations, efficient
air quality management would attempt to optimize the system in relation
to VOC, NOX and SOX emission reductions.
The real benefit of integration is the prospect of a more
systematic, efficient and comprehensive treatment of emission
inventories, episode selection, and atmospheric physics and chemistry
that might empower the air quality manager to characterize source-to-
receptor effects in an orderly way. The addition of data on the costs
and effectiveness of control options would enable the air quality
manager to identify the cost-effective means for attaining a variety of
air quality goals.
To this end, emission bases underlying most current ozone modeling
efforts include most of the sources for aerosol formation (but not
necessarily the aerosol-specific emissions such as organic aerosols
from motor vehicles). Notable exceptions include emissions from many of
the fugitive primary particle sources and most sources of ammonia. The
result of this hypothetical exercise could produce the residual
aerosol- (and regional haze-) related air quality benefits from an
ozone precursor control perspective. [Additional analysis directed at
the specific needs for meeting fine particle and visibility concerns
could follow this ozone oriented approach. Ideally, an objective (and
likely iterative) ability to assess the benefits and tradeoffs
associated with managing all three pollutant categories would evolve.]
Although this example does not represent ``full'' integration given the
unidirectional information flow (ozone to particles), it does
acknowledge similarities among programs and avoids mistakes and
inefficiencies incurred from independent analyses. Aside from any
direct regulatory policy, the linkages across pollutants and emissions
are reasons by themselves for planning for more effective and efficient
development and use of emissions, air quality models and monitoring
networks which address sometimes confounding multiple pollutants and
their related health/welfare effects, and control options.
4. Distinctions Among Ozone, Fine Particles and Regional Haze
Concurrent ozone and fine particle episodes may be expected to
occur given similarities in the meteorological and atmospheric
chemistry processes underlying ozone and fine particle formation,
maintenance and destruction. As discussed above, the linkages
associated with emission source categories and physical and chemical
processes exist more frequently than the occurrence of coepisodic
events. For example, several basic atmospheric chemical reactions
involved in ozone and fine particle formation occur whether or not high
ozone and fine particle levels are generated in the atmosphere.
Nevertheless, several distinctions among the pollutants persist. These
differences include the contribution of primary particles to total fine
particles (and especially PM-10) and wintertime (actually
nonsummertime) fine particle events. Some primary particles are
generated by strong wind conditions (e.g., soil/geologic material) and
other mechanical processes (e.g., roadway fugitives). A fraction of
primary PM peaks in summer in most of the Western third of the country
where there is little precipitation for 6-8 months per year, and dry,
windy conditions lead to the generation and movement of geologic
materials. As discussed earlier, ammonium nitrate, a significant fine
[[Page 65769]]
particle component in the West, is stable at relatively low wintertime
temperatures and therefore does not form significant levels during the
high summertime temperatures. Meteorological effects which influence
the creation, maintenance or removal of high levels of ozone and fine
particles may be significantly different between pollutants, regions of
the country, and times of the year. Other specific emissions-driven
events such as forest burning and wintertime woodsmoke (a major
wintertime source of urban PM) bear virtually no relation to ozone.
Many of these PM episodes can be dominated by either primary or
secondary fine particle components, or by primary anthropogenic coarse
PM emissions. Research exploring the frequency and characterization of
coepisodic and uni-episodic events would yield further insight into
underlying causes of events and provide direction for integrated
implementation opportunities.
Visibility protection presents several additional considerations
beyond the scope of topics covered under ozone and fine particles.
First, fine particle concentrations that are far below any potential
NAAQS can adversely affect visibility in a significant manner,
particularly in more pristine environments, such as Federal Class I
areas in the rural West. For this reason, visibility management needs
to consider the protection of ``clean'' days separately from
assessments focusing on highly impaired days. The meteorology and
emissions characteristics during ``clean'' days differ from those
common during high pollution episodes. This concern raises complex
technical issues related to the ability of models and monitoring
instruments, which often have been designed or tested for meeting
``high'' concentration requirements, to characterize ``low'' level
conditions. Second, relative humidity plays a significant role in
enhancing visibility impairment, particularly in the East. In humid
conditions, particularly above 70 percent relative humidity, sulfates,
nitrates, and certain organics readily take on water and expand to
sizes comparable to the wavelength of light. Particles in this size
range (e.g., 0.1 to 1.0 micron in diameter) are efficient scatterers of
light. Third, unlike the NAAQS approach of setting a national standard,
the regional haze program has as its goal the prevention of any future,
and the remedying of any existing, impairment of visibility in
mandatory Federal Class I areas which impairment results from manmade
air pollution. States are required to make ``reasonable progress''
toward this goal. The notion of background versus manmade air pollution
raises several technical and policy challenges, particularly in the
protection of visibility in ``cleaner'' environments, where small
increases of fine particles can lead to significant visibility changes.
Generally, PM-10 is not considered in the integration discussions
of ozone, fine particles and regional haze. This is because the coarse
fraction (e.g., greater than 2.5 micron) typically is derived from
primary emissions (e.g., fugitives and geologic material) with little
association to ozone from a process (or episodic) perspective. In
addition, visibility impairment leading to regional haze is
overwhelmingly associated with the fine particle fraction of PM-10.
C. Major Technical Issues
The principal technical issues associated with integrated air
quality management involve the adequacy of data bases and models
(including specific process formulations) on which to base credible
assessments. Generally, the tools (ambient data, models and emissions
data) underlying ozone analyses are better developed than those for
fine particles. Major efforts in chemical mechanism development,
ambient monitoring methods and establishment of national and special
study efforts for monitoring, emissions and modeling have resulted in a
wealth of information and familiarity with these tools. This relative
abundance of knowledge for ozone should not be construed as a science
lacking uncertainty as significant technical issues remain (e.g., the
current North American Research Strategies for Tropospheric Ozone
(NARSTO) effort) and even more are yet to be defined. A sampling of
these issues include the representativeness of emission inventories,
particularly biogenic emissions; uncertainties in the modeling system
(e.g., chemical characterizations of aromatics and biogenics, treatment
of vertical mixing processes); difficulties in monitoring techniques
(carbonyls, NOX-NO2, polar VOC); and lack of measurements
(e.g., total reactive nitrogen, upper air data). In some cases, these
gaps are significant and could compromise our ability to perform highly
credible ozone analyses and to ascribe confidence levels in our
results.
Consideration of fine particles and regional haze presents several
additional issues which are a result of: (1) A very complex multiphase,
multicomponent, multiseason aerosol system; (2) the complex covariance
of these data; and 3) the present PM-10 form of the NAAQS which has
resulted in few regulatory needs to hasten an improved
characterization. Significant concerns include major positive and
negative measurement artifacts (related to gas-particle phase changes);
a simple lack of ambient data, especially urban fine particle
measurements; poor quality assurance/control of ambient sampler data;
emissions data with poor general spatial applicability; limited
availability, limited application and evaluation of regionally-accurate
air quality models; and highly empirical treatment of organic aerosols
within the available models. These gaps are interconnected in the sense
that quality model evaluation and improvement rely on available quality
measurements. The issue is further complicated by difficulties (due to
complexities, lack of precedence and resource constraints) in designing
a data collection program to evaluate a gridded model's ability to
characterize fine particles covering wide scales of time (annual,
seasonal, daily) and spatial resolution (regional, urban, local). On
the positive side, a strong history of using ambient data for PM source
apportionment is probably more adaptable to fine particle analyses than
ozone, given that the measurable components of secondary fine particles
(e.g., sulfate) have some direct linkage to precursors, whereas an
ozone measurement by itself provides no inference regarding
contributing precursors.
