### 24672 Federal Register 

### / Vol. 52, No. 126 

### / Wednesday, July 1, :1987 /-Rules 

### and Regulations

ENVIRONMENTAL PROTECTION
AGENCY

40CFR Parti51 and 52
fAD-FRL-3141-9(c)] Regulations for Implementing Revised Particulate Matter Standards
AGENCY: Environmental Protection Agency (EPA). ACTION:Final rule.

SUMMARY: To implement revised national ambient air quality standards (NAAQS) for particulate matter, proposed March 20, 1984 (49 FR 10408), EPAproposed revisions to 40 CFR Parts 51, 52, and 81 on April 2, 1985 (50FR 13130). Part 51 establishes requirements for preparation, adoption, and submittal ofState implementation plans (SIP's); Part 52 sets forth the Administrator's approval and promulgation of implementation plans; and Part 81 sets forth air quality planning area designations. Today's action promulgates revisions toParts 51 and 52

as ofJuly 31, 1987 and announces EPA's final policies for revising SIP's to account for the revised NAAQS for particulate matter. Theproposed revisions to Part 81 area designations

are withdrawn. EFFECTIVE DATE:This action is effective July 31, 1987. ADDRESSES: Material relevant to the SIP policies, guidance, and regulations being promulgated today can be found in Public Docket No. A-82-38. This docket also includes material relevant to the retention of total suspended particulate (TSP)increments and other components of the prevention ofsignificant deterioration (PSD) program originally submitted to Docket No. A-83-48 and other dockets listed below. Material pertinent to related revisions being promulgated today are contained in the following dockets:

a. The particulate matter standards in 40 CFR Part 50, Docket No. A-82-37;

b.Ambient air monitoring reference and equivalent methods in 40 CFR Part 53, Docket No. A-82-43;

c. Ambient airquality surveillance for particulate matter in 40 CFR Part 58, Docket No. A-83-13.

The dockets are located at the U.S. EPA Central Docket Section in South Conference Center, Room 4, 401 M Street SW., Washington, DC 20460. The docket may be inspected between 8:00

a.m. and 3:00p.m. on weekdays, and a reasonable fee may be charged for copying. Availability of Related Information

The EPAprepared the following guidelines to assist States in revising their SIP's in response to the revised particulate matter NAAQS.

* PMo SIP Development Guideline, EPA 450/2-86-001.

* Procedures for Estimating Probability ofNonattainment ofa PMo NAAQS Using Total Suspended Particulate or PMo Data, EPA 450/4-- 017;

* Ambient Monitoring Guidelines for Prevention of Significant Deterioration (PSD). EPA 450/4-87-007.

Copies ofthese guidelines are being
sent to State and local air pollution control agencies. They are available for inspection and copying at:

* State Air Programs Branch, EPA, Region I,JFK Federal Building, Boston, Massachusetts 02203.

* Air Programs Branch, EPA, Region II, 26 Federal Plaza, New York, New York 10278.

* Air Programs Branch, EPA, Region III, 841 Chestnut Building, Philadelphia, Pennsylvania 19107.

* Air Programs Branch, EPA, Region IV, 345 Courtland Street NE., Atlanta, Georgia, 30365.

* Air and Radiation Branch, EPA, Region V, 230 South Dearborn Street, Chicago, Illinois 60604.

9 Air Programs Branch, EPA, Region VI, Allied Bank Tower 1445 Ross Avenue, Dallas. Texas 75202-2733.

* Air Branch, EPA, Region VII, 726 Minnesota Avenue, Kansas City, Kansas 66101. * Air Programs Branch, EPA,. Region VIII, 999 18th Street, Suite 1300Denver, Colorado 80202-2413.

* Air Programs Branch, EPA, Region IX, 215 Fremont Street, San Francisco, California 94105.

o Air Programs Branch, EPA, Region X, 1200 6th Avenue, Seattle, Washington 98101.

A limited number ofcopies can be obtained fromthe EPA library (MD-35), Research Triangle Park, North Carolina 27711, telephone (919) 541-2777 (FTS 629-2777). Copies can also be obtained from the National Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, Virginia 22161.

Emission factors for stationary and mobile sources have been published in the following documents:

a Compilation ofAirPollutant Emission Factors, Volume I, Stationary Point And Area Sources, AP-42, Fourth" Edition, 9/85, Stock #005-000-00251-7.

* Compilation ofAir Pollutant Emission Factors,Volume I, Mobile Sources, AP-42, Fourth Edition, 9/85, Stock #005-000-00252-5.

* AP-42 Supplement A, October 1986. These reports are available from the Superintendent ofDocuments,- Government Printing Office, Washington, DC 20402.

FOR FURTHER INFORMATION CONTACT: Kenneth Woodard regarding the SIP
program at (919).541-5351 (FTS 629- 5351] and Daniel deRoeck regarding the PSD/new source review (NSR) programs at (919) 541-5593 (FTS 629-5593) orwrite
to them at Standards Implementation Branch (MD-15), U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711.
SUPPLEMENTARY INFORMATION: References in this notice are indicated by superscript, lower case letters and

are listed at the end ofthe preamble.
Table of Contents I.Background. I1.Statutory and Regulatory Requirements. A. Statutory Background. 1.State Implementation Plans.

a. Section 110. (1)

Timing. (2) Content of State implementation plans. (3)Consequences offailing to submit a State implementation plan. b. PartDand Associated Amendments. (1)Identification ofair qualityproblems. (2)Content and timing ofplan revisions. (3)Consequences offailing tosubmit a plan.

c. Part Cand Associated Amendments. (1)The increment system. (2)

The preconstruction review program. 2.New Source Performance Standards. B.Regulatory Background. 1.Implementation ofParticulate Matter Standards.

a. Section 110 State implementation plans. b. Part D State implementation plans. (1) Section 107(d) designations. (2)Guidance for Part DSIPrevision: "Reasonably Available Control Technologyplus studies" policy. (3)New source review rules. (4)EPA action on PartDplans: construction bans, conditional approvals, and policy for correcting deficient PartDplans. 2.Implementation ofPrevention ofSignificant Deterioration Requirements. 3.Implementation of New Source Performance Standards. 4.Regulatory Precedents: EPA Actions on National Ambient AirQuality Standards since 1977. III. Interpretation ofClean Air Act Requirements.
A. Legal Interpretation. 1.Conflict in the Literal Language ofthe Clean Air Act. 2.Resolution of the Conflict. B.Comparison ofRevised andPrior Particulate MatterNational Ambient Air Quality Standards. C.The Clean AirAct's Applicability to the Revised National Ambient Air Quality Standards. IV. Requirements for State Implementation
Plans. A. Transition Policy.
B. Technical Support for State Implementation Plans Development. 1.Ambient Data Base.-

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2.Technical Guidance. C.State Implementation Plans Deveiopment Policy. 1.Area Grouping Procedures. 2. Area Designation Policy. 3.Fugitive DustPolicy. 4. EmissionTrading (Bubble) Policy;. 5.Sanctions Policy. D.Prevention ofSignificant Deterioration/ New Source Review.Program. 1.Revised PSD Program for Particulate Matter.

a. Transition. b.Source Applicability.

c. Geographic Applicability. d.Best Available Contr6l Technology.

e. National Ambient Air Quality Standards Analysis. f. Preventionof SignificantDeterioration Increments forParticulate Matter. g. Prevention ofSignificant Deterioration Monitoring. 2.Revised New Source Review.Requirements for Particulate Matter. V.Revised Regulations.. A.Revisions to Part 51. 1.Regulatory Reform. 2.Basic State Implementation Plans Requirements. 3.Section 51.100, Definitions. 4.Section 51.151, Significant Harm Levels. 5.Section 51.165. Permit Requirements. 6. Section 51.166, Prevention ofSignificant Deterioration ofAir Quality. 7. Section 51.322 and 51.323,Annual Source Emissions Reporting. 8.Revisions to Appendix L. 9. Revisions toAppendix S. B.Revisions to Part52. 1. Section 52.21, Prevention ofSignificant Deterioration ofAir Quality. 2. Section 52.24. Statutory Restriction on New Sources. VI.Public Participation. A. Comments on Legal Issues. 1.Comments Favoring an Exclusive Section 110Pathway. 2. Comments Favoring an Integrated Section 110 andPartD Pathway. B.Comments on Use of the Probability Guideline. C. Comments on the SIPDevelopment Policy. 1.Area Grouping Policy. 2. Fugitive DustPolicy. 3.Emission Trading (Bubble) Policy. D. Prevention ofSignificant Deterioration/ New Source Review Program. 1.Revised Prevention ofSignificant Deterioration Program for Particulate Matter.

a. Effective Date ofthe Part 52Federal Prevention ofSignificant Deterioration Regulations. b.Source.Applicability.

c.Prevention ofSignificant Deterioration Geographic Applicability. , d.Best Available ControlTechnoloy (BACT).

e.National Ambient Air Quality Standards Analysis. f.Prevention ofSignificant Deterioration Increments for Particulate Matter. g.Prevention ofSignificant Deterioration Monitoring. h.Transition Provisions. 2.Nonattainment New Source Review Requirements.

-E.Comments on Technical Issues. 1.Preparing anEmission Inventory. 2.Emission Factors. •3.

Receptor Modeling. 4.DispersionModeling. 5.Source Sampling Devices and Procedures. 6. Data Reduction. F. Comments on Miscellaneous Issues. 1.Impact on New SourcePerformance Standards Program. 2.Economic Impact. .3.

Annual Source Emissions Reporting. G. Comments on Procedural Issues. 1.Extension ofthe Comment Periodand Public Hearing. 2.Reproposal. VII Regulatory and Environmental Impacts. A. Regulatory Impact Analysis. B.Impact on Small Entities. C.Impact onReporting Requirements.

L Background

Today's- final rulesfor implementing revised particulate matter standards are the culmination ofseveral actions taken in accordance with sections 108 and 109 .of the Clean Air Act (Act). The EPAhas reviewed and revised the criteria upon which the original primary and secondary particulate matter standards

are based. As a resultofits review and revision ofthe health and welfare criteria, EPAproposed revisions to the particulate matter standards on March 20, 1984 (49FR 10408). The EPA also proposed at the same time to (1) adopt a

new Federal Reference Method (Appendix J to40 CFR Part 50) for measuring particulate matter with an aerometric diameter ofa nominal 10 micrometers or less (PMo) in the ambient air, (2) adopt a new Appendix
K to 40 CFR Part50 to provide guidance

on the statistical nature oftherevised standards, and (3)revise the regulations concerning Ambient Air Quality

. Surveillance (40 CFR Part 58). Notices of finalfrulemaking on those proposed revisions are published elsewhere in today's Federal Register. The Administrator's final decision with respect to the specific levels ofrevised standards for particulate matter include: (1)Changing the indicator for both the primary and secondary standards from TSP to PM 1o,(2) changing the level ofthe 24-hour primary standard to 150

- micrograms per cubic meter ([g/m 3) measured as PMo and replacing the deterministic form ofthe standard with

a statistical form, (3) changing the level and form ofthe annual primary standard to 50 ikg/m s expected annual arithmetic

mean measured as PMo, (4) establishing "secondary 24-hour and annual standards

that are identical in level and form to the primary standards.

'On April2, 1985, EPA proposed (50 FR 13130) to revise its regulations governing SIP programs to account forrevisions to the particulate matter standards.In particular, EPA (1)set forth the policy it proposed to follow regarding revisions
to SIP's to account for the revised .standards;'(2)proposed to amend the significant'harm and air pollution episode levels forparticulate matter: (3) proposed amendments to the regulations for preconstruction review ofnew and modified sources (new source review) in nonattainment areas and in regulations for PSD; and (4) proposed amendments
to Part 81, Designation ofAreas.

.The remaining sections of this preamble describe EPA's resolution of the issues raised during the rulemaking
process. Section II outlines the relevant statutory and.regulatory requirements. Section III describes EPA'slegal interpretation ofthe Act's requirements., Section IV sets out the final policies for implementing therevised NAAQS under EPA's SIPprogram, NSR/PSD programs,. and new source performance standards (NSPS) program. Section V summarizes the revised regulations. Section VI presents the major public comments received on the proposal.and EPA's response.to those comments. The EPA's response tocomments not covered herein is included in Docket No. A-82- 38. II.-Statutory and Regulatory Requirements

A. StatutoryBackground

1. State Implementation Plans

In 1970Congress comprehensively amended the Act to establish ajoint State and Federal program to control air pollution.,Under sections 108 and 109, EPA is responsible forissuing air quality. criteria andproposing and promulgating NAAQS. The States then haveprimary responsibility forimplementing the NAAQS. In broad outline, each State
must develop and submit to EPA a plan that provides for attainment and maintenance ofeach NAAQS as expeditiously as practicablewithin certain time limits.The EPA must review each plan, termed SIP,and
approve or disapprove its provisions. If

a State fails to submit a plan, or submits

a plan which EPAfinds inadequate, EPA
may, and in some cases must, promulgate whatever measures are necessary to fill the gap.

a.Section 110. (1) Timing.Under section 110(a)(1), each State must adopt and submit a SIP ".

. . within 9 months after,the promulgation ofa national.. primary ambient air quality standard (or any revision thereof].

... Section 110(a)(1) also sets a 9-month deadline for submittal ofSIP's for new and

- 

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revised secondary NAAQS; however, section 110(b) authorizes the Administrator to extend that deadline for up to 18 months where "necessary."

Under section 110(a)(2)(A), SIP's must provide forattainment ofany primary NAAQS ".

. . as expeditiously as 

### practicable but [subject to subsection (e)] in no case later than 3years from the date ofapproval of such plan (orany revision thereof to take account ofa revised primary standard).

... The SIP's for secondary NAAQS must provide forattainment within a "reasonable time."

Section 110(e) allows the Administrator to extend the attainment date for the primary NAAQS for 2years, ifhe finds that sources willnotbe able tocomply with theiremission limitations within the 3-year deadline because needed technology willnotbe available. The plan,however,must provide forinterim control ofthe noncomplying sources and controls on all othersources ofthe samepollutant in the same air quality control region.

(2)Contentof stateimplementation plans.A core requirement ofsection 110 is that each SIPmust include:

... emission limitations, schedules and timetables for compliance with such limitations, and such othermeasures as may be necessary to insureattainment and maintenance ofsuchprimary orsecondary standard

.... [section 

### 110(a](2)(B)l]

Theremaining subsections ofsection 110(a)(2) elaborate onthis general framework. Specific to today's promulgation:

* Section 110(a)(2)(C) requires the plan to provide for operation ofa system that collects and analyzes air quality data.

* Section 110(a)(2)(D) states that each SIP mustprovide a preconstruction review program consistingof ".

..a permit or equivalent program for any major emitting facility, within such region as necessary to assure (i)that the national ambient air quality standards

are achieved and maintained

... ,."

e Section 110(a)(2)(F) provides that plans mustrequire owners or operators ofstationary sources to monitor and report on emissions from their sources.

a Section 110(a)(2)(H) requires each plan to contain a self-correction mechanism in case the plan proves unsatisfactory. Theplan mustcontain provisions that the State will revise the plan:

* . .from time-to time as may benecessary 

### to take account ofrevisions ofsuch national primary orsecondary ambient air quality standard orthe availability ofimproved or more expeditious means ofachieving such primary or secondary standard: or ... whenever the Administrator finds on the basis ofinformation available to him that the planis substantially inadequate to achieve the national ambient air quality primary or secondary standard which it implements or to otherwise comply with any additional requirements established under the Clean Air ActAmendments of1977

....

a Section 110(c)(1)(C] authorizes the Administrator to notify a State that it needs to revise its plan in accordance with the section 110(a)(2)(H) requirements for self correction and to set a deadline for submitting the
revision. The deadline must be at least 60 days after the notification, but may be later at the Administrator's discretion. * Section 110(a)(2)(F)(v) provides that SIP's must contain contingency plans for immediate emission reductions where pollution levels increase to the point of presenting an imminent and substantial endangerment to public health.

(3) Consequencesof failingtosubmit

astateimplementation plan.Section 110 provides forFederal intervention ifa State fails to submit an adequate SIP. Under section 110(c)(1), EPAmust promulgate planprovisions for a State if the State fails to submit a plan at all, submits a plan that does not meet the section 110 requirements, or fails to comply with a notification under section 110(c)(1)(C)-i.e., a call for aplan revision under the provisions ofsection 110(a)(2)(H). The EPA must promulgate

a substitute plan unless the State in the interim adopts and submits a plan that EPA finds adequate.

Other sections ofthe Act provide financial incentives forState participation in the SIPdevelopment process such as section 105(b), which gives EPAgeneral authority toimpose conditions on its grants to air pollution control agencies. Thus, EPA may condition grants on the submittal of satisfactory SIP's orSIP revisions. Beyond that, section 176(b) prohibits EPA from making anygrants in any area where the responsible State orlocal authority ".

. . is not implementing any iequirement ofan approved or promulgated plan under section 110

. . . ." Thisprohibition would apply ifa State failed to implement the SIP provision that requires the State to revise its plan under the circumstances stipulated in section 110(a)(2)(H). Thus, ifa State fails torespond to a call fora SIP revision under section 110(c)(1)(C), the section 176(b) grant prohibition is applicable.

b.Part Dand Associated Amendments. In many areas of the country, the original SIP's that were approved and promulgated in the early 1970's failed to bring about attainment 

### within the statutory deadlines. When Congress revised the Act inAugust 1977, it added a new Part Dand amendments
to sections 107 and 110to address this nonattainment problem.

(1)Identificationofair quality problems.Congress first instructed the States and EPA to identify all areas of the country thatwere experiencing violations ofthe NAAQS. A new section 107(d) required each State to listfor EPA by early December 1977 those areas that

were experiencing violations (nonattainment areas), those areas that

were meeting the standards (attainment areas), and those areas that could notbe classified for lack ofair quality data (unclassifiable areas). Itthen required EPA to review the lists, makenecessary modifications, and promulgate them all by early February 1978. Section 107(d)(5) allows Statesto modify a listeven after promulgation:

...[a] State mayfrom timetotimereview, andas appropriate revise andresubmit, the listrequiredunder this subsection.The Administrator shall consider andpromulgate suchrevised list in accordance with this subsection.

(2) Contentandtimingof plan revisions.Congress then added section 110(a)(2)(I) which required each SIP to contain a provision that wouldban the construction or modification after July 30, 1979, ofany major stationary source:

•
. . in anynonattainment area [asdefined In section 171(2)] to which such plan applies, if the emissions fromsuch facility will cause or contribute to concentrations ofanypollutant forwhich anational ambient airquality standard is exceeded insuch area,unless, as ofthe time ofapplication for apermitfor such construction ormodification, such plan meets the requirements ofPartD(relating to nonattainment areas).

Congress then specified other new requirements for SIPcontent in Part D. Inessence, Part Drelaxed attainment dates but tightened control requirements forboth new and existing sources.

In section 172(a)(1), Congress directed the States to adoptplans that provided forattainment ofall ofthe primary standards as expeditiously as practicable, and, except forozone and carbon monoxide, no later than December 31, 1982. Plans were also to provide for all emission reductions available from applying "reasonably available control technology" (RACT). Each plan also had to establish a permit program under section 173 for the construction and modification ofmajor stationary sources.

Congress directed each State to adopt whatever provisions would be necessary to meet these PartD requirements, and submit them to EPA,

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by January 1,1979. See Pub.L.95-95, section 129(c) (uncodified). Congress required the Statesto follow EPA's 1976 interpretive ruling on new source construction and modification in the periodbefore the new plans were to

come into effect.See Pub. L.95-95, section 129(a) (uncodified).

(3) 

### Consequencesof failingto submit

aplan.All ofthe consequences offailing to submit a SIPdescribed above under section 110potentially apply to States that fail to submit PartDSIP's. In addition, afterJuly 1, 1979, the 

### mandatory construction ban required by section 110(a)(2)(I) was to apply in any nonattainment area that lacked a revised plan that met thePart D requirements. Further, ifa State failed to implement its SIPin a nonattainment
area, which includes not complying with

a call for a SIPrevision under section 110(c)(1)(C), the nonattainment area would be subject to a construction ban required by section 173(4).

c. PartCand Associated Amendments. The 1977amendments also added to the Act as Part Cto Title I

a third set ofSIP requirements aimed at the PSD ofair quality in attainment and unclassifiable areas. New section 110(a)(2)(J) generally requires each SIP to satisfy the requirements ofPart C. Revised section 110(a)(2)(D) specifically requires each SIP to meetPart C's requirements fora preconstruction review program for majornew sources and majormodifications. Section 161 of the new Part Crequires that:

... each applicable implementation plan contain emission limitations and such other

measures as may benecessary, as determined under regulations promulgated under this part, to prevent significant deterioration ofair quality in each region (or portion thereof)identified pursuant to section 107(d)(1) (D)or (E) ofthis title

. . .[i.e., the attainment and unclassifiable areas]. 

### The remaining Part C provisions limit deterioration by establishing maximum allowable increases in pollution, commonly called "increments," and by requiring preconstruction review of major new stationary sources and major modifications.

(1) 

### The incrementsystem. For sulfur dioxide and "particulate matter," section 163(a) requires that eachplan "

. . . containmeasures assuring that maximum allowable increases over baseline concentrations of,and maximum allowable concentrations of, such pollutant shall notbe exceeded.

... Section 163(b) establishes three sets of "maximum allowable increases" forthese two pollutants. The mostrestrictive increments apply in Class Iareas, while larger increments apply in areas designated as Class IIor Class III. No provision in the Act, however, defines "particulate matter" as used in section 163.

Section 162(a) designates as Class I

areas all international parks and then all national parks, national wilderness
areas, and national memorial parks exceeding certain sizes and existing on the effective date of the 1977 amendments. Section 162(a) prohibits the States from changing this designation. Other areas that may have been designated as Class I under earlier EPA regulations for PSD retain their Class Idesignations, but may be redesignated under procedures described in section 164. Section 162(b) provides that all other areas"

. . . identified pursuant to section 107(d)(1) (D) or (E) which are not established as Class I

. . . shall be Class 

### IIareas

... 

### " States may, however, redesignate such areas as Class I or Class IIIunder section 164.

While Part C does not contain an increment system for the NAAQS pollutants other than sulfur dioxide and particulate matter, it directs EPA to create such a system or an equivalent

one for those pollutants. Thus, for carbon monoxide, ozone, nitrogen oxides, and ".

. . pollutants forwhich national ambient air quality standards

are promulgated after the date of enactment ofthis part

.... " sections 166 (a) and (d) require EPA to promulgate ".

. . specific measures at least as effective as the increments established in section 163

....

(2) Thepreconstruction review
program.The key element ofthe preconstruction review program required by Part C is the requirement that a company obtain a PSD permit before constructing virtually Iany new major stationary source or making any major modification in an attainment or unclassifiable area. See section 165(a), 40 CFR 51.166(i) [formerly 51.24(i)]. A major stationary source is any plant that has the potential to emit 100 tons per year (tpy), or 250 tpy, depending on plant type, ofanypollutant regulated under the Act, including the NAAQS pollutants. A major modification is, in general, any change to a major stationary source that would result ina significant net increase in emissions ofa regulated pollutant [section 169, 40 CFR 51.166(b)].

IUnder EPA's current regulations,a project that emits someregulated pollutant can escape PSD review only ifit locates in an area that is designated nonattainment forall pollutants to which section 107(d) applies orifit emits only those pollutants forwhich the area isdesignated nonattainment. See 45 FR52a75, 52710-52712 (August 7, 1980). To obtain a permit, an applicant must show that the source or modification would be subject to "best available control technology" (BACT) for each regulated pollutant it would emit in significant amounts [section 165(a)(3), 40 CFR 51.166(j) (1983)]. In addition, an applicant must show that:

...emissions from construction or operation of such facility will not cause, orcontribute to, air pollution in excess ofany [A) maximum allowable increase or maximum allowable concentration for any pollutant in any area to which thispart applies more than one time peryear, (B)national ambient air quality standard in any airquality control region, or (C)any other applicable emission standard

.... [section 165(a)(3)].

Finally, an applicant must provide, for each regulated pollutant emitted by the project, analysis of (1)existing air quality in the project area; (2) the effect the project would have on soils, vegetation, and visibility; and (3) the effect growth associated with the project would have on air quality. ForNAAQS pollutants, the analysis ofexisting air quality generally must include a year's worth ofmonitoring data [section 165(a)(2), (a)(b), and (e); 40 CFR 51.166(k)-(o)]. 2

2. New Source Performance Standards

The 1970 amendments also require EPA to establish NSPS for major new air pollution sources. Under section 111, EPA must promulgate such a standard for any category ofsources that:

... in [the Administrator's] judgment

. . . causes or contributes significantly to, air pollution which may reasonably be anticipated to endanger public health orwelfare

... [section 111(b)(1)(A)I.

The standards apply to "new sources," which include both new and modified stationary sources [sections 111(e), 111(a)(2)]. The standards must:

...reflect thedegree ofemission limitation and the percentage reduction achievable

'Part Cgives special protection toFederal Class I

areas.Itplaces an "affirmative responsibility" on each Federal land manager (FLM) to protect the air qualityrelatedvalues (AQRV'sl ofitsFederal Class Iareas.Itthen forbids the issuance ofaPSDpermit inany case where theFLM ofa ClassIarea shows tothe satisfaction ofthe permitting authority that the project in question would affect the AQRV's of the area adversely, even if the applicant shows that theproject would not cause or contribute toa violation ofan increment over thearea [section 15(dl(2) [B), (C].

On the other hand, Part Cprovides certain variances from the ClassI increments. For instance,

even ifa project would cause orcontribute toan increment violation over aFederal Class Iarea,the permitting authority may issue a permitif theFLM certifies that the project would notviolate certain special increments. Forparticulate matter,these special increments areequal to thenormal Class 11 increments [section 165(d)(2)[C)]. 

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through application ofthe best technological system ofcontinuous emission reduction which [taking into consideration the cost of achieving such emission reduction, any nonair quality health and environmental impact and energyrequirements) the Administrator determines hasbeen adequately demonstrated

. . . [section 111(a)(1)].

B. RegulatoryBackground

1. Implementation ofParticulate Matter Standards

a.Section110StateImplementation Plans.Since 1971 EPAhas promulgated, in 40 CFR Part 51, regulations covering a wide range ofthe planning requirements
set forth by section 110. On November 7, 1986 EPApromulgated (51 FR 40656) restructured Part 51 regulations. References to Part 51 in thisnotice are to the recodified sections.

b.Part D StateImplementation Plans. (1)Section107(d) designations. The EPA promulgated attainment status designations forparticulate matter and four other NAAQS on March 3,1978, in 40 CFR Part 81 Subpart C (43FR 8962).

In the preamble ofthis action,EPA pointed out that ithad designated some rural areas "attainment" or "unclassifiable" for particulate matter despite data showing that these areas

were experiencing violations ofthe particulate matter NAAQS (43 FR 8963), Under its Fugitive Dust Policy, EPA defined as "rural" any area with low population that lacked major industrial development ormajor industrial particulate matter emissions. In the absence of evidence to the contrary, EPA at thattime presumed rural dust to be less harmful than urban dust because it consisted primarily ofnatural materials not contaminated by industrial products.

The EPA also promulgated a rule explaining thatit could redesignate

areas when air quality data showed that

a change was warranted. See 40 CFR 81.300.3

(2) Guidance forPart D State ImplementationPlanrevision: "RACT plus studies"policy. The EPApublished
most ofits guidance for SIP's for nonattainment areas in the form ofa "general preamble" interpreting the Part D planning requirements (44 FR 20372, April 4, 1979). The EPA generally required States to apply RACT to all stationary sources unless the State could show that controls on a particular

source or group of sources would not

3Onecourt has ruledthat section 107(d) does not authorize EPA to redesignate areas to nonattainment unless a Stateconcurs In the redesignation. See Bethlehem SteelCorp.v.EPA. 726 F.2d 1303 (7th Cir.1983). No other court has yet decided this issue. 

### bring about attainment any faster. Moreover, the States had to submit all needed control measures in fully enforceable form (44 FR 20375). For particulate matter, however,EPA allowed States topostpone the adoption 

### ofcontrol measures for "nontraditional"

sources until the States had an opportunity to study what control

measures would be efficacious (44FR 20378). "Nontraditional" sources included area or background sources such as vehicle traffic and construction activities. All emissions from industrial
processes at stationary sources were subject to the requirement for enforceable RACT measures.

Later, as EPA reviewed specific plan revisions, it expanded this policy to allow States to postpone the submittal ofattainment demonstrations for the particulate matter standards until the States had a chance to quantify the effects ofcontrolling nontraditional

sources. However, the demonstrations, when submitted, still had to provide for attainment ofthe primary standards by the end of 1982. Also, EPA required

areas that postponed demonstrations to impose RACT measures on all traditional sources, since they would be unable to show that they could attain with less stringent controls.

(3)Newsourcereviewrules.The EPA originally issued guidance on the NSR requirements ofsection 173 in the general preamble. However, in 1980 EPA promulgated detailed regulations on the
content ofapprovable State programs (45FR 31304, May 13, 1980 and 45 FR 52678,August 7, 1980), codified at 40 CFR 51.165(a) [formerly 51.18(j)]. Part D and these regulations provide, among other things, that State plans must require major stationary sources and major modifications to offset their proposed emissions and achieve the "lowest achievable emission rate" (LAER). 4

(4) Environmental Protection Agency actionon Part Dplans:construction bans,conditional approvals,and policy forcorrecting deficientPart Dplans.By July 1, 1979,no nonattainment areas had fully approved SIP's, and very few had SIPprovisions ineffect that limited construction as required by sections 110(a)(2)(I) and 173(4). Consequently, on July 2, 1979, EPA published a regulation that inserted the section 110(a)(2)(I) and section 173(4) construction bans into all SIP's that lacked them (44 FR 39471, now codified at 40 CFR 52.24). In the same

4Under regulations recently upheld by the Supreme Court, Chevron, Inc.v.NRDC, 104 S. Ct. 2778 (1984), EPA defines "major stationary source" for purposes ofthe nonattainment area NSR
program as essentially an entire plant. 

### notice,EPA announced that the section 110(a)(2)(I) ban had become effective in each nonattainment area that lacked an approved orpromulgated Part Dplan revision. The EPA explained that it would remove these bans when it took final action approving or promulgating a plan that met all relevant Part D requirements. The EPA, however, subsequently concluded that the section 110(a)(2)(I) construction ban would not apply ifa State lacked a Part Drevision for a secondary NAAQS, since section 110(b) allows States to obtain extensions for submitting secondary plans and the legislative history ofPart Dshows Congress' chiefconcern was the protection ofhuman health (47FR 44729, October 12, 1982).



### Many nonattainment areas failed to attain the primary standards by the end of 1982. The EPA has interpreted the Act, however, as notrequiring the Agency to impose the full array of available sanctions immediately in all of these areas. Instead, on November 2, 1983, EPA announced that itwould find plans for areas that failed to attain to be "inadequate" under section 110(a)(2)(H) and 110(c)(1)(C) (48FR 50686). The EPA would require States to submit revisions forthese areas and,ifany area failed to comply, EPA would find that the State

was not implementing the portion ofits SIPthat requires revisions in response to a notice under section 110(a)(2)(H). This finding would trigger a construction ban under section 173(4) and funding restrictions under section 176(b).

The EPA acknowledged in its November 1983 notice that itwas considering a revision tothe particulate
matter standard (48 FR50697). Consequently, EPA deferred, and is continuing to defer, the issuance of notices ofinadequacy for particulate matter plans.

2.Implementation ofPrevention of Significant Deterioration Requirements

Prior to the enactment of Part C in 1977,EPA had promulgated Federal PSD regulations as 40 CFR 52.21 in response to court rulings that the 1970Act required SIP'sto include PSD measures. See SierraClubv.Ruckleshaus,344F. Supp. 253 (D.C. Cir.1972), affdper curiam,4 ERC 1815 (D.C. Cir. 1972), aff'd by an equally divided court, sub. nom. Friv. SierraClub,412U.S. 541 (1973). The EPAinserted the Federal PSD regulations directly into each SIP pursuant to section 110(c) ofthe Act [39 FR 42510]. In 1978EPA substantially 

### amended its Federal PSD regulations to conform themto the detailed PSD requirements contained in the 1977 amendments [43 FR 25380 (now codified,

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as amended at 40CFR 52.21)]. At the

same time EPA inserted the amended Federal PSD regulations into each deficient SIP.

