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Regional Haze Regulations; Availability of Draft Guidance Documents

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Environmental Protection Agency (EPA).




We, the EPA are announcing today the availability of draft guidance to assist State and tribal air pollution control agencies in the implementation of regulations governing regional haze which were published in the Federal Register on July 1, 1999. These draft documents address the establishment of natural visibility conditions and the tracking of progress under the regional haze program.


Comments should be submitted on or before January 11, 2002.


Comments should be submitted to Lara Autry, U.S. Environmental Protection Agency (MD-14), Research Triangle Park, NC 27711; E-mail An electronic copy of the draft guidance can be accessed at:​ttn/​amtic/​visinfo.html.

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Lara Autry at the same address; E-mail; telephone (919) 541-5544.

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In section 169A of the 1977 Amendments to the Clean Air Act, Congress established a national visibility goal as 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.” 42 U.S.C. 7491. These provisions were further supplemented by section 169B of the Clean Air Act Amendments of 1990. 42 U.S.C. 7492. States are required to develop implementation plans that make “reasonable progress” toward this goal.

EPA issued initial visibility regulations in 1980 [1] that addressed visibility impairment in a specific mandatory Federal Class I area that is determined to be “reasonably attributable” to a single source or small group of sources. Regulations to address regional haze were deferred until improved techniques could be developed in monitoring, modeling, and in understanding the effects of specific pollutants on visibility impairment. EPA issued regional haze regulations in 1999.[2]

The overall framework of the regional haze rule requires States to develop SIPs that include (1) reasonable progress goals for improving visibility in each mandatory Federal Class I area, and (2) set of emission reduction measures to meet these goals. Specifically, States will set progress goals for each mandatory Federal Class I area to:

  • provide for an improvement in visibility for the 20% most impaired (i.e., worst visibility) days over the period of the implementation plan, and
  • ensure no degradation in visibility for the 20% least impaired (i.e., best visibility) days over the same period.

Baseline visibility conditions for the 20% worst and 20% best days are to be determined using monitoring data collected during calendar years 2000-2004. Baseline conditions for 2000-2004, progress goals, and tracking changes over time are to be expressed in terms of the deciview index.[3]

Most States (and Tribes as appropriate [4] ) participating in regional planning organizations will submit regional haze implementation plans, including estimates of natural conditions and proposed progress goals, in the 2008 time frame. The regional haze SIP deadlines are linked to the dates when PM2.5 designations are finalized. For states that choose to participate in a regional planning organization, the initial (committal) SIP is due within one year of the PM2.5 designation and the full control strategy SIP is due within three years of the PM2.5 designation, but not later than December 31, 2008. For states that choose not to participate in a regional planning organization, regional haze SIPs are due within one year of the PM2.5 designation (for geographic areas designated as attainment or unclassifiable) and within three years of the PM2.5 designation (for geographic areas designated as nonattainment), which is the same time that control strategies to attain the PM2.5 standard are due. In developing any progress goal, the State will need to analyze and consider in its set of options the rate of improvement between 2004 (when 2000-2004 baseline conditions are set) and 2018 that, if maintained in subsequent implementation periods, would result in achieving estimated natural conditions in 2064.

The purpose of the draft documents announced in today's notice, when completed, will be to provide guidance to the States in implementing the regional haze program and to explain how EPA intends to exercise its discretion in implementing Clean Air Act provisions and EPA regulations concerning the estimation of natural visibility under the Regional Haze program. The guidance is designed to implement national policy on these issues. Sections 169A and 169B of the Clean Air Act and implementing regulations at 40 CFR 51.308 and 51.309 contain legally binding requirements. When completed and issued, these draft guidance documents will not substitute for those provisions or regulations, nor will they constitute regulations themselves. Thus, they will not impose binding, enforceable requirements on any party, and may not apply to a particular situation based upon the circumstances. We and State decision Start Printed Page 64263makers retain the discretion to adopt approaches on a case-by-case basis that differ from this guidance where appropriate. Any decisions by us regarding a particular State implementation plan (SIP) demonstration will only be made based on the statute and regulations. Therefore, you are free to raise questions and objections about the appropriateness of the application of this guidance to a particular situation; we will, and States should, consider whether or not the recommendations in this guidance are appropriate in that situation. These guidance documents will be living documents and may be revised periodically without public notice. We welcome public comments on these documents at any time and will consider those comments in any future revision of these guidance documents. However, for the purposes of completing the current versions of these documents and providing them to the State and tribal air pollution control agencies for their use, we ask that any comments on these versions be submitted to us not later than January 11, 2002.

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Dated: November 28, 2001.

William Lamason,

Acting Director, Emissions Monitoring Analysis Division.

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1.  See 45 FR 80084 (December 2, 1980).

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2.  See 64 FR 35713 (July 1, 1999). See also 40 CFR 51.300-51.309.

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3.  The deciview is a haze index derived from calculated light extinction, such that uniform changes in haziness correspond to uniform incremental changes in visual perception across the entire range of conditions, from pristine to highly impaired. Deciview = 10 ln(bext/10).

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4.  Under the Tribal Air Rule (63 FR 7254; February 12, 1998; 40 CFR part 49), Tribal governments may elect to implement air programs in much the same way as states, including development of Tribal implementation plans.

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[FR Doc. 01-30741 Filed 12-11-01; 8:45 am]