Several interesting atmospheric chemistry questions remain to be
answered; two examples include nitrate fine particle formation and
organic aerosols. Where and when do ammonia and sulfate become limiting
factors in ammonium nitrate formation? The relatively abundant nitrate
fine particles at sites in the urban West contrast with abundant
regional sulfate fine particles in the East. Substantive decreases in
SO2 emissions could lead to increased nitrate fine particle
formation in the East if sufficient ammonia (a highly uncertain
emissions category) is available. What impacts will NOX emission
reductions have on fine particles? Many possibilities exist. If nitrate
is significant, one would expect a reduction in fine particles.
However, if sufficient sulfur remains available, NOX reductions
could increase or decrease sulfate formation (and, therefore, fine
particles) depending on a complex cycling of oxidizing species.
Reductions in NOX emissions could actually lead to sulfate
increases by reducing competition (between SOX and NOX) for
gas phase oxidizing radicals, or by increasing peroxide levels leading
to
[[Page 65770]]
greater aqueous phase sulfate production. Or, NOX reductions could
slow down sulfate formation through overall reductions in ozone and
other oxidants. This relationship is very complex, and we must exercise
caution in associating fine particle benefits with NOX reductions
in the Eastern U.S.
What are the relative contributions of primary and secondary
organic aerosols across varying spatial (and time) scales? The
potential for large secondary organic aerosol production from biogenic
sources (e.g., pinene emissions) exists throughout the East. How
significant are biogenic-derived aerosols compared to local/urban
contributions from primary anthropogenic organic aerosols? How
different are these relative contributions across seasons, given that
secondary organic aerosol formation increases during the summer? Many
uncertainties underlie the integration of primary and secondary
particles, aside from integrating particles and ozone. For instance,
what are the interactive roles exerted by elemental carbon emissions
and other products of incomplete combustion and geologic materials in
both primary contribution to PM and as formation nuclei for highly
complex secondary PM? On balance, the ability to perform ozone air
quality assessments far exceeds that of fine particles. However, the
infrastructure for conducting fine particle analyses appears to be in
place as a result of progress gained from ozone and acid deposition
modeling and existing monitoring programs for ozone and visibility
(i.e., the Interagency Monitoring of Protected Visual Environments
(IMPROVE) program). Finally, although uncertainties remain in
transforming particles into visibility impairment within short
averaging times, the IMPROVE methodologies for particle and visibility
measurements (and the relationships between particles and visibility)
are widely accepted.
Specific issues across PM and ozone include the ability to
formulate fully-integrated models accounting for multidirectional
effects on several pollutants. For example, the formation of secondary
organic aerosols is a loss mechanism for VOC which presently is not
accounted for in ozone modeling efforts. Many other integration topics
exist, and collectively there is uncertainty regarding the overall
importance of one pollutant imparting an effect on another.
Two basic issues span the gap between science and policy: (1) The
manner in which tools are applied, and (2) accommodating scientific
findings and uncertainties in air quality management decision making.
The first topic reflects the concerns of how one applies deterministic
(i.e., models that establish exact cause and effect relationships) and
uncertain air quality models to probabilistic forms of the standard in
ascribing rigid control requirements. The selection of ``severe''
meteorological episodes versus ``prototypical'' episodes for ozone and
PM-10 modeling has been controversial and remains a difficult model
application issue. Equally complicated is the emerging need to model
seasonal and annual cases. The debate on the credibility of models is
fueled by the manner in which they are applied as much as by concerns
about their formulations and supporting data bases. The second topic
acknowledges the need for conducting policy-relevant as opposed to
policy-driven research and recognizing the different time scales
operating in research and policy arenas (where the timeframe demands
move much faster than research results). Extremely useful information
emerges continuously from research programs, yet a separate, sometimes
very significant, time-lag occurs before information is considered in
the policy-setting process. Hence, opportunities must be available to
incorporate the latest science into policy.
D. Integrating Models and Observations for Sound Air Quality Management
Practice
Much emphasis has been placed on the complementary and integrated
use of models and ambient data in air quality management practice (Rao
et al., 1996). Several facets are associated with this topic, ranging
from the need to evaluate models with sound data bases to conducting
fully integrated analysis optimized through the separate, strong
attributes of data and models. As the technical debate on the use of
models and data continues to mature, perceptions such as ``model'' or
``data'' are replaced by the intelligent and integrated use of ``models
and data.'' Clearly, the demand for measurements initiated by the
National Academy of Sciences Ozone Report (NRC, 1991) to provide
feedback information loops, as well as empirically-based corroboration
of predictive tools, has been adopted by large segments of the air
quality community and reflected in major efforts such as the
Photochemical Assessments Measurement Stations (PAMS) and NARSTO.
An appreciation of the strengths of models and observations can
assist the understanding of current analyses and lead to improved
techniques. A model's strength is its ability to: (1) Integrate an
enormous spectrum of data (e.g., emissions and meteorological
variables) and process understandings (e.g., chemical mechanisms and
flow phenomena), and (2) serve as an exceptional space and time mapping
tool. This latter attribute reflects the model's unique ability to
predict into the future and to supplement (or fill in) present gaps in
observed data. The process formulations embedded in models enable the
addressing of many ``what if'' questions related to emissions control.
However, models are engineering tools that invoke substantial
approximations of scientific understandings of natural phenomena, both
their formulations and application methods reflect engineering
principles more than fundamental science. Observations provide a basis
for testing and diagnosing models. Also, in some instances,
observations add another benefit. They can capture process-type
relationships by themselves (e.g., the emergence of observational-based
models for defining NOX and VOC control preferences). However,
often observations are very sparse.
Applied in isolation, the use of either models or observations
alone is not desirable. Space and time constraints often bias the
interpretation of observational analyses (i.e., analysis results
reflect time and space of monitors which may or may not reflect the
scales of concern). Models suffer from a very large spectrum of
weaknesses because they attempt to portray so many phenomena. Most
critical though is the risk of using a potentially biased model that is
assumed bias free. The integrated use of observations and models
mitigates the individual weaknesses of both approaches and produces a
powerful air quality management tool, especially when applied in an
iterative (even retrospective) manner to continually assess model
results and related implementation strategies.