Pursuant to the statutory requirements, the amended PSD regulations established a Federal permitting systemfor preconstruction review ofnew majorprojects and authorized the Administrator to approve construction only ofthose facilities that would employ BACT andwould not

cause orcontribute to ambient air quality in excess ofanyNAAQS or applicable PSD increment [40 CFR 52.21(j), (k)]. The regulations explicitly refer to the statutory increments for sulfur dioxide and "particulate matter" [40 CFR 52.21(c)].

In 1978EPA also promulgated a second set ofPSD regulations outlining the requirements for an approvable State PSDprogram (43 FR26380) (now codified, as amended, at40 CFR51.166]. These regulations mirrored the Federal PSD program for the most part.

Numerous industry and environment groups challenged the amended PSD regulations, which were subsequently affirmed in part and remanded in partin AlabamaPowerCo.v. Castle,636F.2d 323 (D.C. Cir. 1979). The court in 

### AlabamaPower took the position,which

was not essential to any ofits ultimate dispositions, thatEPA haddiscretion to define "particulate matter" to exclude particles ofa size orcomposition determined not to present substantial health or welfare concerns, not onlyfor purposes of theNAAQS, but also for purposes ofthe PSD increments (Id. at 370, footnote 134).

In 1980EPA again amended its PSD regulations, this time to makethem conform to theAlabamaPower decision (45 FR 52676). TheEPA amended both the Federal PSD program at 40 CFR 52.21 and the requirements forapprovable Stateprograms at 40CFR 51.24 (now 51.166). TheEPA again inserted the amended Federal regulations into the SIPfor each State thathad not previously submitted an approvable PSD program. 3.Implementation ofNew Source Performance Standards

The EPA has promulgated NSPS in40 CFR Part 60 that limitparticulate matter emissions from22 categories of stationary sources. The EPA determined that the sources in these categories emit significant amounts ofparticulate matter. ForNSPS, EPAdefined "particulate matter" in section 60.2 of Part 60 as ".

. . any finely divided solid



### or liquid material, other than uncombined water, as measured by reference methods specified under each applicable subpart, or an equivalent method

... "
4. Regulatory Precedents: The Environmental Protection Agency Actions on National Ambient Air Quality Standards Since 1977

The EPA has promulgated two major rules concerning NAAQS since Congress revised the Act in 1977. In 1978 EPA, for the first time,promulgated NAAQS for lead (43 FR 46246, October 5. 1978). In a related action addressing implementation issues, EPA directed States to submit plans controlling new and existing sources under section 110,

as opposed to Part D (43 FR 46264, October 5, 1978). Thus, there are no formal designations ofattainment status under section 107(d) for the lead NAAQS.

Any new major lead source or modification must undergo the PSD review that section 165 requires ofall regulated pollutants, unless the source

ormodification locates in an area that is
not designated attainment or unclassifiable for any NAAQS pollutant. [Since EPAhas not promulgated any section 107 designations for lead, no

source can escape PSD review because it locates in an area designated as nonattainment for lead (see footnote 1J.] Such a source or modification must also undergo the review outlined in sections 51.160(a)-(e), 51.161, 51.162, and 51.163 [formerly 51.18(a)-(i)] to ensure that the project will meet applicable SIP limits and not cause orcontribute to a NAAQS violation.

In 1979 EPArenamed the NAAQS for "photochemical oxidants" so they applied to "ozone" and raised the numerical level of the primary and secondary standards (44FR 8202, February 8, 1979). In this case EPA instructed the States to follow Part D. The EPA concluded that, since the revised standard represented a relaxation, States would have no difficulty meeting the Part D deadlines for submitting plans and attaining standards [43 FR 26962,June 22, 1978 (proposedrule); 44 FR 82021.

Il1.Interpretation of the Clean AirAct Requirements

As indicated above, the Act contains different pathways along which the revised NAAQS could be implemented. These pathways fall under two general categories which, for ease ofdiscussion,

are referred to as (1)the section 110
core, and (2) Part D. For the reasons described below, EPAhas concluded that only section 110governs the implementation of the revised primary and secondary PM 1ostandards. In the following sections ofthis notice, EPA discusses its legal interpretation ofthe Act and applies that legal interpretation
to the revised particulate matter standards.

A. LegalInterpretation

1. Conflict in the Literal Language ofthe Clean AirAct

A literal reading ofsections 110(a)(1) and (a)(2)(A) yields a general rule for implementing revised standards and a partial exception. Section 110(a)(1) requires each State to submit
"... within nine months after the promulgation ofa national

. . . ambient air quality standard (or anyrevision thereof)

. . ." a SIPthat implements the

new standard in all regions ofthe State 5 (emphasis added). Section 110(a)(2)(A), which applies to all plans submitted under section 110(a)(1), stipulates that a plan, to be approvable by the Administrator, mustprovide for attainment and maintenance within certain specified periods except as may be provided in section 110(a(2)(I). Section 110(a)(2)(A)(i), forexample, requires each SIP implementing a primary standard to provide for attainment as expeditiously as practicable but ".

. in no case later than three years from the date of approval ofsuch plan (orany revision thereofto take account ofa revised primary standard]

...."Section 110(a)(2)(I) on the other hand requires the SIPto contain a construction ban that applies after June 30, 1979, ".

. . in
any nonattainment area [as defined in section 171(2)]

. . . unless.

. . such plan meets the requirements ofPart D

. . . ." Section 171(2) defines "nonattainment area" as any area that

"... is shown

. . . to exceed any national ambient air quality standard

. . ."

### (emphasis added).

Since the term "any revision" in section 110 (a)(1) appears to encompass any revised standard, sections 110(a)(1] and (2) appear to set a general rule that (1) States must submit SIPrevisions for all areas to account forNAAQS revisions, generally within 9months after promulgation ofthe revised NAAQS and (2) the SIPrevisions must provide for attainment within the periods specified in section 110(a)(2)(A]-for example, 3 years from plan approval fora primary standard.

However, since the reference to "any national ambient air quality standard" in section 171(2) also appears to encompass any revised standard,

aSection 110(b) allows EPA to extend this submittal deadline an additional 18 months for revised secondary NAAQS undercertain conditions. 

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section 171(2) together with section 110(a)(2)(I) seem to state an exception to section 110(a)(2)(A) for areas that are "nonattainment" for any standard, new

orrevised. The exception is that SIP revisions forall such "nonattainment areas" mustinclude a construction ban that can be avoided by satisfying all of the provisions ofPart D instead of providing for attainment within the usual periods of section 110(a)(2)lA).

Thus, the Act appears to contain two different and conflicting blueprints for SIPpreparation with respect to both
content and timing, one in section 110 and the other in Part D, for SIP's for

areas that are "nonattainment" under a revised primary orsecondary standard.

2. Resolution ofthe Conflict

In the April 1985 proposal, EPA set out various legal interpretations it could use to reconcile the inherent conflict between section 110 and Part D as to the requirements for "nonattainment areas." After subsequent analysis ofthe legal issues and review ofthe numerous public comments received, EPAhas concluded that the best legal interpretation is that Part D applies only
to those NAAQS that existed when Congress created Part D in 1977 and to revisions to those NAAQS that do not impose significant new planning burdens on the States. Only section 110 applies to new NAAQS and to revised NAAQS that do impose significant new planning burdens on the States.

Congress created Part D in 1977 to deal with the persistent failure ofmany

areas to attain the then existing NAAQS by the statutory attainment dates despite sufficient time for preparation and execution ofSIP's. Congress imposed strict new requirements on these nonattainment areas to encourage them to promptly complete the retooling
necessary to bring them into attainment. The EPA's review ofthe relevant statutory language and legislative history leads it to conclude that these

more rigorous Part D provisions should
not apply to revised standards that impose significant new planning burdens on the States.

In particular, the fixed attainment deadline ofDecember 31, 1982, could produce unreasonable results if strictly applied to such a revised NAAQS. Since that date has already passed, an area under a literal application ofthe statutory language would become subject to Part D sanctions immediately after a finding that the area exceeds the revised NAAQS, despite the fact that the area could not demonstrate attainment ofthe revised NAAQS without completing the additional new planning burdens imposed by the revised NAAQS. Thus, the area would be penalized for having failedto submit

a SIP demonstrating attainment by December 31, 1982, even though the planning burdens the area must complete to demonstrate attainment

were neverrequired until sometime substantially after that date.

The EPA does not believe thatit should apply Part D to these areas and then attempt to ease this burden by interpreting the 1982 attainment deadline as inoperative so that the residual PartD requirement for attainment "as expeditiously as practicable" would apply to areas shown toexceed a revised standard. Under this approach, the meaning of section 110(a)(2](A)'s 3-year deadline as it relates to revised standards would be lost. It would also mean that an area exceeding a revised standard that imposes significant new planning burdens would notbe subject to section 110(a)(2)(A]'s 3-year attainment deadline, while areas exceeding an entirely new standard would be. This would treat these two areas differently, and would treat revised standards more flexibly, even though they would face essentially the same type ofplanning requirements, which would in all probability be more challenging for new than for revised standards. It is unlikely that Congress would have intended these inconsistent results.

The EPA also rejects the legal interpretation that the relevant Part D provisions do not govern revised standards at all. Arguably, section 171(2) defines "nonattainment areas" as

areas exceeding "any national ambient air quality standard," without reference
to revised standards. In contrast, section 110(a)(1) expressly applies its 9-month SIP submittal deadline, and section 110(a)(2)(A) its 3-year attainment deadline forprimary standards, to "revisions." Congress could have included a similar reference to revised standards in section 171(2) ifit had intended Part D to apply to revised standards. This indicates that Congress may have intended the general section 110 scheme togovern the implementation ofall revised standards. This reading, however, would produce the result that a relaxation ofa pre-1977 NAAQS would automatically shield

areas exceeding the revised standard from the strict Part D requirements, even though the revision made it easier for them to attain. It is clear that Congress would not have intended this result. Hence, EPA reads the section 110(a)[2)(A) exception, and thus Part D,

as applying to the nonattainment planning problems that Congress faced when it enacted Part Din 1977 and to those revised NAAQS that result in no significant increase in those problems.

The legislative history ofsection 110 and Part D also supports the view that revised standards requiring significant

new planning burdens should not be implemented under Part D. Congress in 1970 created a SIPdevelopment scheme that until 1977 clearly applied to all revised NAAQS. When Congress added Part D in 1977, it did not repeal the requirements eitherfor SIP submittal in section 110(a)(1) orfor attainment and maintenance in section 110(a)(2)[A). Moreover, the conflicts between section 110 and Part D (e.g., their different attainment deadlines) show that a single revised standard could not have been intendedto be subject to both schemes
at one time. Congress, therefore, must have intended section 110 to remain effective for areas that are not attaining
at least some revised NAAQS.

Many areas failed to plan adequately
to attain the standards EPA promulgated in the early 1970's.The legislative materials behind Part D strongly indicate that Congress' main purpose in enacting Part D was to address the nonattainment problems thatpersisted because ofthose planning failures. Congress chose to solve the problems by giving States one last planning opportunity before imposing the sanctions authorized in Part D. In contrast, the history reveals no evidence that Congress intended these tougher

measures to apply also where EPA revises a NAAQS so as to impose planning burdens significantly beyond what the Act imposed under the pre1977 standards. Stated simply, areas that exceed such a revised standard are unlike those for which Part D was plainly intended-namely, areas that had already failed to plan adequately in the first SIPround. Moreover, inferring congressional intent that these measures apply to such revisions would conflict with the pattern oflegislation in this

area. Congress reserved substantial
power to the States when it enacted the 1970 Act. The tough Part D measures, by providing fora significant Federal intrusion on what had previously been the States' domain, represented an exception to the Act's general scheme of cooperative State and Federal regulation. Interpreting ambiguity in the Act's language so as to authorize the
most intrusive implementation ofPart D would be inconsistent with the basic thrust of the Act.

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B. Comparison ofRevised and Prior Particulate Matter National Ambient Air Quality Standards

The EPA assessed the impact of the revised primary and secondary NAAQS

on the planning requirements ofState air pollutibn control agencies.b It estimated the probability ofviolating the PM,o NAAQS at each TSP State and local air monitoring station based on 1983-1985 TSPdata. These estimates indicate that sites in over 100 counties could violate the PMio NAAQS. The EPA's SIPdevelopment policy which is discussed in section IV.C. ofthis preamble requires new PMo SIP's to be developed for each ofthose areas. To develop SIPrevisions for each ofthe counties, EPA estimates that an average of4 work years and $250,000 in State

resources could be required. In addition, all States must revise their SIP's to respond to the new monitoring and new

source review requirements. Therefore, EPA concludes that the PM 10 NAAQS will impose a significant new planning burden upon the States.

The change in the indicator for the revised NAAQS from TSPto PM,o could also create regulatory burdens. This change couldresult in the need for control strategies to refocus on sources emitting smallparticles. States may also need to develop PM,o emission inventories and perform modeling based
upon PMo. Thus, the change in indicators alone will cause significant impacts which are a factor to consider in interpreting the Act.

C. The Clean Air Act's Applicability to the Revised National Ambient Air Quality Standards

As stated earlier, EPA has concluded that section 110 governs the implementation ofall revised standards that would impose significant new planning requirements beyond what the pre-1977 standards required. For the

reasonsjust described, EPA believes that the revised PM,o standards will impose new planning requirements in a significant number ofareas. Hence, only section 110 will govern nonattainment problems arising from the revised primary and secondary standards. The policies and rules thatEPA discusses in the remainder of this notice implement the EPA's basic conclusion that section 110, and not Part D, applies to implementation ofboth the primary and secondary PMo standards.

IV. Requirements for State Implementation Plans

Sections A, B, and C ofthis portion of the preamble set forth EPA's policy for actions that States must take to prepare and submit appropriate SIP revisions for existing sources. Section D focuses on the SIP preconstruction review ofnew sources, including the PSD permit
program.
A. TransitionPolicy

The particulate matter control strategies in existing TSP SIP's reduce ambient concentrations ofPM 0 as well

as TSP.Therefore, to avoid unnecessary disruption ofthe existing particulate
matter control program, States will want to utilize existing SIPrequirements as much as possible in their PMo SIP's. The regulatory requirements ofa State's existing TSP SIPmust remain in effect, therefore, until a PMo SIP is approved by EPA [see section 110(i),42 U.S.C. 7410(i)]. The existing regulations will continue to be enforced by Federal and State agencies and through citizen suits during the period oftransition from a TSP SIP to a PM SIP.

It is unlikely that the level ofcontrol required by the current SIP is significantly more than will be necessary to attain and maintain the PMo NAAQS. Therefore, regulations in the existing SIP cannot be relaxed without a demonstration that the revision will not interfere with attainment ormaintenance ofthe PM 0 NAAQS.

B. TechnicalSupport forState ImplementationPlansDevelopment

1. Ambient Data Base

In 1979 EPA began operating ambient samplers in the inhalable particulate (IP) network. That network consisted of ambient air monitoring stations containing high volume samplers, collocated with dichotomous samplers having inlets designed to measure particles nominally 15 micrometers and less (PM 15). The stations in the network

were located in urban and suburban

areas thoughout the U.S. to reflect maximum concentrations and population exposure due to urban and industrial sources, and also in nonurban

areas toprovide information on background levels.

The EPA began operating ambient samplers with inlets designed to collect PM,0 early in 1982. Since August 1984, EPA has distributed PMo samplers to State and local air pollution control agencies. As of December 31, 1986, about 900 samplers were operating at 550 sites. However, sufficient ambient PMlo data are not yet available to allow States to comprehensively evaluate the PMo attainment status for all areas.

Analysis ofthe available ambient data reveals that the PMo portion of TSPvaries widely, making it inappropriate to establish a single nationwide conversion factor to simply
convert ambient TSP values to ambient PMo values. Therefore, EPAhas developed a statistical approach for estimating from ambient TSPdata the probability that PM1oNAAQS are being violated in the area represented by the ambient sampler. This probability has been termed the "nonattainment probability."

Procedures for using statistical probabilities in the absence ofambient PMo data are explained ina document titled, PMo SIP Development Guideline (EPA450/2-86-001).' A companion document, Procedures forEstimating 'Probability ofNonattainment ofa PM 0 NAAQS UsingTotal Suspended Particulate or PMo data (EPA450/4-86-- 017 referred to herein as the "probability guideline"), explains in detail the methods for estimating PMlo levels using ambient PM,5 data. or for estimating the probability ofPM 0 nonattainment using TSP data.d The probability guideline also contains guidance on determining the spatial extent ofPM,o nonattainment problems (i.e., the "PMoexceedance area" represented by an ambient PM0 sampler). The extent ofthe PMo exceedance area must be determined in order to develop a control and compliance strategy that encompasses the area.
2. Technical Guidance

The PMo SIPDevelopment Guideline provides technical information onhow
to meet the implementation requirements in this rulemaking. Topics discussed include monitoring PM air quality, determining from ambient data when nonattainment problems are apparent, using PM1oemission factors, performing joint dispersion and receptor modeling, interpreting model results, writing emission regulations, and measuring PM emissions. It is meant to

cover all aspects ofSIPdevelopment where additional guidance isneeded due to the new focus on a PMo size
range. References to other sources of information are included where more detail may be required. The guideline is available from EPA's Regional Offices. The EPA's Office ofAir Quality Planning and Standards will be working through itsRegional Offices toprovide further guidance to States on developing SIP revisions to account for the revised NAAQS.

C. StateImplementationPlans DevelopmentPolicy

For the reasons described earlier, EPA is requiring implementation. ofthe PM standards under section 110 of the Act. 

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Section 110(a)(1) provides that each State shall adopt and submit, within9 months afterrevision ofa NAAQS, a SIPproviding for attainment and maintenance of the primary NAAQS everywhere in the State as expeditiously

as practicable but no later than 3years from the date EPA approves the SIP. Section 110(a)[2) requires that a SIP contain emission limits, schedules, and timetables and such other measures as may be necessary toassure expeditious attainment and maintenance. TheEPA's regulations in 40 CFR 51.112 (formerly section 51.13) adopted under section 110(a)(2) oftheAct, require that States demonstrate through modeling or an adequate alternative that this control strategy will indeed assure timely attainment and maintenance.

The EPAhas considered different ways ofimplementing this control strategy demonstration requirement under the 9-month SIPsubmittal schedule in section 110(a)(1). There is a great deal ofmeritin obtaining ambient PM1

### odata in all areas to specifically define the extent and degree ofPM1

### o nonattainment situations before developing control strategies. However, due to applicable Actrequirements and the environmental riskin areas with

severe air quality problems, the Administrator cannot permit delay in the development ofPMio control programs simply because ambient PMio data are unavailable.

Another approach would be simply to call upon States todevelop and submit a full PMo attainment demonstration and control strategy forevery area ofthe country within the 9-month period. The EPA believes, however, that such a requirement would be unreasonable for certain areas. An analysis of the latest ambient TSPdata in conjunction with themethodology in the probability guideline indicates that there could be from around 50 to 150 counties in which thePM 1o 

### NAAQS will not be attained.b While these numbers are the best indication at this time of the potential nonattainment situation forPMo, they

are onlyestimates and, furthermore, will probably change as new ambient TSP and PM~o data become available. The estimates are, however,useful as an indication ofthe degree ofPMo SIP development that may eventually be necessary.The key pointis that many of the 3141 counties in the nation may need

no additional particulate matter SIP provisions to meet the revised NAAQS. Thus, formany areas, the existingTSP SIP's may already provide for timely attainment and maintenance of the PMio NAAQS. To call upon areas that almost certainly have adequate SIP's to resubmit those SIP's along with full attainment demonstrations would be unnecessary and therefore wasteful of limited State resources.0



### There are, also, several areas where available data indicate that air quality may be close to the level ofthe NAAQS. Many ofthese areas may actually be shown,with more ambient data, to be in attainment ormay need onlyminor SIP changes. Therefore, EPA believes that a demand forimmediate submissions of attainment demonstrations and control strategies for all ofthese areas is unreasonable when additional air quality data could provide a more clear picture ofthe status of the area.

For the reasonsgiven immediately above, EPA is adopting the SIP development policy itproposed April 2, 1985.The EPA is dividing all areas ofthe country into three categories: (1)

### Areas with a strong likelihood ofviolating the PMo NAAQS and requiring substantial SIP adjustment (Group I),(2)areas where attainment ofthe standards is possible and existing SIP'sprobably need less adjustment (GroupII), and (3)

areas with a strong likelihood of attaining the PMo NAAQS and therefore needing only adjustments to the PSD/NSR provisions in their SIP (Group III). For purposes ofthis program, "areas" are conceptually the

same as "areas" for which classifications are designated in Part81, although there willbe no area designations in Part 81 forPM 0


### .The spatial extent ofa PM 0

### attainment or nonattainment situation may differ from TSP areaboundaries. Guidance is provided in the probabilityguideline for determining the area of exceedance of the PMio NAAQS.
1.Area Grouping Procedures

For those areas where there are sufficient ambient PMo data to define PMo NAAQS attainment or nonattainment in accordance with Appendix Kof40 CFR Part 50, the need for SIPrevision canbe determined relatively easily.The SIP's are due within 9 months for such areas that cannot demonstrate attainment. For other areas with insufficient PMio data, EPAwill use a three-step process to categorize areas.

First, where only ambient TSP data

are available, or limited amounts of

6Developing a sound attainment demonstration is generally resource intensive, It requires an in-depth study ofthe emission characteristics of specific

sources in the demonstration area and a thorough evaluation of the anticipated effects ofvarious emission levels from those sources. The EPA estimates it could require up to 4 work years and $250,000 to develop a SIP for each area found tobe violating the NAAQS. PM,o are available, EPAin cooperation with State agencies will use those data and the probability guideline to classify

areas preliminarily as Group 1,11, or 1II.1 The EPA will presume that (1) areas with a probability ofnot attaining the PMo standard ofat least 95 percent fit into Group 1,(2) areas with a probability ofbetween 20 and 95percent fit into Group II, and (3) areas with a probability ofless than 20 percent fit into Group III.

Second, EPA's Regional Offices, after consulting with the appropriate State and local agencies, will evaluate the existing TSP SIP's and other relevant information for each area in their jurisdiction (1) to see whether information other than the probability of nonattainment justifies changing the
group for an area, and (2) to determine the appropriate group for areas that the EPA could not classify under the first step because ambient TSP data were unavailable.

7The EPA has computerized the procedures described inthe probability guideline and has made the computer software available to States to calculate nonattainment probabilities. The EPA has also made the results ofits own calculations available to the States.

The EPA has found that some uncertainty exists in the PMo measurements collected priorto 1987 with the PMis instruments available at that time. Specifically, a study performed by EPA in Phoenix has shown that in extreme situations, data collected by the Sierra Anderson SA-321A size selective PMjo instrument can be influenced by coarse particles to the extent that concentrations may be biased high by asmuch as 20percent.*In addition, data collected by the Wedding and Associates GMW9000 instrument may be biased low 20 percent due

to soiling problems and improper cleaning. In order
to account for the uncertainty associated with such reported PMo concentrations, a zone ofuncertainty

or "gray zone" of±20percent will be placed around the standard for the purpose ofcalculating the probability ofnonattainment. Further, the gray

zone will be divided into two portions: the lower
gray zone, defined as 0.8 NAAQS to NAAQS, and the upper gray zone, specified as NAAQS to 1.2 NAAQS. In particular, whencalculating probabilities based on PMo fromSA-321A instruments, PMo observations within the upper gray zone will not be counted as exceedances ofthe 24-hour standard and PM~o annual means [calculated using all PM,0 data) that fall inthe upper gray zone will not be counted as exceedances ofthe annual standard. Similarly, when calculating probabilities based on PMo data from GMW-9000 instruments, 24-hour PM,. values and annual PM~o

means (using all data) that are within the lower gray

zone will be counted as exceedances ofthe respective standards.

Ifan area's nonattainment probability using TSP data and PMo data drops below 0.20 orrises above 0.95, as a result ofPMo data in the "gray zone," it will be classified Group IIin order to resolve the possible uncertainty associated with the PMto data and to ensure that a determination is made as to whether the existing SIPprovides for attainment and maintenance ofthe PMio standards. Areas will
notbe classified Group Isolely on the basis of SA321A data that are within the upper gray zone. Similarly, areas will not be classified Group IIIon the basis ofdata, Produced by GMW-9000 instruments, that are within the lower gray zone.

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Third,to insure national consistency, all grouping will be reviewed by representatives ofEPA's Headquarters staffand Regional Offices.

Requirements forGroupIAreas. States will be required to submit complete SIP's forall areas in Group I within9 months ofpromulgation of the PMo NAAQS. These SIP's will have to contain full PM1

### ocontrol strategies including ademonstration ofattainment

as expeditiously as practicable,but not later than 3years (forthe primary standards) from approval ofthe SIP, and provisions for maintenance, as well as meeting the PSD/NSR requirements discussed in section Dbelow.

Asprovided in section 110(e) of the Act, the Governor may apply, at the time the SIPis submitted, for up to 2 additional years for attainment ofthe primary standards. TheAdministrator may grant an extension ifhe determines that:

.... (A) one or more emission sources (or classes ofmoving sources) are unable to comply with the requirements ofsuch plan whichimplement such primary standard because thenecessary technology orother alternatives are notavailable orwill notbe available soon enough topermit compliance within such 3-year period, and

(B)the State has considered and applied as
a part ofits planreasonably available alternative means ofattaining such primary standard and has justifiablyconcluded that attainment ofsuch primary standard within the 3years cannot be achieved.

The Administrator mustalso determine that the planprovides for:

... (A) application oftherequirements of the planwhich implement such primary standard to all emission sources in such region otherthan the sources (or classes) described in paragraph (A) [above] within the 3-year period,and

(B)such interim measures ofcontrol ofthe

sources (orclasses) described in paragraph (A)(above) as the Administrator determines to bereasonable under the circumstances.



### Requirements forGroupII Areas. States will also be required to submit SIP'sfor all areas in Group II within9 months ofNAAQS promulgation. but those SIP's need notcontain full control strategies and demonstrations of attainment and maintenance. Instead, States may submit "committal" SIP's that supplement the existing SIP's with 

### enforceable commitments to:

(a) Gather ambient PMio data, at least to an extent consistent with minimum EPA requirements and guidance.8

8Section 58.13 of40CFR Part 58 requires States. within 1yearafter PMo NAAQS are promulgated, to begin sampling PM,o everyday (at at least one site) in areas with a PM'0nonattainment probability of95percent orgreater, andevery other day (atat leastone site) inareas with anonattainment probability between 20 and 95 percent. (b) Analyze and verify the ambient PMo data and report 24-hour PM1o NAAQS exceedances to the appropriate Regional Office within 45 days ofeach exceedance.

(c) When an appropriate number of verifiable 24-hour NAAQS exceedances becomes available (see Section 2.0 of the PMo SIP Development Guideline) or when an annual arithmetic mean (AAM) above the level ofthe annual PMo NAAQS becomes available, acknowledge that a nonattainment problem exists and immediately notify the appropriate Regional Office.

(d) Within 30 days ofthe notification referred to in (c) above, or within 37 months ofpromulgation, whichever

comes first, determine whether the

measures in the existing SIPwill assure timely attainment and maintenance of the primary PM1ostandards, and immediately notify the appropriate Regional Office.

(e) Within 6 months of the notification referred to in (d) above, adopt and submit to EPA a PMo control strategy that assures attainment as expeditiously

as practicable but no later than 3 years from approval ofthe committal SIP.

The EPA proposed (50 FR 13130) that States determine whether measures in the existing SIP were adequate [item (d) above] and notify the appropriate Regional Office within 18 months after approval ofthe committal SIP.Assuming the committal SIPwas submitted to EPA 9 months after promulgation and EPA approved the SIPin 6 months, the notification ofSIP adequacy would have been due within 33 months of promulgation. The EPAis changing the latest date ofnotification of SIP adequacy to 37 months after promulgation for two reasons. First, 18 months was allowed initially for making PM10 air quality measurements. However, 3 years ofvalid air quality data arerequired to determine the attainment status ofan area in accordance with Appendix K of40 CFR Part 50. Second, if the committal SIPis submitted late or approval is not completed in6 months, the date of notification would extend beyond 33 months after promulgation. The EPA believes it is best to have a firm date by which the adequacy ofthe existing SIP
must be determined for Group II areas and still allow adequate time to collect PMo data. The PMo monitors have been operating for several months already in many Group IIareas. The time a State has to implement a control strategy and comply with the PMio NAAQS could be shortened by 4 months ifthe committal SIPis submitted in 9months, approved in 6months, and the notification ofSIP adequacy is not made until the end of 

### the 37-month period. However, any area that requires a full 3years ofmonitoring to determine that it is violating the NAAQS, mustbe very close to the NAAQS. Therefore, only very minor adjustments to the control strategy shouldbe required to attain the NAAQS.



### The following factors should be considered in determining the adequacy 

### ofthe existing SIPin item (d) above:

(1) Airqualitydata.(Time is alloted forup to 3years ofPMo data to be collected ifa NAAQS is not violated

sooner. At the end ofthat time, the available PMo data must be examined 

### to determine ifattainment can be demonstrated in accordance with Appendix K of40 CFR Part 50 or the "Guideline on Exceptions to Data 

### Requirements forDetermining Attainment ofParticulate Matter Standards" in the absence ofadequate PMo data.) 1

(2)Thepresentcontrolstrategy.(The existing control strategy mustbe evaluated to determine ifit is fully implemented; ifitis adequately enforced; ifstart-up, shutdown, and malfunction regulations are adequate to prevent circumvention of the emission limitations; and it can adequately attain and maintain the PMo NAAQS ifthe. above conditions are met. The evaluation should include the use of dispersion and receptor modeling techniques where appropriate.)

(3)Emissionsdata.(The emission inventories must be evaluated to determine ifemissions can increase 

### significantly because actual emissions

are far below allowable emissions for the area, ifsources with operating permits are not operating or are operating at reduced capacity. and if "banked" emissions could impact future air quality.)

The committal SIP must include an enforceable schedule with appropriate milestones orcheckpoints. The EPA will review and act on both the committal SIP's and on control strategies submitted under step (e). For Group IIareas, States
may, ifthey wish, submit full PMio attainment demonstrations within 9 months as required for Group Iareas in lieu ofthe committal SIP.

The SIP revisions necessary to meet the PSD/NSR requirements detailed in section D below must be submitted in 9 months, also.



### RequirementsofGroup lIAreas.For Group III areas, EPA will presume that the existing SIP is adequate to demonstrate attainment and maintenance ofthe PMo standards. States, therefore, need only make SIP revisions as required under the

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preconstruction review program (see section D) within 9 months. The EPA will make a final determination ofthe adequacy ofindividual Group III SIP's at the time it takes action on these revisions. Any ofthese areas which subsequently observe violation ofthe PMo NAAQS will be treated as newly discovered nonattainment areas.
2. Area Designation Policy

The EPA proposed to amend Part 81, "Designation ofAreas forAir Quality Planning Purposes," by transferring the

area designation ofnonattainment for the primary TSP standard to an area designation ofnonattainment for the secondary TSP standard. Since the Administrator has determined that the indicator for the secondary standard should also be changed from TSPto PMo, EPA is withdrawing this proposed change to Part 81.

The EPAwill continue to accept requests by the State to revise area designations for TSPfrom nonattainment to attainment or unclassifiable. The requests will continue to be reviewed during the transition period forcompliance with EPA's redesignation policies as issued in memorandums fromthe Director ofthe Office ofAir Quality Planning and Standards (OAQPS) April 21, 1983, and September 30, 1 98 5.9.h

States are encouraged to request redesignation ofTSP nonattainment

areas tounclassifiable at the time the PMo control strategy for the area is submitted. When EPA approves the control strategy as sufficient to attain and maintain the PM 0 NAAQS, it will also approve the redesignation. An area designation must be retained until EPA promulgates PM1oincrements because the section 163 PSD increments depend
upon the existence ofsection 107 designations. Once States have PMo SIP's in place and EPA has promulgated PMo increments, EPA will act on requests to delete TSPdesignations. See section D below for a full discussion of thisissue in connection with the requirements for PSD programs.
3.Fugitive Dust Policy

The EPA proposed to continue a 1977 fugitive dust policy which directs the efforts to control particulate matter be expended first at sources inurban areas and next at certain large manmade

sources in rural areas.a.? In response to

a broad range ofcomments on this issue, EPA has developed three alternatives to the existing policy. Elsewhere in the Federal Register today EPA is publishing

anotice proposing those alternatives. Until EPA has reviewed comments on the proposal and takes final action, the existing policy will remain in effect.

