[Federal Register Volume 66, Number 6 (Tuesday, January 9, 2001)]
[Notices]
[Pages 1665-1668]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-565]
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ENVIRONMENTAL PROTECTION AGENCY
[FRL-6931-5]
National Ambient Air Quality Standards for Sulfur Oxides (Sulfur
Dioxide); Availability of Information
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice.
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SUMMARY: The EPA is announcing today the following actions: The
availability of new information on 5-minute average sulfur dioxide
(SO2) concentrations in the ambient air; The status of EPA's
ongoing activities to characterize and address 5-minute peak SO2
levels that may pose risk to sensitive individuals with asthma,
including plans to consider taking final action on the proposed
intervention level program (ILP) for the reduction of SO2
emissions published on January 2, 1997 and to respond to the remand of
the final decision on the national ambient air quality standards
(NAAQS) for SO2 published on May 22, 1996; The solicitation
of comments on the new air quality information.
DATES: Comments should be submitted on or before March 12, 2001.
ADDRESSES: Comments should be submitted to Susan Lyon Stone, U.S.
Environmental Protection Agency (MD-15), Research Triangle Park, NC
27711; email [email protected].
FOR FURTHER INFORMATION CONTACT: Susan Lyon Stone at the same address;
e-mail [email protected]; telephone (919) 541-1146.
SUPPLEMENTARY INFORMATION: On May 5, 1998, EPA announced its plans for
responding to a remand of its final decision not to revise the SO2
NAAQS (61 FR 25566, May 22, 1996) and for final action on the proposed
ILP (62 FR 210, January 2, 1997); identified interim actions that we
planned to take to address 5-minute peak SO2 levels that may
pose risk to sensitive individuals; and solicited new information and
analyses on 5-minute peak SO2 levels (63 FR 24782). The
sensitive population for the effects of 5-minute peaks of SO2
consists of children, adolescents and adults with mild or moderate
asthma who are physically active outdoors. As discussed in this 1998
notice, the primary issue in our SO2 NAAQS decision was
whether a new 5-minute NAAQS was appropriate to protect sensitive
individuals with asthma from the risk posed by exposure to 5-minute
SO2 levels of 0.6 ppm or above. Given the available health
effects information; information as to the localized, infrequent, and
site-specific nature of the risk involved; and the advice of the Clean
Air Scientific Advisory Committee (CASAC), the Administrator concluded
that short-term (i.e., 5-minute) peak concentrations of SO2
do not constitute a public health problem for which the establishment
of a NAAQS would be appropriate.
Consistent with our final SO2 NAAQS decision, and to
supplement the protection provided by the existing SO2
[[Page 1666]]
NAAQS, we subsequently proposed an ILP to assist States in
determining whether 5-minute peak concentrations of SO2
posed a significant health risk in the local population, and if so, to
identify appropriate remedial measures. A key element of the proposed
ILP was the establishment of a concern level of 0.6 parts per million
(ppm), 5-minute average SO2 concentration, and an
endangerment level of 2.0 ppm, 5-minute average. The proposed ILP would
require that State and tribal plans contain the authority to take
whatever action is necessary to prevent further exceedances of such
concern and endangerment levels when the State/tribe determines that
intervention is appropriate. The proposed ILP includes factors that the
State/tribe should consider in making such determinations, including
the magnitude and frequency of peak concentrations exceeding these
levels, the history and nature of any citizen complaints, available
information on potential exposure of sensitive individuals with asthma,
and information about the source(s) causing the peak SO2
concentrations. Based on these factors, the proposed ILP provides for
flexibility for the State/tribe to determine the nature and degree of
intervention that is warranted in any area and to relocate existing
SO2 monitors to areas where 5-minute peak concentrations may
be of concern.