E. Summary
Air quality assessments for fine particles, ozone, and regional
haze must consider emissions, meteorological processes, atmospheric
chemistry, and deposition, all of which interact over multiple spatial
and temporal scales. Examining in detail the sources only from the MSA/
CMSA surrounding the monitor reporting nonattainment levels of air
quality may need to be augmented (on a space and time basis) for
responsibly allocating those levels to the sources causing them. When
examining the issues on expanded time and space scales, the air quality
management should also take into account the similarities of these air
quality indices,
[[Page 65771]]
such as their common precursor emissions (e.g., NOX, VOC); common
emissions sources (e.g., mobile sources, stationary and area source
combustion emissions, biogenics); and shared chemical and
meteorological processes (e.g., transport, transformation,
precipitation, and removal).
The principal technical issues associated with integrated air
quality management involve the adequacy of data bases and models
(including specific-process formulations) on which to base credible
assessments. Many of these gaps are interconnected since model
evaluations rely on available high quality measurements of emissions,
atmospheric processes (such as wind fields) and ambient concentrations.
On balance, the ability to perform ozone air quality assessments far
exceeds that of fine particles, due mostly to the development of ozone
research as well as a lack of urban fine particle measurements and
important emissions components. However, many of the components of the
infrastructure for conducting fine particle analyses appears to be in
place as a result of progress gained from ozone, acid deposition, and
visibility modeling and monitoring programs. The integrated application
of models and observed data is strongly encouraged. In combination,
both approaches help to mitigate the weakness of an isolated approach,
producing a powerful tool for air quality management.
III. Schedules
Both the ozone NAAQS notice of proposed rulemaking (NPR) and the PM
NAAQS NPR are expected to be published in December 1996 with
promulgation of both the PM and ozone NAAQS scheduled for mid-1997. The
previously-described IIP will be proposed for comment in late 1996 and
finalized in mid-1997 and will apply during the time period following
promulgation of any revised NAAQS. The ozone, PM and regional haze
programs are tentatively planned to be developed on a common schedule.
As indicated above, the integrated implementation strategy for
ozone and PM NAAQS will be issued in two phases. The Phase I
implementation strategy which will give guidance to State and local
agencies concerning actions prior to and including designation of areas
not attaining potential new PM and ozone NAAQS will be proposed in mid-
1997 with a public comment period prior to adoption of the strategy.
The EPA expects that the Subcommittee and CAAAC will make
recommendations regarding formulation of the Phase I strategy prior to
proposal. In mid-1998, the Phase I implementation strategy will be
finalized. (Note that prior to recommendations from the Subcommittee
and CAAAC, EPA will refer to areas not attaining new NAAQS as
nonattainment areas.)
Also in mid-1998, the Phase II implementation strategy will be
proposed. This strategy will provide guidance for the events and
actions between area designation and submittal and approval of State
implementation plans (SIP's). This will include control strategies. The
EPA expects that the Subcommittee and the CAAAC will also make
recommendations regarding formulation of the Phase II strategy prior to
proposal. In mid-1999, the Phase II implementation strategy will be
finalized.
Unlike the NAAQS, the regional haze rule will not set a specific
ambient pollutant standard. However, the rule will include criteria for
measuring reasonable progress and the methods to measure progress. The
EPA currently intends to publish the regional haze NPR in mid-1997
(with Phase I). The EPA is exploring ways to coordinate regional haze
program implementation with NAAQS implementation.
IV. Framing of Phase I Implementation Issues
The Phase I issues below were identified by EPA with substantial
input from the Subcommittee and represent the priority issues which
must be addressed as soon as possible after the revision of the NAAQS.
These issues and options are subject to change as the FACA process and
deliberations continue. The options/principles/questions which are
presented are not all inclusive and are designed to stimulate public
discussion. These options/principles/questions are not intended to
indicate preference or represent any decisions and are under active
FACA consideration. Consistent with the broad mandate given to the
Subcommittee, the EPA is actively seeking new ways to implement the
potential revised ozone and PM NAAQS and regional haze programs, and at
this time is not evaluating legal constraints in the Clean Air Act
(Act) which may limit or change some policy options identified below.
For example, revision of an ozone or PM NAAQS will require EPA to
determine the effect of the new planning requirements triggered by the
revised NAAQS on the existing planning requirements in the various
subparts of part D of title I of the Act. The EPA is not addressing
such legal issues in this notice. The purpose of this advance notice is
to stimulate public interest and comments on a wide range of policy
issues and options, without limitation at this stage, from legal
constraints. After the FACA process produces policy options and
recommendations and as the EPA develops a proposed and final integrated
implementation strategy, the EPA will consider legal authorities and
constraints which may be present in the current Act.
The issues identified below regarding implementation of a potential
ozone or PM NAAQS revision generally use as their frame of reference
the basic planning requirements of part A of title I of the Act and the
basic nonattainment planning requirements of subpart 1 of part D of
title I of the Act. Similarly, the discussion below addressing
development of a regional haze program does not analyze pertinent legal
issues but endeavors to use as a general frame of reference the
visibility protection provisions in sections 169A and 169B of the
current Act. Rather than focusing on the statutory requirements,
however, the following discussion identifies technical and policy
issues and options under consideration. Again, interested readers are
directed to the EPA TTN and WWW site for an up-to-date status of FACA
deliberations on these issues. The EPA is including the issues with
sufficient background information in this ANPR to allow interested
individuals to comment on the development of the implementation
strategies.
Upon a proposal to revise current NAAQS or promulgate new NAAQS for
ozone and PM and regulations for regional haze, the following
characterize the most important implementation issues identified so far
that should be considered. The issues are divided into two phases of
implementation development. The options/principles/ questions are
presented as a broad range of possibilities and are not listed in any
order of preference.
A. Phase I Issues
1. Regional Haze Program Development
In order to place the following discussions on the issues
associated with joint programs in the proper perspective, this section
begins with a discussion of issues and questions related to the
development of a regional haze program. As described in section II,
regional haze is produced by emissions of fine particles and their
precursors from a multitude of manmade and natural sources located
across a broad geographic area. Fine particles impair visibility by
scattering and absorbing light. Average visual range in most of the
Western U.S. is
[[Page 65772]]
100-150 km. In most of the East, the average visual range is less than
35 km. The following discussion includes general background on the
existing visibility protection program, recommendations to EPA for
improving regional haze conditions, and key issues for consideration in
a new regional haze program.
Under a national visibility goal that calls for the prevention of
any future, and the remedying of any existing, impairment of visibility
in mandatory Federal Class I areas which impairment results from
manmade air pollution, the EPA's 1980 visibility regulations addressed
local visibility impairment that was ``reasonably attributable'' to a
single source or small group of nearby sources. Under these rules, the
36 States containing mandatory Federal Class I areas were required to:
(1) develop a program to assess and remedy visibility impairment from
new and existing sources, (2) develop a long-term strategy to assure
progress toward the national goal, (3) develop a visibility monitoring
strategy, (4) consider ``integral vistas'' outside of Federal Class I
areas in all aspects of visibility protection, and (5) notify Federal
land managers (FLM) of proposed new major stationary sources and
consider visibility analyses conducted by FLM in their permitting
decisions.