4. Emission Trading (Bubble)Policy

In EPA's initial bubble policy (44FR 71780, December 11, 1979), alternative emission reduction options (bubbles) approved as part ofa SIPfor TSP are treated as any other existing SIP provision that may ormay not be revised in order to control emissions from other sources to attain the PMo NAAQS. The recently published final Emissions Trading Policy Statement Technical Issues Document confirms this position by stating that ifambient violations of any standard are discovered in an area where EPA has approved a trade, sources in the trade could potentially be subject to requirements for additional emission reductions just as all other sources in the area [see 51 FR 43814 (December 4, 1986)]. Although there is no specific requirement to review existing bubbles, bubble agreements cannot interfere with State efforts to attain and maintain the PM10 NAAQS.

5. Sanctions Policy

Section 110 provides forFederal intervention ifa State fails to submit an adequate SIP. Under section 110(c)(1), EPA must promulgate plan provisions for a State ifthe State fails to submit a plan at all, submits a plan that does not
meet the section 110 requirements, or fails to comply with anotification under section 110 (c)(1)(C), i.e., a call for a plan revision under the provisions ofsection 110(a)(2)(H). TheEPA must promulgate

a substitute plan unless the State in the interim adopts and submits a plan that EPA finds adequate.

The EPA intends to explore the legal issues, appropriateness, and authority for imposing a construction ban under sections 110(c) and 301 ofthe Act as the first element ofa Federal plan. A construction ban would serve to limit
anygrowth of PM~o emissions in a nonattainment area while EPAis developing a control strategy forthe

area.The EPA will also explore the appropriateness and authority ofusing funding sanctions to stimulate development and implementation of plans.

D. PreventionofSignificant Deterioration/New SourceReview Program

Today's notice promulgates certain

new andrevised provisions which will change the way in which EPA and State and local air pollution control agencies implement preconstruction review requirements for particulate matter. The
most significant effects oftoday's actions are that: (1) Proposed new and modified sources must evaluate their emissions ofparticulate matter on the basis oftwo separate indicators-TSP and PMo, and (2) the preconstruction review ofmajor new and modified

sources which emit particulate matter will be conducted primarily under the PSD program. Since EPA is not using section 107 area designations for PMlo, Federal requirements which apply to the preconstruction review of sources locating in designated section 107 nonattainment areas will generally not apply with respect to particulate matter in the long run, as explained inmore detail below.

1.Revised PSD Program for Particulate Matter

a. Transition.Today's amendments to the Part 52 PSD regulations, establishing

new requirements for PM 10,take effect 30 days from today on the effective date ofthe revised NAAQS for particulate
matter. The EPAis making these amendments effective at the earliest possible date because once the PM NAAQS becomes effective, EPA will be responsible for the protection ofthe PM,o NAAQS as well as the review of PM~o as a regulated pollutant." Consequently, PSD applicants requesting preconstruction review approval fromEPA or a State that implements PSD under a Federal delegation ofthe Administrator's PSD authority mustbegin to address the new PM 0 requirements unless they are eligible for grandfather status as described below.

States with approved PSD SIP's will have 9 months from the effective date of today's PSD amendments to revise their SIP's forPMo and submit them to EPA for approval. See revised section 51.166(a)(6) [formerly section 51.24(a)(6)]. In the meantime, the EPA expects these States to continue implementing their existing programs for particulate matter. In some cases, this
may involve the automatic assumption ofresponsibility for the review ofPMo. EPA believes that some States may have PSD rules which, likeEPA's Part 52 PSD

9Section 52.21(k)(1) contains ageneral provision requiring prospective PSD sources to demonstrate that theirpotential emissions will notcause or contribute to airpollution in violation of"any" NAAQS. On thedate that EPA'srevisions tothe NAAQS for particulate matterbecome effective, EPA willbecome responsible forprotecting the revised NAAQS, instead ofthe oldTSP NAAQS, under thepreconstruction review process. Similarly, various PSD provisions, e.g. 52.21(j)(2), apply to "any pollutant subject to regulation underthe Act," and would,thereby, automatically include the PMo indicator for particulate matter on the datethis new indicator becomes effective.

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regulations, are sufficiently open-ended

so as torequire-the, immediate protection ofthe PMo-NAAQS and review ofPM,o as a regulated form- of particulate matter.

Over the course of the next several months, EPA will audit State.PSD. permitting activities to determinewhether'or not States are implementing their existing PSD requirements for particulate matter. In-the event EPA finds that a State is not protecting the NAAQS for particulate matter in. either ofitsregulated forms,.EPA will initiate action pursuant to section 110(c)(1) of the Act to disapprove the-State's PSD program with respect to particulatematter and will reinstate amended Part 52PSD regulations into the SIP for such State. The EPA will then protect.the PM,o NAAQS in that State through the Part 52 PSD program until the State submits, and EPA approves, a PMio SIP which includes adequate PSD provisions,

As a result oftoday's amendments additional new sources and modifications may be required to undergo PSD review for particulate matter,and sources already required,to undergo PSD review for particulate
matter may be subject to additional analyses forPMo. In fairness to certainofthese applicants, EPAis phasing in the new requirements by means oftwo grandfather provisions and a monitoring;
program.

The first grandfather provision prevents* the retroactive review of

sources thatwere not,previously subject
to PSD review for particulate matter, provided that the.affected sources: (a) Obtained all the necessary approvals under the SIP'before the effective date ofthe new requirements, and (b) commenced construction within.18 months from the effective date ofthe

new requi:ements orany earlier time. required under'the SIP [see new section 52.21(i)(4)(ix)].

The second provision excludes from PSD review for PMo any applicant that,. before the effective date oftoday's Part 52 PSD amendments for PMo, submits to EPA or its delegated representative a complete PSD application which already addresses:particulate matter, even though a final determination has not.yet been made on the permit [see new section 52.21(i)(4)(x)]. Any source eligible forthis grandfather provision must meet the requirements for particulate matter thatwere in effect before the-effective date ofthe PMo amendments.

Today's action also providessome relief to certain-applicants who.would otherwise be expected to include.up to I year ofambient monitoring data for PMo as, part of'a:complete PSD: application..Three transition'provisions relating'to the:preapplication monitoring requirements will'take effect These provisions are described below-under g. PSD'Monitoring.

b.SourceApplicability.A,major new

source ormodification will'be subject to PSD review for PMo ifit: would emit PM10 in significant amounts.10 Today's action amends the definition of' "significant" for particulate matter under section 5L166(b)(23)(i) [formerly 51.24(b)(23)(1)] and.section,52.24(b)(23)(i)
to include anemission.rate for the new PMo indicator. Upon,its effective date, the new significant emission rate, 15 tpy ofPMo emissions,.wilEbegin to apply to. each PS9I applicant subject to EPA's Part 52 PSD regulations.

States with approved PSD SIP's are expected tomake similar amendments
to their PSD rules to add the new significant emissionrate:for PMio withinA the 9-month7period allowed under the Act. In.the meantime, States must examine the source applicability provisions in their existing PSD rules to determine.whether PMo is automatically incorporated as a "regulated" pollutant (byvirtue ofthe fact that itwill be a pollutant regulated under the Act) or whether-specific rulemaking action must be taken"to accomplish thatresult. The EPA. believes"that some States may have PSD rules which could immediately require the review ofPMo as a regulated. pollutant,, even though the!State rules do) not yet contain a specified significance level for PM. emissions. Prospective PSD applicants should inquire as to the
status ofexisting State PSD rules with respect to PM10.

The existing "particulate matter" significance levelof.25 tpy is being clarified to-apply to.particulate:matter emissions: [see revised sections 51.166(b)(23)(i)"and 52.21(b)(23.)(i)]._' I

10 PSD applies to new major-stationary sources and majormodifications.of'existing majorstationary sources. A "major-stationary source" for PSD purposes is; (1),any source type belonging to a. list.of.28 source.categories that emits or hasthe potential to emit.100 tpy ormore'of'any pollutant regulated undertheAct,.or.(2)any other sourcethat. emits or has the potential to emit any pollutant regulated underthe Act in.an amount equal toor. greater than 250 tpy. The PSD'review requirements apply to any regulated'pollutant'which the new-or modified-major stationary source would emit in significant amounts. Thus,a source may be,"major" for only one pollutant, but PSI review would apply to other pollutants emittedin "significant"amounts..

I Elsewhere in today's notice, the Administrator has established new definitions, "particulatematter: emissions" and."PMo-emissions." to distinguish between those emissions of.the pollutant.particulate matterwhich affect ambient concentrations of TSP and PMs. respectively: [See new section51.100 (oo)' and'(qq).] TheEPA considbrs TSP,to remain regulated,under'the'Act because, eventhough a NAAQSwi1 no longer exist for TSP, the statutory'PSD'increments for particulate matterwill'still be expressed' in terms-ofTS. It follows then that, since PSD applicability'is defined in terms'of'significant emissions of'any pollutant subjectto regulation under the' Act, significance.levels for both regulated indicators ofparticulate
matter are necessary.

The fact that there-are now two, different indicators'for particulate,
matter means-that sources ofparticulate. matter'could be required toundergo PSD review for either or-both forms of the pollutant. Conversely, an emission rate lower,than the significant emission rate for one form ofparticulate matter wouldc allow a source-to be excluded from PSD review only'with respect to that specific form ofthe pollutant.

For source modifications, the PSD review requirements will apply to whichever form ofparticulate matter results ih a significant net emission. increase. Any determination ofwhether

a proposed modification would.exceed the PMia significance threshold.shoul'd be basedonl', on PM 0 emission. changes which include actual emission changes from.a particular modification and other creditable increases.and decreases ofactuaLPMo.emissions that

are contemporaneously associated with: the modification..For PM 0,that portion of the.contemporaneous particulate.
matter emission.change with aparticle size larger than-PMo.would not be creditable.. Ifboth PM

,o, andTSP particulate matter emissions% increase significantly, then both are subject to: PSD review.

c. Geographib, Applicability..Under the section 1-10,implementation,pathway: applicable toPMo the new PSD requirements for PM 0 will generally apply ifthe otherwise subject source locates in an area.designated attainment

or unclassifiable under section-l07 for
any pollutant.This means that-the PSD, requirements forPM0 will apply in all. locations because there are.no,areas where a section 107 nonattainment designation currently applies,to all pollutants. The Administrator's determination that only section 110 applies to the.revised (PMlo):NAAQS.for particulate,mattermeans: that there will, be no.Federal requirements under-a Part Dbased nonattainment area preconstruction review with respect to, PM 10. For TSP,,the PSD'requirements will continue to, apply a any area wl ich does notha.ve'a, section 107 nonattainment designation for TSP: 

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Since the indicator forthe particulate
matter NAAQS has been changed to PM10

### ,arguably it is no longer meaningful
to maintain section 107 designations (whether attainment, nonattainment, or unclassifiable] with respect to the TSP NAAQS.' 2

### However, EPAbelieves that

as stated in the April 2,1985,proposal, the Class IIincrements for particulate matter only apply in areas that bear a designation ofattainment or unclassifiable specifically forthe NAAQS forparticulate matter, notjust for anyNAAQS. 13 

### Consequently, in order to preserve the applicability ofthe increments as desired, EPA will not approve any State requests to completely delete these TSP designations until the new PMlo increments have been established (see further discussion below in section f. PSDIncrements forParticulate Matter). States may request redesignation of theirexisting TSP nonattainment areas to unclassifiable areas, pursuant to section 107 and EPAwill approve such request on or after the date that EPA approves the State's control strategy as sufficient to attain and maintain the PM 1

### oNAAQS. Such redesignations would enable PSD review to be applied with respect to both indicators for particulate matter and will avoid the complexity of conducting the nonattainment NSR forTSP, while simultaneously conducting PSD for PM10.



### d.BestAvailableControlTechnology. While no actual changes have been made to the control technology review requirement forPSD, today's action by the Administrator to regulate a PMo indicator forparticulate matter means that any major stationary source or majormodification having the potential to emit PMo in significant amounts, i.e., 15 tpy ormore, and seeking a PSD permit under the Part52 PSD regulations mustnow consider how it will ensure

12Section 107(d) authorized the States to submit, and EPA to subsequently promulgate, a list ofareas thaton August 7, 1977, did ordid not comply with the various NAAQS in existence on that date. Although section107(d)(5) continues to provide for revisions to these lists, it wouldmake no sense to continue to maintain alist indicating ongoing compliance with a standard that is nolonger in effect.

Is See 50FR 13147, discussion under d.NAAQS Analysis/IncrementConsumption.The same argument would also apply to Class Illincrements; however, no Class Ill designations have been made
to date under thePSD program, (With respect toall subsequent discussions pertaining to Class IIareas and increments, such discussions will also apply to Class Ill areas and.increments.) On the other hand, mandatory Class Iareas and the ClassIincrements wouldremain ineffect since their general applicability is independently established by the Act and is not linked tothe section 107 area designation process See sections 162(a) and 163(b)(1) oftheAct. the application ofBACTfor PM1o emissions. A similar source undergoing PSD review under EPA-approved State regulations will also be required to address BACT forPM~o ifthe applicable State's PSD rules automatically cover PMo as a regulated pollutant, despite the lack of a specified significance level forPMo emissions in the State rule; otherwise, no BACT requirement will apply to PMo in such Stateuntil the SIP is appropriately revised.

Where PSD applicants request permit approval under the Part 52 PSD regulations, the Administrator will seek
to establish emission limitations defined in terms ofPMo emissions contingent
upon the availability ofemission factors and control efficiency information for the source under review. The feasibility ofestablishing a PMo emission limitation will thereby be a case-by-case determination. Compliance in each case is to be based on an acceptable test method also to be determined on a caseby-case basis. Appendix C ofEPA's PMo SIP Development Guideline describes procedures for modifying existing sampling techniques to collect PM 10 emissions data. The EPA is also developing specific PMo emissions
measurement methods which will be available in the future.

Where a quantifiable PMo emission limit isnot yetfeasible, the Administrator intends to allow the use ofTSP-based emission limitations, provided that the reduction ofPMo emissions-and not just "particulate
matter emissions"-has been considered
to the extent possible in the BACT determination.

e.National AmbientAirQuality Standards Analysis
When the revised NAAQS for particulate matter become effective, each PSD application subject toEPA's Part 52 PSD regulations, and not eligible
tobe grandfathered under today's action, must contain a PM~o NAAQS analysis. Applicants seeking permits from States with SIP-approved programs will also have to demonstrate compliance with the PMo NAAQS if the State's regulations are sufficiently openended to accommodate EPA's revised NAAQS for particulate matter without further rulemaking action on thepart of that State. Otherwise, PSD applicants will have additional time before a PMo NAAQS analysis will be required by the State's revised preconstruction review procedures.

The required PMo analysis must demonstrate that the proposed major

new ormodified source will not cause or contribute to ambient concentrations of PM1oexceeding the PMio primary and secondary NAAQS as required by section 165 ofthe Act.This analysis applies in general toPSD sources which have the potential to emit significant
amounts ofPMo emissions. In the event that such demonstration indicates that the proposed source would cause or contribute to ambient PMo levels exceeding the revised NAAQS, the Administrator will require the applicant
to obtain, at a minimum, sufficient PMo emission offsets to compensate for the source's ambient impact in the area of the violation. 14 In addition, the Administrator intends that emission offsets allowed forPSD purposes must meet applicable creditability criteria equivalent to those setforth under section 51.165(a) [previously section 51.18(j)) 5

14In the April 2,1985 proposal, the Administrator indicated that under the Part 52 PSD regulations he intended torequire, at a minimum, that sources found to cause or contribute to a PMIo NAAQS violation must obtain sufficient emission offsets so

as toprovide a "net air quality benefit," thus satisfying the "cause or contribute to" language under section 165(a)(3) ofthe Act.Later in the proposal, he stated that the "net airquality benefit"

test would also apply to offsets required under State PSD programs and section 51.1s(k) [now section 51.165[b)] programs as well.The Administrator has since concluded that the "net air quality benefit"
test for the required offsets is appropriate in only

some areas, namely areas where violations ofthe PM~e standard already exist but donot have an approved plan demonstrating attainment of the PMo standard as expeditiously as practicable. In these areas, new sources would otherwise continue
to "contribute" to the existing violations ifthey merely compensated on a one-for-one basis for their

own ambient impact and failed to also provide air quality progress, inasmuch as such areas haveyet
tosatisfactorily provide for attainment through available reductions from existing sources. Only by providing for some air quality improvement could

new sources help to remedy the existing nonattainment problems insuch areas rather than "contributing" tothem. Conversely, inareas that are not experiencing existing violations ofthe PMo NAAQS, new sources would notneed to provide air quality progress because once such sources adequately compensate for their own adverse air quality impacts, the areas would remain in attainment ofthe PMo NAAQS. Similarly, inareas that may be experiencing violations ofthe PMIO NAAQS but that do have an approved plan demonstrating attainment asexpeditiously as practicable, new sources that adequately compensate fortheir own projected ambient impacts would not need toprovide additional emissions reductions since the areas are already moving towards attainment as expeditiously as is practicable. States may, of course,require additional offsets in these latter areas should they desire to do so.

15On August 25, 1983, EPA proposed
amendments to its regulations concerning the construction ofnew and modified stationary

sources of air pollution (48 FR 38742). Included were two proposed changes to the offset creditability
criteria contained in section 51.18(j) [recodified as section 51.165(a)]. Specifically, EPA proposed to revise subparagraph (j)(3)}ii){T3c} [now (a)(3)(ii)(c)l which pertains tothe creditability ofemission reductions achieved by shutting down an existing Continued

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Where a State must first revise its SIP
to redefine the ambient air quality standards for particulate matter in terms ofPM,o before a PMo review would be required, EPA anticipates that a proposed source seeking a State permit (including a PSD permit where applicable) will have to continue.to demonstrate its ability tomeet the TSPbased NAAQS as a matter ofState law. Moreover, the particular State preconstruction review requirements which must be met will continue to be based on geographic applicability as governed by current section 107 area designations for TSP. It ispossible, therefore, that a source could be subject
to EPA's Part52.PSD regulations requiring compliance with the newlyrevised PMo primary and.secondary NAAQS and the applicable State. preconstruction review procedures requiring compliance with the-old TSP NAAQS. This particular outcome.will
not occur, however, after such State revises its SIP forthe PMio NAAQS. 

### f. Preventionof Significant Deterioration Increments-for Particulate Matter

The Administrator today is announcing his intention to establish PMo increments pursuant to section 166 ofthe Act.'1 In accordance with the procedures established by Congress under paragraphs (a] and (b) ofsection 166, over the next several years, EPA will propose and promulgate regulations which set forthnew PSD increments measured by the PM,0 indicator. These regulations are to.become effective 1:
year after the date upon which EPA promulgates them, whereupon States will be given time to revise their SIP's to include the new PMo increments and submit them to EPA forapproval. Ultimately, EPAplans to allow States to,

use the new PMo increments to effectively replace the existing increments for "particulate matter," as further described below.

During the period oftime required to incorporate the new PMo increments

source Or permanently curtailingproduction or operating hours: and to change subparagraph (jJ(3Jlii(e) [now (a)(3)(ii)(e)] which currently requires that all emission reductions claimed as offset credit be federally enforceable. The EPA intends to apply the existing offset creditability criteria to PSD offsets untilit'takes final action on the August 25, 1983, proposal. In the event that such. final actionchanges the offset creditability criteria in section 51.165(a), then the changes would also be applied with respect to-the PSD offset program.

10 Section 166 ofthe Actrequires in part that, forpollutants for which NAAQS-arepromulgated after August 7. 1977,EPA must promulgate.regulations which "shall provide specific measures-at least as effective as the increments established in section 163

... and may contain air quality increments, emission density requirements, orother measures." into State PSD programs; the Administrator is taking-steps to ensurethat the existing.PSD.increments for particulate matter ira section 163 ofthe. Act will continue to be measured.by the. TSPindicator. Although the statute does
not specify an indicatorto beused to

measure particulate-matter levels against the statutory increments (they

are simply referred to as increments for "particulate matter"), it is clear fromthe. legislative history that Congress could only have intended these increments to be measured asTSP..

At the time Congress.created.the increments, the particulate matter NAAQS were measured as TSP Congress created the "particulate matter" increments in.section 163 by taking a percentage ofthe lowest NAAQS concentration for each
measurement period [see e.g., H.R. Rep. No. 95-294, 95th 

### Gong., 1st Sess. (1977),
p. 153ff]. In thisway, ambient concentrations of particulate matter. could generally be restricted to levels below the NAAQS levels. This approach only makes sense ifCongress intended
to use the same indicator forthe increments as was then in use for the NAAQS. Therefore, under today's revisions EPA is,clarifying these increments so as to apply them, specifically to ambient TSP concentrations.

The TSP increments will.continue to apply in mandatory Class I areas (see footnote 13) and in Class II areas for TSP, i.e., area's which, pursuant to section 107, are designated attainment

or unclassifiable forTSP..The EPA anticipates a potential problem ifStates. should request deletion'oftheir section, 107 TSP designations-when they adopt PMo 0 NAAQS to replace the oldTSP NAAQS. As noted earlier in-this preamble, the statutory Class II TSP increments will no longer apply in an
area once EPA has deleted the existing section 107 designations for TSP pursuant to State request, since Class II

areas are defined as a subset-of section 107 area designations. IfEPA were to grant such requests in the.absence of PMo increments, many areas would be subject to no PSD increments for particulate matter in either ofits regulated forms.This potential.result would,clearly conflict with congressional intent to prevent significant deterioration with respect to particulate matter.

The EPA intends to,deny State requests for deletion ofsection 107 TSP designations pending-each State's adoption ofPMo increments, In support ofthis position, EPA-will rely-upon the introductory phrase in section 107(d) 

### which states "[flor the purposes of

. . .part C (relating to preventionof significant deterioration,ofair quality):

..... Although section 107

area designations withrespectto TSP
may no longer be appropriate:i.i th absence ofthe-TSP NAAQS, EPA will, require.the retention ofthe:TSP designations.for the" purposes ofPart:C ofthe Act untilPMe 0 increments are in place.

The,EPA. ,ill:also rely on.its authority under section 301"to "prescribe such regulations as-are necessary to carry out [its] functions" under the Act That is, until PM 0 increments.arepromulgated, it will be "necessary" within the meaning ofsection 301 to retain existing section 107(d) TSP designations so that the Class IrTSP increments will continue to apply in Class II areas for particulate matter. However, as described earlier, States willhave the opportunity toremove theirexisting TSP nonattainment designations by requesting toEPA that each area be redesignated as unclassifiable. The EPA will approve such redesignations on or after the date,it approves.each State's. plan to attain and maintain" the PMo NAAQS

The redesignation to "unclassifiable" pursuant to section 107of the Act will enable the PSDtpreconstruction review requirements to apply to subsequent major new sources and major modifications proposing to locate in such redesignated areas. Hence, at the time that the first complete PSD. application affecting the redesignated

area is filed, the baseline date will beestablished for TSP and the amount of increment which would be consumed.
mustbe determined. The EPA plans to develop guidance toenable PSD sources. and States to determine which changes, ifany, in actuaLPMo emissions, occurring during the time that the area

was designated nonattainment, affect the amount ofTSP increment consumed.

Once EPApromulgates PMo increments a,dual increment system for particulate matter, i.e., TSP and PM 1o, will exist. The EPA believes that ar mandatory dual increment system will' be unnecessarily burdensome:and cumbersome. A partial remedy to a mandatory dual system exists in: the fact that States will be given the opportunity
to request the deletion.of all or a portion. oftheir existing:section 107 area designations for TSP. In any area designated as attainment.or unclassifiable for TSP, States,may effectively end the:applicability ofthe Class II increments-for' "particulate matter" under section 163of'the Act when the TSP area designation for such 

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areas is deleted. However,because the ClassIincrements forparticulate matter under section 163 of theAct are not similarly affected bythe deletion ofthe section 107 area designations, EPA intends to construct Class IPMo increments that are equivalent in effect to the statutory Class ITSP increments. In the event thatEPA can do so,it will then allow Statesto use these Class I PMo increments as surrogates for the Class ITSPincrements. Thus, PSD permit applicants and permit reviewers might not have todeal with two separate increment analyses.

g.PreventionofSignificant Deterioration Monitoring Today's action adds a second significance concentration for the purpose ofrequiring PSD preapplication monitoring data for particulate matter. Under the amended Part 52 PSD regulations, EPA will use the newlydefined significant ambient concentration, 10 ;.g/m3 (24-hour average) ofPM1

### o,to help determine when a proposed PSD source must, prior to the submittal of itsPSD application, collect and evaluate ambient PMo data. See revised section 51.166(i)(8)(i) and section 52.21(i)(8)(i).1 7



### Although TSPmonitoring will continue tobe required under the newly amended regulations, TSPwill no longer be a pollutant forwhich a NAAQS exists. Therefore, discretionary authority in accordance with section 52.21(m)(1)(ii) and section 51.166(m)(1)(ii) is available to exempt TSP monitoring in certain situations. When an exemption is granted, the required air quality analysis would instead have to use air quality dispersion modeling to estimate ambient impact.

The Administrator will phase in new PMo monitoring according to a transition program being set forth today

I The Administrator is taking this opportunity to correct several errors that haveexisted inthe table ofsignificant ambient concentrations since the time the table was first published on August7,1980. First, the averaging period forlead is being revised toa 3-month average. Thiswould conform to the3- month averagingperiod specified for the lead NAAQS. The averiging period foreach criteria pollutant wasintended to conform to the shortest averaging period forwhich aNAAQS was defined forthat particular pollutant.

Second, the Administrator is revising the significant concentrations forberyllium and hydrogen sulfidebecause these concentrations were listedincorrectly. The berylliumconcentration was promulgated as0.0005, which waslow by a factorof 2.Itshould have been 0.001 ;tg/m 3

. Thehydrogen sulfide concentration was promulgated as0.04 ftg/

m

3

,which is the minimum detectable concentration and did not reflect the factor of5as used to establish each ofthe othersignificant ambient concentrations. The correct value forhydrogen sulfide should therefore be 0.2 jg/m3

. 

### in thePart 52 PSD regulations. The three monitoring transition provisions are essentially the same as those in the proposal, except that time periods focus

on the effective date ofthe PSD amendments for PMo rather than the promulgation date ofthe amendments. For complete applications submitted during the first 10 months after the PMo amendments become effective, no new PMo monitoring willbe required; however, the Administrator may require

an applicant to consider existing air qualitydata (PM1

### o,PM

,5

### ,orTSP)ifit is available and representative. 1 8



### When aPSD application would become complete after 10 months and not laterthan 16 months from the effective date ofthePSD amendments forPMo, theprospective PSD source must use existing PM1

### oorPM15 

### representative air quality data orcollect PMo monitoring data. 9The collected data can come from nonreference samplingmethods. The amount ofPMo data collected during this period will involve at least 4 months ofsampling, but will depend on the applicant's ability to collect more data before the application would otherwise become complete.

Finally, for complete applications submitted after 16 and not laterthan 24 months from the effective date of today's amendments, applicants must collect ambient PMo data from reference method PMo samplers. The amount ofdata collected from the

18The EPAhas revised its "AmbientMonitoring Guidelines for Prevention ofSignification Deterioration (PSD)" to fully describeAgency policy for implementing each ofthe transition provisions which are setforth in today's notice.

19The April 2,1985,proposal contained a discrepancy concerning the specific kinds of nonreference sampling methods that the Administrator would accept during the second transition period (after 10but not later than 10 months from thePSD amendments). In the FEDERAL REGISTER preamble (p. 13150) there is a statement indicating that EPAwould accept data based onTSP sampling forcomparison with the proposed PMoprimary NAAQS. The inclusion of TSP as acceptable data was inerror. TheAugust 1984 draft ofEPA's "Ambient Monitoring Guidelines for Prevention ofSignificant Deterioration (PSD)," which was made available for public comment simultaneously withthe proposed PSD amendments, contained the Agency's intended policy which was to allow TSPdata tobe used during the second transition period only in comparison with thethen proposed TSP secondary NAAQS (see section 2.5.2.2, p.44 ofthe draft guidance). The Administrator's decision not to allow theuse ofTSPdata forcomparison with the PMo NAAQS is based onthe fact that the relationship between PMlo and TSPmay vary quite widely onboth a temporal (day-to-day) and spatial (site-to-site)basis so that no singleconversion factor canbe used to reliably determine PMlo concentrations using TSPdata. Thus, the Administrator wishes to discourage the use ofTSP data after theinitial 10-month transition phase. After such time, sources should be able to gather at least 4months ofambient PM,o orPM, 5data. 

### reference monitors mustinclude at least
4 

### months of databut, as above, depends

on when thePSD application would otherwise become complete.
2.Revised New Source Review Requirements forParticulate Matter

The fact thatEPA will implement the PMo NAAQS under a section 110 pathway significantly limitswhich Federal NSR requirements will apply to major sources with PMo emissions. For the reasons described elsewhere in this preamble, the NSR requirements contained in section 51.165(b) [formerly section 51.18(k)] will apply,but the other major source NSRrequirements for

areas not attaining theNAAQS, including thenonattainment regulations under section 51.165fa) [formerly section 51.18(j)], the offset rule under 40 CFR 

### Part 51 Appendix S, and the construction ban under section 52.24 will not apply with respect to PMo.

The purpose ofthe section 51.165(b) NSR regulations is to require States to establish preconstruction review procedures which address major sources proposing tolocate in designated attainment or unclassifiable areas and whose proposed emissions would cause
or contribute to a NAAQS violation in any area. States have been required to implement a preconstruction review program which meetsthe requirements of section 51.165(b) forthe particulate
matter NAAQS which until now were based on the TSPindicator. Current State programs may ormay not continue toprotect theTSP-based primary and secondary NAAQS for particulate
matter depending upon thelanguage in their regulations pertaining to NAAQS. Such programs must continue to be implemented withrespect to TSP NAAQS until the States revise their SIP's where necessary to define the NAAQS in terms ofPMo.

The EPA expects Statesto implement their section 51.165(b) NSR program in accordance with the samegeographic and source applicability criteria as apply forPSD purposes with one exception. That exception pertains to the definition of "major source." The NSR source applicability requirement

with respect to major sources is more inclusive than the PSD source applicability requirement in that "major" forNSR purposes includes all

sources which have the potential to emit
at least 100 tpy ofany regulated pollutant as defined in section 302(j) of the Act.The EPA is amending the section 51.165(b) regulations to clarify the ambiguity thatwas present in the original requirements [see new section 51.165(b)(1)]. The Actrequires that this

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definition ofmajor source, in section 302(j) ofthe Act, be used for the purposes ofsection 110(a)(2)(D) ofthe Act,which is the primary basis for the section 51.165(b) NSR requirements.

In accordance with the April 2,1985, proposal, the Administrator will allow States, as part ofan approvable section 51.165(b) NSR program forPMio, to establish an emission offset program. Such emission offset program, in order to be approvable by the Administrator, must be consistent with the PSD offset creditability criteria as described earlier (also see footnote 15). Emissions offsets must be applied as a prerequisite for approving a construction permit forany applicable majornew or modified

source whose prospective construction would otherwise cause orcontribute to

a PMo NAAQS violation. "Cause or contribute to" would be determined in accordance with numerical criteria at least as stringent as the significance criteria set forth under new section 51.165(b)(2). States which experience

more severe nonattainment problems may need to consider more stringent significance criteria to address new construction that wouldoccur in the

area ofa nonattainment problem. In any case, the required offsets must be sufficient to compensate forthe proposed source's ambient impact in the

area ofa NAAQS violation to the extent that the source's emissions would cause
or contribute to the violation [see new paragraph 51.165(b)(3)].

