[Federal Register Volume 63, Number 86 (Tuesday, May 5, 1998)]
[Notices]
[Pages 24782-24784]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-11874]


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ENVIRONMENTAL PROTECTION AGENCY

[FRL-6009-8]


National Ambient Air Quality Standards for Sulfur Oxides (Sulfur 
Dioxide); Intervention Level Program

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.

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[[Page 24783]]

SUMMARY: The EPA is announcing today the following actions:
    (1) The schedule for responding to the remand of the final decision 
on the national ambient air quality standards (NAAQS) for sulfur 
dioxide (SO2) published on May 22, 1996, and any final 
action on the proposed intervention level program (ILP) for the 
reduction of SO2 emissions published on January 2, 1997.
    (2) The interim actions EPA will take to address 5-minute peak 
SO2 levels that may pose risk to sensitive asthmatic 
individuals.
    (3) The solicitation of comments and associated information and 
analyses on 5-minute peak SO2 concentrations in the ambient 
air, with emphasis on the characterization of the likelihood of 
exposure of sensitive asthmatic individuals to peak SO2 
concentrations at 0.6 parts per million (ppm) and above during 
exercise.

DATES: (1) The EPA will propose its response to the SO2 
NAAQS remand for public comment in the summer of 1999 and take final 
action no later than December 2000. The EPA will take any final action 
on the proposed ILP, consistent with its final action on the 
SO2 NAAQS, no later than December 2000.
    (2) In the interim, until such final actions are taken, EPA will 
now begin taking actions to address known problem areas with high 5-
minute peak SO2 levels that may pose risk to sensitive 
asthmatic individuals.
    (3) Comments and associated information and analyses should be 
submitted on or before November 1, 1998.

ADDRESSES: Comments and associated information and analyses should be 
submitted to Ms. Susan Lyon Stone, U.S. Environmental Protection 
Agency, MD-15, Research Triangle Park, NC 27711.

FOR FURTHER INFORMATION CONTACT: Ms. Susan Lyon Stone at the above 
address or telephone (919) 541-1146 on matters pertaining to 5-minute 
peak SO2 levels and the SO2 NAAQS remand. For 
information on the interim actions EPA plans to take to address 5-
minute peak SO2 levels and the ILP, contact Mr. Eric Crump 
at the same address or telephone (919) 541-4719.

SUPPLEMENTARY INFORMATION:
    On May 22, 1996, EPA announced its final decision that revisions of 
the SO2 NAAQS were not appropriate (61 FR 25566). At issue 
in making that decision was whether a new 5-minute NAAQS was 
appropriate to protect sensitive asthmatic individuals 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 risk 
involved; and the advice of the Clean Air Scientific Advisory Committee 
(CASAC), the Administrator concluded that short-term peak 
concentrations of SO2 do not constitute the type of 
ubiquitous public health problem for which the establishment of a NAAQS 
would be appropriate.
    Because of the localized, infrequent, and site-specific nature of 
the risk, as characterized in its final decision notice (61 FR 25575-
25576), the Administrator further concluded that the residual health 
risk posed by short-term SO2 concentrations remaining after 
attainment of the current SO2 NAAQS are most appropriately 
addressed by the States. It was the Administrator's judgment that the 
States are in a far better position than EPA to assess the highly 
localized and site-specific factors that determine whether occurrences 
of 5-minute peak SO2 concentrations in a given area pose a 
significant risk to sensitive asthmatic individuals in the local 
population, and if so, to fashion an appropriate remedial response. In 
light of its characterization of the nature of 5-minute peak 
SO2 concentrations and the likelihood that these peaks would 
result in exposure conditions that could cause significant health 
effects in sensitive asthmatic individuals during exercise, EPA also 
announced that it intended to propose a new program and associated 
guidance to assist States in determining whether 5-minute peak 
concentrations of SO2 in the range of 0.6 ppm to 2.0 ppm 
posed a significant health risk to sensitive asthmatic individuals in 
the local population, and if so, to identify appropriate remedial 
responses. Consistent with its final SO2 NAAQS decision, EPA 
subsequently proposed for comment the intervention level program (ILP) 
for the reduction of SO2 emissions on January 2, 1997 (62 FR 
210). This proposed ILP was intended to supplement the protection 
provided by the existing primary and secondary SO2 NAAQS.
    A key element of the proposed ILP was the establishment (to be 
codified in part 51 of the CFR) of a concern level of 0.6 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 a discussion of the 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 asthmatic individuals, and information 
about the source(s) causing the peak SO2 concentrations. 
Based on the above 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. The States/tribes are also given the 
flexibility in the proposed ILP to relocate existing monitors to areas 
where 5-minute peak concentrations may be of concern through changes to 
SO2 monitoring requirements. The proposed ILP recognizes 
that authority to take such actions, when justified on a case-by-case 
basis, currently exists under section 303 of the Clean Air Act. 
Building upon this authority, the proposed ILP codifies the health 
benchmarks for such actions (i.e., the concern and endangerment levels) 
and provides guidance to assist States/tribes in identifying and taking 
appropriate actions.