The 1980 rules were designed to be the first phase in EPA's overall
program to protect visibility. The EPA explicitly deferred action
addressing impairment from regional haze due to the need for further
research and improvements in several technical areas, including
visibility monitoring, modeling, and the relationship between specific
emitted pollutants and visibility impairment. The GCVTC was established
to assess scientific and technical information regarding adverse
impacts on visibility in the transport region and provide
recommendations to the EPA for addressing these adverse impacts. Within
18 months of receipt of the GCVTC recommendations, the Administrator is
required to carry out her ``regulatory responsibilities under section
169A, including criteria for measuring 'reasonable progress' toward the
national goal.'' In developing the regional haze program, EPA will also
have the benefit of recommendations from the 1993 report of the NRC
Committee on Haze in National Parks and Wilderness Areas, Protecting
Visibility in National Parks and Wilderness Areas, and from the work of
the FACA Subcommittee on Ozone, PM and Regional Haze Implementation
Programs. The following addresses key issues for consideration in
developing a regional haze program.
Issue: Applicability--Currently, States containing mandatory
Federal Class I areas where visibility has been identified as an
important value, or having sources which may reasonably be anticipated
to cause or contribute to any impairment of visibility in any such
area, must revise their SIP's to make reasonable progress toward the
national visibility goal. Existing visibility regulations apply to the
36 States containing one or more mandatory Federal Class I areas.
Studies have shown that regional haze can be caused by fine particles
that are transported hundreds or even thousands of kilometers. Thus,
sources in States having no mandatory Federal Class I areas could
potentially contribute to impairment in Federal Class I areas in other
States. The regional haze program should address the potential
applicability to all States.
Issue: Regional Haze Planning Areas--It has been recognized in many
forums that programs to mitigate regional haze may require multistate
or regional approaches to technical assessment, planning, and/or
control strategy implementation. Potential regional approaches are
currently under discussion through the FACA process. Key questions to
be considered are: (a) if regional approaches are taken, should one set
of multistate groupings be developed to address ozone, PM, and regional
haze implementation programs, or should separate approaches be taken
for each of the three programs; and (b) should existing or new
institutions be responsible for future planning activities related to
these three programs?
Issue: Definition of Reasonable Progress--The term ``reasonable
progress'' was not specifically defined in the 1980 visibility
regulations for purposes of regional haze. Current regulations require
SIP's to contain such emission limits, schedules of compliance and
other measures as may be necessary to make reasonable progress toward
the national goal, including: (1) requirements for best available
retrofit technology (BART) for certain major sources of pollution, and
(2) a long-term strategy for making reasonable progress toward meeting
the national goal.
In the June 1996 report from the GCVTC, the Public Advisory
Committee defines reasonable progress as ``achieving continuous
emission reductions necessary to reduce existing impairment and attain
steady improvement in visibility in mandatory Federal Class I areas,
and managing emissions growth so as to prevent perceptible degradation
of clean air days.'' In the GCVTC report, visibility impairment is
defined in terms of total light extinction and deciview. The
legislative history of the 1990 Amendments to the Act also addresses
the issue of reasonable progress and perceptible improvement. Senator
Adams, the sponsor of the 1990 revisions to the visibility protection
program stated that, ``At a minimum, progress and improvement must
require that visibility be perceptibly improved compared to periods of
impairment, and that it not be degraded or impaired during conditions
that historically contribute to relatively unimpaired visibility.''
Question: What should be the criteria for measuring reasonable
progress?
The assessment of reasonable progress can involve quantitative and
nonquantitative factors. From a quantitative perspective, measurement
of reasonable progress could incorporate assessments of visibility
trends, emission reductions, or a combination of both. Tracking
visibility trends suggests a periodic assessment of visibility
conditions (e.g., averages of 20 percent best and worst days, annual
average) as derived from visibility monitoring data and use of a common
metric nationally. The light extinction coefficient would be a logical
choice since it has been used widely for years and is routinely
calculated from optical and aerosol measurements for all IMPROVE sites.
Tracking progress will also require the initial documentation of a
baseline level of anthropogenic visibility impairment at mandatory
Federal Class I areas. The GCVTC has recommended an emission reduction
target approach, including review of compliance with an SO2
percent emission reduction target in the year 2000 and 5-year progress
reviews thereafter. Nonquantitative progress factors could address
whether a State has taken certain administrative or technical actions
determined necessary for measuring and achieving progress over time.
Other questions related to reasonable progress include:
Question: How frequently should progress be measured?
Question: Since monitors are located at only about one-quarter of
the 156 mandatory Federal Class I areas, how can progress be
demonstrated for sites without monitoring?
Question: Should reasonable progress be demonstrated on a
``regional'' basis (i.e., for groups of Federal Class I areas), with
certain IMPROVE sites deemed
[[Page 65773]]
representative of others lacking monitoring?
Question: Would tracking of emissions reductions and conducting
regional modeling be an acceptable surrogate to using monitoring data?
Question: Would the GCVTC approach, which specifies maintaining
(rather than improving) average ``clean day'' conditions, be
appropriate for areas with higher levels of anthropogenic pollution and
thus greater room for improvement (such as most of the Eastern U.S. and
selected areas in the West)?
Question: How should a reasonable progress determination take into
account the degree of improvement in visibility which may reasonably be
anticipated, the costs of compliance, the time necessary for
compliance, and the energy and nonair quality environmental impacts of
compliance, and the remaining useful life of any existing source
subject to such requirements?
Question: What should be required in a State's long-term strategy
for making reasonable progress under the regional haze program?
One element of the reasonable progress demonstration should
describe the State's strategies for preventing future impairment and
ensuring continued progress for a long-term strategy. Estimates of
future population growth and associated changes in emissions, and a
plan to ensure reasonable progress under these anticipated conditions,
could be required by the program. Current visibility regulations
require States to revise their long-term strategies every 3 years with
respect to reasonably attributable impairment. A regional haze program
should address long-term strategies for mitigating all types of
visibility impairment, including regional haze impacts.
Another consideration is the implementation of current statutory
requirements. An EPA Report to Congress dealing with the effects of the
1990 Act Amendments on visibility in Class I areas estimated that Class
I areas from Maine to Georgia would see perceptible improvements in
summer and winter visibility under expected implementation of the
Amendments. The most significant improvements are expected for Class I
areas along the Central and Southern portions of the Appalachian
Mountains. The 1993 report indicates that modeled future improvements
in annual average Eastern regional visibility are directly related to
expected reductions of SO2 emissions under title IV of the Act
(i.e., the acid rain program). Note, however, that current models are
not reliable enough to estimate the extent of improvement in the number
of clear and hazy days at specific locations.
Question: How should regional haze regulations address the
requirement for BART for sources that may reasonably be anticipated to
contribute to regional haze?
Rules for regional haze are required to address BART for any major
source placed in operation between 1962 and 1977 that ``emits any air
pollutant which may reasonably be anticipated to cause or contribute to
any impairment of visibility'' in a mandatory Federal Class I area. The
EPA's current visibility rules limit BART to major stationary sources
whose contribution is ``reasonably attributable'' to impairment in a
Federal Class I area. Recognizing that determinations of BART for
regional haze involves contributions from multiple sources, EPA
solicits comment on how technological controls, costs, the degree of
improvement in visibility which may reasonably be anticipated, and
other factors contained in section 169A(g)(2) should be considered.