With respect to federally-imposed construction bans already ineffect for TSP, such bans will automatically be liftedwhen EPA's PMo NAAQS in40 CFRPart 50become effective in 30 days. EPAfinds that it willno longerhave authority under section 110(a)(2)(I) of theAct to impose the construction ban against violations ofthe oldTSP NAAQS. Under that statutoryprovision and 40CFR 52.24, a construction ban is to apply within designated nonattainment areas failing to meetPart D oftheAct for a major new source or modification that would cause or contribute toa violation ofa NAAQS. While TSPnonattainment designations will be retained at least forthe time being, the TSP NAAQS will be replaced byPMio NAAQS in40 CFR Part50. Thus, EPAwill be unable to continue imposing a ban tocompel new Part D planning for TSP.States will, however, be expected to continue implementing their existing NSR rules, including those based onPart DoftheAct. V. Revised Regulations
A. Revisions toPart51
1.Regulatory Reform

On November 7, 1986, EPA promulgated (51 FR 40656) restructured 40 CFR Part 51 regulations. Part 51 was changed by deleting obsolete provisions, removing unnecessary requirements, reducing reporting burdens on the States, and restructuring the entire part into a new format that will be easier to

use than the existing format. Now restructured, Part 51 reflects the Act requirements pertaining to SIP's in general terms rather than specifying requirements by pollutant. This action simplifies formerly detailed regulations and provides more flexibility. In keeping with that effort, the revisions to Part 51 beingpromulgated today are inthe new format. Since most references to specific pollutants have been removed from Part 51, only a small number ofchanges, aside from the NSR/PSD changes, are needed in this action to revise Part 51 in response to the revised particulate
matter standards.
2. Basic State Implementation Plans Requirements

The new Subpart G, Control Strategy, ofPart 51 contains general requirements that must be met by States in order that their PMo SIP be approvable by EPA. For example, Subpart G requires that each SIPinclude a description ofthe control measures being adopted, a demonstration ofthe adequacy of those

measures to provide fortimely attainment and maintenance ofthe NAAQS, and a description of the procedures for implementing and enforcing those measures. These requirements were formerly included in sections 51.12 and 51.13.

The new Subpart K, Source Surveillance, requires provisions for recordkeeping by owners or operators of stationary sources, testing inspection, and enforcement ofregulations through visibile emission limitations. These requirements were formerly included in section 51.19. The Administrator will judge the PM1 oSIP's against these requirements to determine their approvability. Where SIP's already contain certain provisions, such as a description ofadministrative procedures, these need not be repeated in the SIP revision submitted for the PM 0 NAAQS.

3. Section 51.100, Definitions

The EPAis adding definitions to section 51.100 (formerly section 51.1) to help clarify the distinctions between the terms, "particulate matter," "particulate matter emissions," "PMo," "PMo emissions," and "total suspended particulates." A generic definition of "particulate matter" is added which parallels the use ofthe term in the revised criteria document for particulate
matter. The term "TSP"is defined as particulate matter as measured by the high-volume method described in Appendix B of40 CFR Part 50. The term "PM 0"is defined as particulate matter with an aerodynamic diameter less than

or equal to a nominal 10 micrometers as measured by a reference method described in Appendix J of40 CFR Part 50.

The terms "PMo emissions" and "particulate matter emissions" are defined as those respective materials as measured during a source test that are emitted to the ambient air.For example, particulate matter emissions are finely divided solid or liquid material as measured during a stack test (e.g., EPA Reference Methods 5 or 17) of the

sources emissions. The PMo emissions

are finely divided solid or liquid material with an aerodynamic diameter less than or equal to a nominal 10 micrometers, as measured during a stack test ofthe source's emissions.
4. Section 51.151, Significant Harm Levels

The review and revision ofhealth and welfare criteria for particulate matter and sulfur oxides and revisions to the NAAQS for particulate matter necessitate certain changes to the significant harm levels. The indicator for the particulate matter significant harm level is changed from TSP toPMo to conform with the revision ofthe primary NAAQS for particulate matter.

Also the significant harm concentration level forparticulate
matter is revised. The criteria document and its addendum indicate that a scientific consensus exists linking increases indaily total mortality and particles during the historical London wintertime pollution episodes when particle levels, measured as British Smoke (BS),2 0 and sulfur dioxide (SO2) levels were both in the range of500 to 1000 pg/m3.JStrong evidence exists showing an association between pollution and mortality at substantially lower levels. However, substantial disagreement exists as to whether such associations are causal at these low concentrations.k While the relative

10 British Smoke isa pseudo-mass indicator related tosmall particle (size less than a nominal 4.5 micrometers) darkness. This particulate matter indicator was widely used in Britishand other European studies. 

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importance ofSO2 cannot be specified unequivocally, the conservative assumption (withrespect to particles) is that similar responses might have occurred without substantial amounts of SO2 present as discussed in the EPA staffpaper and the staffpaper addendum for particulate matter (p.98)." In addition to potential SO2 interaction, consideration must also be given to comparing BS and PMo. Because the smoke reading responds to darkness instead ofmass, the relationship between BS and a mass index such as PMo is particularly uncertain. To
account for this, the staffpaper (p.99) derives general boundary relationships comparing BS and PM~o units from the available aerometric data. The lower bound assumes a BS reading equals a PMo mass reading while the upper bound assumes PMo mass=BS reading+100 pg/m. The lowerbound includes a margin ofsafety compared with the upper bound of the range. A reasonable estimate ofPMo that may

cause significant harm can be made by combining the conservative assumption that particulate matter above 500 pg/m (BS>500 pg/m s)will cause increased mortality and the less conservative assumption thatPMo=BS+100 Ag/m s

. On this basis, EPA is changing the significant harm level for particulate
matter to 600 jig/m measured as PM~o (PMo=BS> 500 pg/imn+100 g/m').

The significant harm level lor the combined levels ofparticulate matter 

### (measured as 

### TSP) and SO2 are deleted. As noted in the staffpaper (p. 71), it is
not clear from the relevant scientific evidence that such a combined particulate matter S02 index provides
any improvement in protecting against significant harm from particulate matter

over a single significant harm level for particulate matter that is chosen with due consideration ofthe potential interactive effects. As discussed above, the proposed significant harm level for particulate matter does take into account, in a conservative fashion, potential SO interaction. Continuation ofthe current combined TSP-SO, index is. therefore, no longer appropriate nor needed from the standpoint of particulate matter.

More detailed discussion ofthe information supporting these revisions

can be found in the criteria document and staff paper which are available for inspection at the Central Docket Section (Docket No. A--82-37). The address of the Central Docket Section is gien at the beginning ofthis notice.

5. Section 51.165, Permit Requirements

In subsection (a) ofthis section, the significance level for particulate matter 

### is deleted because the TSP-based NAAQS have been deleted and the new indicator forparticulate matter, PMo,is
not subject to the provisions of this section concerning nonattainment NSR. In paragraph (b)(1) reference is added to paragraphs (a)(1) 

### (iv)and (v) ofsection 51.165 which contain definitions of "new major stationary source" and "major modification." Also in paragraph (b)(1) a change is being made to replace "40 CFR 81.300 et seq." with "section 107 ofthe 

### Act" wherereference is made to area classifications. Atable similarto the table in section III.A ofAppendix S is being added in a new paragraph (b)(2) to indicate significant ambient impact concentrations. Within this table, the annual and 24-hour concentrations are being deleted forTSP since there is no longer an annual or24-hour TSP NAAQS.2 1

### Concentrations forthe annual and 24-hour averaging times are being added to define significant ambient impacts for PMo.

Paragraph (b)(3) isbeing added to clarify EPA'sposition that Statesmay allow proposed major sources ormajor modifications to obtain emission offsets
to compensate for their adverse ambient impacts where such sources or modifications would otherwise cause or contribute to a violation ofa NAAQS. Finally,paragraph (b)(4) is being added
to exclude a source from the requirements ofparagraph (b)with respect to any pollutant for which the location ofthe source is designated as nonattainment.
6. Section 51.166, Prevention of Significant Deterioration ofAir Quality

Various amendments to the requirements forthe prevention of significant deterioration are being added to section 51.166. Paragraph (a)f6)(i) is changed to allow States 9months from the effective date ofany new PSD amendments to adopt and submit the appropriate SIPrevisions.In paragraph (b)(231(i), theexisting significant emissions rate forparticulate matter is changed so as to clarify that it is to be measured in terms of "particulate matter emissions." A new significant emissions rate forparticulate matter is also added and is expressed in terms of"PMo emissions." Thus, there are significant emissions rates for two regulated forms ofparticulate matter, i.e., TSP and PMo.

The increments for particulate matter inparagraphs (c) and (p)are clarified to

2'The annual and 24-hour concentrations forTSP in the table as it occurs inAppendix S are not being deleted at this time because States may continue to

use these concentrations to address the TSP NAAQS which may remain in effect within their SIP's untilthe SIP's arerevised withrespect to PM~o. 

### indicate that the specified concentrations apply to ambient TSP.In paragraph (i)the significant ambient concentration forparticulate matter is changed toindicate that the specified value applies to either TSPor PMo.Also in paragraph (i),technical and clarifying amendments are being made to lead, beryllium, and hydrogen sulfide to correct for previous typographical

errors. Finally, a new provision is being added that would allow States to adopt PMo transition provisions that parallel theproposed transition provisions in section 52.21.

7. Sections 51.322 and 51.323, Annual 

### Source Emissions Reporting

The EPArequires annual reporting of actual emissions ofcriteria pollutants in order to perform various types of national analyses and to prepare national emissions trends reports. The EPA proposed to amend section 51.322, "Sources subject to emissions reporting," and section 51.323, 

### "Reportable emissions data and information," to specify requirements for State reporting ofboth particulate
matter emissions and PM 0 

### emissions on

an annual basis. However, since the Administrator has determined that the indicator forbothprimary and secondary standards should be changed from TSPto PM~o, the promulgated amendments simply replace particulate matter emissions reporting with PMo emissions reporting. To provide time for States to develop the capability for reporting PMo emissions data and for EPA to store and retrieve such data, Statereporting ofPMo emissions data is
to begin with calendar year 1988 emissions. Therequirement to report particulate matter emissions data ends with State reporting ofcalendar year 1987 emissions.

8. Revisions toAppendix L

Appendix Lto Part 51 contains example airpollution episode levels and contingency plans for thepurpose of preventing airpollution from reaching the significant harm levels prescribed in section 51.151. To conform with the 

### revisions to the significant harm level for particulate matter,the Administrator is making thefollowing revisions to the example episode levels forparticulate matter: (1)

### Theindicator for particulate matter episode levels is changed fromTSP to PMo, as it is forthe significant harm level;

(2)The combined particulate matter/ sulfur dioxide episode levels are deleted:

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(3)The example alert level for particulate matter (measured as PMs) is changed to 350.tg/m3, 24-hour average;

(4) The example warning level for particulate matter (measured as PM 10)is changed to 420 /g/m 3 24-hour average; and

(5)The example emergency level (measured as PMo] is changed to 500

g/m3, 24-hour average. The basis for changing the indicator for particulate matter and for deleting the combined particulate matter/SO 2 episode levels is the same basis as discussed above forthe revisions to section 51.151. With respect to example episode levels, the proposed alert level reflects the upper bound ofthe range of interest in the staffpaper. The staff
paper concludes that at or above 350 )lg/m3 health effects are likely to occur incertain sensitive population groups. Therefore, itwould be appropriate under the episode criteria to initiate first stage control actionwhen this ambient level ofparticulate matter occurs. The warning and emergency levels are set at approximately equal increments between the alert level and the significant harm level. This approach provides opportunity for the control actions associated with each episode level to take effect before the next stage is triggered and additional control actions become necessary.
9. Revisions to Appendix S

In Appendix S, the emission rate which defines significant amounts for "particulate matter" in paragraph II.A.10(i) is changed to clarify that such emissions are to be measured as "particulate matter emissions," consistent with the newly defined term added to section 51.100. The new indicatorfor particulate matter, PMo, is
not subject to the nonattainment provisions ofthis Appendix.

B.Revisions to Part 52

1.Section 52.21, Prevention of Significant Deterioration ofAir Quality

The amendments for the Part 52 PSD regulations in section 52.21 include the amendments described for section 51.166 concerning (1)the significant emission rate for particulate matter; (2) the ambient increments forparticulate matter; and (3) the significant ambient concentrations forparticulate matter, lead,beryllium, and hydrogen sulfide. Also, inparagraph (i)(4) new provisions

are being added to grandfather certain applicants from additional PSD review resulting from new PMo requirements when prescribed criteria have been met by the applicant. In paragraphs (i)(11), (m)(1)(vii), and (viii), new transition provisions for preconstruction monitoring are added to exclude applicants from PM1omonitoring methods depending on when a complete application is submitted relative to the promulgation date ofthe PMo NAAQS. Finally, paragraph (w)(2) is changed to replace the date "June 28, 1978," with the date of the PSD requirements in effect immediately preceding the effective date ofthe new PMo amendments.

2. Section 52.24, Statutory Restriction on New Sources

The provisions for prohibiting construction in certain designated nonattainment areas are revised by deleting the significaht emission rate for particulate matter from the definition of "Significant" under paragraph (f)(12). This emission rate is no longer needed because, through the deletion of the TSP NAAQS, construction ban provisions of this section no longer apply to particulate matter.

VI. Public Participation

The proposal to implement the revised particulate matter standards drew many responses during the public comment period. Since the issues raised by
commenters had a significant effect on the contents oftoday's final rule, EPA feels it is important to make the connection between comments and the development ofthis final rule as clear as possible.

Accordingly, there is a separate discussion belowfor each part of the proposal that drew comments in which issues ofmajor importance were raised. In order ofpresentation, these parts are: legal issues, attainment probability estimates, SIP development policy, PSD and NSR issues, technical, miscellaneous, and procedural issues.

Each discussion opens with a brief review ofwhat was proposed. This is followed by a summary ofthe issues raised by the commenter and EPA's response. TheEPA's response to comments not addressed in this preamble may be found in the docket.

A. CommentsonLegalIssues

A full discussion ofthe legal issues raised in the proposal is presented in section III above.

1. Comments Favoring an Exclusive Section 110 Pathway

Many commenters who supported use ofsection 110 exclusively for implementation ofthe revised PMo NAAQS argued that Part D by its own terms does not apply to anyrevisions to

a NAAQS. The EPA does not agree with thispremise. As explained in Section III 

### above, ifthis were true, a relaxation ofa NAAQS that reduces a State's planning burden would shield an area that had failed tomeet the original NAAQS from the strict Part Drequirements despite thefact that it wouldnow be easier for the area to attain. Itis unlikely that Congress would have intended such a result. The term "national ambient air quality standard" in section 171(2) must therefore encompass revised standards

as well.

These commenters similarly pointed to thefixed attainment dates in PartD

as evidence thatPart Dcould not apply to any NAAQS revisions after the statutory 1982 attainment date. However, as a matter ofstatutory construction, the duty to demonstrate attainment bythe PartDattainment dates should properly still apply to NAAQS relaxations after 1982 that reduce an area's planning burdens and

ease opportunities to demonstrate attainment, or thathave no significant effect on planning burdens.22 

### There is

no reason forCongress to have provided such areas with additional time to prepare SIP'sto meet such revisions. All such areas were already under a duty to demonstrate attainment ofthe prior NAAQS by 1982, and no further planning would be required ofsuch

areas by virtue of such relaxations. Where NAAQS revisions do impose significant additional planning burdens, States could notbe expected to show that they could attain by dates that had already passed before the planning burdens were imposed and thus Congress would nothave wanted Part D to apply to such areas.

One commenter pointed to section 406(d)(2)(B) ofthe 1977 amendments, arguing thatthis provision required the

use ofsection 110in all cases unless the Actexpressly statedotherwise. In fact, thisprovision makes no mention of section 110, 

### butmerely states that SIP revisions should be submitted within 9 months ofpromulgation ofEPA regulations necessitated by the 1977 Amendments.

One commenter discussed the legislative history ofPart Dand concluded that Congress only intended it to apply in 1977 to areas that then exceeded the then-existing NAAQS. These arguments support EPA's position that PartDshould not apply to NAAQS revisions that impose significant new

21 TheEPA notes that under its sanctions policy (48 FR 50686), EPA would in practice approve a Part D SIP andlift the construction ban upon a demonstration that the SIP would provide for attainment as expeditiously as practicable after 1982. This policy would apply to particulate matter SIP's in all areas subject to Part D. 

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planning burdens. But it would drastically undercut any benefits of the
program Congress established in 1977 to

remove Part D applicability as to NAAQS revisions that reduce planning burdens and ease opportunities for attainment ofthe NAAQS as they existed in 1977, the very standards Congress sought to see attained when it created Part D. Any area not in attainment of such a revised standard would presumably have exceeded the pre-1977 NAAQS as well.

Several commenters supporting use of section 110 cited Bethlehem Steel Corp.

v.EPA, 723 F.2d 1303 (7th Cir. 1983), quoting the court's statement that the Part D deadlines only make sense as applied to areas that data indicated in 1977 were in violation ofthen-existing NAAQS. This case had to do with EPA's authority to reclassify areas so as to bring new areas not previously subject
to it under Part D. The EPA's position that revisions which impose significant

new planning burdens are not subject to Part D is consistent with this case, in which the court concluded that EPA could not unilaterally apply the strict Part D requirements to new areas after 1977. This case does not support the position that Part D would not apply to revisions that impose no new planning burdens because all areas subject to Part D under such revisions should already have been subject to PartD under the original pre-1977 NAAQS.

A few commenters cited U.S.Steel v. EPA,595 F.2d 207 (5th Cir. 1979), asserting that the court had construed section 406(d)(2) ofthe 1977 Amendments as applying section 110

even to SIP's subject to Part D but incapable ofmeeting its deadlines. Actually, this case merely heldthat the relevant Part Dplans would be due within 9 months ofnecessary EPA regulations as stated in section 406(d)(2)(B) and made no reference to section 110.

Finally, one commenter cited the opening sentence of the Supreme Court decision in Chevron USA v.NRDC,104 S. Ct. 2778 (1984), where the Court stated that Congress in 1977 enacted additional requirements for areas that had failed to achieve previously established standards. This statement ismerely descriptive ofCongress' actions in1977 and does not reflect any thought on the Court's part as to the relative applicability ofsection 110 orPart D to future NAAQS revisions.

Numerous commenters addressed EPA's alleged concern that application of section 110to all NAAQS revisions, including relaxations, would automatically shield States fromhaving
to show that SIPrelaxations would not 

### interfere with attainment and maintenance ofthe revised NAAQS. These commenters apparently misunderstood EPA's actual concern that use ofsection 110 in cases of NAAQS relaxation would shield areas from the strictPart Drequirements despite eased attainment burdens. Consequently, the commenter's suggestions that existing Part DSIP's would continue to applypending SIP revisions to comply with the revised NAAQS arenot relevant toEPA's actual

concern over ultimate SIPrelaxation in such cases. Under either section 110 or PartD,States would still have to show that any SIPrelaxation would not interfere with attainment and maintenance ofthe revised NAAQS.

One commenter alleged that historical precedent supports use ofthe section 110pathway in all cases. The commenter pointed first to an EPA decision in 1979 to accept less than all reasonably available control measures in a Part Dplan so long as reasonable further progress toward attainment could be demonstrated as evidence of EPA's alleged past practice of dispensing with certainPart D requirements. In reality, EPAmerely stated in 1979its interpretation that Part Donly requires implementation of such

measures as necessary to insure reasonable further progress and attainment as expeditiously as practicable, and that Part Ddoesnot require implementation ofadditional cost effective measures that would not further expedite attainment. The EPA did notpurport to dispense with any applicable PartD requirements (see 44 FR 20375).



### This same commenter also stated that EPA's 1979 position onimplementation ofthe revised ozone standard did not support use ofPartDfor NAAQS relaxations. The commenter allegedthat EPAmerely concluded that SIP revisions would notbe required as a resultof the ozone NAAQS revision since States couldkeep more stringent requirements in their SIP'sifthey desired. Itis true that EPA concluded that additional SIPrevisions would not be required to implement the relaxed

ozone standard. However, EPA also stated that the deadline forPart DSIP submission established in the 1977 Act would notbe affected by the ozone NAAQS revision (44FR 8202). Implicitly, EPA concluded that PartDwould continue to apply to all areas that failed to meet the new relaxed ozone standard.

Several commenters noted that use of Part Dforrevisions thatdid not impose significant new planning burdens could result in a more stringent implementation scheme for welfarebased secondary standards than for health-based primary standards if only therevised primary standard imposed

new planning burdens, a result that Congress allegedly would not have intended. Since EPA has concluded that the primary and secondary PM1

### o standards shouldbe identical in all respects, this hypothetical situation will
not arise forPMo. TheEPA notes that a similar situation could also arise ifEPA revised a primary standard to impose additional planning burdens while making norevision to a secondary standard forthe same pollutant. However, as discussed in section II.B.l.b.(4) above, EPAhas determined that sanctions do not apply for failure to have PartDrevisions for a secondary NAAQS.



### Finally, some commenters suggested that an exclusive section 110pathway would be preferable in that it would relieve EPA of the duty ofdetermining which revisions imposed additional new burdens. TheEPA agrees that a uniform section 110pathway would be simpler to administer,butbelieves that the adopted interpretation is the better reading ofthe statute.
2. Comments Favoring an Integrated Section 110 and Part DPathway

Several commenters urgedEPA to read section 110 and Part Das an integrated whole, applying Part D to any
areas not attaining any NAAQS. These commenters noted that section 110 specifically incorporates Part Din sections 110(a) (2)(D), (H) and (I). However, EPA reads these cross references as onlyincorporating PartD to theextent it would otherwise apply by its own terms.The EPA doesnot see that the cross references reconcile the inherent conflictconcerning applicability ofsection 110 and PartD.

In support oftheintegrated approach,

one commenter cited CityofSeabrook v. EPA, 659 F.2d 1349 

### (5th Cir. 1980). There, 

### thecourt heldthat EPA's duty to approve or disapprove SIP's under section 110 applies also to plans submitted under Part D.Again, EPA believes thisrefers onlyto Part DSIP's submitted for areas subject to PartD by its own terms. The decision merely clarifies the cross references to Part Din section 110 and makes no statement about applicability ofeither pathway to

new or revised standards.

One commenter supporting the integrated approach addressed the conflicting attainment deadlines in section 110 and Part Dby suggesting that the PartDdeadlines provide exceptions to the 3-year deadline in section 110 only forthose areas

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originally designated nonattainment in 1977. The commenter thus felt that any

areas designated nonattainment at later dates would still be subject to Part D but would have to attain as expeditously as practicable, but in no case later than 3
years, as required by section 110. This argument ignores the plain language of section 172(a)(1) which establishes the alternative Part D deadlines for "each such area" subject to Part D.The
commenter did not provide further legal support for its interpretation.

Another commenter supporting this position pointed out that section 110 sets the general rule, i.e., the 3-year deadline, while Part D merely establishes an exception to the rule for certain areas. Since the exception would not make

sense as applied to areas not in attainment ofa new orrevised NAAQS after 1982, the general rule of section 110 would necessarily apply. Again, this argument ignores the clear sense of section 172(a)(1) that the 1982 deadline apply to all areas subject to Part D.

A different commenter suggested resolving the attainment deadline issue by acknowledging that the 1982 deadline would apply to all areas subject to Part D, but giving the States the opportunity
to demonstrate under section 110(a)(2)(H)(i) that more time would be needed to complete additional planning necessary to attain the revised standard. The commenter suggested that ifEPA found the demonstration adequate, it could hold the section 110(a)(2)(I) construction ban in abeyance. This may be possible in practice, but EPA believes it is not relevant to the statutory construction ofPart D. Congress required in section 110(a)(2)(1) that for all areas subject to Part D each SIP must provide fora ban that would apply unless the SIP provides for meeting all ofthe requirements ofPart D, which necessarily includes the Part D 1982 attainment deadline. Given this, Congress would not have intended Part D to apply to areas that could not possibly plan to meet the 1982 attainment date because a revised NAAQS imposes significant new planning burdens after that date. As a policy matter, one commenter noted that failure to apply Part D to the revised PMo standard would produce the undesirable result that implementation of the revised standard for particulate matter would proceed under weaker substantive provisions than the original TSP standard, which

was one of the standards Congress clearly intended to be subject to the strict Part D requirements. This result would occur, but is not necessarily undesirable in light of the significant 

### new planning burdens imposed upon States to demonstrate attainment ofthe revised PMo standard. PartDis clearly

aremedial provision and should not apply to a new or revised standard that imposes significant additional planning burdens which States have never previously addressed. This is so even if the standard applies to a pollutant which hadpreviously been subject to a different standard for which States had failedto plan adequately.

Commenters alsoreasoned thatEPA shoulduse an integrated approach because ofbenefical program results, such as continuation ofexisting Part D SIP's and sanctions and alleviation of the need to determine which revisions impose additional planning burdens. Whether or not EPA would like to see these results, they do notprovide a different basis for determining statutory applicability where EPA can do so based upon the statutory language and legislative intent.

One commenter claimed that EPA's past practice did not support its current position. The commenter pointed out that although EPA did apply Part Dto the 1979 ozone relaxation, it did not then indicate thatPart Dwould not have applied ifthe revision had imposed significant new planning burdens. This is true, but EPAhad no reason to do so because Part Ddid in fact apply in that instance. The commenter similarly found no precedent in the case ofEPA's 1978 statements that PartDdid not apply to the lead NAAQS because it

was an entirely new,as opposed to a revised, standard. Presumably, the commenter felt that areas which had failed to plan adequately to demonstrate attainment ofthe original particulate matter NAAQS should notbe relieved of the strictPart Drequirements in implementing the revised NAAQS for particulate matter. The EPA, however, believes that a revised NAAQS which imposes significant new planning burdens is similar to a new NAAQS in thatit imposes burdens on the States which they were not subject to prior to the revision and which they consequently should notbe penalized forfailing tohave completed.

This same commenter also noted that many areas which Congress subjected to PartD in 1977 had not submitted SIP's prior to1977 and thus had full planning burdens ahead ofthem. This may be so, but the relevant factis that those planning burdens were originally imposed in the 1972 Act. Whether ornot given areas had complied with previous planning duties, Congress created Part D in 1977 to encourage areas thateither failed toplan at all orplanned poorly to promptly complete the planning
necessary to show attainment of the standards that should have been attained years earlier.

This commenter also pointed to the

sum of congressional action since 1967 in which Congress reacted to State's planning failures by granting more time but only while imposing specific additional requirements. This line of reasoning is inapplicable to NAAQS revisions which impose significant new planning burdens because States that have had no previous opportunities to meet new planning burdens can hardly be said to have failed to do so.

One commenter argued thatEPA should apply Part D merely because implementation under section 110 has produced little progress toward attainment. Whether this is true ornot, it does not provide a legal basis for applying Part Drather than section 110.

This same commenter pointed to EPA's policy for newly designated nonattainment areas, indicating that there EPA applied Part D but substituted alternative dates for the 1979 SIP submittal and 1982 attainment dates where these dates had passed prior to discovery ofa nonattainment problem. In that case, EPA was faced with a situation where Part D appeared to clearly apply. The EPA attempted to fashion a reasonable approach for applying Part D to areas found to be in nonattainment after the normal Part D deadlines had passed. There, EPA attempted to effectuate congressional intent as closely as possible by honoring the spirit ofthe statute since the literal language did not fit the situation. The EPA's actions in that context are not relevant to a statutory interpretation of the proper applicability ofPart D to new

or revised NAAQS.

In addition, EPA notes that the court in BethlehemSteel Corp.v.EPA, supra, held that EPA could not redesignate newly found nonattainment areas so as to bring them under Part D and apply the above-described schedule in the absence ofa State request.The Court relied heavily on the onerous nature of Part D and its conviction that EPA should thus not unilaterally create analogies toPart D and apply them to

areas not clearly subjected to Part D by Congress. This line ofreasoning would apply equally to areas subject torevised standards imposing significant new planning burdens, and consequently supports EPA's statutory interpretation that Part D does not apply to such areas. 

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B. Comments on Use oftheProbability Guideline

Because ofa lack ofPMo data, EPA proposed to use statistical probabilities
to estimate PMo concentrations from the relatively abundant TSPdata. The EPA calculated this relationship by relating available PM1oand Inhalable Particulate (III) monitoring data to collocated TSPmonitors. As discussed earlier, procedures for using statistical probabilities in the absence ofambient PMo data were explained in the probability guideline (EPA 450/4-86- 017).

Commenters were concerned with the concept ofthe guideline as well as technical problems with the guideline. First, they felt thatEPA should base its SIP development program on actual ambient air quality data, not probability estimates. To do this, the commenters stated, EPA should allow sufficient time
to obtain adequate data on the new standards, identify problem areas, and develop and submit necessary revisions
to SIPcontrol strategies. Second,there

were several comments of a technical
nature. The commenters were concerned about many issues, among them the use of anational probability distribution instead ofregional and seasonal distributions, and the use ofPMo/IP ratios instead ofPMo/TSP distribution ratios.

In response to the first comment, when EPA promulgates a new orrevised standard, the Actrequires the States to develop a SIP within 9 months to show attainment of the standard. This schedule presents a problem because

some areas do not yet have sufficient PMo air quality data to determine their attainment status. However, TSP air quality data is readily available and, together with available PMo data, a reasonable probability of the attainment
status ofthe area may be determined. Thus, the likelihood that any given area will or will not attain the PMo NAAQS

can be determined by using the available TSP and PMo data as explained in the probability guideline. The EPA is using its estimate ofthe probable attainment status ofan area in conservative manner by requiring only

areas with at least 95 percent probability ofnonattainment to submit full SIP's within 9 months. Areas with less than 95 percent probability have additional time tocollect PMio data and determine their attainment status prior
to submission offull SIP's.

In response to the second group of
comments on the probability guideline, EPA has made several technical revisions in the guideline. A number of
comments dealing with the basis for the 

### distribution were anticipated and resolved through an evaluation and refinement ofthe procedure conducted concurrently with the publicreview period. Theresults ofthis study are described in a report, An Examination of1982-1983 Particulate Matter Ratios and Their Use In The Examination of PMo NAAQS Attainment Status (EPA450/4-85--010) which is in Docket No. A82-38.m The report reexamines the 

### seasonal and regional specific ratio issues and supports the useof a national distribution. As a result ofthis study and the public comments, the guideline, including the probability curves, has been revised. The curves are now based

on onlyelevated TSPand PMo data collected concurrently in1982 and 1983. The recommended procedure no longer relies on a single conversion factor between IP and PMo.A distribution has been prepared forPMo/IP data. Also theguideline was clarified in several

areas to address comments that were prompted by misinterpretation ofits instructions. The guideline has been updated justprior to promulgation to incorporate charts for the specific level of the NAAQS, thus simplifying the computations somewhat. Acomputer program is available to help accomplish the computations. Adetailed response to thetechnical comments on the Guideline and the corresponding revisions have beenplaced in Docket No A-82-38.
C.Comments onthe SIPDevelopment Policy

1. Area Grouping Policy



### TheEPA proposed the same SIP development policy described in section IV(c) above with one exception. The EPAproposed to use PMo and PM5 data where available to determine when

a control strategy demonstration is needed. Where sufficient PMo data are not available, EPA willuse TSPdata and the probability guideline to classify

areas into GroupI,II, or III. Group I

areas are required to submit a complete SIPwithin 9months that provides for attainment ofthe NAAQS. For Group II
areas, a State would submit a "committal" SIPwhich need not contain

a full demonstration ofattainment and maintenance. The "committal" SIP would pledge the State togather ambient PModata, analyze and verify the data, and develop an adequate SIP where nonattainment is shown.The EPA proposed to allow up to 18 months from approval ofthe committal SIP to collect and analyze PMo data.The EPA's final policy is to allow up to 37 months from today to collect and analyze PMo data. Ifa State notifies EPA, during that time, that they have found a violation ofthe PMo standard in

a Group IIarea, the State has 6months thereafter inwhich to develop and submit a control strategy to EPA. The strategy must then show attainment as expeditiously as practicable but no later than 3years from the EPA's initial approval ofthe committal SIP as required by the Statute.The EPA will
presume that the existing SIP in Group III areas (less than 20 percent probability ofnonattainment) is adequate to maintain the standards.

Industrial and governmental organizations that commented felt the SIPdevelopment policy shouldbe based

on PMo air quality data and not on probability estimates based on TSP data. The commenters recommended several paths to achieve this end. The paths basically would result inEPA allowing States time to develop a PMo data base before requiring a control strategy. Commenters suggested this could be done in avariety ofways, such

as postponing the effective date ofthe PMo NAAQS or classifying all high nonattainment probability areas as Group IIfor committal SIP's. Commenters also felt an area might be moved from one group to another without a thorough evaluation ofthe data. They wanted detailed guidance'on how EPAwould consider such issues as unusual events, poor quality control, and installation ofrecent additional controls in an area after the air quality

was measured.