On January 30, 1998, the Court of Appeals for the District of
Columbia issued a decision in a case brought by the American Lung
Association (ALA) and the Environmental Defense Fund, American Lung
Association v. Browner, No. 134 F.3d 388 (D.C. Cir. 1998) (ALA) that
challenged our decision not to establish a new 5-minute SO2
NAAQS. The court found that we had failed to provide an adequate
explanation for our determination that no revision to the SO2
NAAQS was appropriate, and remanded the decision to us to more fully
explain our decision. id. In the absence of any court-established
deadline for EPA action, EPA agreed with ALA to finalize our response
to the remand by the end of the year 2000 (63 FR 24782). Subsequently,
in light of a decision by the court in another case relating to EPA's
1997 revisions of the NAAQS for ozone and particulate matter, American
Trucking Associations v. EPA, 175 F.3d 1027, 195 F.3d 4, cert. granted
120 S. Ct. 2003 (U.S. May 22, 2000) (No. 9901257) (ATA), the ALA agreed
to extend the time for us to respond to the remand of the SO2
NAAQS decision to accommodate our need for additional time and pending
additional court action in the ATA case.
In conjunction with extension of this schedule, we committed to
take a number of actions, building upon the actions discussed in our
1998 notice (63 FR 24782). These ongoing actions focus on broadening
our efforts to collect and analyze data on 5-minute average SO2
concentrations, providing further guidance to States on monitoring 5-
minute SO2 concentrations around industrial sources, and
addressing specific situations relating to short-term SO2
exposures that are of concern in local communities. c
Availability of Information on 5-Minute SO2
Concentrations
This section discusses new information that is now available on 5-
minute SO2 concentrations, and includes descriptions of the
nature of such data in EPA's Aerometric Information Retrieval System
(AIRS) and data in other formats, and analyses that we have conducted
of these data. Our 1998 solicitation of new information and analyses on
5-minute peak SO2 levels (63 FR 24782) resulted in the
submission of relatively little additional 5-minute SO2
monitoring data. On June 30, 2000, we directly requested the assistance
of EPA's Regional Offices and the State and Territorial Air Pollution
Program Administrators/Association of Local Air Pollution Control
Officers (STAPPA/ALAPCO) in obtaining any additional 5-minute
SO2 monitoring data that may have been collected but not
submitted to AIRS.\1\ In response to this request, we have received
from nine States additional 5-minute SO2 monitoring data
from more than 48 monitoring sites, recorded during the period 1994-
2000. We note, however, that the newly submitted data generally have a
number of limitations, such that neither EPA nor the States express any
opinions about the validity of these data at this time. More
specifically, much of the data has been provided to us in a variety of
formats not directly compatible with AIRS; only one State and the
District of Columbia submitted their additional data into AIRS. Most of
the data files lacked information on monitor location and type, or
nearby source types, and a number of States have warned us that the
data have not been subjected to appropriate quality assurance/quality
control (QA/QC) procedures.\2\ To the extent possible and appropriate,
we are working with States to address these limitations. However, at
this time, we do not believe it is appropriate to disseminate or rely
on these data. At such time as the data are validated, they will be
available to the public in AIRS.
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\1\ Robert Perciasepe, Assistant Administrator for Air and
Radiation, to S. William Becker, Executive Director, STAPPA/ALAPCO,
June 30, 2000; Robert Perciasepe, Assistant Administrator for Air
and Radiation, to EPA Regional Administrators, Regions I-X, June 30,
2000.
\2\ For example, in our preliminary review, we have noted that a
number of recorded values appear to have been automatically flagged
by the data loggers as reflecting monitor malfunctions and
calibration measurements.
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To supplement prior assessments \3\ and improve our understanding
of the frequency, magnitude, and number of locations at which high 5-
minute concentrations of SO2 may be occurring, we have
undertaken analyses of the data in AIRS that include the following
activities:
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\3\ Prior assessments were done as part of our 1996 review of
the SO2 NAAQS and are available in the docket for that
rulemaking (Docket No. A-84-25).
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(1) We have evaluated monitoring data from 83 monitoring sites
reporting 5-minute concentrations in 14 States to determine the
frequency of peak concentrations greater than or equal to 0.6 ppm, the
variations of such frequencies across locations, whether there are
industrial sources located nearby that may be contributing to measured
peak concentrations, and the size of the surrounding population within
a 5-km radius of the monitor.
