April 14, 1998 

MEMORANDUM 

SUBJECT: Potential to Emit (PTE) Guidance for Specific Source Categories 

FROM: John S. Seitz, Director /s/ 

Office of Air Quality Planning and Standards, OAR (MD-10) 

Eric Schaeffer, Director /s/

Office of Regulatory Enforcement, OECA (2241A)

TO: See Addressees 

This memorandum provides guidance for addressing the minor source status under the 

Clean Air Act (Act) for lower-emitting sources in eight source categories. 

Background Information 

Many Act requirements apply only to major sources with a potential to emit air pollutants 

at levels greater than a given amount. The Environmental Protection Agency (EPA), in its current 

regulations, defines a source’s potential to emit air pollutants as follows: 

“Potential to emit” is the maximum capacity of a stationary source to emit under its 

physical and operational design. Any physical or operational limitation on the source to 

emit an air pollutant, including air pollution control equipment and restrictions on hours of 

operation, or on the type or amount of material combusted, stored, or processed, shall 

be treated as part of its design if the limitation is enforceable by the (EPA) 

Administrator.”1 

1

The EPA is currently reviewing the requirement in EPA’s regulations that limitations 

must be federally enforceable in order for sources to take credit for those limits. Because this 

review is not yet complete, and is the subject of an upcoming rulemaking, the EPA has developed 

interim policies on this issue. The following policy memorandums describe EPA’s interim 

policies: “Release of Interim Policy on Federal Enforceability of Limitations on Potential to Emit” 

(January 22, 1996) and “Extension of January 25, 1995 Potential to Emit Transition Policy” 

(August 27, 1996). The EPA describes the ways a State or local limit achieves “federally 

enforceable” status in a 1995 policy memorandum, "Options for Limiting the Potential to Emit 

(PTE) of a Stationary Source Under Section 112 and Title V of the Clean Air Act" (January 25, 

1995). 
2

Often, in describing the overall stationary source population regarding potential-to-emit issues, 

EPA groups sources into three general types: 

(1) Major sources - those that actually emit major amounts of air pollutants, or have the 

potential to do so; 

(2) “True minor”2 (also called “natural minor”) sources - those that do not have the 

physical or operational capacity to emit major amounts (even if the source owner and regulatory 

agency disregard any enforceable limitations); and 

(3) “Synthetic minor” sources - those that have the physical and operational capability to 

emit major amounts, but are not considered major sources because the owner or operator has 

accepted an enforceable limitation. 

Many sources have the “capacity” to emit major amounts of air pollutants, but actually 

emit amounts that are much lower than the major source threshold. For such sources, States and 

local permitting agencies provide opportunities to obtain limits on their potential to emit through 

construction permit programs, operating permits, general permits applicable to multiple sources, 

State implementation plans (SIP), and other mechanisms. 

There are two overall approaches that States and local agencies can use to establish 

enforceable emission limits which ensure that a source’s potential emissions are below the major 

source threshold. Using the first approach, case-by-case permitting, agencies create terms and 

conditions tailored to a given plant site. This approach is essential for complex sources 

warranting close scrutiny, such as sources that comprise many different sources and source types, 

and sources that limit their emissions to near-major amounts. Under the second approach, 

generally appropriate for less complex sources, States and local agencies create a standard set of 

terms and conditions for many similar sources at the same time. The terms air quality agencies 

use to describe this approach include “general permits,” “prohibitory rules,” “exclusionary rules,” 

and “permits-by-rule.” (From this point on, rather than to repeat each of these terms, this 

guidance will use the term “prohibitory rule” for the latter three terms.) For a general permit, the 

permitting agency establishes a standard set of terms and conditions, and then incorporates those 

terms and conditions into the general permit. Sources wishing to be subject to the general permit 

must provide a notification to the permitting agency, and must comply with the standard terms 

and conditions. From the source’s perspective, the administrative procedure for receiving a 

general permit is typically much more streamlined than receiving a case-by-case permit. State 

“prohibitory rules” are similar to general permits, but States or local agencies put them in place 

with a regulation development process rather than a permitting process. 

2

The Act requirements for criteria pollutant programs refer to nonmajor sources as “minor 

sources,” while the air toxics program in section 112 refers to nonmajor sources as “area 

sources.” For purposes of this discussion, the term “minor” means all nonmajor sources. 
3 

What Is The Purpose Of This Guidance Memorandum? 