The environmental groups generally felt that EPA should follow the letter of the law and require complete plans for all areas within 9 months of promulgation. Even though EPA states that Group II areas are to attain the NAAQS within 3 years ofapproval of the committal SIP, such areas are not required to submit a full control strategy for EPA approval until 3years after promulgation. The environmental groups contend that even if such a schedule is adhered to, it is very unlikely that a complete control strategy will be implemented within 1year of submittal
to EPA.

Many PM1omonitoring sites have been put into operation since the notice ofproposed rulemaking was published April 2, 1985. It is EPA's policy to use valid PMo data to determine the attainment status ofan area in preference to TSP-based probabilities. However, 3 years ofPMo data are required to demonstrate attainment in accordance withAppendix K of40 CFR Part 50. Accordingly, EPA developed statistical relationships between TSP and PMo data, reviewed and confirmed 

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the validity ofthose relationships and thus feelsjustified in using those relationships, where sufficient PMo data

are not available, topredict PMo attainment status. After a preliminary

area classification based on 1983-1985 

### TSP data, the EPAwill consult with State and local agencies to evaluate available PMo data and consider other factors affecting the air quality data and theexisting SIP.Thus, EPAbelieves that the State and local agencies willhave adequate opportunity to discuss issues which might determine the final grouping ofan area. The EPA's policy is

to require only areas with high 

### probability (>95 percent) ofviolating the PMo NAAQS to immediately begin 

### developing a SIP. Other areas willbe allowed up to 3years from promulgation
to collect additional air quality data and determine theirattainment status.The amount ofemission reduction required foran area is notbased entirely upon air quality measurements exceeding the NAAQS. TheEPA also requires an 

### examination ofallowable emissions, meteorological conditions, and the use ofproportional models to demonstrate 

### that air quality will beprotected under the worst conditions.

Regarding the concern of environmental groups, EPAproposed to allow up to 18 months for air quality monitoring following approval of a committal SIP. Since a State can take 9 months to submit a SIPand EPA may take 6months to approve it,a State would not berequired to notify EPAof the adequacy ofthe existing SIP forup to 33 months after promulgation. This notification date would be even later if the date ofSIP approval slipped. Therefore, EPA has decided to set the latest date fornotifying the Agency of the adequacy of theexisting SIPat 37 months from promulgation. This schedule allows 3years of air quality data to be collected, yetit sets a firm date for declaring the attainment status of an area. The final date ofdeclaration may be 4months later than originally proposed orseveral months earlier ifSIP approval is delayed.The EPArealizes that it may be difficult to implement a SIPand attain the NAAQS within 3 years after approval ofthe committal SIP. However,EPA believes that the
worst nonattainment situations can be identified quickly, and the States would not need the entire 37 months to collect data. To assist the States, EPA has supplied themwith several hundred PMo samplers. These samplers have been deployed in areas ofhigh probability ofnonattainment on a priority basis. In addition, EPA monitoring regulations (40 CFR Part 58) require every other day sampling in Group II areas in order to expeditiously confirm their attainment status. Thus,
any significant problems with attaining the PMo standards should be found early. Areas requiring the entire 37 months ofmonitoring to determine their attainment status shouldbe very close
to the NAAQS and require only slight adjustments in the existing SIP to show attainment. Thus it should be possible to implement these minor changes inless than 1 year.
2. Fugitive DustPolicy

The Administrator proposed to continue the fugitive dust policy as it

was implemented in urban and rural

areas exceeding the TSPNAAQS." i Reaction to the proposal to continue the existing fugitive dust policy was received from many industrial groups, environmental groups, and State and local agencies. Comments ranged from suggestions that the policy be expanded
to opposition to continuing the existing policy.

The existing policy would place all Rural FugitiveDust Areas (RFDA's) in Group III for SIP development. The EPA hasdeveloped three alternatives to that policy. The first alternative would place RFDA'sin Group 1, 11, orIII basedupon the area's probability ofnot attaining the annual or 24-hour PM,o NAAQS. The second alternative would place RFDA's in Group II orIIIbased upon the area's probability ofnot attaining annual or24- hour PMo NAAQS. The third alternative would place RFDA's in Group II or III based only on the area's probability of
not attaining the annual PMo NAAQS. These alternatives are discussed in

more detail in EPA's proposal, published elsewhere in today'sFederal Register.

Until EPA issues a revised policy, it is continuing the existing rural fugitive dust policy. To do otherwise would require States to expend resources to develop what may turn out to be
unnecessary SIP's.

3.Emissions Trading (Bubble) Policy

It was noted in the proposal notice that past emission trade agreements
cannot interfere with a State's efforts to attain and maintain the revised NAAQS. Sources were warned in the initial bubble policy published on December 11, 1979 (44 FR 71780), that ifEPA revised the TSPNAAQS to a PM10 NAAQS some alternative approaches initially approved by EPA might no longer be adequate to protect the PMo NAAQS. On this basis, States were advised in the proposal notice to consider bubbles approved prior to development ofPM,o SIP's as any other existing SIPprovision and therefore subject to revision.

The recently published final Emissions Trading Policy Statement Technical Issues Document confirms that ifambient violations ofany standard are discovered in an area where EPA has approved a trade,

sources inthe trade could potentially be subject to requirements for additional emission reductions just as all other

sources in the area [see 51 FR 43814, 48847 (December4, 1986)].

Commenters stated that revisions of the TSP NAAQS should not automatically trigger reconsideration of bubble plans, especially in Group II and III areas. They alleged that control techniques applied in bubbles to meet the TSP standard are likely to be the

same techniques that would be used to meet a PMo NAAQS, and itwas therefore unnecessary to reopen bubble plans to ensure attainment ofthe revised standard. Also, one commenter thought itwould be inequitable for EPA
toreopen an agreement with a source after the source has invested incontrols.

It is notEPA's intent to automatically
reopen all emission trading plans. The EPAmerely intended tomake three points in the notice ofproposed rulemaking:

(1)Bubble agreements cannot interfere with a State's efforts to attain and maintain the revised NAAQS;

(2) States should consider bubbles that were approved afterpublication of the policy but priorto development of PMo SIP's as any other existing SIP provision; and

(3) Sources were warned in the initial bubble policy published on December 11, 1979, thatEPA was considering revising its particulate matter NAAQS and that some bubbles initially approved by EPA might no longer be adequate under the revised NAAQS.

For example, a process source emits 100 tpy ofPMo. Instead ofcontrolling the process source, emissions from a

source of fugitive dust were reduced 100 tpy in order to attain the TSP standard. If only half ofthe fugitive dust (i.e. 50 tpy) was PMo it may be necessary for the State to require some portion ofthe 100 tpy ofPMo from the process source to be controlled in orderto attain the revised PM1oNAAQS.

D.PreventionofSignificant Deterioration/New SourceReview Program

In his April 2, 1985, proposal, the Administrator announced that the proposed revisions to the NAAQS for particulate matter would potentially affect six existing sets of 

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preconstruction review requirements contained in Parts 51 and 52 and would, in turn, lead to substantial revisions to existing SIPprocedures for PSD and nonattainment NSR (PSD/NSR). Because ofsome uncertainties as to which implementation pathways would apply to the revised primary and secondary NAAQS, the program proposal included several alternative approaches to account for the different
outcomes possible. Many comments

were received on this part of the proposal, describing support of specific implementation pathways and the resulting PSD/NSR requirements. This section presents a review ofthe relevant portions ofthe original proposal, the comments, and EPA's responses.
1. Revised Prevention of Significant Deterioration Program for Particulate Matter

a.EffectiveDateofthePart 52 Federal Preventionof Significant Deterioration Regulations.In the proposal, the Administrator announced his inclination tomake the changes to the Part 52 PSD regulations effective immediately upon promulgation ofthe revised PMo standards. The intended effect ofsuch an outcome was thatEPA and presumably State and local agencies who had been delegated the Administrator's PSD authority wouldbe required to begin immediately to implement the new PSD requirements for PMo on the effective date ofthe PM1oNAAQS, even though States with EPA-approved PSD SIP's would have an additional 9 months to adopt new PSD rules for PMo and submit them for EPA approval.

While expressing his inclination to require immediately effective Federal PSD amendments for PMo, the Administrator acknowledged some potential problems concerning the legal ability ofdelegated agencies toproceed with their implementation ofthe PMo requirements under section 52.21. First, it was known that the delegation agreement between EPA and the State

orlocal agency in some cases did not require that the delegatee implement

new requirements based on future standards or amended procedures. Second, some PSD delegations could onlybe implemented after equivalent PSD requirements were enacted into law
at the State or local level (although not submitted toEPA as part ofan approved SIP). Consequently, even with an adequate delegation agreement, some State orlocal programs might not be able to implement PMo requirements until their own PSD rules are appropriately changed. 

### For these reasons, the Administrator said hewould consider delaying the implementation ofthe PMo changes where EPAor its delegatees had PSD permitting responsibility. To assist in this consideration, he solicited comments on the merit ofdelaying the effective date ofthe Part52 regulations and asked whether an immediate conversion to PMo was necessary to provide adequate environmental protection for particulate matter.

Most commenters expressed their support for EPAto delay its implementation ofthe PMo amendments under the Part52 PSD regulations until all States are required to have approved PM0 

### preconstruction review procedures in their SIP's.However, the reasons given typically did notrelate to problems associated with delegation agreements orother potential legal problems that might occur duringthe transition period.

Several commenters indicated that a delay would be desirable because it would result in a uniform implementation scheme that would keep the PSD permittingrequirements essentially the same in all States. In this way, thecommenters noted, Congress' original concern about possible interstate competition from new industry would generally be eliminated. Some commenters stated that thedelay would give EPAand the Statestime to work out any technical difficulties with the new rules before they become effective. Two commenters felt that the delay would allow additional time to expand the data base fordeveloping PMo emission factors. One commenter stated simply that thedelay would result in less complication and confusion.

Concerning potential legal problems,

oneairpollution control agency favored

a delay in the new PMorequirements in order to provide additional timeto resolve anyregulatory orstatutory problems in making the transition from TSPto PMo.However, the agency commenting did not specify whether it would experience any such problems. Onthe other hand, another airpollution control agency fully supported EPA's immediate implementation ofthePMo amendments because such action on EPA's partwould enable agencies desiring full PSD delegation to make their request as soon after promulgation

as they are able.

A number of the commenters who supported EPA's delay ofthe PMo requirements added that a continuation ofthe existing requirements for a TSP review under the PSD program would provide adequate interim protection for the particulate matter NAAQS. This was
a key concern to EPAwhen the possibility ofa PMo program delay was originally announced. The EPA generally believes that its continued implementation ofa TSPreview under the PSD program would have been acceptable as long as such review provided forprotection ofthe TSP NAAQS. However, EPA failed to adequately consider the fact that on the effective date ofthe revised NAAQS for particulate matter, the previously effective TSPNAAQS will no longer exist and consequently EPA will notbe able torequire PSD applicants to demonstrate that their proposed emission increases will not violate the withdrawn TSPNAAQS. ThePSD regulations at 40CFR 52.21(k) require PSD sources to demonstrate that their emissions will not cause orcontribute to air pollution in violation of"[any national ambient air quality standard.

•
. ."At any time, the applicable NAAQS encompassed by this PSD provision are those standards which are independently defined under 40CFR Part50. Moreover, theeffective dates of the NAAQS are independently established when the standards are promulgated and are clearly not affected by the status ofany amendment to the PSD program.

IfEPAdoes not amend thePart 52 PSD regulations as ofthe effective date ofthe revised NAAQS for particulate matter,PMo willbe subject to PSD review but EPA's PSDprocedure would be devoid of thevarious PMo thresholds (for source applicability, ambient monitoring, and significant ambient impact) and transition provisions which

are necessary to determine when and to what extent a PMo review is to be required. Thus, given thefact that PMo NAAQS become effective 30days from promulgation, as published elsewhere in today's Federal Register, EPA believes that it would notbe appropriate to consider a delay beyond theeffective date ofthe PM 1

### oNAAQS in its implementation ofthePMo amendments to the Part 52PSD regulations.

b.SourceApplicability.The Administrator proposed a new emission rate within section 52.21 (b)(23)(i) that would define "significant" forPM~o. The

new rate would be used to determine when PMo emissions (asopposed to particulate matter emissions which relate toTSP) would require PSD review. Anemission rate lower thah the

new significant emission rate would allow a source to be excluded from PSD review, with respect to PMo, on the grounds that such lower emissions would be insignificant, i.e., de minimis.

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In the proposal, the Administrator set the significant emission rate forPM1 0 

### at 15 tpy. He explained that the approach used to derive this value was based on the methodology used to set the original particulate matter significance level promulgated on August 7,1980 (45FR 52676). Basically, this approach used an emission rate forwhich themodeled ambient concentration represented approximately 4 percent ofthe 24-hour primary standard. TheAdministrator also announced in the proposal that two additional points needed to be considered duringthe final selection process for thePMo significant emission
rate.

First,the proposed value of15 tpy assumed that the 24-hourprimary standard for PMo would be set at 150 Lg/m 3



### .Second, EPAwas in the process ofstudying the potential effects of alternative significance levels in terms oftheir environmental benefits versus administrative burden. The study was completed afterthe publication ofthe proposal notice,but was placed in the rulemaking docket approximately 30 days laterforpublic inspection. The Administrator statedhis intention to take into consideration the results ofthe study and all relevant comments pertaining to it.

Seven commenters expressed opposition to theproposed 15 tpy significant emission rate forPM 1

### o,while three commenters conditionally supported it. Ofthose in opposition, five commenters sought a higher emission rate and two expressed their concern that proposing any significance level at this time ispremature.

Two ofthe opposing commenters

were particularly concerned about the effect ofa 15-tpy significant emission rate on surface mining activities. One stated that while it did not object to establishing a significance level for PM,o, use ofthe proposed 15 tpy rate wouldbe completely inappropriate for determining major modifications at surface mines ifsuch facilities are made subject to thePSD program. This commenter noted that even a minor extension ofa haul roadat a large surface mine could increase emissions

more than 15 tpy. The commenter argued that such activity should not be considered a major modification which would subject an existing coal mine to PSD review.

The EPA doesnot believe that special consideration ofthe effects on surface mining activities orany other specific category of source should generally

serve as the basis forselecting the significant emission rate forPM,o emissions.The significance values provide a categorical exemption from the PSD preconstruction review requirements based on the deminimis
nature oftheprescribed emission rate with respect to itspotential contribution to the 24-hourprimary NAAQS, regardless ofthe specific emitter ofthe pollutant.

In addition, the Administrator found that the commenter's position indicating that many surface mines would be adversely affected by a 15 tpy PM~o threshold in particular is not totally
correct. Minor extensions ofhaul roads,

as are typically made during the course of carrying outthe mining operation, would not generally be considered modifications forPSD purposes as long

as such activity would already be allowed under the permit granted to the

source. Even ifthis were not the case, the extension ofa haul road could easily result in emissions which would exceed any oftheemission rates that EPA considered for developing a PMo threshold.

At the present time, however, the fugitive emissions from surface coal mines are generallynot included in the determination ofwhether such source is major for the purposes ofPSD [see e.g., 52.21(i)(4](vii)] and consequently the 15 

### tpy significance threshold would generally not apply to theirPMo emissions. The EPA is considering, under separate rulemaking, whether it is appropriate to extend the requirements forinclusion offugitive emissions to surface coal mines (45FR 43215, 

### October 26, 1984). TheEPA believes that the commenter's concerns would be

more appropriately addressed under that rulemaking action.

Several of thecommenters stated that EPA should set the significant emission rate forPMo at a level higher than 15 tpy and gave a variety ofreasons for this conclusion. First,two ofthe commenters said that the 24-hour standard canbe significantly higher than 150 Ig/m s

,i.e., 250pg/ m, and still 

### protect publichealth with an adequate margin ofsafety. This comment has

more to do with the level selected for the 24-hour NAAQS than with the significant emission rate forPMo. Having promulgated a 24-hour standard of150jg/m 3



### ,the Administrator finds no specific argument from the commenters that the proposed significance threshold should notbe 15 tpy.

Second, a commenter claimed that the proposed significance value was based

on very conservative modeling. Thus, the commenter reasoned that the significance rate could be raised without causing any significant real-world impacts on air quality. The Administrator wishes to point outthat the techniques usedto derive the selected value followed EPA guidance, using procedures and assumptions

common to air quality impact analyses. Such techniques couldbe used by

sources as well to calculate their own ambient impact. The commenter provided no demonstrations to support the allegation that the modeling techniques which EPAused were not appropriate for selecting the PMlo significant emission rate.

Third, a commenter used EPA's study ofalternative significance levels to conclude that EPA had nojustification for selecting a significant emission rate for PMo below 20 tpy. The commenter's conclusion was based on a study finding that, regardless ofthe PMo significance level considered, up to 25 tpy, approximately 90 percent ofall PMo emission increases would be subject to PSD review. The commenter stated that "thousands ofdollars" in annual costs
toprepare and review applications with respect toPMo would be saved by using

a significance level of20 tpy rather than 15 tpy. The Administrator acknowledges that, according to the study, the additional PMo reviews required under

a 15 tpy significance level would not add appreciably to total PM 1oemissions brought under PSD review. The Administrator, however, is unable to conclude that the additional number of reviews estimated toresult from selection ofa 15 tpy significance level would cause an administrative burden worthy ofconsideration for special relief. The court inAlabamaPower stated that EPA's authority to exempt sources-from PSD review "is narrow in reach and tightly bounded by the need
to show that the situation is genuinely de minimis or one ofadministrative necessity" [Alabama Power Company v. Costle, 636 F.2d 323, 361 (D.C. Cir. 1979)]. In keeping with the previous approach for setting de minimis cutoffs, a source capable ofconsuming almost 5percent of the primary 24-hour NAAQS is not insignificant, and EPAdid not find a compelling need foran exemption by

reason ofadministrative necessity.

One commenter, in an apparent misunderstanding ofEPA's approach for selecting a significant emission rate, disagreed with "EPA's modeled calculations of25 tpy ofTSP and 15 tpy ofPMo to define 'significant' emissions." This commenter stated that the emission
rate for TSP and PMo "should both be the same for most efficient combustion sources." The commenter's finding that

an efficiently operated combustion

source would have TSP emissions comprised almost entirely ofPM1o size particles has no bearing on the process of selecting a significant emission rate 24695

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forPMo which may differfrom the rate forTSP. The significant emission rates for PMio and TSPare based on the relationship-of a selected amount of emissions to theresultingimodeled. ambient concentrations from such level ofemissions. These ambient concentrations are then compared to the appropriate primary 24-hour NAAQS to determine whether the emission rate is, significant.

Of the three commenters who conditionally supported the proposed significance level, two stated that,if EPA setsthe primary PM 10 

### standard higher than 150-pg/m3, EPA shouldraise the significance-level by a proportionate amount. The third supportive commenter agreed with.the 15-tpy 

### emission rate as, long as EPA did not eliminate the 25 tpy significance-level for-TSP. IfEPA were, to abandon the TSPstandards altogether, thecommenter suggested thatEPA shouldreevaluate the 15 tpy level in order to provide,continued and equivalent ambient air quality protection. As. with previouscommenters, the Administratorfinds no argumenthere concerning-the 15 tpy significance level based-on.the fact that: (1) He is today promulgating a 24-hour PM 10 

### NAAQS of 150pjg/m s 

### in an accompanying final notice in today's Federal Register and (2] the existing significance level for TSPis,being retained.

Finally, the two commenters who felt that the proposal.ofa-significantemission rate forPM 10 

### was-premature claimed that the technology,for accurately-predicting PM 1

### oemissions from a-.s6urce does not yet exist. One stated in particular thatifEPA cannot promulgate areference method as part of the implementation package, thensources shouldbe.allowed'to use the existing significance level-of25 tpy in making applicability determinations with.the existing.reference method for particulate matter emissions..The EPA acknowledges that a reference method forPMo. source testing does.not'yet exist.Nevertheless, the Agency has developed and used PMo. source test protocols to collect data from a number ofsource categories to develop PM emission factors.The EPA believes that this data is ofgood quality and can be used,to determine.potential PMo emissions tQbe compared against the

new PM 10 

### significant emission rate. The EPA will continue to develop and update PM 10 

### emission factors as additional.test-data become available. The EPAbelieves.that-sufficient information is already,available-to estimate the level ofPMio emissions from;many,sources that.will come under PSD/NSR. However; when it is not feasible to estimate the amount ofPM, emissions from a particular source, then it would be appropriate to proceed only'

on the basis ofparticulate matter emissions (TSP).

c. Prevention. ofSignificant Deterioration Geographic Applicability. Because of the uncertainty as to whether section 110 or Part Dwould apply to the revisions being.proposed, the Administrator described various alternatives as to how the PSD requirements with.respect to particulate.
matter would apply-based on the geographic location ofthe proposed

source. In turn, commenters based their responses on certain assumptions and opinions as to which legal pathway would apply. In lightof the fact that the Administrator has concluded that only section 110 shouldbe used to implement both the primary and secondary NAAQS, this section will address only those portions ofthe proposal which pertained to thatparticular setof alternatives. The issue ofwhether ornot commenters agreed with the Administrator's selection ofthe section 110 implementation approach was addressed in an earlier partofthis preamble.

Under the section 110 pathway for implementing the,proposed-PMmo primary NAAQS, EPA anticipated that PMo preconstruction review-would be covered under thePSD requirements in all locations. The proposal explained that this result would occur because States wouldnot be required to designate PMo nonattainment areas pursuant to section 107 of the Act. Inthe absence ofPM10 

### area designations, PSD would apply to PM1

### osources in.any area designated as attainment or unclassifiable pursuant to section 107 for any pollutant unless the area was nonattainment for allpollutants having section 107 designations.2 2

### There are, at.

22Ifa proposed source or-modification qualifies

as major,its existing orprospective location must be in aPSD area inorder foraPSD review to apply. APSD area is one designated asattainment or unclassifiable under section 107 for anypollutant forwhich aNAAQS exists,regardless of.what pollutant emissions cause the source to be major. Ih general, once it is determined that a proposed major

source ormajor modification would occur in aPSD
area, the PSDreview applies.to significant emissions increases ofeach regulated air pollutant unless the area is designated.nonattainment under section 107 forthat pollutant.In the case ofa pollutant-not subject to the section 107 area designation process (e.g., lead, PM,.),PSD would not apply onlywhen the area is designated nonattainment forall pollutants subjectto section 107. 

### this time; no-such-pervasive nonattainment situations to be found in the nation.

The proposal also-discussed the possibility that-the Administrator.would make the secondary NAAQS equivalent
to the primary NAAQS in all respects, includingparticle size. If'this were to
occur,.the proposal noted that under a section 110 implementation pathway for the secondary NAAQS, geographic applicability would be the same as the
program outlined for the PMo primary NAAQS.

Some commenters disagreed with EPA's assertion that a section 110 implementation approach precludes the

use of section 107 area.designations with respect to-the revised NAAQS for particulate matter. These commenters, while divided overwhich indicator to

use with.the term "particulate matter," claimed that there is no authority in section 107 for States to completely

remove the area designations for particulate matter. Moreover, the
commenters disagreed with EPA's conclusion that the term "national ambient air quality standards" in section 107(d)(1) must mean only the NAAQS in effect in 1977'even ifthat is the accepted meaning ofthe same phrase in section 171(2).

The Administrator interprets section 107(d)(1) of.the Act to require States to list those air-quality control regions which, "on the date ofenactment of'the Clean Air ActAmendments of1977," do

or do not comply with the NAAQS in. existence on that date.In turn, the Administrator believes that section 107(d)(5) provides for States to revise the originallist from time to time to reflect changes in air-quality relative to those.NAAQS in existence in 1977. If Congress meant-for the section 107(d)(5)' revision process to include new section 107 area designations for new NAAQS,

or for revised NAAQS which would
create significant new planning burdens, then it would follow that Congress also intended for Part D requirements to apply in areas newly designated as nonattainment for such pollutants after the December 31, 1982, statutory deadline-for demonstrating attainmenteven though the affected area had no opportunity to complete newly imposed planning burdens and to demonstrate attainment within the statutory timeframe. The Administrator does notbelieve that:Cbngress intended this
outcome. Similarly, it would make no

sense to continue to maintain a list indicating ongoing compliance status relative to a.level.or form ofthe standard that no longer exists.

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The Administrator has concluded, therefore, that the use ofa section 110 implementation pathway-applying to a

new NAAQS orrevised NAAQS involving significant new planning burdens-does preclude the use of section 107 area designations. The term "national ambient air quality standards" in section 107 was intended by Congress
to mean only the NAAQS in effect in 1977, orrevisions to such NAAQS which would not impose any significant new planning burdens and would therefore continue to be subject to Part D ofthe Act. The section 107 area designations for TSP are being retained for the interim,however, in order to support the continued applicability ofthe section 163 increments for "particulate matter," which the Administrator believes Congress intended to beTSP-based increments. As explained earlier in this preamble, these TSPdesignations will continue to apply until EPA completes rulemaking to establish PMo increments and such increments become effective in accordance with section 166 ofthe Act.

One ofthe commenters who supported continuation ofthe section 107 area designations forparticulate matter, citingAlabamaPowerat 361- 363, alleged that the areas originally identified as unclassifiable or attainment under section 107(d)(9) (D) and (E), respectively, remain PSD areas subject to section 163 increments regardless ofany future change in their section 107(d) area designation status. The Administrator does not find anything within theAlabamaPower decision to support the commenter's conclusion. Section 107(d)(5) provides States with the authority to "from time
to time review, and as appropriate revise and resubmit" the area designations as originally promulgated by the Administrator. Ifgeographic applicability for PSD (and nonattainment NSR) was to be permanently affixed to the original area designations, then there would be little

reason to revise the designations. The EPA policy to date has always allowed States to revise their section 107 area designations as appropriate and to base PSD/NSR geographic applicability on the most current designations. In the

case ofPM~o, however, the Administrator has already stated his position that the section 107 area designation process does not apply, and the existing designations for particulate
matter apply only with respect to TSP.

Several commenters stated that although they agreed thatPSD may apply everywhere forPMio as the primary standard, EPA's approach of using TSP for the secondary standard could prevent the desired "PSD everywhere" approach because a section 107 nonattainment designation for TSPwould prevent anyPSD review for particulate matter in those nonattainment areas. One commenter in particular stated that EPA's proposal glosses overthis difficulty, and EPA could not achieve the result it wants without also changing its position that the PMo standards arerevisions ofthe existing particulate matter NAAQS rather than new NAAQS.

Even though EPA decided not to retain the TSP indicator for the secondary NAAQS, the commenters' main concern focused on the alleged problems that would result from EPA's retention of the section 107 area designations for TSP.For the reasons already given, the Administrator does
not agree that the section 107 area designation process applies to the PMo NAAQS and thus a section 107 nonattainment designation forTSP would not prevent PSD review for the PMo indicator. Instead, a nonattainment designation forparticulate matter will only affect which preconstruction review requirements will apply with respect to the TSPindicator. In addition, the Administrator does notbelieve that it is necessary to consider the PM~o NAAQS as new NAAQS-rather than revisions to the existing standards-to independently address PMo as a form of particulate matter. The Administrator believes instead,that it is possible to regulate two forms of the pollutant particulate matter through the establishment ofdifferent indicators and regard each as being a separate pollutant regulated under the Act. Thus, by establishing a new PMo indicator for the particulate NAAQS and retaining the existing TSPindicator for the section 163 increments as an interim measure, it is possible to have two regulated forms of particulate matter. In turn, it is appropriate to determine PSD applicability independently foreach regulated form.

Some commenters were concerned that an EPA interpretation requiring no section 107 area designations for PMo under a section 110 implementation pathway would pose a significant hurdle
to EPA's acceptance ofthe legal argument that section 110 should govern all PMlo SIP revisions. As described earlier in the preamble, EPA's position concerning the applicability ofsection 110 or Part D is based on whether a NAAQS revision would impose significant new planning burdens. The ultimate applicability of section 107 area designations was not a factor in arriving
at this conclusion. 

### d.BestAvailableControlTechnology (BACT).In the proposal. EPA stated that its proposed action to regulate PMio was not expected to immediately cause significant changes in the way that BACT determinations would bemade for particulate matter.This statement

was based on the beliefthat current control technology forparticulate matter appears to be effective forcontrolling both PMo and TSP.Meanwhile EPA further indicated that it would be in the process ofevaluating the effectiveness ofvarious existing NSPS for controlling PMo and, at a later date,would make any necessary adjustments in BACT policy.

In order tobegin implementing the BACT requirement forPMo, the Administrator proposed that as a matter ofpolicy he would accept emission limitations in terms ofeither PMo emissions orparticulate matter emissions provided the selected emission limitis enforceable and represents selection ofthe appropriate control technology for meeting BACT for PMo.The proposal explained that the alternative of aparticulate matter emission limit rather than a PMo emission limit to represent BACT for PMo might oftenbe more desirable initially for several reasons, including: (1)

### The continuing reliance on TSPbased SIP's until a comprehensive PM1

### o SIPcould be developed, (2) 

### the present lack ofa standard reference method to

ensure source compliance with a PM1

### o emission limitation, and (3)

### thefact that theNSPS were not likely to directly reflect PMo emissions for some time. Commenters generally supported EPA's proposed policy that, as an alternative
to expressing the BACT emission limitations in the PSD permit in terms of PM~o emissions, the permitting authority may instead express theemission limitations in terms ofparticulate matter emissions.

Several commenters urged, however, that such policy should be strictly interim and that emission limitations shouldbegin to be expressed interms of PMo emissions as soon as possible pending thedevelopment ofa reference methodfor measuring PMo emissions.

Sharing a similar concern, two other
commenters indicated that theproposed BACTpolicy forPMo shouldbe tightened with respect to allowing the

use ofparticulate matter emission limitations. One commenter pointed out that while EPA's proposal for BACT determinations appears to be the same
as its guidance on lowest achievable emission rate (LAER), they considered the BACT proposal to be farless protective. This conclusion was based 24697

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on the fact:that EPA's LAER proposal would allow,substitution ofparticulate matter'emission controls for PMto emissioncontrols only when the-latter

areunavailable-or completely unreliable, while the BACT proposal would allow similar substitutions at any time, whether they are necessary or not..

The othercommenter cautioned that EPA should permitparticulate matter emission substitution only-when PMo emission limitations are-not feasible, or when the applicant undertakes the responsibility fordemonstrating the continued effectiveness ofthe particulate matter emission limit for controlling PMio emissions. This
commenter explained that even slight variations in assumed-operating conditions could affect the PMlo/TSP relationship tremendously. Under worst

case parameters, the commenter claimed, a source could emit several times more PM1oemissions than anticipated while the particulate matter emission rate remained constant.

The Administrator agrees that,when PM 1oemissions would occur in significant amounts, BACT defined in
terms of.PMo emissions should be encouraged whenever possible. While the proposed policy was intended as an interim approach, the way that it was expressed would have allowed for the continued use ofparticulate-matter. emission limitations beyond the point that they were ofnecessity. Therefore,

as described in W.D. PSD/NSR Program, the Administrator has reformulated his BACT'policy to promote-the use ofPMo emission limits in most cases contingent

on the availability ofemission factors and.control efficiency information for the source under review. When it is not. feasible to quantify PMo emissions, EPA will-allow the use ofemission limits based onparticulate matter emissions

as a substitute.

Objecting to the proposed BACT policy, one commenter said that it would be arbitrary for EPA to require sources. subject to BACT for PMo to meet a TSP emission limit. Thelcommenter wasconcerned that a source may not need additional controls to meet.a PMo 

### emission limitation, yet.could be found in violation because it.exceeds the particulate.matter emission limit. The proposed policy was.not.an attempt to require a source subject to BACT for PMio to meet a particulate matter emission limit. Instead, it.was presumed. that there wouldbe a desirability or need to do.so during the.period when

source testmethods, SIP's, and NSPS,

were under development.with.respect to PM1o.The fact that.the Administrator has revised his-policy concerning the use ofTSP substitutions should alleviate



### some ofthe commenter's objections. However, when it should become necessary to define a source's emission limitations in terms ofparticulate matter emissions, source compliance must be based on the source's ability to continuously meet that particulate
matter emission limit.

Finally, a commenter disagreed with EPA's statement on the overall effectiveness ofcurrent particulate
matter technology for controlling both PMo emissions and particulate matter emissions. The commenter argued that, fromhis experience, significant changes

are required when handling high percentages ofPMo particles. The
commenter expressed doubt that a system handling particulate matter emissions successfully will also handle PMo emissions to-the same degree.