Section 169A(g)(2) defines BART as follows: ``* * * in determining
best available retrofit technology, the State (or the Administrator in
determining emission limitations which reflect such technology) shall
take into consideration the costs of compliance, the energy and nonair
quality environmental impacts of compliance, any existing pollution
control technology in use at the source, the remaining useful life of
the source, and the degree of improvement in visibility which may
reasonably be anticipated to result from the use of such technology * *
*.'' (42 U.S.C. 7491(g)(2).
Under the existing visibility program, the BART process has
involved extensive technical assessments to demonstrate that emissions
from a specific major source contribute a specific amount of impairment
at a specific Federal Class I area. The regional haze program should
address whether the BART requirement would be interpreted differently
for the purposes of remedying existing impairment due to the cumulative
emissions from sources located across broad regions.
One alternative interpretation could involve the identification of
sources potentially subject to BART, development of emission rates
determined to be equivalent to BART for key source categories, the
estimation of total emission reductions that would be achieved if BART-
level emission rates are implemented, incorporation of these reductions
into regional emission reduction targets, and implementation of
programs by the States to achieve these emission reductions. Regional
emission reduction targets for BART could be met through reductions
from BART-eligible stationary sources, or the program could potentially
allow an equivalent level of reductions through some other means, such
as a trading program. Under such an approach, proposed emission
reductions planned for attaining any new NAAQS will improve visibility
conditions to some degree. Thus, program integration is needed to
assess the extent to which strategies for attaining the NAAQS will help
meet section 169A requirements for making reasonable progress and
implementing BART.
Question: What should be the process for FLM's and EPA involvement
in reviewing SIP revisions and reasonable progress demonstrations?
States are required to consult in person with the appropriate FLM's
before holding a public hearing on any SIP revisions for visibility.
The regional haze program, therefore, should define roles and
responsibilities of FLM's, States, and EPA in the review of SIP
revisions and reasonable progress demonstrations. It should include
ways that input from FLM's and EPA can be incorporated early in program
planning activities.
Issue: Visibility SIP revisions due after 12 months--States will be
required to revise their SIP's within 12 months of promulgation of
regional haze regulations.
The regional haze rules will need to identify the program elements
to be addressed in these SIP's. Monitoring strategies, emissions
inventories and tracking, emission limitations, schedules of
compliance, and adequacy of personnel, funding, and authority for
program implementation are all important areas for consideration. The
EPA seeks input on other elements that should be included in visibility
SIP's and how to coordinate regional haze program implementation with
NAAQS implementation.
Issue: Monitoring Program--Since 1987, EPA has supported the
IMPROVE network in cooperation with the National Park Service, other
FLM's, and State organizations. The IMPROVE network employs aerosol,
optical (i.e., nephelometers and transmissometers) and scene (i.e., 35
mm photography) measurements. Direct measurements are taken of fine
particles and precursors that contribute to visibility impairment at
more than 40 mandatory Federal Class I areas across the country.
Aerosol measurements are taken twice a week
[[Page 65774]]
for PM-10 and fine particle masses and for key constituents of fine
particles, such as sulfate, nitrate, organic and elemental carbon, soil
dust, and several other elements. Measurements for specific aerosol
constituents are used to calculate ``reconstructed'' aerosol light
extinction by multiplying the mass for each constituent by its
empirically-derived scattering and/or absorption efficiency. These
reconstructed light extinction levels are cross-checked with
nephelometer and/or transmissometer measurements. Knowledge of the main
constituents of a site's light extinction ``budget'' is critical for
source apportionment and control strategy development. These
methodologies allow estimates of how proposed changes in atmospheric
constituents would affect future visibility conditions.
Currently, the IMPROVE monitoring protocols for aerosol, optical,
and scene measurements are not included as Federal reference methods
because visibility is not regulated under the NAAQS. The EPA is
developing a visibility monitoring guidance document, however, that
will identify important methods and procedures for effective aerosol,
optical, and scene monitoring.
Question: Will the current IMPROVE network be sufficient to
determine reasonable progress for mandatory Federal Class I areas?
States implementing a new regional haze program can benefit from
the existing infrastructure of the IMPROVE network, established
protocols, existing sites, and historical data available. The fact that
monitoring equipment is located at only about a quarter of the 156
mandatory Federal Class I areas, however, raises the issue of whether
the current configuration is representative of all sites, and whether
the network needs expansion. The GCVTC, in its recommendations on
future technical needs, states that: ``The current IMPROVE monitoring
network only measures aerosol samples twice a week and at only a few
Federal Class I sites * * *. Consideration should be given to expanding
the coverage or redeployment of resources in the IMPROVE network to
enhance completeness of the data set, including on tribal lands. In
addition, background surveillance sites could be established at
intermediate locations between Federal Class I areas and large regional
sources (metropolitan areas) to provide a better understanding of the
intermediate course of atmospheric chemistry and transport. Monitoring
should be maintained at existing sites in order to allow for long-term
trend analysis.''
As discussed above, visibility SIP submittals and State reasonable
progress demonstrations likely will rely on monitored data from the
IMPROVE network. Thus, it should be determined whether the existing
geographic distribution of IMPROVE network sites is adequate for making
future determinations of reasonable progress in all Federal Class I
areas and for verifying models for predicting possible visibility
effects of future air quality management strategies. In addition, the
ability for the current cooperative arrangement between EPA, FLM's and
the States for managing and funding the network in the future should be
assessed.
2. Designations for New NAAQS and Regional Haze Planning Areas
Under the current statutory requirements and EPA policy, EPA is
required to designate areas as attainment, nonattainment, or
unclassifiable after promulgation of a new or revised NAAQS. The
designation process allows EPA to identify geographic regions where the
public is subject to potential health risks, to alert the public to the
existence of those areas, and to require States to establish control
programs to mitigate those health risks.
The EPA is giving advance notice that regional haze planning areas
(to address Federal Class I areas) may need to be established for the
purposes of conducting technical assessments and developing plans to
abate haze on a regional basis. This is the approach to reducing haze
recommended by the NRC, as well as the GCVTC. Because haze results from
direct emissions of fine particles and fine particle and ozone
precursors, the Subcommittee is considering whether regional haze
planning areas should coincide with nonattainment areas or other types
of control strategy areas established to reduce ozone and PM.
Given that EPA will designate areas and may establish regional haze
planning areas, there are several issues that must be resolved. These
relate mainly to the timing of designations, the basis for designations
(e.g., the use of monitoring or modeling data), the size of
nonattainment areas, and the role of transport in the designations
process. These requirements raise questions such as the following.
Question: What are EPA's options in developing designation schemes
for areas violating the new revised NAAQS?
Question: Should there be differentiation in designations between
areas where violations are occurring and the source areas contributing
to the problem?