The EPA issues this guidance to assist States and local agencies in efficiently creating 

potential-to-emit limits for small sources, and to assist States and source owners in identifying 

sources that are minor sources without additional limits. Where States and local agencies need 

and use this guidance, small business owners will achieve greater certainty that EPA, States and 

local control agencies, and the public do not consider them major sources under the Act. 

Trade groups for a number of industries, typically those representing small business 

owners, have informed the EPA that these owners have significant uncertainties and confusion 

over their major or minor source status. These groups have also indicated to EPA that they 

would prefer that EPA give explicit guidance showing with certainty how a source can be 

considered a natural minor or synthetic minor, rather than for source owners to be left with 

continuing uncertainty. 

Today’s guidance addresses eight specific industry categories. The guidance provides 

technical information useful in devising potential-to-emit limits for small sources in the included 

industries. A State may find this information particularly useful for creating generic potential-toemit limits in prohibitory rules and general permits for numerous similar, small sources in an 

industry. 

The EPA has developed this guidance as a pooled technical effort with the State and 

Territorial Air Pollution Program Administrators (STAPPA) and the Association of Local Air 

Pollution Control Officials (ALAPCO). The EPA hopes that this information-sharing exercise 

will help to reduce uncertainty and help to foster technical consistency among permitting agencies. 

While this guidance summarizes the results of a significant amount of technical work, and 

should provide information readily usable by permitting agencies, EPA also recognizes that many 

States and local agencies have already addressed issues related to many categories discussed in 

this memorandum. Additionally, States and local agencies may possess State-specific emissions 

information for given source types. It is not EPA’s intent to imply that the screening cutoff levels 

described in this guidance are the only limitations that would be appropriate for a given type of 

sources in a given State or local area. The EPA does not intend that these calculations should 

result in the only values that EPA would find acceptable. Also, EPA does not intend to imply that 

calculations previously approved by the EPA in prohibitory rules or general permits must be 

revisited to conform to this guidance. 

In providing guidance that should help provide easy ways for sources to clarify that they 

are minor sources, the EPA is not intending to imply that minor sources are not important air 

quality sources. Readers should not interpret this guidance as making any judgment about the 

wisdom of emission control measures targeted at minor source categories. 
4 

What Types Of Source Categories Are Included In This Guidance? 

In identifying source categories to be covered within this guidance, the EPA included 

those categories for which a single type of activity tends to dominate emissions, and for which 

most sources in the category actually emit at levels well below their potential, and well under the 

major source thresholds. For sources with numerous categories at the plant site and/or that emit 

amounts that are just below the major source threshold, EPA believes that there is generally no 

feasible way to ensure their minor source status without a case-by-case permitting process. In 

addition, categories covered by this guidance tend to be those for which the parameters that affect 

emissions are relatively easy for EPA to describe and characterize. With some exceptions, this 

guidance does not cover categories involving control equipment. 

Which Specific Source Categories Are Included? 

Eight source categories are included: 

(1) gasoline service stations; 

(2) gasoline bulk plants (bulk plants are small bulk gasoline distribution facilities that 

distribute less than 20,000 gallons per day, and that receive gasoline by truck rather than by rail or 

barge); 

(3) boilers (specifically, the guidance addresses natural gas and oil combustion in 

industrial boilers having a capacity of 100 million BTU/hour or less); 

(4) cotton gins; 

(5) coating sources; 

(6) printing, publishing and packaging operations; 

(7) degreasers using volatile organic solvents; 

(8) hot mix asphalt plants. 
5

What Guidance Does EPA Provide For Those Categories? 

In the attached tables, EPA provides guidance in the form of operational cutoffs. The 

tables contain cutoffs that States and local agencies can use as limits in general permits and 

prohibitory rules.3 

How Did EPA Calculate The Cutoffs? 

The EPA’s calculations are discussed in a separate document attached to this guidance 

memorandum entitled “Technical Support Document for Lower-Emitting Source Guidance 

Memorandum Documentation of Emission Calculations.” For some categories, calculations were 

easy to make because the amount of pollutant used equates to the amount of pollutant emitted. 