(2) Since we have AIRS data from far more monitoring sites (695)
recording 1-hour average concentrations than from monitors recording 5-
minute concentrations, we have constructed and applied mathematical
models to aid in estimating the potential for the occurrence of 5-
minute peak concentrations at and above 0.6 ppm SO2 at
locations where only 1-hour average concentrations are available. These
models are based on determining the relationships of 5-minute peak
concentration distributions \4\ to 1-hour mean concentration
distributions and evaluating the statistical strength of these
relationships.
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\4\ Five-minute peak concentrations are taken to be the maximum
5-minute block average within each hour.
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Although we intend to extend these analyses to include additional
data to the extent they become certified for inclusion in AIRS, we have
substantially completed the analyses described above. A draft report
summarizing our preliminary findings has been placed on EPA's website
at http://www.epa.gov/ttn/amtic.
Status of Ongoing Activities
This section discusses the status of our ongoing activities to
characterize and address 5-minute peak SO2 levels
[[Page 1667]]
that may pose risk to sensitive individuals with asthma. These
activities include: (1) Efforts to obtain State certification of newly
submitted 5-minute SO2 monitoring data and related
information, to be followed by analysis of this additional certified
data, as appropriate; (2) development of guidance on monitoring 5-
minute SO2 concentrations; (3) additional 5-minute
SO2 air quality monitoring, in coordination with States' and
industry's monitoring activities; (4) consideration of taking final
action on the proposed ILP; and (5) consideration of our response to
the remand of our 1996 SO2 NAAQS decision.
We are now in the process of working with States who submitted new
5-minute SO2 monitoring data to facilitate their
certification of the data. We are also working to obtain related
information, as appropriate, such as monitor location, nearby source
types, and surrounding population. To the extent that such information
warrants further analysis, we intend to extend the analyses discussed
above to include these data, and to complete these analyses by mid-
2001.
In a separate but related effort, we are evaluating our ambient air
monitoring regulations and approaches. As part of a broad, integrated
monitoring strategy for all the criteria pollutants, which we expect to
propose late Spring 2001, we also expect to propose regulatory changes
necessary to reflect current data needs, which in part will involve
SO2 monitoring. We initially proposed revisions to
regulations at 40 CFR parts 53 and 58 to modify reference and
equivalent methods for SO2 and to revise the minimum
requirements for ambient monitoring in compliance with the
SO2 NAAQS in order to facilitate additional monitoring of 5-
minute concentrations (60 FR 58959, March 7, 1995). We will consider
the input received from the earlier proposal in developing these
changes.
In addition, we also intend to issue a guideline specifically on
SO2 monitoring. We have already developed a draft guideline,
which is intended to assist State and local air pollution control
agencies in evaluating their networks and the appropriateness of
revising those networks to better address the potential for 5-minute
concentrations of concern. The draft guideline provides relevant
background information, summarizes recommended procedures for network
review, suggested procedures for review of available ambient data to
determine the potential for high 5-minute concentrations, and
recommendations for short-term monitoring network design, including
cost estimation procedures to help assess the costs of network
revisions. This draft document may be obtained at EPA's website at
http://www.epa.gov/ttn/amtic. In addition to these efforts, we will
work with the States to facilitate implementation of the SO2
monitoring guideline and the broader integrated monitoring strategy.
We are also starting to develop plans for collecting additional 5-
minute SO2 air quality monitoring data. We intend to work
with States and industry to elicit their support and participation in
this project, which we expect will provide important new information as
to the likelihood and nature of 5-minute peak SO2
concentrations that may now be occurring around various types of
industrial facilities. We anticipate that this project will take
approximately two years, including planning, coordination, data
collection and analysis. We expect that this information will help
inform our response to the remand of the SO2 NAAQS decision
as well as the next periodic review of the SO2 NAAQS.