Question: Should nonattainment status be changed to indicate only a
public health risk or should nonattainment both indicate the public
health risk and trigger control strategies?
Other questions identified to date include the following.
Question: What information should be used as a basis for
designating areas and establishing regional haze planning areas, e.g.,
monitoring data, modeling data, other data, or combinations of
monitoring, modeling, and other data?
Question: If monitoring or modeling data are relied upon, will
adequate information be available within the appropriate timeframe?
Question: To what extent, if any, should the boundaries of
nonattainment areas, control strategy areas and regional haze planning
areas coincide or should there be separate areas for ozone, PM, and
regional haze?
Question: How can incentives be created to monitor air quality in
order to gain a better scientific understanding of the pollutants and
avoid disincentives when NAAQS violations are measured? How can
incentives be created for private sectors to form monitoring
partnerships with EPA and States?
3. Mechanisms to Address Regional Strategies
Question: How do we develop or use existing institutional
mechanisms to effectively implement control strategies incorporating
multistate regionally--or nationally-applicable measures?
Reviews of monitoring/modeling data suggest that violations of new
ozone NAAQS in the center of the range described by the Clean Air
Science Advisory Committee (CASAC) are likely to be more widespread
than is the case with the current NAAQS. Further, data available at
this time suggest that if a PM-2.5 NAAQS is established in the lower
end of the range being considered, it too may result in a problem which
is regional in scope. By its definition, regional haze is a regional
problem. Areas that present the most concerns for visibility protection
(i.e., Federal Class I areas such as national parks and wilderness
areas) are often located at considerable distances from anthropogenic
sources of visibility degradation.
The likely regional scope of problems meeting new NAAQS or
visibility goals implies a need for measures applied over large (e.g.,
multistate) geographical areas.
Question: Should a framework for institutional mechanisms be
identified
[[Page 65775]]
and developed for facilitating development and implementation of
strategies to reduce regional transport of ozone, fine particles, and
their precursors?
Recently, several cooperative efforts have emerged to better
understand and address regional problems. Some of these have been
mandated, others are voluntary. Examples include NESCAUM, Mid-Atlantic
Regional Air Management Association (MARAMA), Lake Michigan Air
Directors Consortium (LADCO), OTC, Southeast States Air Regional
Management (SESARM), OTAG, Western States Air Resources Council
(WESTAR), GCVTC, State and Territorial Air Pollution Program
Administrators/Association of Local Air Pollution Control Officials
(STAPPA/ALAPCO) and the Environmental Commissioners of States
organization (ECOS).
Question: What attributes of existing multistate institutions have
been successful or appear essential for assisting in the development
and implementation of a regional strategy? Can or should multistate
institutions be developed using one or more existing institutions as a
starting point?
To identify an appropriate institutional mechanism to facilitate
State implementation of programs to meet several air quality goals
which are regional in scope, it is first necessary to more specifically
define what principles are appropriate for such a group. The following
principles, developed by the National and Regional Strategies Work
Group to guide their deliberations, are proposed for consideration.
Principle: The institutional mechanism which is established should
develop an operating protocol whereby participating States can reach
agreement on regional measures to implement. The protocol would address
such issues as, who gets to vote?; what constitutes consensus?; to what
extent are consensus decisions binding?; what should be the role of the
private sector?; what steps should be followed if there is no
compliance with an agreement?
Principle: The institutional mechanism should develop a means for
summarizing and distributing information on the scientific basis,
technical viability and capital/operating costs associated with
measures under consideration. In addition, the institution should
provide a means, along with the EPA, for facilitating distribution of
consistent information regarding emissions, air quality, meteorological
data and modeling results to member States.
Question: When considering possible regional strategies, what
limitations are imposed by State laws or other constraints? Are clear
priority options or ``operating principles'' needed for any
institutional mechanism which is formed to help implement regional
control measures? The following principles serve as possible examples.
Principle: Use the institutional mechanism as a means to establish
positive incentives for upwind areas to reduce precursor emissions.
Possible approaches to consider include: having downwind areas/sources
defray some of the control costs at upwind locations in exchange for
not having to implement the most costly controls in their area, use of
performance goals rather than specific measures, and providing a
``bonus credit'' for early implementation.
Principle: Use the institutional mechanism as a means for fostering
communication among States and the private sector involved with
implementing measures. This goal envisions the mechanism as providing
an information clearinghouse on what different States are doing and the
appropriate contacts for further details. The institutional mechanism
might also serve as the means for facilitating periodic meetings on
various subjects related to implementing regional strategies in a
coordinated fashion.
Principle: Use the institutional mechanism as a means for promoting
use of improved analytical tools and data bases as well as to promote
use of consistent assumptions among the States which are implementing
regional measures.
4. Integration of NAAQS and Regional Haze Implementation Programs
Question: When and where does it make sense to develop and
implement integrated criteria and policies for urban ozone, fine
particles and regional haze control programs?; for regional ozone, fine
particle and regional haze control programs?
As discussed in the previous science section, the photochemical
reactions involving VOC, NOX and sunlight which produce ozone also
produce other secondary pollutants. The photochemical reactions can
result in oxidation of SO2 and NOX to produce visibility-
reducing species which may be regarded as fine PM or as haze. This
realization leads to the question of whether control of ozone, fine
particles and haze can be optimized through consideration of all of
them together in an integrated fashion rather than considering each
separately. This issue considers first how to decide if integration is
appropriate and second, if it is, then what integrated control
strategies should be implemented to reduce the impact on public health
and improve visibility caused by regional haze?
Before key national/regional/multipollutant control strategies can
be developed, a clear understanding of what integration of ozone, PM,
and regional haze means to the implementation process must be
established. For instance, if the goal is to minimize the burden on the
regulated industry, then the outcome of the control strategy may look
different from one with the goal of maximizing the risk reduction to
public health and welfare. Will the knowledge and understanding of
these approaches be understood and the technical tools needed to
integrate the programs be available, or must new state-of-the-science
and technical tools be developed?
While the focus of control strategy integration centers around the
ozone, PM and regional haze programs, some consideration of how other
programs affect these programs will need to be assessed (i.e., acid
rain, climate change, stratospheric ozone, ecosystem protection,
toxics). A number of questions arise when considering the feasibility
of an integrated strategy.
Question: What should be the basis for designing control
strategies?
Question: Should integration utilize consistent or uniform modeling
approaches to understanding long-range transport? What is the most
practical way to accomplish this?
Question: Is an atmospheric chemistry linkage needed between all
the programs? Currently, efforts are under way for fine particles and
ozone. There may be some SO2 chemistry included and limited toxics
integration. Are these adequately characterized?
Question: How should multipollutant integration fit into the
development and initiation of control strategies and programs?
Question: How can contributing sources be identified?
Question: If equity between control of long-range transport and
control of local generation of pollutants is important, how could it be
defined?
Question: What qualitative considerations can be made to provide
assurance that control programs for ozone, PM, regional haze, toxics,
acid deposition, etc., are integrated with one another?