SO2 NAAQS Remand

    In July 1996, the American Lung Association and the Environmental 
Defense Fund petitioned the District of Columbia Court of Appeals for 
judicial review of EPA's decision not to establish a new 5-minute 
NAAQS. On January 30, 1998, the court issued a decision in that case 
American Lung Association v. Browner, No. 96-1251 (D.C. Cir.). The 
court found that EPA failed to provide an adequate explanation for its 
determination that no revision to the SO2 NAAQS was 
appropriate. As a result, the court remanded the case to permit EPA to 
more fully explain its decision not to set a standard for short-term 
peak SO2 levels of 0.6 ppm or greater.

Schedule for EPA Final Actions

    In remanding the case to EPA, the court did not establish a 
deadline for EPA to take action consistent with the remand. In lieu of 
pursuing further litigation to seek a court-ordered schedule for EPA's 
response to the SO2 NAAQS remand, the petitioners in the 
case initiated discussions with EPA to establish such a schedule for 
EPA's response. Based on these discussions, it was agreed that EPA 
would take final action no later than December 2000. In order to meet 
this date for final action, EPA intends to propose for public comment 
its response to the remand by

[[Page 24784]]

the summer of 1999. In conjunction with taking final action on its 
response to the SO2 NAAQS remand, EPA also intends to take 
any final action on the ILP no later than December 2000. In so doing, 
EPA will draw upon its response to the remand on the SO2 
NAAQS decision so as to ensure consistency between these actions.

Interim Actions

    Between now and when final action on the SO2 NAAQS 
remand and the ILP is taken, EPA intends to work with States/tribes 
with known areas of high 5-minute peak SO2 concentrations to 
undertake a number of actions. These actions include the following: 
determining whether the existing SO2 NAAQS and State 
Implementation Plan (SIP) requirements are being met in such areas; 
taking regulatory action in such areas where appropriate (e.g., SIP 
calls); and initiating enforcement review/action to ensure SIP 
requirements are met. The EPA also plans to issue monitoring and other 
guidance to States/tribes/regions to assist them in identifying and 
addressing high 5-minute peak problems.

Solicitation of Information on 5-Minute Peak SO2 
Concentrations

    To supplement its current information on 5-minute peak 
SO2 concentrations and exposures of sensitive asthmatic 
individuals to peak levels of concern, EPA is soliciting comments and 
associated information and analyses on such 5-minute peak 
SO2 concentrations. The EPA will consider this information 
in the context of the interim actions described above and in its 
response to the remand and in its final ILP decision. More 
specifically, EPA solicits information and analyses on the following: 
sources or source types and the nature of events that are most likely 
to give rise to short-term peak SO2 levels; the magnitude 
and frequency of such peaks; the time of day of the occurrence of such 
peaks; meteorological conditions in the area in which such peaks occur; 
the density of the population near the source(s) involved; and the 
frequency with which asthmatic individuals would likely be exposed to 
peak SO2 concentrations at 0.60 ppm and above while at 
elevated ventilation rates (i.e., during exercise).

    Dated: April 29, 1998.
Richard D. Wilson,
Acting Assistant Adminstrator for Air and Radiation.
[FR Doc. 98-11874 Filed 5-4-98; 8:45 am]
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