The Administrator appreciates the pointbeing made by this commenter and acknowledges that one should not arbitrarily assume that a particular control device or operating system will work equally well forboth particulate
matter emissions and PMio emissions. While the Administrator continues to believe that current particulate matter control technology has the effect of controlling both forms ofparticulate matter, he emphasizes that the reviewing agencies have the responsibility to evaluate each BACT situation carefully to determine which particular emission reduction system is
most appropriate for the source configuration under review.

e. National AmbientAirQuality Standards Analysis.Section 165(a)(3) of the Act provides that no PSD source can be approved for construction ifit would

cause orcontribute to ambient concentrations ofa pollutant that would. exceed the applicable NAAQS. 2 3 The Administrator proposed that, at a minimum, he would require that PSD

sources subject to the Part 52 PSD regulations and found to cause or contribute to a PMio NAAQS violation obtain sufficient PM 1oemission reductions (offsets) toprovide a net air quality benefit in the affected area. Such offsets would be considered to satisfy the "cause or contribute to" language under section 165(a)(3) ofthe Act (see

23 As explained earlierinthe preamble, the Administrator'sdetermination that section 110
governs the PM,o implementation requirements

means thatthe PSD program forPMo will apply in all locations regardless of how the existing air quality compares with-the PMlo NAAQS. Consequently, the PSD NAAQS analysis andall other applicable PSD requirements.will serve to determinethe approvability of a new ormodified PMosource seeking to constructin anarea where PMto NAAQS violations may alreadyexist. footnote 14,and accompanying text). In 

### addition, theAdministrator indicated that he was considering whether it might be necessary to impose additional conditions beyond offsets to adequately address nonattainment situations involving PMo. He solicited comments

as to what.additional requirements should be considered.

The commenters generally stated that EPA can implement, without any changes to its PSD rules, the requirement that in areas where the PM 0

### NAAQS would be exceeded a proposed source can make a showing that it will not cause or contribute to a NAAQS violation by offsetting its projected emissions. Infact, some commenters saidthat EPA has no authority torequire that PSD programs include LAER and statewide compliance requirements. The commenters claimed that the Stateshave a responsibility to submit a SIPwhich provides for attainment as required by section 110(a)(2)(A). Onlyifa State fails to satisfy this requirement does EPAhave any authority to impose additional requirements.

The EPA generally agrees with these. commenters. In.their initial PM1

### oSIP's, States will notbe required by EPA to impose LAER and statewide compliance provisions butneed onlyrequire that proposed sources and modifications demonstrate that their emissions will not cause or contribute to ambient concentrations in excess ofthe PMo NAAQS. In the event initial.PMo SIP's fail to provide for timely attainment and. maintenance ofthe PMio NAAQS, EPA will then investigate the need to impose: additional requirements onproposed

new sources.

Several commenters suggested that, since PSD offsets will become more

common under a section 110pathway,

some creditability criteria might be helpful in managing offsets under the PSD program. TheAdministrator agrees; hebelieves that creditability criteria are not only helpful but are necessary to determine the adequacy ofemission offsets obtained by PSD sources. In the proposal, the Administrator indicated that hewould approve a State's emission offset program under section 51.18(k) [recodified at 51.165(b)] onlyif creditability criteria at least as stringent

as the criteria set.forth under section 51.18(j) [recodified at-51.165(a)] are required to be applied to all offsets.. These.criteria-should alsobe applied to offsets obtained by a source under a StatePSD program (see footnote-15 and related discussion).

Where-EPA is implementing the PSD program under.its Part 52 PSD

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regulations and the applicant must obtain emission offsets with respect to a pollutant subject to PSD review, the Agency's general policy is not to be involved directly in approving emission offsets which would involve the modification ofpermits issued by State permitting authorities. Instead, EPA will require the owner or operator ofthe proposed source to obtain offsets (whether from another facility on the

same premises or from an external source) through the appropriate State or local new source review program before EPA can approve the proposed source under PSD. These offsets must meet EPA-approved creditability criteria which are equivalent to the criteria under section 51.165(a) and contained in the applicable SIP.

One commenter objected to the Administrator's proposal to require a

source that would cause orcontribute to

a PM 0 NAAQS violation to obtain sufficient offset so as to provide a "net air quality benefit" in the affected area. The commenter argued that this requirement is unlawful, and that a

source whose emissions have been offset one-for-one cannot be said to "cause orcontribute" to a NAAQS violation.

As explained in footnote 14, EPA has decided to restrict the use ofthe "net air quality benefit" test inconjunction with the offsets which EPA requires for
purposes ofPSD and section 51.165(b). Offsets producing air quality benefits would onlybe required in areas already experiencing violations ofthe PM 1o standard where the State does not have

an approved attainment demonstration. The EPA does not agree with the commenter's conclusion that one-for-one offsets will always satisfy the "cause or contribute to" criterion with respect to NAAQS violations. Where an area is shown to have existing violations and does nothave an adequate attainment plan, new sources that fail to provide
progress would continue to "contribute"
to the nonattainment problem inasmuch

as the area has not yetprovided for expeditious attainment through reductions from existing sources.

In an area that does not have existing violations, a new source would need only tocompensate for its own adverse ambient impacts to fully remedy any projected violations. Where an area is experiencing violations but does have

an adequate attainment plan, new

sources again need only compensate for their own ambient impacts since the

area is already moving toward attainment as expeditiously as is practicable. As pointed out in the preamble to the recently published final Emissions Trading Policy Statement, since EPA can do no more than require States to demonstrate timely attainment, EPA will approve trades, including offsets, in areas experiencing violations that have adequate attainment demonstrations so long as air quality impacts are equivalent [see 51 FR43814, 43818 (December 4, 1985)]. States are of

course free to require additional offsets in such areas. However, the Emissions Trading Policy Statement requires substantial additional air quality
progress for trades in areas without adequate attainment demonstrations to insure that such trades will help move the areas forward toward eventual attainment 

### (see 51 FR 43814, 43820). Further, even in areas that are not experiencing violations, offsets may need to exceed one-for-one in terms of emissions in order to produce equivalent ambient impacts, depending upon

source parameters and geographic conditions.

Finally, several commenters stated that, ifa new facility fully offsets its emissions, EPA should waive the PSD requirements for ambient monitoring and modeling. TheAdministrator does
not find anyjustification for a blanket waiver from the PSD monitoring and modeling requirements simply because a prospective source would obtain emission reductions which fully offset its emissions.The commenters have failed to consider the importance of modeling and monitoring (conceivably both preapplication and post construction monitoring) in demonstrating that the emission offsets would satisfy the air qualityimpact test associated with the required emission offsets and described above in the
response to the previous comment; in fact, such a demonstration would of necessity require modeling, Consequently, the Administrator finds

no reason to changeEPA's present requirements for PSD monitoring and modeling as a result oftoday's action to promulgate PM1oamendments.

f.PreventionofSignificant Deterioration Increments forParticulate Matter. In the 1985 proposal, the Administrator indicated his belief that the PSD program would need to include

a dual increment systemfor particulate matter; that is, separate sets of increments forTSP and PMo. To carry this out, the Administrator proposed to: (1) Clarify that the existing increments, defined under section 163 ofthe Act, would be measured as TSP; and (2) establish new increments measured as PMo in accordance with the procedures under section 166 of the Act. While he believed that thisproposal could be readily accomplished under the proposal
to promulgate aPMlo primary NAAQS implemented under a section 110 pathway and a TSP secondary NAAQS implemented under a Part D pathway, the Administrator raised a number of questions as to how the increment system for particulate matter would be affected by other alternatives for revising the particulate matter NAAQS.

Relevant to today's announced action, the Administrator raised the issue regarding the continued applicability of the existing increments for particulate
matter in the event that the secondary NAAQS was defined as a PMio-based standard and implemented via section 110 ofthe Act as is the case in today's final action. Specifically, the Administrator indicated that it was not clearwhether TSPwould continue to be regulated under the Act, whether the section 107 designation process would continue to apply to particulate matter,

orwhether the TSP-based increments would continue to apply. Thus, the Administrator requested comments concerning all possible impacts on the PSD increments forparticulate matter if he were to usePMlo to define both the primary and secondary NAAQS.

With respect to PMo increments, the Administrator indicated thathe would consider using the approach applied by Congress, which initially created the TSP increments, to establish new PMo increments (i.e., basing them on specific percentages of the NAAQS). In addition, he described possible means of implementing such increments relying

on many ofthe same criteria that are currently beingused to implement the existing increments forparticulate
matter.This particular discussion was raised to identify issues associated with the eventual development ofa PM1o increment system which would proceed under a subsequent rulemaking action in accordance with section 168 ofthe Act.

The EPA received numerous comments concerning the PSD increments forparticulate matter. The Administrator's announced intention to establish a dual increment system was opposed by most of the commenters. Many ofthese commenters also opposed the retention ofTSP as the indicator for measuring the increments. In addition to the comments concerning the appropriate way to express the increments, a number ofcommenters presented arguments concerning the selection of the proper implementation pathway (section 110 versus Part D) in relation to the continued applicability o the increments for particulate matter.

Several commenters pointed to the PSD provisions of the Act and the 

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legislative history to argue against the Administrator's proposal to define the section 163 increments for "particulate matter" as TSPincrements. The
commenters pointed out that section 163 establishes increments, at levels that cannot change, for "particulate matter" inwhatever way EPA wishes to define it.Congress, the commenters noted, intended section 166 to be used to set "numerical measures" for totally different pollutants and not forvarious indicators of the same pollutant, e.g., particulate matter. These commenters stated that there isno requirement on the face ofthe Act, or in the legislative history of section 163, to suggest that Congress intended to require EPA to define the increments for particulate
matter interms ofTSP.The commenters cited the use by Congress ofthe term "particulate matter" without any reference to TSP.One commenter in particular stated that, although at the time Congress adopted section 163 of the Act in1977 particulate matter was generally equated with TSP and Congress did use TSP as the basis for setting the section 163 increments, it does not necessarily follow that Congress intended the increments forever to be tied toTSP ifEPA changed the indicator forpurposes ofthe NAAQS.

On the other hand, one commenter supported retention ofthe existing statutory increments as TSPincrements based on the very fact that Congress

was aware ofthe use by EPA ofTSP as the indicator for particulate matter. Therefore, the commenter believed that Congress intended the term "particulate matter" to meanTSP. This commenter also claimed that there is no authority in the Act for EPA to administratively change this clear example oflegislative policyjudgment. Referencing the legislative history, this commenter went

on to say thatby choosing increments that were numerically a small fraction of the then'current NAAQS, Congress was clearly hoping to minimize the amount ofenvironmental damage associated with the congressional objective to accommodate a specified level ofnew economic activity. Thus, the commenter concluded, ifthe statutory increments

were modified.to "track" a NAAQS o revision, both the absolute amount of additional pollution allowed in each

area and the number ofadditional polluting sources permitted wouldbe changed. The commenter stated that since the latter was the subject of intense congressional scrutiny, there is a strong presumption that Congress did
not intend to give the Administrator discretion to change the statutory 

### increments in section 163because ofa particulate matter NAAQS revision. According to this commenter, EPA has authority under section 166 to establish

a PSD program for aparticulate matter indicator other thanTSP, but as a supplement to, not a replacement for, the section 163 increment program.

The Administrator agrees with the latter commenter that Congress did intend to fix the measure of the particulate matter increment defined in section 163 in terms ofTSPand to provide forestablishment ofnew increments in the appropriate form under section 166 oftheAct for anynew NAAQS. In defining the section 163 increments for particulate matter, Congress used the same term that EPA used in establishing the then current NAAQS, clearly understood to apply to TSP. Further,Congress relied upon TSPbased emissions data from a number of specific source categories to agree upon specific allowable increases that Would accommodate a certain level of source growth.2 4

### This pointis important because it assigns to the "particulate matter" increments a fixedreference point, i.e., the TSP indicator, upon which

source growth is to be measured. To change thisreference point, as the latter commenter notes,would change a significant partofthe nondegradation system which Congress chose to define in section 163by means ofspecific maximum allowable increases forboth TSP and SO2

### .The Administrator wishes to note here thatwhile he strongly believes that the statutory increments for "particulate matter" mustbe measured in terms ofTSP, he does not believe that he shouldnecessarily continue to retain TSP increments beyond the date when new PM0 

### increments become effective. Thiswill be discussed more fully in response to subsequent comments which support the dual increment system which the Administrator originally proposed.

Finally, Congress apparently considered excluding "naturally

24 Committee onEnvironment and Public Works, 95th Cong., 2nd Sess., ALegislative History ofthe Clean Air Act Amendments of1977, at 330-331 (1978). Discussion recorded in theHouse debate on the selection ofPSD increments indicates that acceptance oftheincrements then under consideration was based heavily on the assurance that power plantsusing BACT could normally be built up to approximately 6,000 megawatts in Class I1

areas, and that constraints in the construction of other types ofnew plants would be in the equivalent range. Iffor some reason the section 163 Increments were to be redefined in such a way that they wouldbecome more stringent, then it is not at all clear that Congress would have selected such levels. Itcannot be concluded, therefore, that redefining the existingincrements to make them less stringent would havebeen anymore acceptable
toCongress. occurring particulate matter" from subsection 163(c) and rejected that alternative. 25 Thus particulate matter increments must include all suspended particles for Congress to consider it
necessary to exclude some fraction of those particles.

Several commenters stated that it was clear that the court inAlabamaPower acknowledged EPA's power to define "particulate matter," both for NAAQS and PSD increment purposes as something other than TSP. The
commenters quoted from footnote 134 of that opinion:

EPAhas discretion to define the pollutant "particulate matter" to exclude particulates ofa sizeor composition determined notto present substantial public health orwelfare

concerns. 636 F. 2dat 370 n. 134.

The Administrator acknowledges that, in dicta, the court inAlabamaPower describes such an approach, which could be used to ultimately redefine the statutory increments forparticulate
matter as PMo increments. However, the court clearly premised this approach

on a finding by EPA that larger particles present no substantial health or welfare effects. The EPA has not reached this conclusion. Rather, EPA believes that large particles do present some welfare

concerns but that controls necessary to meet a PMlo NAAQS will adequately address any such concerns. Further, EPA does not read footnote 134 to mean that EPA could administratively redefine the statutory increments to apply to PMo. Such a reading would be inconsistent with the court's stated rationale. Moreover, the court's
statements appear in a footnote not essential to the ultimate disposition of the case, and are thus not entitled to the weight ofajudicial holding.

The court's conclusion that once EPA excludes certain particles from the NAAQS for particulate matter then PSD increments for TSP should not apply to such excluded particles is sound. However, it does not follow that EPA

can administratively alter the statutory TSP increments. The court didnot analyze the issue ofwhich indicator Congress intended to use for the statutory increments prior to drafting the footnote. After a careful review ofthe relevant statutory and legislative background, as discussed above, EPA has concluded that Congress intended

25The 1977 House bill had an exclusion for naturally occurring particulate matter in the forerunner ofsubsection 163(c) [see HR Rep. No. 95- 294,95th Cong., 1st Sess. 165 (1977)]. Theconference committeeremanded the exclusion and it wasnot included in subsection 163(c)as adopted. However, the term particulate matter was used unchanged in both versionsofthe provision.

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the statutory increments tobe measured

as TSP. TheEPA therefore agrees with the commenter who claimed that footnote 134 doesnot change the statutory construction. This commenter further pointed out that footnote 134's sole authority is section 166,but that section contains no authority to modify the section 163 increments; rather section 166 establishes a duty for EPAto expand the PSD program beyond the statutory increments ofsection 163.

TheAdministrator agrees that the proper approach fordeveloping new PMo increments is found in section 166 ofthe Act, and earlier in this preamble indicated his intention to proceed along that prescribed path.Further explanation ofhis effort and its effect on the PSDincrement system for particulate matter is provided in response to subsequent comments below.

Some commenters gave other reasons for opposing the retention ofTSP as the indicator for theparticulate matter increments. Anumber ofthese commenters stated that retention ofTSP would lead to complex, duplicative, and therefore wasteful practices in that it would require sources subject to the PSD program to implement dual systems for monitoring, establishing emission limitations and control strategies, obtaining offsets, andpreparing and evaluating permits-one forthe sizespecific indicator oftherevised NAAQS and another forTSP as the indicator for the PSD increments.

The Administrator acknowledges that, during theinterim periodwhen the section 163 TSPincrements are to be retained,the PSD program will entail review requirements for both TSPand PMo. Suchrequirements would cause permitting agencies and PSD sources to consider both forms ofparticulate matter when such sources could emit both TSP and PMo in significant amounts. This situation is intended to be temporary, however, and should improve when EPA completes the statutory process for developing PM 1

### o increments in accordance with section 166.The EPA believes such asituation is necessary during theperiod required to establish PM,o increments. The alternative, that is, temporarily eliminating increment protection for particulate matter,cannot reasonably be justified.

Anumber ofcommenters associated with the mining industry expressed their

concern that ifEPA finalizes its October 1984 proposal to list surface coalmines

as major sources forwhich fugitive emissions are tobe included in determining PSD applicability, retention ofthe TSP increments would result in severe economic consequences for surface coal mines. These commenters noted that the adoption ofa size-specific indicator for the increments, instead of TSP, wouldreduce the adverse economic effects although there would still be substantial limits on mine production.

The Administrator recognizes that certain industries may be affected more than others under the requirements of the PSD program; however, this situation cannot serve as the basis for defining the form ofparticulate matter used to measure the increments for particulate matter in section 163 ofthe Act.The Administrator has already explained the legal basis by which he concluded that the statutory increments forparticulate matter mustbe measured by the TSPindicator. Eventually, the Administrator intends to promulgate PMo increments which States may use effectively to replace the statutory TSP increments.

Some commenters supported EPA's retention ofthe TSP-based increments and even suggested that PM1o increments should be addedto supplement rather than replace the statutory increments. Several air pollution control agencies stated that EPA shouldretain the TSP increments to prevent deterioration beyond what would be allowed under the TSP increment system and to prevent potential soiling and nuisance impacts ofparticles greater than 10 microns. A Federal agency noted that the development ofPM 1oincrements would be a significant additional management tool.Another control agency claimed that abolishment ofthe TSP secondary NAAQS (and presumably the TSP increments) would weaken the PSD program because PSD applicability would be based on a source's potential
to emit PMo, which may be only a fraction ofTSP, i.e., particulate matter emissions.

While theAdministrator agrees that the statutory increments for particulate matter are appropriately expressed as TSPincrements, he does not agree that it is necessary orreasonable to continue measuring air quality deterioration in
terms ofTSP in lightof the fact that both the primary and secondary NAAQS for particulate matter will be measured by a PMo indicator, particularly when PM1o increments are developed in accordance with section 166. In fact, once EPA approves State requests-to delete section 107 designations for TSP,the Class IITSP increments will no longer have any applicability since Class II increments by definition apply only in designated section 107 areas. The statutory Class I TSP increments will of course remain applicable. However, EPAintends to develop PM,o increments under section 166 which are equivalent
to the existing TSPincrements. To the
extent this can be done, protection of thePM,o increments will fully protect the TSP increments. The EPA will then accept a demonstration ofprotection of the PMo increments as a surrogate for the required demonstration ofprotection ofthe TSP increments so that permit applicants and reviewers will be able to avoid the then unnecessary burdens and complexities ofa dual increment system. The EPA believes it has the authority to do this under section 301(a) ofthe Act.

With respect to any weakening ofthe PSD program as a result ofbasing major

source status on PMo emissions rather than particulate matter emissions, the Administrator recognizes that eliminating regulation ofTSP altogether could reduce the number ofsources emitting major amounts of "particulate matter" and consequently would allow such sources to avoid PSD review. As part of the EPA's effort to develop a PM 10 increment system, the Administrator intends to evaluate the effects on PSD source applicability of changing the indicator forparticulate
matter. Should a significant negative effect be foreseen, the Administrator would consider alternatives for correcting the problem such as redefining "major" forPMo sources under section 166.

One commenter, who supported redefining the section 163 increments as PMo increments, also stated that EPA's

concern about the geographic applicability ofthe section 163 increments forparticulate matter was unfounded. This commenter noted that Congress designated mandatory Class I

areas and then designated all other

areas as Class II ifthe area was attainment orunclassifiable for at least

one pollutant. The commenter then concluded thatbecause the Class II area classifications are not pollutant specific-as opposed to the section 107(d) designations which are-the area classifications will survive the NAAQS revision and subsequent deletion of section 107 area designations for TSP, and the section 163 Class II increments for particulate matter will retain their applicability as well.

The EPA disagrees with the comments claiming that the Class II area classifications are not pollutant specific. Ifthat interpretation is correct, then it would follow that Congress intended the PSD review including the increment analysis to apply to emissions ofa nonattainment pollutant (basedon a section 107 designation) simply because 240 

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the area was also designated attainment for another pollutant.The structure of the Act suggests otherwise, indicating instead that Congress did not intend for

a source to undergo PSD review for a pollutant that was subject to a section 107 nonattainment designation. The EPA believes that by adding Part D to the Act in 1977, Congress intended that separate preconstruction review requirements set forth under section 173 ofthe Act were to apply in such situations instead.

Other commenters who recognized the Class II area classifications as being pollutant-specific were concerned that EPA's proposal not torequire section 107(d) area designations for PM1owould result inno ClassII PSD areas for particulate matter, and thusno areas in which the section 163 Class II increments forparticulate matter would apply. As mentioned earlier, EPA does
not believe that Congress intended for either the section 163 increments or the section 107(d) area classification system to apply to PMo. The EPA believes that

new PMo increments, developed pursuant to section 166 ofthe Act, can be applied independently from the section 107(d) area designations forTSP and the Class II areas-both ofwhich determine the applicability ofthe section 163 TSPincrements. Also, EPA will establish appropriate areas to which the PMo increments will apply during the course ofthe upcoming section 166 rulemaking process.

Since EPAbelieves that the section 107(d) area designations forTSP are necessary to provide for the continued applicability ofthe section 163 Class II increments, it will decline to completely eliminate these TSP designations until PMo increments are in effect and replace the existing TSP increments. As mentioned earlier, the Administrator believes that retention ofthe TSP increments is necessary during the interim to implement Congressional intent to keep air quality deterioration within the limits established by the statutory increment system.

Finally a number ofcommenters stated that since there is allegedly no scientific reason toretain the TSP-based increments (because there are no soiling

or nuisance effects), an EPA decision
not to eliminate TSP as the indicator for the PSD increments wouldbe a violation ofthe binding and enforceable settlement agreement in CMA v.EPA, D.C. Cir., No. 79-1112. 26These

26 Pursuant to asettlement with petitioners in ChemicalManufacturers Association v.EPA. D.C. Cir. No. 79-1112. the EPA agreedto propose revisions to certain PSD requirements, if appropriate, at thetime it proposed revisions tothe particulatematter standards on public health or comments actually addressed EPA's earlier proposal on March 20, 1984 (49 FR 10408], which in addition to proposing revisions to the NAAQS for particulate matter proposed not to change how "particulate matter" would be defined for the purposes ofthe PSD increments. In that proposal, the Administrator indicated that based on EPA's review ofthe data, particles larger than 10 microns could contribute
to soiling and nuisance and therefore may have substantial welfare effects. Consistent with this finding, the Administrator proposed to retain TSP as the indicator forthe secondary NAAQS for particulate matter, and consequently for the PSD increments, because it includes most ofthese larger particles and could therefore be a betterindicator ofall particles that produce soiling and nuisance. The Administrator also raised the possibility that a size cutoffbelow TSPcould ultimately be selected to replace TSP as the indicator for the secondary NAAQS, but even ifthat

were to occur, there was considerable question as to whether EPA could then adopt the same cutoffforthe purposes ofthe PSD increments (49 FR 10421).

By the terms of the CMA agreement itself, the Administrator believes that he acted appropriately in then proposing to retain TSP as the indicator forthe PSD increments and concluding that the contemplated interim reliefwas not available. In any event, the thrust ofthe settlement provision was to cause EPA
to initiate arulemaking on the question ofhow the NAAQS revisions for particulate matter should affect the particulate matter increments. In no way

was itintended to bind EPA to any particular outcome. Here EPAin its 1984 proposal not to change the increments and its 1985 proposals on PSD increment issues ingeneral certainly initiated such

a rulemaking-indeed a rulemaking that has resulted in thorough public discussion, debate, and subsequent Agency deliberation. Thus the spirit as well as the letter ofthe provision has been satisfied.

Moreover, the Administrator now firmly believes that for the reasons set forth earlier in this section of the preamble, Congress intended the section 163 increments for particulate matter to

welfare. In relevant part, the settlement statedthat "[when EPA proposes anew size cutofffor purposes of the NAAQS, it shall also propose: (a) A
new size cutoff for PSD purposes that would remain in effect indefinitely (i.e., the permanent PSD cutoff]; and (b) an interim sizecutoff for PSD purposes to remain ineffect until EPA takes final action on the permanent PSD cutoff.The interim cutoff will exclude only those particles which clearly appear not to pose substantial health and welfare risks and therefore are highly likely tobe excluded permanently." be measured as TSP. The Administrator is taking the course of action he believes

was intended by Congress to implement different "particulate matter" increments. That is, he will promulgate

newPM1oincrements in accordance with section 166 ofthe Act and allow such increments to the extent that they

are equivalent toreplace effectively the statutory TSP increments at the appropriate time.

g. PreventionofSignificant Deterioration Monitoring.The Administrator proposed a new significance level, expressed as an ambient concentration ofPMo, for PSD monitoring purposes. He proposed that a concentration of 10 /g/m3 

### (24-hour average) be used as a criterion to determine whether a PSD applicant would berequired to collect (or, conversely, be excluded from having to collect) ambient PMo data for the 1-year period preceding submittal ofa complete PSD application. The Administrator also indicated that the significant ambient concentration for TSP,10 g/m 3 (24-hour average), would be retained due to the proposed TSP secondary NAAQS.

In addition to proposing a significant ambient concentration for PMo, the Administrator proposed a transition
program related to the preapplication monitoring requirements for PMo (see section h. Transition Provisionsfor details on the proposed provision, issues raised by commenters, and EPA's response). As part ofthe proposed
program, the Administrator indicated that he intended to allow the use of ambient data collected from samplers
not designated as PMo reference or equivalent methods until such reference

or equivalent methods are designated and made commercially available. The Administrator specified PMo, PM 5, and TSP as the particulate matter size fractions which couldbe measured from acceptable alternative samplers. This data would then be used in accordance with EPA-approved estimating procedures to demonstrate compliance with the PM 0 NAAQS.

The EPAreceived no comments opposing the proposed significant ambient concentration for PMlo; several
commenters expressed general support for the proposed value. However, several commenters did raise certain questions concerning the proposed monitoring and ambient air estimating procedures. These procedures would be used to meet the preapplication monitoring and air quality analysis requirements for PMo during the transition period before PM1oreference

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or equivalent methods become available.

One commenter stated thatEPA needs to address the frequency of required monitoring since this is not addressed with respect to PSD monitoring. Since States are required to conduct daily monitoring for 1year at high priority sites, the commenter asked whether PSD applicants would be required to do the same.

The EPA addressed the frequency of PSD monitoring for PMlo in its draft revisions to theEPA document entitled "Ambient Monitoring Guidelines for Prevention ofSignificant Deterioration (PSD)," which was made available for review duringthe public comment period.The Administrator intends to retain the language contained in the draft guidance which described different samplingfrequencies as appropriate for

usewith PMo, PM15

### , orTSP data used to demonstrate compliance with thePMo NAAQS. The frequencies described are consistent with the final 40CFR Part 58 sampling frequencies as published elsewhere in today's Federal Register.

Another commenter questioned EPA's ability to use undesignated interim alternative sampling methods to gather ambient PM 0 

### data. This commenter stated thatEPA must insteadpropose and subject the interim sampling methods to public and scientific review before any final monitoring implementation rule is promulgated. The Administrator disagrees with this position for two reasons. First, the Clean AirAct requires States to submit control strategies to EPA within 9 months ofthe revision oftheNAAQS. However, it will take approximately 6 months after promulgation of the PM1

### oNAAQS before PMo reference method samplers are designated. TheEPA's policy, therefore, is to require States to use available particulate matter data forPM10 

### SIP evaluation andplanning purposes during the period before reference methods are designated. The use ofinterimmethods forPSD purposes is also considered acceptable byEPA. Thus, when PM,o data are required during the transition period and PM1

### oreference method data

are not available, particulate matter data that mustbe used in order of preference arePMo nonreference method data, PM 15

### data, and, forup to 10 months after theeffective date ofthe

new requirements, TSPdata.

Second, on March 20, 

### 1984, EPAdid propose in AppendixJofPart 50 

### a general reference method for determination ofparticulate matter as PMo in the atmosphere. Public comments were taken and were considered before final promulgation of this reference method. Actual designation ofreference method samplers,however, does notrequire proposal in the Federal Register.Under theexisting 40 CFR Part53 regulations, EPAhas the authority to designate reference or equivalentmethod samplers without firstproposing the method(s) in theFederal Register for public comment provided that the methods meetthe performance specifications and other requirements contained in Parts 50 and 53.

Concerning efforts to meet the air quality analysis requirements before a reference method is available, one commenter stated that EPAmust propose for comment the specific "estimating procedures" that mustbe used to determine ambient concentrations ofPMo based on data collected from undesignated samplers.

-The commenter was apparently not

awarethat the prescribed "estimating procedures" were provided in the draft revisions to EPA'sPSD monitoring guideline referenced above. The monitoring guideline actually reflects guidance provided elsewhere for purposes ofSIPdevelopment which prescribes that PM5 

### data be multiplied by a correction factor of0.8, and that PMo data be used directly even though itwas collected with a nondesignated reference or equivalent method. In addition, the monitoring guideline allows TSP data to be used only as a one-for-one substitute for comparison to thePMo standards and only during the first 10 months ofthemonitoring transition. Theuse ofPMmo and PM 15 

### data willresult in much lessuncertainty than the practice ofcomparing existing TSPdata to the PMio standards. Alternatively, awaiting the availability ofreference method monitoring and making no estimates ofthe PMo particulate matter air quality in the meantime would be even less desirable in light ofthe need to demonstrate ambient impacts ofproposed sources on thePMo NAAQS.

h. TransitionProvisions. The Administrator proposed several provisions whichwould delay forsome applicants all or some ofthe new PSD requirements forPMo. Complete exclusion from thenew requirements

was proposed under two grandfather provisions.The first excluded from review sources thatwere notpreviously subject to PSD review,provided that the

sources: (a)Have already obtained all the necessary approvals under the SIP before the effective date ofthenew requirements, and (b) commenced construction within 18 months ofthe effective date ofthe new requirements (orany earlier time required under the SIP). The second grandfather provision excluded from PM review any sources that have submitted a complete PSD application (including those for which a final determination has not yet been made) to EPA orits delegated representative on or before the promulgation ofthe Part52 PSD amendments for PMio.

In addition to the above provisions, the Administrator proposed to enact a transition program to phase in the new requirements for PMlo monitoring. These monitoring provisions were necessary because the proposed grandfather provisions could not offer adequate reliefto those applicants whose applications had not been submitted but whose on-site monitoring efforts were well underway, except, ofcourse, for
any new PMio monitoring that would otherwise be required.

There were several other factors that influenced the design of the monitoring transition program as well. One important factor was the concern that development ofambient PMo samplers suitable for designation as reference or equivalent method samplers could be delayed as long as 1 year. Another was that once the samplers became available and designated, additional time would be needed for applicants to actually install and calibrate the samplers on site before a PMlo samplingnetwork could begin to operate. Finally, the PSD regulations require that a minimum of4 months ofdata must be collected from any site [see section 52.21(m)(1)(iv)] and submitted as part ofthe complete PSD application.

Taking into account these factors, the Administrator proposed three provisions
to phase in the preapplication monitoring requirements for PMo. The first oftheseprovisions gave the Administrator discretionary authority to exempt from the PMo ambient data requirements certain PSD applicants who wouldbecome subject to the requirements because ofPMo, provided the applicant submitted an otherwise complete application within 10 months afterpromulgation ofthe Part 52 PSD amendments for PMo.

The second proposed provision allowed eligible applicants to sample PM 1ousing nondesignated PMo orPM,5 samplers during the period oftime when they would be unable to establish a PM 1omonitoring network utilizing designated PMo samplers. In the proposal, the preamble incorrectly indicated that TSP data would also be acceptable during this phase but EPA's draft monitoring guidance made available for public comment correctly indicated thatTSP monitoring data 

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would not be accepted for PM~o purposes, but only for comparison with the then proposed TSP secondary NAAQS. This provision would affect complete applications (except for PM1o) submitted between 10 and 16 months afterpromulgation ofthe PSD amendments for PMo.