To identify an appropriate framework for implementing efficient
programs that meet several air quality goals for pollutants which are
regional in scope, it is first necessary to more specifically define
what principles are appropriate. As indicated above, the following
[[Page 65776]]
principles are guiding the National and Regional Strategies Work Group
deliberations and could provide an initial set for consideration:
Principle: Pursue integrated control strategies for simultaneously
reducing ambient concentrations of tropospheric ozone and fine PM if
there are sufficient observation-based data to demonstrate both an
environmental and economic benefit to integration.
Principle: Emphasize performance-based control strategies in lieu
of prescriptive command-and-control strategies.
Principle: Develop controls that establish emission reduction
responsibility based on the contribution to the problems, while also
considering cost-effectiveness.
Principle: Emphasize broad-scale control strategies for
contributing sources where dictated by sound science.
Principle: Focus on the interactions of the pollutants and the
interactions between control strategies, identifying both positive and
negative interactions.
Principle: Integrate the implementation of the three programs
(ozone, PM, and regional haze) to the greatest extent possible.
Principle: Recognize that decisions need to be made based on
scientific information that is improving and find institutional
mechanisms to allow for mid-course corrections when significant new
information is available.
5. Prevention of Significant Deterioration (PSD) of Air Quality and
Nonattainment New Source Review (NSR)
Protection of the NAAQS, including new and revised standards, is
provided in part under Federal regulations requiring the
preconstruction review of large new and modified stationary sources of
air pollution, referred to as ``major stationary sources.'' As
described below, the nature of the changes which EPA will be proposing
to the implementation policies for the NAAQS for both ozone and PM will
necessitate consideration of significant changes to these regulations
commensurate with the types of issues already described in this ANPR.
Two separate preconstruction review programs exist, based on the
air quality attainment status of the proposed location of source
construction. Major stationary sources locating in areas designated
attainment or unclassifiable for a particular pollutant are subject to
requirements for the PSD of air quality. Major stationary sources
located in areas designated nonattainment for a particular pollutant
must undergo review via nonattainment NSR requirements.
Under the PSD program, a major stationary source is defined as one
that emits or has the potential to emit 250 tons per year (tpy) or more
of any air pollutant, except where a source is one in a category
specifically listed as a 100 tpy major source category. In addition to
the pollutant for which the source is major, the PSD preconstruction
review applies to each regulated pollutant which the major source will
have the potential to emit in significant amounts, as defined by EPA
regulations. Sources required to undergo PSD review generally must
demonstrate to the applicable permitting authority that proposed
emissions increases will not cause or contribute to violations of the
NAAQS or maximum allowable pollutant concentration increases (known as
increments). Under certain circumstances, the source may also need to
demonstrate that emissions will not have an adverse impact on air
quality related values in Federal Class I areas. The air quality impact
analyses associated with these demonstrations rely upon the use of both
predicted (modeled) air quality and measured (ambient monitoring) data.
The predictions of air quality using air dispersion models require the
use of emissions data for the new or modified source and certain
existing sources within the potential area of impact. Where adequate
ambient data are not available, the permitting authority may require
the PSD applicant to collect 1 year of ambient monitoring data. As
described earlier in this ANPR, changes in the way which air quality
assessments are made, considering how emissions, meteorological
processes, atmospheric chemistry, and deposition occur over multiple
spacial and temporal scales, will likely affect the way in which future
PSD air quality impact analyses are carried out for ozone and PM.
In addition, the PSD applicant must demonstrate that proposed
emissions increases will be controlled through the use of best
available control technology (BACT). The determination of BACT involves
the selection of the most effective control technology for reducing
emissions of a particular pollutant on a case-by-case basis, taking
into consideration energy, environmental and economic impacts and other
costs. Decisions for controlling PM, for example, could be affected by
the particle size, as well as the chemical composition, of the PM
proposed to be emitted. Moreover, changes to the requirements for
applying BACT to individual sources may be needed to more adequately
address the consideration of precursor contributions and atmospheric
chemistry in selecting the best controls to provide the most effective
ambient benefits for ozone and PM.
Increments for PM were originally defined for total suspended
particulate (TSP). The EPA later replaced those increments with PM-10
increments following replacement of the TSP NAAQS with the PM-10 NAAQS.
Should EPA adopt NAAQS for PM which include standards for both PM-10
and fine particles, then EPA will need to consider how that will affect
the current PM-10 increments. Increments for ozone have never been
established because of the technical difficulty associated with
predicting ambient concentration changes resulting from individual
stationary sources of VOC.
Under the nonattainment NSR regulations, ``major source'' is
defined generally as any stationary source that emits, or has the
potential to emit, in consideration of controls, 100 tpy or more of the
nonattainment pollutant, except in specific cases where lower
thresholds apply to more serious nonattainment classifications. The
basic nonattainment NSR requirements for the construction or
modification of major stationary sources in nonattainment areas and the
ozone transport region include the requirement that the lowest
achievable emission rate technology be installed, and that the
increased emissions of the nonattainment pollutant from the proposed
new major source or major modification be offset by actual emissions
decreases of the same pollutant from one or more existing sources. The
offsets may come from the same nonattainment area or another
nonattainment area of equal or higher classification as long as the
offsetting emissions contribute to the air quality problem in the area
where the decrease is being credited. As with PSD, the NSR requirements
for control technology application and offsets do not adequately
account for precursor activities or for the complexities associated
with atmospheric chemistry.
Any revised ozone and PM NAAQS may suggest that existing
implementing guidance, EPA's nonattainment NSR rules, and the States'
nonattainment NSR programs will need to be reviewed and revised in
various ways to address the integrated implementation approach being
contemplated.
The FACA Subcommittee and work groups will look into how the
current PSD/NSR programs for ozone and PM-10 attainment, unclassifiable
and nonattainment areas could be adapted
[[Page 65777]]
or modified. Some PSD/NSR questions that may consider include:
Question: What types of mitigation procedures should be required of
major new or modified sources that would contribute to violations of
the revised NAAQS for ozone or PM, or to visibility impairment in
Federal Class I areas?
Question: Should PSD/NSR requirements reflect the potential for
broad intra and interstate nonattainment areas, control areas, and
regional haze planning areas that could result when addressing
implementation under revised NAAQS for ozone and PM?
Question: What approach should be developed for the treatment of
ozone and fine particle precursors for PSD/NSR applicability purposes?
Question: Should the PSD/NSR programs allow for precursor
substitutions when environmentally beneficial to meet offset and
control technology requirements?
Question: How can availability, crediting, and location of
emissions offsets be restructured under a more regionalized
implementation strategy for PM?
6. Attainment Dates
Areas designated nonattainment with respect to a primary NAAQS are,
under the current statutory structure, required to achieve attainment
as expeditiously as practicable, but no later than 5 years from the
date the area was designated nonattainment. The EPA may extend this
date up to an additional 5 years. This extension may be a full 5 years
or any 1 year increment in between. Additionally, the Administrator may
grant two 1-year extensions.