In our consideration of taking final action on the proposed ILP (62
FR 210, January 2, 1997), we will take into account comments received
in response to this notice as well as comments received on our 1997
proposed action. We received 62 comments on the proposed ILP, of which
11 comments were from State and local agencies and a related
organization, 38 comments were from individual industry commenters and
trade groups, four were from public advocacy groups, and four comments
were from private citizens. Many commenters supported the proposed ILP
and its flexible implementation strategy, while others commented that
States already have sufficient regulatory authority to deal with
sources emitting high 5-minute peaks of SO2 that may pose a
risk to the health of asthmatic individuals living nearby, and
therefore an additional regulatory program is not necessary. The
commenters disagreed about the significance of the health effects
associated with exposure to short-term peaks of SO2,
particularly at the concern level (0.6 ppm SO2, 5-minute
average). Some expressed the view that the health effects associated
with exposures at this level are not significant enough to warrant
remedial action, while others expressed the view that this level was
not sufficiently health protective and urged us to set the concern
level at a lower concentration (e.g., 0.3 ppm SO2, 5-minute
average). Many commenters expressed concern about the costs associated
with implementing the proposed ILP, especially when compared to the
relatively small size of the sensitive population (i.e., individuals
with asthma who are active outdoors) that might be affected. In
addition, some State and local agency commenters expressed concern
about the costs associated with the additional source-based monitoring
(e.g., for monitor purchase, monitor relocation, or additional staff
members) that might be needed to implement the proposed ILP.
With regard to moving forward with a final ILP, we note that the
results of the data analyses completed to date continue to suggest that
there may be a number of locations in the country where repeated
exposures to 5-minute peak SO2 levels of 0.60 ppm and above
could pose a risk of significant health effects. Taking into account
this information, the results of planned additional analyses, and
public comments, we will consider taking final action on an ILP. We
anticipate reaching a final decision on an ILP by the summer of 2001,
as a separate matter from our consideration of our response to the
remand of the 1996 SO2 NAAQS decision.\5\
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\1\ Although we are in the process of considering whether to
move forward with an ILP during the same time that we continue to
consider our response to the remand in the ALA case, it is important
to note that we view our ILP activities and our response to the ALA
remand as independent actions. Our consideration of taking final
action on the proposed ILP is not intended as a substitute for a
decision on the ALA remand, nor is it intended to indicate that we
have reached any particular outcome regarding the need for a revised
SO2 NAAQS. Regardless of our decision in response to the
ALA remand, we believe that it is appropriate at this time to
consider taking final action on an ILP to provide any supplementary
protection from exposures of concern to short-term SO2
peaks that may be appropriate.
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Since the court decision in the ALA case, remanding our decision
not to revise the SO2 NAAQS, we have continued to take a
number of actions relating to 5-minute SO2 peaks of 0.6 ppm
or greater, including the solicitation and review of additional
information and analyses described above. Although we continue to
evaluate this and other information in light of the ALA remand, the
ruling of the Court of Appeals for the District of Columbia Circuit in
the ATA case, and its subsequent appeal to the United States Supreme
Court, has created potential uncertainty regarding the appropriate
framework for decisions under section 109. As a result, we believe that
the better course of action is to await a decision from the Supreme
Court, which is expected during the spring of 2001, before responding
to the ALA remand of our SO2 NAAQS decision. This will
better enable us to
[[Page 1668]]
review and assess all relevant information, including the court's
opinion and any additional analyses and technical information, that
could shed additional light on the appropriate response to the remand.
We intend to publish our schedule for considering the relevant
information and responding to the remand by mid-2001.
Request for Comments
We are soliciting comments on the data analyses and preliminary
findings in our draft report that is now available, to better inform
future actions to reduce the health risk that may be posed by potential
exposures of exercising asthmatics to short-term peaks of
SO2. More specifically, we solicit comments on the
following: the appropriateness of using 1-hour average SO2
monitoring data as one element in our efforts to estimate the potential
for 5-minute peak concentrations greater than or equal to 0.6 ppm
SO2; the usefulness of these types of analyses in
identifying the need for additional monitoring or other actions and the
sources likely to contribute to high 5-minute SO2
concentrations; and, for the purpose of assessing the need for
additional monitoring around SO2 sources, the
appropriateness of using just the hourly maximum 5-minute average
SO2 concentrations, rather than all the 5-minute averages in
an hour, including any relevant data storage and management
considerations. We will consider this information in the context of
taking final action on the proposed ILP, conducting future analyses of
5-minute SO2 air quality data, responding to the ALA remand
and conducting the next periodic review of the SO2 NAAQS.
Dated: January 3, 2001.
Robert Perciasepe,
Assistant Administrator for Air and Radiation.
[FR Doc. 01-565 Filed 1-8-01; 8:45 am]
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