The third and final proposed provision relating to the phase-in ofPM1o monitoring equipment allowed certain applicants to commence reference method PM1omonitoring and gather ambient data over only the period extending from the date 12 months from promulgation ofPMo amendments to the date the application becomes otherwise complete with respect to all other existing monitoring requirements. This provision applied to complete applications (except for the PM1o monitoring requirements) submitted between 16 and 24 months after promulgation.

The,Administrator also proposed to allow States to adopt transition provisions for PM1omonitoring ifthe provisions are compatible with the intent ofthe Federal transition provisions proposed in the Part 52PSD regulations.

Grandfatherprovisions. While most commenters expressed general support for EPA's proposed grandfather provisions which protect certain sources fromhaving to meet the PSD requirements forPMo, a few concerns

were noted.

One commenter objected to the use of different qualifications for grandfathering sources not previously subject to PSD versus sources previously subject to PSD. For the former category, sources are grandfathered only ifthey have received all otherwise required preconstruction approval and permits and commence construction within 18months. In the latter category, sources are grandfathered ifthey have merely submitted an otherwise complete PSD application. The commenter felt this provided inequitable treatment to
sources, and that it would be more fair and rational to grandfather all sources based on the submittal ofa complete application.

The EPAdoes not believe that the alleged discrepancy in the two provisions as they were intended to be applied is inequitable. However, in reviewing the proposed provisions, EPA recognized that there was some ambiguity as to exactly who would be eligible for grandfather status under each provision. The EPA-intended the first grandfathering provision to apply to all sources not previously subject to PSD for particulate matter, even ifthey were subject to PSD for some other pollutant. The EPA intended the second grandfathering provision to apply only
to those sources that were previously subject to PSD forparticulate matter and had consequently included analyses for particulate matter in their PSD applications. The use ofmore lenient grandfathering qualifications for sources previously subject to PSD is keyed to the presence ofparticulate matter analyses in the completed application. The EPA has clarified the grandfather provisions in the final action to remove the stated ambiguity [see new section 52.21(i)(4) (ix) and (x)].

In addition, to further enhance consistency between the two provisions, EPA has also changed the wording of the second grandfather provision so that the same eligibility cutoffdate is used for excluding sources from the new PMo amendments. Under the proposed language, applicants previously subject
to PSD (forparticulate matter) would have had an extra day (i.e., "on or before" versus "before") inwhich to gain grandfather status. Based on these changes, EPA does not agree that an inequity exists between the two new grandfather provisions.

The EPA has found it necessary to make several other changes to the new grandfather provisions. First, the second grandfather provision in today's notice contains a key final sentence that was unintentionally omitted from the provision as originally proposed. Without this sentence, the affected

source ormodification would have been excluded from the original PSD requirements for particulate matter in addition to being grandfathered from today's amendments. This was clearly
not the intent ofthe provision. The proposed grandfather rules were to exempt applicants from new requirements but require them to continue to meet existing requirements instead.

Secondly, the date upon which both provisions will be based is changed to the date 30 days from today's date of publication. The proposal, in using the date ofpublication, did not take into account the fact that the amendments beingpublished intoday's Federal Register will become effective 30 days later. Finally,reference to the August 7, 1980, PSD regulations inboth ofthe proposed grandfather provisions has been changed because this reference does notproperly account forPSD amendments occurring since August 7, 1980.Those sources or applicants which
may be grandfathered from the new PMo amendments are expected to meet the Part 52 PSD requirements, including applicable amendments made after August 7, 1980, which are in effect immediately preceding the effective date ofthe newPMo amendments.

Several commenters noted that EPA should also include these proposed grandfather provisions in section 51.24 (recodified as 51.166] where States have the permitting authority, and notjust include them in the Part 52 PSD regulations where EPA or its delegate is the permitting authority. The Administrator agrees that States with approved PSD regulations in their SIP's should have the same ability to grandfather certain sources from the

new PMo requirements. Although it was not mentioned in the proposal, States
may adopt such provisions in their regulations and EPA will approve them pursuant to section 51.166(a)(6](ii which requires that when a State revises its PSD rules itmust specify when and as to what sources such revisions will take effect. Consequently, there is no need to further amend the section 51.166 PSD requirements to satisfy the commenter's

concern.

MonitoringTransition.Many
commenters expressed general support forEPA's proposed phase-in ofthe new PSD monitoring requirements for PMo. Some ofthese commenters, however,
gave recommendations thatwould change the transition procedures in certain ways.

Most ofthe commenters expressed

concern about the eventual availability ofan acceptable sampling method. One.
commenter stated that EPA should delay action on its PM10 proposal until an acceptable reference method sampler is available for widespread use by PSD permit applicants. Another commenter stated that EPA should allow the States
to waive orto adjust the PMo monitoring requirement on a case-bycase basis beyond the time periods provided ifa sufficient supply of approved PM 1omonitoring equipment is
not available. Yet another commenter
went further by stating that the PSD requirements should contain some triggering mechanism requiring the Administrator to take an affirmative action finding that monitors are available before requiring their use.

Finally, a commenter said that all three transition provisions should apply uniformly to all applicants who meet the requirements and should be revised to reflect the delayed effective date of EPA's PSD regulations. (This commenter recommended a 9-month delay before the Part 52 PSD regulations would apply.) That is, the first transition provision should exempt fromPM monitoring those applicants who submit

a complete application within 3 months

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after the effective date ofthe PSD amendments for PM~o; the second provision should apply to applicants who submit a complete application between 12 and 18 months after promulgation ofthe revisions and should allow them to monitor PMo or other particulate matter size fractions during the interim period when approved samplers are not available; and the third provision should apply to applicants who submit complete applications from 18 to 24 months after promulgation, requiring sampling with designated samplers beginning 12 months after promulgation.

The Administrator believes that the

concern relating to potential unavailability ofreference or acceptable PMo samplers isno longer a valid issue. At the time ofthe 1985 proposal, it was generally agreed that relatively few acceptable PMo samplers were readily available. However, since the 1985 proposal, at least 900 commercially available PMo samplers have been placed in operation by State and local agencies and suppliers are already advertising the availability ofPMo samplers that will meet the proposed requirements.

The Administrator believes that the three transition periods as proposed are reasonable, provide sufficient flexibility for implementation, and do ensure that adequate estimates ofambient PM10 concentrations are available for air quality analysis purposes. Consequently, no changes to the proposed PSD regulations or draft PSD monitoring guideline are being made based on concerns overthe unavailability ofPMo samplers. However, with respect to the effective date ofEPA's Part 52 PSD regulations, the Administrator has revised the language in the monitoring transition provisions toreplace the reference to the date ofpromulgation with the effective date ofthe regulations which is actually 30 days later.

2. Nonattainment New Source Review Requirements

In the 1985 proposal, the Administrator proposed separate sets of preconstruction NSR requirements with respect to the primary and secondary NAAQS for particulate matter. The EPA did this because: (1)the NAAQS proposal included PMo primary standards and TSP secondary standards, and (2) the Administrator proposed to establish implementation requirements for attaining the PMo primary NAAQS using the section 110 pathway and requirements to implement the TSP secondary NAAQS using the Part D pathway. While concentrating on these particular assumptions, the Administrator also described alternative programs that could result from subsequent decisions to use different implementation pathways foreither the primary or secondary NAAQS, or to select the PMo indicator for the secondary NAAQS, thereby eliminating TSP-based NAAQS altogether.

For the primary PMo NAAQS, the Administrator proposed that the PSD program (as described in the previous section) in conjunction with the requirements in section 51.18(k) [now recodified as 51.165(b)], concerning protection ofthe NAAQS in designated section 107 attainment and unclassifiable areas as required by section 110(a)(2)(D) ofthe Act,would apply in all areas to major sources or modifications whose PMo emissions would cause orcontribute to NAAQS violations. The Part D NSR requirements under section 51.18(j) [now recodified as 51.165(a)] and the construction ban under section 52.24 wouldhave no applicability to PM10. However the Administrator proposed that until States received EPA approval for their section 51.165(b) program for PM 1oSection III of the Offset Rule (40 CFR Part 51 Appendix S (1985)), would govern the preconstruction review process for PMo.

Under section 51.165(b), the EPA proposed both to add requirements for PMo and to clarify the existing requirements as they apply to other criteria pollutants as well. First,EPA proposed to establish annual and 24- hour significant ambient impact levels for PMo similar to the existing levels for other pollutants which would be used to determine when a source's emissions

are considered to cause or contribute to

aNAAQS violation at any location. Sources having a modeled significant ambient impact must address such impact by getting emission offsets. The EPAproposed values ofI Lg/m3 (annual) and 5 ug/m3 (24-hour average).

With respect to the applicability ofthe section 51.165(b) program requirements, EPAproposed to clarify that major

source status would be based on the applicable definition under section 302(j) ofthe Act, i.e., 100 tpy ormore ofany regulated pollutant. Using this definition, section 51.165(b) covers all PSD sources as well as certain non-PSD
sources, namely sources that have the potential to emit more than 100 tpy (but less than 250 tpy) ofany regulated pollutant and are not included on the 28-

source category listing for PSD.

ForPSD sources, EPAproposed that the requirements ofsection 51.165(b) would be applied in addition to all applicable PSD requirements. FornonPSD sources, section 51.165(b) would apply in addition to any other applicable preconstruction review requirements in the approved SIP.

The Administrator also indicated that he would give States considerable flexibility in designing an offset program under section 51.165(b) as necessary to prevent new or modified major sources from causing orcontributing to a NAAQS violation. He proposed that, as

a minimum, an approvable section 51.165(b) program would merely have to require emission offsets which: (1) Provide a net air quality benefit, and (2) conform with creditability criteria at least as stringent as the offset criteria
set forth under section 51.18(j) [recodified as 51.165(a)]. However, because ofthe broad range of nonattainment situations that section 51.165(b) would be expected to deal with in the absence ofPart D applicability for PMo, the Administrator also requested comments concerning the need to impose additional Part D-like requirements such as LAER and statewide compliance.

The Administrator's proposal with respect to the proposed secondary TSP NAAQS called for a continuation ofthe Part D-based NSR requirements except for the construction ban under section 52.24 should he select the Part D implementation pathway as proposed. Thus sources proposing tolocate in

areas designated nonattainment under section 107 for TSP wouldhave been required to fully offset theirproposed particulate matter emissions, apply LAER, and ensure that all other sources under common ownership statewide

were in compliance or on a compliance schedule.

Ifhe were to choose to implement the revised TSP secondary NAAQS under section 110 rather than Part D, the Administrator indicated that the PSD requirements in conjunction with the section 51.165(b) requirements would apply to TSP in the same manner as proposed for the primary PMo NAAQS. Moreover, in the event that the Administrator set the secondary NAAQS equivalent in all respects to the primary PMo NAAQS, then the preconstruction requirements proposed for the primary PMo NAAQS would apply for the secondary NAAQS as well.

Finally, while proposing thatno construction ban under either section 110(a)(2)(1) or section 173(4) ofthe Act would apply to PM1o,the Administrator raised the issue ofwhether to consider imposition ofa construction ban for PMo under authority ofsection 301 ifa State failed to meet its obligation to 

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submit an acceptable plan revision within the required 9-month time frame

or failed to implement a plan after it had been approved.

The commenters' views on the proposed NSR requirements were generally based on whether they supported a section 110 or a Part D implementation pathway. The majority ofcommenters, believing that the development ofSIP'sfor any NAAQS revision should be governed by section 110, opposed anyretention ofPart Dbased NSR requirements. These
commenters supported an offset requirement under section 51.165(b) as proposed,but disagreed that EPA had any authority to impose LAER or other requirements under Part D or the Offset Rule-even during the interim period before States submitted and received EPA approval oftheir section 51.165(b)
program for PMo.

A fewcommenters who supported an integrated section 110/Part D implementation pathway felt that it would beinappropriate for EPA not to continue imposing Part D NSR requirements where PMlo NAAQS violations may exist. One commenter stated that by failing to do so, one must conclude that Congress intended a more relaxed regime for the persistent particulate matter problems thanit required earlier for initial particulate
matter nonattainment problems.

For reasons stated earlier, the Administrator finds no statutory basis for applying Part D to PM 10 and thus it would not be appropriate to try to impose for PMo purposes the NSR requirements forLAER or statewide compliance contained inPart D oftne Act.The Administrator here wishes to reemphasize the fact that the nonapplicability ofPart D does not result simply because EPA is revising the NAAQS for particulate matter, but because such revisions are believed to result in significant new planning burdens required to demonstrate attainment ofthe revised PMo standards.

In taking the position thatPart D does
not apply to the revised primary NAAQS, the Administrator acknowledges that,as one commenter noted, the NSRprogram for PMo may in

some respects represent a relaxation of the nonattainment NSR program that had been required for TSP. The Administrator believes that this must
occur, however, under the implementation scheme that Congress
appears to have intended when a NAAQS revision causes significant new planning burdens. Nevertheless%States

are still required to revise their SIP's (including the applicable NSR requirements) to demonstrate attainment ofthe revised NAAQS within the time frame required by Congress. Even ifthe PMo preconstruction review program adopted by a State appears tobe a weakened

one by comparison, the PMo SIP must show that attainment ofthe revised NAAQS will occur within 3years.

Where violations ofthe PMo NAAQS already exist, some States may indeed find that the minimum required offset
program under section 51.165(b) isnot adequate to address the nonattainment problem. Such States must then decide
to what extent it may be appropriate to establish additional preconstruction review requirements for major new or modified sources under section 51.165(b) in addition to requiring emission reductions from existing sources of PMo. The Act, under a section 110 implementation pathway, gives States adequate flexibility to take the measures they deem appropriate and necessary to demonstrate attainment of the revised PMo NAAQS within 3years.

Several commenters opposed EPA's proposal to apply the requirements under the offset rule to govern certain preconstruction review until the State submitted and received EPA approval of its section 51.165(b) program for PM 0. These commenters stated that EPAis
notjustified in proposing to impose the Part D-type requirements ofthe offset rule, i.e., LAER and certification of statewide compliance, until the State has failed to meet the statutory deadline for achieving the revised NAAQS.

The EPAhas reviewed the proposal in light ofthese comments and agrees that it would not be appropriate to apply the requirements ofthe offset rule to PMo at this time. However, until States revise their SIP's to demonstrate attainment and maintenance ofPMo NAAQS and presumably redesignate TSP nonattainment areas to unclassifiable
areas, they will be expected to continue implementing, where applicable, a preconstruction.review program for particulate matter based on their existing TSP-based nonattainment area requirements which may include the provisions ofthe offset rule. The requirements which the Administrator is today promulgating will not seek to impose the offset rule directly with respect to PMo.

An air pollution control agency opposed EPA's proposal to use only section 51.165(b) to define NSR permitting requirements forPMo. The
commenter criticized EPA's approach by saying that due to the language ofthe regulation, section 51.165(b) could neither adequately address PMo nonattainment situations nor ensure progress toward attaining the PM1o standards. At.the center ofthe commenter's concern is the ambient impact screening test which EPA allows States to use as part of the applicability requirements for section 51.165(b). First, the commenter claimed that section 51.165(b) would provide no effective control ofPM 0 emission growth because

new sources could be permitted to
construct without sufficient mitigation if modeling fails to demonstrate a significant ambient impact. In comparison, under EPA's Part D-based nonattainment NSR requirements, there would be no ambient test and each major source locating in a nonattainment area would be presumed
to contribute to the existing air quality problem.

Second, the commenter stated that section 51.165(b) provides no mechanism for addressing precursors to nonattainment pollutants. That is, because ofthe ambient impact screening test, section 51.165(b) is dependent on the capability ofmodels which are not available to accurately predict downwind concentrations.

In response to the commenter's first

concern, section 51.165(b) does allow
states to exclude certain sources from its coverage on the basis oftheir insignificant modeled ambient impact. In proposing the significant ambient impact levels for PMo, EPA sought to enable States to use the same de minimis modeling testfor PMo that is already available for other criteria pollutants to determine whether the modeled ambient impact of a new

source or modification would significantly affect the air quality. At points beyond the location where a

source would have significant modeled impacts, the source's impact would not be sufficient to cause or contribute to a NAAQS violation.

These de minimis numbers are keyed
to the limits ofreliability ofthe models used to predict a source's ambient impact some distance away. The
commenter correctly points out that the

use of such significant levels may not be desirable for applying the section 51.165(b) program to PM

,owhen a serious nonattainment situation is known to exist in the area where a

source proposes to locate. (A similar problem could occur for any other pollutant as well when a State chooses
not to redesignate an area to nonattainment under section 107 even though a widespread nonattainment situation may exist.)

Under such conditions ofwidespread NAAQS violations, EPA advises States
to consider a more stringent

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applicability framework than the one minimally set forth under section 51.165(b), based on criteria other than modeled ambient impacts. Such additional stringency could include a provision to require offsets from all

sources-even those that the ambient screening testwould otherwise exempt. The Administrator continues to believe, however, that it is generally reasonable to apply the de minimis testunder section 51.165(b) to determine whether the modeled ambient impact of a source would significantly affect air quality. Since that is the intended purpose of the de minimis provisions, EPA therefore finds itappropriate to promulgate the proposed PMo values.

It should be pointed out that when a
source is allowed to be excluded from the section 51.165(b) requirements on the basis ofits de minimis impact in the affected area, the SIPfor PMo must continue to account for any potential accumulation ofsuch allowed de minimis emission increases which affect the NAAQS exceedance. Presumably the SIP will address this through additional emission reductions at existing sources.

In response to the commenter's second concern about thelack ofmodels to predict PMo levels caused by precursors, theAdministrator anticipates that thisis only a temporary drawback. TheEPA is developing modeling methods thatwill estimate ground level PM1

### oconcentrations caused by precursors. Where thecontribution of PM1

### oprecursors is anticipated to be of significant concern,EPA also permits the development ofsite-specific models to estimate precursor contribution to the source's ambient PMo impact.

The same government agency commenter, noting that EPAproposed to grant States considerable flexibility in designing their emission offset program under section 51.165(b), suggested that intrapollutant offsets for secondary pollutants be accepted as mitigation for PM,o emission increases. The Administrator recognizes that secondary aerosols in theform ofsulfates and nitrates may contribute significantly to the ambient PMo levels in a number of locations and believes that in certain situations intrapollutant offsets could be considered appropriate to enable States to effectively address such problems. This matter further points to the need for models to predict the ambient PMo concentrations caused byPM,o precursors. The Administrator intends to review on a case-by-case basis State requests to incorporate in the SIP a provision which would allow precursor offsets for PMo. Several commenters supported the need for creditability criteria for emission offsets required as part of a section 51.165(b) program; however, two commenters specifically questioned the need for the offsets to be federally enforceable. One commenter in particular claimed that the process of ensuring that an offset is "federally enforceable" rather than simply "enforceable" can be burdensome, timeconsuming, costly, and unnecessary if the source owner is already subject to a State permit condition that requires the emissionreduction and is enforceable by the State.

The general issue of federally enforceable emission reductions (offsets) is being addressed in a separate rulemaking action. On August 25, 1983, EPA proposed amendments which among other thingsproposed changes to the Federal enforceability requirements contained in a number of preconstruction review provisions, including the requirement for federally enforceable emission reductions (48FR 38742). Specifically, EPA proposed to delete the requirement in section 51.18(j)(3)(ii)(e) [recodified as 51.165(a)(3)(ii)(e)] that emission offsets obtained by one source from another

source in order to obtain preconstruction approval befederally enforceable. Subsequent to that proposal, EPA received extensive public
comment which isbeing subjected to careful review.

The Administrator finds no basis for evaluating the issue ofFederal enforceability separately with regard to PMo and he will take final action on the August 25, 1983, proposal at the appropriate time. Until such time as a final action is taken, the requirement for Federal enforceability ofemission offsets will continue to apply to all pollutants, including PMlo. In the event that EPA deletes the existing requirement for Federal enforceability in section 51.165(a)(3)(ii)(e), then the change would also be applied to PSD offsets.

A number ofcommenters strongly opposed any attempt by the Administrator to impose a construction ban for PMo under any circumstances. Some ofthese commenters noted that section 110 does not provide the Administrator with any authority to reestablish aban to stimulate timely PMo SIPdevelopment. Other
commenters agreed, adding that even section 301 withits narrow, gap-filling grant ofauthority is not an appropriate implementation vehicle for something as "major, extraordinary, and controversial" as the ban. Some commenters expressed the opinion that imposition ofa construction ban could actually worsen the nonattainment problem because it would prevent areas from obtaining the
net emission reductions provided by

new and modified sources through their offsets and also the replacement of older, higher emitting facilities with
newer, better controlled ones.

A few commenters noted that the ban penalizes the wrong party since stationary sources are generally not responsible for inadequate SIP's. Others added that a better way to deal with recalcitrant States is to use the funding sanctions of section 176(b) and 105, and the EPA SIP promulgation authority of section 110(c)(1), all ofwhich directly affect the States.

Two commenters stated that ifthe ban is to be used, it shouldbe imposed only on a case-by-case basis after an opportunity for a public hearing, and only when emissions from stationary

sources are the cause of the problem.

In support of a construction ban, several commenters stated that the existing construction ban is applicable because section 110(a)(2)(I) applies to all post-1979 SIP submissions. One ofthese
commenters stated that ifEPA decides that section 110(a)(2)(I) does not apply, then it would be appropriate forEPA to establish a provision equivalent to section 110(a)(2)(1).

Because the Administrator has concluded that Congress did not intend the Part D requirements to apply to such NAAQS revisions as are being promulgated today, itwould be inappropriate in the absence ofstatutory authority for EPA to impose the existing Part D-based ban provisions under section 110(a)(2)(I) and section 173(4) withrespect to PMo. In addition, today's action does not include any new provisions for imposing a construction ban for PM10 sources under the Administrator's section 301 authority. The EPA does not believe it would be appropriate to consider the need to impose such a ban until Stateshave first had an opportunity to prepare and begin implementing SIP's which provide for attainment ofthe revised PMo NAAQS.

Nevertheless, EPA intends to fully analyze all ofthe legal issues and

reserve for a future determination the appropriateness of,and authority for, imposing a construction ban under sections 110(c) and 301 ofthe Act on a case-by-case basis in States that fail to develop PMo SIP's in a timely manner

or fail to implement a PMo SIP after it has been approved by EPA. Where authorized and appropriate, EPA will also consider the use of other sanctions, 

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such as funding sanctions or Federal rule promulgation to stimulate the development and implementation of plans which adequately demonstrate timely attainment and maintenance of the PM1 0 NAAQS.

E.Comments on TechnicalIssues

Along with the notice ofproposed rulemaking, EPA issued a draft "PM1 0 SIP Development Guideline." Several
comments were received regarding development ofPMlo emission inventories, air quality modeling procedures, PMo source testing procedures, and other matters covered in the guideline.

1.Preparing an Emission Inventory

Several commenters recommended that EPA amend its PMo SIP Development Guideline to provide guidance on how to inventory directly emitted nitrates and sulfates and that the definitions of "particulate matter emissions" and "PMo emissions" be revised to include secondary particulate
matter precursor emissions.

The size specific emission factors developed by EPAfor various particulate matter source categories include directly emitted nitrates and sulfates, but do not specifically identify the portion ofthe emission factor thatis primary nitrate or sulfate. However, EPA has published chemical characterization information fora number ofsource categories which could be used to estimate the fractional emissions ofprimary nitrates and sulfates. This information is available in Receptor Model Source Composition Library, EPA-450/4/85-O02.0

The EPA does not agree that secondary particulate matter precursor emissions should be included in the definition ofparticulate matter emissions. Particulate matter emissions

are intended to include materials which

are directly emitted from sources as particles. Directly emitted particles are distinctly different from secondarily formed particles, which are emitted as gases and form particulate matter as a result ofchemical reactions that occur

some time after being emitted by a

source. As such, secondary particulate matter precursor emissions contribute to ambient PMo concentrations but do not contribute to PMo emissions per se.
2.Emission Factors

Commenters stated that EPA has no detailed emission information upon which to base the development ofPM1o emission factors since a standard reference source test method has not been adopted for PMo emissions. The
commenters believe there are significant 

### technical problems with the two basic PMo measuring techniques (cascade impactors and multistage cyclones) and with measuring condensible particulate matter. Also, the commenters allege that the use ofparticle size fraction multipliers in conjunction with existing emission factors requires excessive attention to specific source characteristics to prepare arealistic emission inventory.

Aspart ofa special data collection effortto develop PMo emission factors forcertain source categories, starting in the 1970's, EPA tested and evaluated severalparticle size source sampling techniques. The PMlo source test protocols were developed and utilized in collecting data forthe development of PMo emission factors under this program. While it is true that EPA does not have a standard reference method forPMo source testing, theAgency believes the data collected under the special PMo emission factor program
were ofgood quality. Nevertheless, it is generally recognized that much ofthe particle size data collected and reported in theliterature in the past are oflimited value. Literature data were used by EPA
to develop emission factors for sources not tested under EPA's field program. The limited quality ofthese data has been generally noted bythe use of EPA's letter rating system for emission factors.

The EPA recommends that sourcespecific emission data be collected to characterize emissions from any particular source. This is particularly true forlarge point sources ofPMo, whose emissions are known to be a function ofidentifiable process and design variables. Emission factors and/

or fractional multipliers are intended to be used as a fallback to estimate emissions when source specific data are not available.

The fractional multipliers represent an average ofavailable test data and are most appropriately applied when estimating emissions from numerous
sources in an areawide source inventory. Because these multipliers are averages, they will yield emission estimates and distributions that may not necessarily be representative ofan individual source. However, when applied to multiple sources, these differences tend to balance out across the inventory. The EPA published particle sized emission factors in the CompilationofEmissionFactors,AP42, in September 1985 and Supplement A 

### which was issued in October 1986.p The EPA will continue to develop and update PMo emissions factors as more data become available. 3. Receptor Modeling

Industrial commenters stated that the receptor modeling techniques recommended by EPA (chemical mass balance, automated scanning microscopy and optical microscopy) have limitations that make their general endorsement for SIPdevelopment inappropriate at this time. They felt EPA should acknowledge that there are certain situations, primarily in simple air sheds, in which use ofthese techniques by technicians trained to understand the capabilities and limitations ofeach techinque would assist in control strategy development. They recommended EPA should concentrate

on standardizing and providing better guidance and training regarding these techniques.

The EPA does recognize the limitations (and strengths) ofreceptor modeling and our guidance reflects this. Receptor models should be used collaboratively with dispersion models, where possible, to apportion the contribution of sources to various receptors.

The EPA guidance reflects the fact that chemical mass balance (CMB) is
most useful in those cases where: (1) The identification ofsource categories will provide sufficient information or, alternatively, that the impacts ofspecific

sources within a category can be allocated by emission inventories or models; (2) the number of major impacting categories in an air shed is likely to be small. TheEPA recommends that source profiles, based on sourcespecific data, be used in CMB just as

source emission measurements are preferred to the use ofAP-42 factors as the basis for emission estimates in dispersion model. As a fall-back, EPA has developed a source composition library which is a compendium of available source profile information that assigns arating to each profile to assist the user in determining its usefulness. It is agreed that a PMo CMB analysis on TSP glass fiber filters is likely to be unsatisfactory in complex air sheds. The proposed guidance recommends that a CMB analysis be corroborated if possible by microscopic analysis, ifTSP data collected on glass fiber filters are all that are available. Many areas have (or will have) PMo orPM15 data collected on quartz fiber filters or Teflon filters orwill likely obtain additional samples priorto SIPpreparation.

Microscopic techniques will likewise be useful in conjunction with some models. Microscopy is less useful when

a TSP sample collected on glass fiber filters is all that is available; ithas been,

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however, demonstrated to be valid as a corroborative technique with appropriately collected samples.

Agencies with moderately sophisticated technical staffs shouldbe able toperform the CMB analysis after appropriate training. The EPA has conducted five workshops on receptor modeling nationwide; several have been conducted by the Air Pollution Control Association and private consultants have conducted several. The EPA has published a six-volume set oftechnical reports on receptor models which is available fromNTIS. Volume IV ofthe Receptor Model Technical Series provides useful information to agencies interested in commissioning studies or interpreting results, though it is not an exhaustive treatment ofthe subject.

In some cases, a consultant willneed to provide the necessary analyses just

as some dispersion modeling is done by consultants. The EPA is revising the

users guide for the CMB model and preparing a protocol for application and validation ofthat model, as well as a document explaining how differences between receptor and dispersion model results canbe reconciled. r, 

### s.t

4. Dispersion Modeling

Two commenters raised concerns about the availability and applicability of air quality dispersion models in complex terrain. Both commenters suggested EPA either approve air quality dispersion models foruse in such terrain

orpermit the use ofsimpler approaches.

Commenters alsoraised concerns about the ability of current air quality dispersion models to assess the impact ofparticle formation as a result of oxides ofsulfur and nitrogen emitted to the atmosphere, i.e., secondary aerosols,

on PMo air quality.

Commenters asserted that fine particles ingeneral, and secondary aerosols in particular, are potentially majorcontributors to PM10 

### in some
areas and may originate outside of the region under the control oflocal or State authorities. They alleged gaseous as well as particulate matter emissions reductions may beneeded to reduce PMo concentrations and that distant

sources ofprecursors may prove difficult to identify.

The EPAdoes not intend that each

area where complex terrain is of

concern develop its own model where the State believes the available techniques do not accurately describe the physical circumstances. To eliminate the use ofair quality dispersion models in complex terrain would be inappropriate because while receptor modeling and other similar approaches provide information relevant to the SIP development effort, analyses using air quality dispersion models are more likely to include themeteorological circumstances resulting in the maximum expected air quality concentrations.

The EPA proposed the addition of another complex terrain screening model, the Rough Terrain Diffusion Model (RTDM), foruse in performing these air quality analyses on September 9, 1986 (51 FR 32180). Use of these 

### techniques, when approved, should result in more credible analyses of complex terrain impacts.

With regard to secondary aerosol, preliminary analysis offine particulate
matter data collected in the National Inhalable Particulate Network indicates that sulfate and nitrate generally total less than halfoffine particulate matter

on days with high concentrations. This indicates that a substantial portion of fine particulate matter in urban areas is likely to be oflocal origin.

The formation ofsecondary aerosols is the concern ofmany ongoing research activities withinEPA as well as the scientific community at large. The validity ofmodels that represent the formation ofsecondary aerosols must, however, be demonstrated to EPA, and approval forapplication ofsuch models in a specific area must be received before incorporating the results in a SIP. The EPA is developing a model, the Particulate Episodic Model (PEM-2), that calculates foreither one ortwo pollutants the average surface concentrations ofboth the primary (reactant) and secondary (reaction products) pollutants, provided they are coupled through a first-order chemical transformation. Its use in specific regulatory applications will have to wait until the model and its associated limitations can be established.

Where the contribution ofsecondary aerosols is anticipated to be of significant concern, EPApermits the development ofsite-specific models to address these concerns. With respect to determining distant sources of precursors, EPAis evaluating the performance oflong range transport models.Therefore, none canbe recommended at this time on other than

a case-by-case basis. Recommendations

on the use oflong-range transport models will be accomplished through revisions to the Guideline on Air Quality Models." Appendix D of the SIP development guideline provides guidance on identifying the background portion ofPMo and provides a working definition ofbackground. 5. Source Sampling Devices and Procedures

A commenter stated that the two techniques available to measure PM,o in

a gas stream, cascade impactors and cyclone samplers, have numerous problems. Specifically, the commenter alleged that cascade impactors:

a. Are very sensitive to small weight changes and operator error;

b.Are notversatile enough to

measure wide variations ofparticle concentrations and size distribution;

c. Have significant wall losses; d.Are subject to particle bounce which affects reliability:

e. Are affected by reactions between the collection medium and SO2 in the
gas stream; and

f. Have difficulty achieving isokinetic sampling.

The commenter also alleged that cyclone samplers have many of the

same problems, and that there is very little experience using cyclone samplers.

Appendix C ofthe PMo SIP Development Guideline describes modified Method 5 source sampling procedures that can be used to measure PMo in a gas stream. The EPA believes Appendix Cprocedures can be used by knowledgeable source testingpersonnel in the interim until development of a PMo reference method is completed. Several precautionary statements are made in Appendix Cto make clear the fact that size selective measurements

are more complex and require greater skill and attention to detail than Method 5 and 17 tests. Regarding sampler versatility, any one of several devices will cover the majority ofconditions in ducts downstream ofparticulate matter controls with gas temperatures less than 650 *F.Wall losses for particles smaller than 10 micrometers are acceptably small, particle bounce can be avoided with proper operation, and reactions of SO 2 with the filter media can be prevented by pretreatment ofthe filter media.