With respect to a potential new secondary ozone NAAQS, areas
designated nonattainment are required, under the current statutory
structure, to achieve attainment of the secondary NAAQS as
``expeditiously as practicable'' following designation. Secondary
nonattainment areas are not bound to the same 10-year deadline as
primary areas.
Question: Given the preceding discussion, how should attainment
dates for primary and secondary NAAQS be established?
B. Phase II Issues
As discussed earlier in this notice, in Phase I, the FACA
Subcommittee and work groups will address air quality management
framework issues. The EPA plans to propose the resulting Phase I
strategy in mid-1997. Phase II of the integrated implementation
strategy will focus on more detailed control strategy development. The
EPA plans to propose the Phase II strategy in mid-1998. The Phase II
implementation issues include:
--Classifications of nonattainment areas;
--Control requirements (e.g., reasonably available control measures
including reasonably available control technology);
--Economic incentive programs;
--State implementation plan requirements;
--Overall control program integration;
--Measures of progress; and,
--Institutional processes.
All of these issues will be discussed in greater detail at a later
date. Interested readers are directed to EPA's TTN and WWW site for an
up-to-date status of the work groups and Subcommittee deliberations on
these issues.
V. Administrative Requirements
A. Executive Order 12866
Under Executive Order 12866, 58 FR 51735 (October 4, 1993), the
Administrator must determine whether the regulatory action is
significant and therefore subject to the Office of Management and
Budget (OMB) review and the requirements of the Executive Order. The
Order defines significant regulatory action as one that is likely to
result in a rule that may:
(1) Have an annual effect on the economy of $100 million or more or
adversely affect in a material way the economy, productivity,
competition, jobs, the environment, public health or safety or State,
local, or tribal governments or communities;
(2) create a serious inconsistency or otherwise interfere with an
action taken or planned by another Agency;
(3) materially alter the budgetary impact of entitlements, grants,
user fees, or loan programs or the rights and obligations of recipients
thereof; or
(4) raise novel legal or policy issues arising out of legal
mandates, the President's priorities, or the principles set forth in
the Executive Order.
Pursuant to the terms of Executive Order 12866, it has been
determined that this ANPR announces a significant regulatory action,
and as such, will be submitted to OMB for review. Any written comments
from OMB to EPA, any written EPA responses to those comments, and any
changes made in response to OMB suggestions or recommendations will be
included in the docket. The docket is available for public inspection
at the EPA's Air and Radiation Docket and Information Center, which is
listed in the ADDRESSES section of this notice.
B. Miscellaneous
Requirements under the Unfunded Mandates Act of 1995, the Paperwork
Reduction Act, and the Regulatory Flexibility Act will be addressed if
and when the Agency issues a proposed rule based on the comments
received on this ANPR.
List of Subjects in 40 CFR Part 51
Environmental protection, Administrative practice and procedure,
Air pollution control, Carbon monoxide, Nitrogen dioxide, Ozone,
Particulate matter, Sulfur oxides, Volatile organic compounds.
Dated: December 4, 1996.
Carol M. Browner,
Administrator.
Appendix
Definitions
Annual sulfate conversion: Although significant gas phase
transformation of sulfur dioxide occurs, aqueous phase oxidation is
believed to be responsible for the majority of annual sulfate
conversion in the Eastern U.S.
``Best'' and ``worst'' days: Can be defined as the average of
the 20 percent best and worst days, respectively, as measured in
terms of total light extinction.
Chemical sinks: Termination compounds that essentially remove
other compounds (e.g., nitric acid, hydrogen and organic peroxides).
Some ``sinks'' can eventually break down and reform precursor
compounds (e.g., peroxy acetyl nitrate, PAN).
Deciview: Derived from the light extinction coefficient and
describes changes in uniform atmospheric extinction that can be
perceived by a human observer. It is designed to be linear with
respect to perceived visual changes over its entire range in a way
that is analogous to the decibel scale for sound. A 1-deciview
change is roughly equivalent to a 10 percent change in visibility.
Improve: A federally-administered visibility monitoring network
for Federal Class I areas in several States that failed to submit
SIP's containing monitoring strategies as required in the 1980
visibility regulations. Intermediates: Include the short-lived
radicals (hydroxyl, hydro-, and organic-peroxy) which perform many
of the important atmospheric oxidation reactions.
Mandatory Federal Class I Areas: Areas designated as mandatory
Federal Class I areas are those national parks exceeding 6000 acres,
wilderness areas and memorial parks exceeding 5000 areas, and all
international parks which were in existence on August 7, 1977.
Precursors: Compounds which contribute or lead to the formation
of a secondary pollutant. For example, NOx and VOC are ozone
precursors.
Reasonably attributable: Visibility impairment, as defined in 40
CFR 51.301, that is ``attributable by visual observation or any
other technique the State deems appropriate.'' It includes impacts
to mandatory Federal Class I areas caused by
[[Page 65778]]
smoke, plumes or layered hazes from a single source or group of
sources.
Visibility regulations: See 45 FR 80084 (December 2, 1980)
(codified at 40 CFR 51.300-307).
VOC species: Most low molecular weight VOC species (which are
most prevalent in ambient air) are not expected to contribute
significantly to secondary aerosol formation. Certain aromatics, and
higher molecular weight alkanes and alkenes (>6 carbons) are
believed to be the major contributors to secondary organic aerosol
formation.
References
1. Appleton, E.L., ``A Cross-Media Approach to Saving the
Chesapeake Bay,'' Environ. Sci. Technol., 1995, 29, 550A-555A.
2. Dennis, R.L., Personal Communication, 1996.
3. EPA, 1996, ``PM Criteria Document.''
4. GCVTC, ``Report of the Grand Canyon Visibility Transport
Commission'' to the U.S. EPA, June 1996.
5. NESCAUM, ``Preview of 1994 Ozone Precursor Concentrations in
the Northeastern U.S.,'' 1995 Northeast States for Coordinated Air
Use Management, Boston, MA.
6. NRC, ``Rethinking the Ozone Problem in Urban and Regional Air
Pollution,'' National Academy Press, 1991.
7. NRC, ``Protecting Visibility in National Parks and Wilderness
Areas,'' National Academy Press, 1993.
8. Rao, 1996, Personal Communication, 1996.
9. Rao et al., ``Dealing with the ozone nonattainment problem in
the Eastern United States'', 1996.
10. Rao, S.T.E. Zalewsky and I.G. Zurbenko, ``Determining
Temporal and Spatial Variations in Ozone Air Quality,'' J. Air &
Waste Management Association; 1995,45, 57-61.
11. Trijonis, J. et al., ``Report 24--Visibility: Existing and
Historical Conditions--Causes and Effects,'' from Acidic Deposition:
State of Science and Technology,'' Volume III, National Acid
Precipitation Assessment Program, 1990.
12. U.S. Senate, Committee on Environment and Public Works, ``A
Legislative History of the Clean Air Act Amendments of 1990,''
Volume IV, p. 6093.
[FR Doc. 96-31343 Filed 12-12-96; 8:45 am]
BILLING CODE 6560-50-P