6. Data Reduction

A commenter stated that the PADRE computer routine for test data reduction has shortcomings that make prediction ofactual PMo emissions difficult. Specifically, the commenter stated, the PADRE program:

a. Allows the use ofgeneric calibration constants;

b.Uses fixed cut-point data for any preseparator device; and

c.Requires designation ofa maximum expected particle diameter within the sample. 

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The PADRE was developed for analysis ofcascade impactor data. It

was used to facilitate entry ofparticle size data into the Fine Particle Emission Inventory System (FPEIS). The PADRE contains an algorithm for interpolating and to some degree extrapolating data
to obtain size distribution information at diameters other than those provided directly by the impactors. The accuracy ofthis algorithm has been demonstrated
to be reliable. The "generic" calibration
constants used in PADRE are based on averages ofcalibration data for several specific samplers ofeach model of cascade impactor. When the corresponding stages from all units of the same model are averaged, the standard deviation ofthe averages for each stage are typically within 8 percent ofthe mean values.

The PADRE program does not assume

a fixed preseparator cut point.Because equations and constants governing the performance ofvarious precollectors are not the same, operators are expected to verify the cut point and input the correct value as part ofthe data entry into PADRE.

The maximum particle size ofconcern in the PADRE input is the maximum size in the sample. This can be measured with sufficient accuracy using a microscope. This value is used to establish a boundary condition in the algorithm used to extrapolate data to diameters larger than the maximum stage or precollector cut size. Since 10 micrometers is almost always within the
span covered by the impactor and precollector cuts, extrapolation ofdata should seldom be needed. The EPA believes these procedures can yield results adequate for development of site specific emission factors ifthe suggested precautions are taken.

F.Comments onMiscellaneousIssues
1.Impact on New Source Performance Standards Program

The current 22 NSPS that reflect best demonstrated control technology for particulate matter have the effect of controlling PMo. Therefore, EPA proposed to take the following actions

on NSPS in response to a revision of the particulate matter standards:

(1)Complete an assessment ofthe
current NSPS to determine whether or not to revise them because ofPMo considerations. The assessment would identify the source categories that are significant emitters ofPM1oand condensible gases that form PMo in the ambient air after release from the stack, and the effectiveness ofthe controls required to reduce such emissions. The EPA would then proceed to revise the NSPS; giving highest priority to the most significant emitters ofPMo.

(2)Assess all NSPS for effectiveness in controlling PM1owhen reviewed periodically as required by section 111(b)(1)(B) ofthe Act; and

(3)Consider PMo in developing any future NSPS.

Several commenters stated that there is no inconsistency between having TSP-based NSPS requirements and having PMo as the indicator of particulate matter in the NAAQS. The particulate matter regulated by the NSPS is measured by Reference Method 5, and is probably closer in size to PMto than TSP afterpassing through the particulate matter control device almost invariably required on any source of such emissions subject to NSPS requirements.

The EPA acknowledges that NSPS for

sources ofparticulate matter are not based on the NAAQS indicator whether that indicator is TSP or PM10. Rather the standards are based on the effectiveness ofcontrol technology as measured by various reference test methods. Consequently, EPA does not intend to revise any NSPS at this time to account for revisions to the NAAQS. Since proposal, EPA has completed a draft screening study that identifies the NSPS

source categories that are significant emitters ofPMo. As part ofany future review of these NSPS under section 111(b)(1)(B] of the Act, EPA will consider the effectiveness ofthe NSPS in controlling PM1o.TheEPA will also consider PMo control in developing any future NSPS.

2. Economic Impact

The EPA determined that the particulate matter NAAQS proposal of March 20, 1984, was a major action and prepared a Regulatory Impact Analysis (RIA) as required by Executive Order (E.O.) 12291. However, the EPA determined that the proposal ofApril 2, 1985, as to how the standards will be implemented, did not in itselfresult in the economic effects set forth in Section Iof the E.O. as grounds for finding a regulation to be amajor rule.

A commenter disagreed with the Administrator's finding that the implementation proposal is not in itself

a major action, especially ifthe PMlo standards are selected from the low end of the range proposed.

The EPA recognized that selection of

a PMto standard in the lower part ofthe
range would be a major action. Accordingly, both the draft and final RIA account for those impacts. That analysis is discussed inthe final action

on new particulate matter standards that appears elsewhere in this Federal Register and is also available inDocket No. A-82-37. Since both the draft and final RIA account for the level of the NAAQS selected, the EPA determined that no separate study was required for related actions taken to implement the NAAQS.

3.Annual Source Emissions Reporting

The proposal required States to report 

### annually both particulate matter emissions data and PMo emissions data and specified procedures applicable to annual reporting of emissions for both 

### pollutants.

One State commented that it expects to estimate directly emitted amounts of PMo by multiplying total particulate
matter emissions [as reported to the National Emissions Data System (NEDS)] by PM 1osize fractions and added that, "EPA has PMo size fractions and could apply them to existing NEDS data for particulate matter." Based on this, and "the small contribution ofpoint sources," the State proposed that EPArequire PM1o emissions reporting only for sources where estimates are not made by applying a PM1ofraction to total particulate matter emissions.

Since the Administrator has determined that the indicator for the secondary standard should also be changed from TSPto PMo, EPA does
not require, as was proposed, annual reporting ofboth particulate matter emissions and PMo emissions. Required annual reporting of particulate matter emissions ends with State reporting of calendar year 1987 emissions. Required annual reporting ofPMo emissions begins with State reporting ofcalendar
year 1988 emissions. Since the reporting burden will not increase and since the ratio ofPMo emissions to particulate
matter emissions can vary greatly
among sources, it is better for the State
to choose the appropriate method of determining PMo emissions for each

source.

One State noted that a basic problem will be the establishment ofPMo emission factors for sources and default values where data do not exist. This State also said that the criteria for

source emissions reporting for PMo should be a lower number than for particulate matter "as proposed in the offset rule significant emission rate determination."

The EPA agrees that providing emissions factors and default values is critical to the States' capabilities to comply with EPA's PMo emissions reporting requirements. The EPA plans
to provide this and other necessary information to States by the time needed

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to meet the reporting requirements. The States' first annual reporting ofPMio emissions begins with the reporting of calendar year 1988 emissions. Regarding the differences in the criteria for emissions reporting and the criteria for "significant emission rate determination" in the offset rule, EPA agrees thata lowernumber forreporting PM1

### owould prove useful, since it could continue to require approximately the

same number ofsources to be reported. However, the reporting system is generally set up to track sources with 100tpy or more ofactual emissions regardless ofthe pollutant or the method used to measure that pollutant. This keeps the system limited to the very large sources ofeach pollutant, and EPA feels still provides the data needed for various types ofnational analyses at minimal resource costs.The "significance" values in the offset rule

serve a totally different purpose; they

are potential emissions (notactual) used
to determine whether an emissions increase at an existing source should be subject topreconstruction review. The threshold values for new source preconstruction review, alsoin the offsetrule, are generally 100 tpyfor major sources as definedby statute which fits in well with the reporting requirement. Therefore, the threshold limit for emission reporting is notbeing changed.

One commenter stated that reporting PMo emissions to the Hazardous and Trace Emissions System (HATREMS) with otherpollutants opens the doorfor false accusation ofemitters ofPMo as being emitters ofhazardous materials.

The EPA'sproposal to report PMo emissions to HATREMS was strictly for the purpose ofdata management. The NEDS does not have the capability to store data for bothparticulate matter and PM 1

### o.The EPA plans to replace both the NEDS and HATREMS with a new facility subsystem being developed as part ofthe Aerometric Inventory Retrieval System. The subsystem will be able to store and retrieve emission data

on all pollutants.
G. CommentsonProcedural Issues
1.Extension of theComment Period and PublicHearing

The proposal allowed a 60-day comment period for submission of written comments. It also provided an opportunity for oral comment and stated that persons wishing topresent oral testimony at a public hearing should notify EPAwithin 2 weeks of publication of the proposal.

Several commenters requested a 60- day extension in the comment period. One commenter made a request 45 days after the proposal notice requesting that EPAschedule a publichearing for a reasonable time (30days) after the close ofthe comment period.

The EPA granted a 30-day extension ofthe public comment period. The EPA believes that a 90-day comment period provided the public with ample opportunity to submit written comments. The EPAdid not hold a publichearing because only one commenter requested it, and the request was not madeuntil 30 days after thedeadline established in the proposal notice for suchrequests. The EPA feltthat one untimelyrequest did not indicate sufficient interest to justify scheduling apublic hearing.
2.Reproposal

Because no scientific consensus existed on specific levels for the standards, and the analytical and policy basis formaking these decisions under the statute were limited and difficult to implement, the Administrator did not propose specific standard levels but proposed a range oflevels in the March 1984 proposal. The April2, 1985, proposal ofregulations forimplementing revised particulate matter standards also included a variety ofscenarios and implementation issues.The EPA proposed to implement a PMo primary standard under section 110 oftheAct rather than PartD.The SIP development policy proposed was essentially the

same as that promulgated today (i.e., dividing thecountry into Group 1, 11, and III areas). Implementation policiesfor a TSPsecondary standard were proposed forboth the section 110 and Part D pathways.

Several commenters felt that it was virtually impossible to comment on implementation oftherevised particulate matter NAAQS as proposed because ofthe numerous alternative scenarios, what tney termed undue complexity, and in places alleged incomprehensibility ofEPA's discussion ofits regulatory package.

The commenters listed several problem areas where they felt uncertainties mustbe resolved before an actual proposal on implementation issues could be published on which the public could meaningfully comment. Among these problem areas were: (1) Lack ofa reference method for measuring particulate matter stack emissions; (2) lack of specified numerical values for the PM,o primary standards; (3)lack ofa decision on whether the secondary standard would be expressed asTSP orPM,o,and the specific numerical value for the secondary standard; and (4)lack ofa clear legal "pathway" chosen to implement the revised standards. Thus, the commenters felt EPA should withdraw the April2,1985, proposal and rewrite, simplify, and repropose the PMo implementation action after final action on the standards.

The EPAagrees that the proposal presented many options. However, EPA believes that each option was discussed in detail and the publichad meaningful opportunity to comment on each option

even though they did not know which option EPA would eventually choose. The EPAcannot repropose the SIP implementing provisions after the NAAQS are finalized because the Act requires the Statesto implement the standards as soon as they become effective. The Act requires States to submit SIP's to EPAwithin 9 months of promulgation ofa standard. If EPA reproposed the SIP implementation regulations and policy when the NAAQS were promulgated, EPA could
not finalize them soon enough togive States time to develop their SIP submittals within 9 months.

VII. Regulatory and Environmental Impacts
A. RegulatoryImpactAnalysis

Under E.0. 12291, EPAmust determine whether a regulation is a "major rule" forwhich an RIA is required.The EPA has determined the particulate matter NAAQS revision is a major action, and has prepared a RIA which is discussed in that notice. This action addresses the implementation ofthe revised NAAQS and does not itselfresult in the economic effects set forth in Section I of the E.O. as grounds for finding this regulation to be a major rule.

B.Impacton SmallEntities

TheRegulatory FlexibilityAct requires that all Federal agencies consider the impacts of final regulations

on small entities, which are defined to be small businesses, small organizations, and small governmental jurisdictions (5U.S.C. section 601 et seq.). The EPA has considered the potential impacts ofrevising the particulate matter NAAQS on small entity groups and included a detailed discussion ofthat effort in Section V.F. ofthe RIA. Thereader isreferred to that discussion forfurther details.
C.ImpactonReportingRequirements

Therevisions to Parts 51 and 52 were submitted to the Office ofManagement and Budget (OMB) forreview as required by EO 12291. The reporting and recordkeeping provision addressed in thisnotice, moreover, have been submitted separately for review by OMB 24711

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### 24712 Federal. Register./ Vol. 52, No. 126 / Wednesday, July 1, 1987 / Rules and Regulations

under section 3504(b) ofthe Paperwork Reduction Act of'1980,U.S.C. 3501 et seq. The OMBcomments and EPA
responses to those comments are available for public inspection in the docket for this action.

List ofSubjects

40CFR'Part 51

Administrative practice and procedure, air pollution control, intergovernmental relations, reporting and recordkeeping requirements. hydrocarbons, ozone, carbon monoxide, sulfur oxides, nitrogen dioxide, lead, particulate matter, State implementation plans.

40CFRPart 52

Air pollution control, ozone, sulfur oxides, nitrogen dioxide, lead, carbon monoxide, hydrocarbons, particulate
matter.

Dated: June 2,1987. lUe M. Thomas, Administrator.

References

a. Tuerk, Edward F. (Acting Assistant Administrator for-Air and Waste. Management) "Guideline on SIP Development and New Source Review in Areas Impacted by Fugitive Dust." Memorandum to Regional Administrators. August 16, 1977.

b.Woodard, Kenneth R. U.S. Environmental Protection Agency, Plans and Policy Section. PM1oNonattainment Areas. Memorandum to David. Stonefield, Chief,Plans and Policy Section, February 1987.

c. U.S. Environmental Protection Agency. "PMo SIP Development Guideline." Office ofAir Quality Planning and Standards, Research. Triangle Park, N.C. EPA 450/2-86-001, February 1987.

d. U.S. Environmental Protection Agency. "Procedures for Estimating Probability ofNonattainment ofa PMo NAAQS Using Total Suspended Particulate Matter orPMo Data." Office ofAir Quality Planning and Standards, Research Triangle Park,N.C. EPA 450/ 4-86-017, December 1986.

e. Purdue, L. et.al. "Intercomparison of High-Volume Samplers at a Site with High Particulate Concentrations," JAPCA, Vol. 36, No. 8, August 1986, pp. 917-920.

f. U.S. Environmental Protection Agency. "Guideline on Exceptions to Data Requirements for Determining Attainment ofParticulate Matter Standards." Office ofAir Quality Planning and Standards, Research Triangle Park, N.C. September 1986. 

### g,Meyers, Sheldon [Director, Office of Air Quality Planning and Standards] Section 107 Designation Policy Summary,Memorandum to Directors of Air Management Divisions, Regions I-X, April 21, 1983.

h.Emison, Gerald A. [Director, Office ofAir Quality Planning and Standards] Total Suspended Particulate Redesignations. Memorandum to Directors ofAirDivisions, Regions I-X, September 30, 1985.

i.Hawkins, David G.[Assistant Administrator forAir and,Waste Management]. Model Letter Regarding State Designation ofAttainment Status. Memorandum to Regional Administrators. October 7,1977.

j.U.S.Environmental Protection Agency. "Review ofNational Ambient Air Quality Standards for Particulate Matter: Assessment ofScientific and Technical Information-OAQPS Staff Paper." Office ofAir Quality Planning and Standards, Research Triangle Park, N.C. EPA450-82001, NTIS PBB2-177874. pp. 14-51. 1982.

m. U.S.Environmental Protection Agency. "An Examination of 1982-1983 Particulate Matter Ratios andTheir Use in theExamination ofPMo NAAQS Attainment Status." Office ofAir Quality Planning and Standards, Research Triangle Park,N.C. EPA 450/ 4-85-010. August 1985.

n.U.S. Environmental Protection Agency. "Ambient Monitoring Guidelines forPrevention ofSignificant Deterioration (PSD)." Office ofAir QualityPlanning and Standards, Research Triangle Park, N.C. EPA 450/ 4-87-007, May 1987.

o. U.S. Environmental Protection Agency. "Receptor Model Source Composition Library." Office ofAir QualityPlanning and Standards, Research Triangle Park,N.C. EPA450/ 4-85-002. November 1984.



### p.U.S. Environmental Protection Agency. "Compilation ofAirPollutant Emission Factors, Fourth Edition, Volume I,Supplement A." Office ofAir Quality Planning and Standards, Research Triangle Park, N.C. October 1986.

q. U.S. Environmental Protection Agency. "Receptor Model Technical Series, Volume IV-Technical Considerations in Source Apportionment by Particle Identification." Office ofAir Quality Planning and Standards, Research Triangle Park, N.C. EPA 450/4-83-018. June 1983,

r. U.S. Environmental Protection Agency. "Receptor Model Technical Series Volume Ill-User's Manual for Chemical Mass Balance Model." Office of Air Quality Planning and Standards,. Research Triangle Park, N.C. EPA 450/ 4-83-014, July 1983.

s. U.S. Environmental Protection Agency. "Protocol for Applying and Validating the CMBModel." Office of Air QualityPlanning and Standards, Research Triangle Park, N.C. EPA 450/ 4-87-010, May 1987.

t.U.S. Environmental Protection Agency. "Protocol for Reconciling Differences Among Receptor-and Dispersion Models." Office ofAir Quality Planning and,Standards, Research Triangle Park, N.C. EPA 450/ 4-87-008, May 1987.

u. U.S. Environmental Protection Agency. "Guideline on Air Quality Models (Revised)." Office ofAir Quality Planning and Standards, Research Triangle Park, N.C. EPA 450/2-78-027R, July 1986.

v.U.S.Environmental Protection Agency. "Regulatory Impact Analysis on the National Ambient Air Quality Standards for Particulate Matter." Office ofAir Quality Planning and Standards, Research Triangle Park, N.C. February 21, 1984:

PART 51-REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS

Forthe reasons set forth in the preamble, EPA amends Part 51 of Chaptdr IofTitle 40 of the Code of Federal Regulations as follows:

1. The authority citation for Part 51 is revised to read as follows:

Authority: This rulemaking ispromulgated under authority ofsections 101(b)(1), 110, 160-169, 

### 171-178, and 301(a) ofthe Clean Air Act 42 U.S.C. 7401(b)(1), 7410, 7470-7479, 7501-7508, and

### 7601(a).

2. In § 51.100, paragraphs (oo), (pp), (qq), (rr) and (ss) are added to read as follows: §51.100 Definitions.

(oo) "Particulate matter" means any airborne finely divided solid orliquid material with an aerodynamic diameter smaller than 100 micrometers.

(pp) "Particulate matter emissions"

means all finely divided solid or liquid material, other than uncombined water, emitted to the ambient air as measured by applicable reference methods, oran equivalent or alternative method, specified in this chapter, orby a test method specified in an approved State implementation plan.

(qq) "PM1o"means particulate matter with an aerodynamic diameter less than

or equal to a nominal 10 micrometers as measured.by a reference method based,

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### Federal Register / Vol. 52, No. 126 / Wednesday, July 1, 1987 / Rules and Regulations

on Appendix 

### IofPart 50 ofthis chapter and designated inaccordance with Part 53 of this chapter orby an equivalent method designated in accordance with Part53 of this chapter.

(rr} "PM1

### oemissions" means finely divided solid orliquid material, with an aerodynamic diameter less than or equal
to a nominal 10 micrometers emitted to the ambient air as measured by an applicable reference method, or an equivalent oralternative method, specified in this chapter orby a test method specified in an approved State implementation plan.

(ss) "Total suspended particulate"

means particulate matter as measured by the method described in Appendix B ofPart 50 ofthis chapter.

3.In §51.151, the third unnumbered subdivision beginning "sulfur dioxide and particulate matter combined" is removed and the second unnumbered subdivision beginning "particulate matter" is revised to read as follows:
§51.151 Significantharm levels.

a * * a *

PM 1 O--600 micrograms/cubic meter; 24- hour average.

* a a * a 4. In §51.165, the fourth entry in the 

### listin paragraph (a)(1)(x) is removed and paragraph (b) is revised to read as follows: §51.151 Permit requirements.



### (b)(1) Each plan shall include a preconstruction review permitprogram
orits equivalent to satisfy the requirements -f section 110(a)(2)(D)(i) of the Act for any new major stationary

source or major modification as defined in paragraphs (a](1) (iv) and (v) ofthis section. Such a program shall apply to any such source ormodification that would locate in any area designated as attainment orunclassifiable for any national ambient air quality standard pursuant to section 107 ofthe Act, when itwould cause or contribute to a violation ofany national ambient air quality standard.

(2)A major source ormajor modification willbe considered to cause
orcontribute to a violation ofa national ambient air quality standard when such

source ormodification would, at a minimum, exceed the following significance levels at any locality that does not orwould not meet the applicable national standard:

Averaging time (hours) Annual
24 8 3 1

Pollutant

S0

.......................... 1.0 .g/m3

................ 5 pg/m

.................... .............................. / 25 i n/m 3

................. PM.

........................ 1.0 Pg/m

............... 5 Pg/m

................... .............................. NO.

.......................... 1.0 pg/m

................ ................. ............................... CO

........................................................... .............................. 0.5 mg/m3

............................... 2 mg/m

(3)Such aprogram may include a provision which allows a proposed major source or major modification subject to paragraph (b) ofthis section
to reduce the impact ofits emissions
upon air quality by obtaining sufficient emission reductions to, at a minimum, compensate for its adverse ambient impact where the major source or major modification would otherwise cause or contribute to a violation ofany national ambient air quality standard. The plan shall require that, in the absence ofsuch emission reductions, the State or local
agency shall deny the proposed construction.

(4] The requirements ofparagraph (b) ofthis section shall not apply toa major stationary source or.major modification with respect to a particular pollutant if the owner or operator demonstrates that, as to that pollutant, the source or modification is located in an area designated as nonattainment pursuant
to section 107 oftne Act. 5.In §51.166, paragraph (a)(6)(i) is revised, the fourth entry in the list in paragraph (b){23)(i) isrevised, the entries under the headings "Particulate matter" in the tables in paragraphs (c) and (p)(4) are revised, paragraphs (i)(8)(i) (c), (f), (h), and (1)are revised, and new paragraph (i)(10) is added to read as follows: 

### §51.166 Prevention of significant deterioration ofair quality.



### (a) a a a (6) aa * (i) Any State required to revise its implementation plan by reason ofan amendment to this section, including any amendment adopted simultaneously with this paragraph, shall adopt and submit such plan revision to the Administrator for approval within 9 months after the effective date ofthe

new amendments.



### (b) a a a (23)(i) a a a Particulate matter: 25tpy ofparticulate
matter emissions. 15 tpyofPMo emissions.

* * * * *



### (c) * * *

Maximum allowable increases Pollutant (micrograms per cubic meter)

Class I Particulate matter:

TSP, annual geometric mean

........................ 5 TSP, 24-hr maximum

................................... . 10

Class II Particulate matter: 

# I

TSP, annual geometric mean

........... *........... 19 TSP, 24-hr maximum

....................................... 37 .80

Class IIn Particulate matter.

TSP; annual geometric mean

........................ 37 TSP, 24-hr maximum

....................................... 75

*i * * a

(8) a a *
(c)Particulate matter-l0 ,g/m 3 TSP, 24-hour average.-10 ;g/m3 PMlo, 24- 

### hour average.

* * * * *

(j)Lead--O.1 tg/ms

,3-month average.

, a *r * *

(h)Beryllium--0.001 t.g/m 3

,24-hour
average:

(I) Hydrogen sulfide-0.2 ikg/m3, 1- hour average:

(10) IfEPA approves a plan revision under §51.166 as ineffect before 'July 31, 1987 , any subsequent revision which
meets the requirements ofthis section
may contain transition provisions which parallel the transition provisions of §52.21 (i](11)(i)(iii), and (m)(1) (vii) and (viii) of this chapter as in effect on that date, these provisions being related to monitoring requirements for particulate
matter. Any such subsequent revision
may not contain any transition provision which in the context of the revision would operate any less stringently than would its counterpart in §52.21 of this chapter.

* a a *t *

(p) (4) * * *

Maximum allowable increases Pollutant (micrograms per

cubic meter)

Particulate matter:

TSP, annual geometric mean

............................ 19 TSP, 24-hr maximum

.......................................... . 37 

### 24713

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### 24714 Federal Register / Vol. 52; No. 126 / Wednesday, July 1, 1987 / Rules and Regulations

Maximum allowable Increases Pollutant (micro. grams per

cubic meter)

* , * * *

6. In 

### §51.322, paragraphs (a)(1) and, (b](1) are revised to read as follows: §51.322 Sources subjectto emissions reporting.

(a) * * * (1)For particulate matter. PMo, sulfur oxides, VOC and nitrogen oxides, any facility that actually emits a total of90.7 metric tons (100 tons)per yearor more ofany one pollutant. For particulate
matter emissions,,the reporting requirement ends with the reporting of calendar year 1987 emissions. For PMo emissions, the reporting requirement begins with the reporting ofcalendar
year 1988 emissions.

* * * * *



### (b) * * * (1) For particulate matter. PMio, sulfur oxides,, VOC and nitrogen oxides. 22.7 metric tons (25 tons) per yearor more. For particulate matter, the reporting requirement ends with the reporting of calendar year 1987 emissions. ForPMio, the reporting requirement begins with thereporting ofcalendar year 1988 emissions.

* * * * *

7. In § 51.323; paragraphs (a)(1] and (a)(2) are revised and paragraph (a)(3) Is added to read as follows: §51.323 Reportable emissions data and Information.



### (aJ; * * * (1),Emissions:ofparticulate matter;, sulfur oxides, carbon monoxide, nitrogen oxides, and VOC as specified: by AEROS Users Manual,.Vol. II (EPA 450/2-76-29, OAQPS No. 1.2-039) to be coded into the National Emissions Data Systempoint source coding,form,

(2) Emissions oflead or lead compounds measured as elemental lead

as specified by,AEROS Users Manual, Vol. II(EPA 45/2-76-029, OAQPS No. 1.2-039) to be coded into the Hazardous and Trace Emissions System points

source coding forms, and

(3)Emissions ofPMo as will be specified in a future guideline.

* * *. * *.

8. In Appendix L, paragraphs 1.1 (b), (c), and (d) are amended by removing the unnumbered subdivisions beginning
"SO2 and particulate combined" and by revising the unnumbered subdivisions beginning "Particulate" to read as follows: 

### Appendix L--Amended]

APPENDIX L-EXAMPLE REGULATIONS FOR PREVENTION OF AIRPOLLUTION EMERGENCY EPISODES

1.1 **. 

### (b) * * * PM1o-350 Ag/m3, 

### 24-houraverage. 

### c) * **
PMo-420pg/m 3

,24-hour average. 

### (d) *** 

### PM1o-500';Lg/m3 ,

### 24-hour average.

Appendix S-[Amendedl

9. In Appendix 9, the fourth line 

### beginning "Particulate matter" in the list in section 11.A.10(i) is amended by adding the words "ofparticulate matter emissions" after the words "25tpy."

* * * * *



### PART 52-APPROVAL AND PROMULGATION OF IMPLEMENTATION, PLANS

Forthe reasons set out in the 

### preamble, Part 52 ofChapter IofTitle 40 ofthe Code ofFederal Regulations is amended as follows:

1.The authority citation forPart 52 continues to read as follows:

Authority: 42 U.S.C. 7401-7642.



### 2. In §52.21, the fourth item in the table in paragraph (b)(23)(i) is revised; theentries under theheading. "Particulate matter" in thetables in paragraphs (c) and (p)(5) are revised; paragraphs (i)(4) (ix)and (x)are added; the third, sixth, eighth, and twelfth items in thelist in paragraph (i)(8)(i) are revised; paragraph (i)(11), and paragraphs (m)(1)(vii) and (viii) are added; and paragraph (w)(2) is revised

as follows:

§52.21 Prevention of significant deterioration of airquality.

* * * * *



### (b)Definitions. *** 

### (23)(i) * * *
Particulate matter: 25 tpy ofparticulate
matter emissions; 15 tpyofPMro emissions.

* * * * *



## (c) * * *

Maximum allowable increases Pollutant (micrograms per cubic

meter),

Class I

Particulate matter:

TSP, annual geometric mean

........................ 5 TSP, 24-hr maximum

....................................... . . 0 Maximum allowable increases Pollutant (micrograms per cubic meter)

Class It

Particulate matter.

TSP, annual geometric mean

........................ 19 TSP, 24-hr maximum

....................................... 37,

Class Ill

Particulate matter.

TSP, annual geometric mean

........................ 37 TSP, 24-hv maximum.

...................................... 75

t * * * *



## (i}* * *

(4) *** (ix)The source or modification was not subject to §52.21, with respect to particulate matter, as in effect before July 31, 1987, and'the owner or operator:

(a) Obtained all final Federal, State, and local preconstruction approvals or permits necessary under the applicable State implementation plan before July 31, 1987.



### (b)Commenced construction within 18 months after July 31, 1987, or any earlier time required under the State implementation plan: and

(c)Did not discontinue construction for a period of 18months or more and completed construction within a reasonable period oftime;

(x)The source ormodification was subject to 40 CFR 52.21, with respect to particulate matter, as in effect before July 31, 1987 and the.owner or operator submitted an application for apermit under this section before that date, and the Administrator subsequently determines that the application as submitted was complete with respect to the particulate matter requirements then in effect in.this section. Instead, the requirements ofparagraphs (j)through (r) ofthis section that were in effect before July 31. 1987 shall.apply to such

source or modification.

• * * (8)

... 

## (i) * * *

Particulate matter

10 1Lg/m 3 ofTSP,24-hour average: 10 Jug/m 3 ofPMto. 24-hour average:

* a * * *

Lead--0.1 ,±g/m 8

, 3-month average:

* * * * a

Beryllium--0.001 pg/m 3

,24-hour
average;

* * * * *

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### Federal Register / Vol. 52, No. 126 / Wednesday, July 1, 1987 / Rules and Regulations

Hydrogen sulfide--0.2 g/m 3



### ,1-hour average;

(11)(i) Atthe discretion ofthe Administrator, the requirements for air quality monitoring ofPMto inparagraphs (m)(1)(i]-(iv) ofthis section may not apply to a particular source or modification when the owner or operator of the source ormodification submits an application for a permit under this section on or before June 1, 1988 and the Administrator subsequently determines that the application as submitted before that date was complete, except with respect to the requirements for monitoring particulate matter in paragraphs (m](1)(i)-iv).



### (ii)The requirements for aif quality monitoring ofPMio in paragraphs (m](1) (iii) and (iv)and (m](3) ofthis section shall apply to a particular source or modification ifthe owner oroperator of the source ormodification submits an application for a permit under this section after June 1,

### 1988and no later than December 1,1988. The data shall have been gathered over atleast the period fromFebruary 1,1988 to the date the application becomes otherwise complete in accordance with the provisions setforth under paragraph (m)(1)(viii) ofthis section, except thatif the Administrator determines that a complete and adequate analysis canbe accomplished with monitoring data over

a shorter period (not to be less than4 months), the data that paragraph (m)(1)(iii) requires shall have been gathered over that shorter period.

* * * * *

(in)Airqualityanalysis. 

### (1)* * * (vii)For any application that becomes complete, except as to the requirements ofparagraph (m)(1) (iii) and (iv) pertaining toPMo, after December 1, 1988 and no later than August 1, 1988 the data that paragraph (m)(l)(iii) requires shall nave been gathered over at least the period fromAugust 1,1988 to the date the application becomes otherwise complete. except that ifthe Administrator determines that a complete and adequate analysis can be accomplished with monitoring data over

a shorter period (not'to be less than 4 months), the data that paragraph (m)(1)(iii) requires shall have been gathered over that shorter period.

(viii) With respect to any requirements for air quality monitoring ofPMio under paragraphs (i)(11) (i)and (ii] ofthis section, the owner or operator ofthe source ormodification shall use a monitoring method approved by the Administrator and shall estimate the ambient concentrations ofPMio using the data collected by such approved monitoring method in accordance with estimating procedures approved by the Administrator.

* * * * *

(p) *,, 

### (5) * **

Maximum allowable increases Pollutant (micrograms per

cubic meter)

Particulate matter TSP, annual geometric mean

................................ .. 19 TSP 24-hr maximum

................................. 37

* * * * *

(w)Permit rescission. (2)Any owner oroperator ofa stationary source ormodification who holds a permit for the source or modification which was issued under § 52.21 as in effect on July 30, 1987, or any earlier version ofthis section, may request that the Administrator rescind the permit or a particular portion ofthe permit.

* * * * *
§52.24 [Amended]

3.In § 52.24,paragraph (f)(10) is amended by removing the fourth entry, beginning "Particulate matter," from.the list of significant emission rates. [FR Doc. 87-13709 Filed G-30-87; 8:45 am]

BILLING CODE 6560-50-M 

### 24715

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