For others, EPA needed to make more difficult technical judgments to make the calculations. In 

about half the cases, EPA relied on AP-42 emission factors as part of the technical basis for 

calculating the cutoffs. It is important to note that the AP-42 factor was not the entire basis for 

the calculation, and that the calculations leave a margin, generally about 50 percent to account for 

uncertainty in the emissions estimate.4 

3

For categories with annual limits, the cutoffs are listed as values not to be exceeded 

during any rolling 12-month period. The EPA is accepting, on an interim basis, the use of a 12-

month period, rather than the shorter time periods recommended by EPA’s June 1989 policy 

memorandum “Guidance on Limiting Potential to Emit in New Source Permitting,” given that the 

guidelines provide for cutoffs at levels nominally 50 percent of the major source threshold. 

Please note that EPA will be revisiting issues in an upcoming rulemaking related to the averaging 

times of potential-to-emit limits, including those for prohibitory rules and general permits. 

4

The EPA reiterates its position that emission factors, such as those in EPA’s AP-42 

compilation, are based upon the average of the values from available testing, and are not generally 

recommended as the approach to characterizing emissions from any given source for purposes of 

applicability determinations. The EPA believes, however, for the purposes of this guidance, that 

in a number of cases emission factors provide the only available means from which a cutoff could 

be determined. Rather than eliminate any such source category from consideration under this 

memorandum, the EPA feels that a reasonable approach is to make use of the AP-42 emission 

factors, building in a margin of error to account for the uncertainty in the data. The EPA believes 

that this approach should ensure that there is a low probability that any potentially major-emitting 

source would escape review. For source categories addressed by the guidance, which tend to be 

dominated by low-emitting sources for which source-specific emission factor data are not likely to 

be generated, the EPA believes this to be a reasonable approach. However, to the extent that 

source-test data, or other information indicate that the emission factors, or other assumptions 

made in calculating the limits are not appropriate for a specific source within a category, the 

source and permitting authority should not apply to this guidance. The EPA has not changed its 

position that such emission factors are not an acceptable approach for large industrial facilities. 

Finally, the EPA recognizes that as the emission factors used as the basis for the guidance are 

updated, it will be necessary to review the calculations in light of the revised factors to determine 

whether the guidance should be amended. 
6 

Similarly, the EPA believes that for nearly all source categories, even those that are simple 

enough to be good candidates for this guidance, there will usually be emitting activities that will 

be co-located with the activity described in the cutoff. Generally, these sources are a very low 

percentage of the emissions from the entire facility. Some examples of co-located sources are 

cold cleaners at gas stations, consumer product usage such as cleaners and white-out, lawn 

mowers, and small portable generators. To account for any such sources, EPA calculated the 

cutoffs leaving a small margin for any such sources that may be present. (Note that EPA does not 

mean to imply that overall these types of co-located sources are not environmentally significant-­

just that they probably have little bearing on whether a source is major or minor.) 

Will This Guidance Replace The EPA’s January 25, 1995 Transition Policy? If So, When Does 

That Transition Policy Expire? 

Many lower-emitting sources in categories addressed by today’s guidance may be 

operating under EPA’s transition policy, first announced in a policy memorandum of January 25, 

1995. The purpose of this transition policy was to alleviate concerns that sources may face gaps 

in the ability to acquire federally enforceable PTE limits. For sources lacking federallyenforceable limitations with low actual emissions, the transition policy provided a 2-year period 

extending from January 1995 to January 1997 (for sources lacking federally-enforceable 

limitations). On August 27, 1996, the EPA extended the transition period until July 31, 1998. 

During this transition period, State and local air regulators have the option of treating loweremitting sources as minor, if the source owner maintains adequate records to demonstrate that 

actual emissions are less than 50 percent of the major source threshold. Today’s guidance, in 

addressing sources that are common and numerous, should cover most of the lower-emitting 

sources that States may address by creating general permits or prohibitory rules. The EPA 

believes, however, that States will need a reasonable amount of time to implement today’s 

guidance. 

The EPA will release a separate guidance memorandum in the future to address issues 

related to the expiration of the transition policy. The transition policy involves other issues, in 

addition to those for sources emitting less than 50 percent of the major source threshold, and the 

EPA prefers to address all of those issues at the same time. 

How Does This Guidance Relate To State And Local Minor Source Construction Permit 

Programs? 

This guidance is NOT intended to affect minor source new source review (NSR) 

programs. Those programs are necessary for attainment and maintenance of the national ambient 

air quality standards (NAAQS), and for generally managing and protecting air quality in a given 

location. These are considerations independent of whether a source is a “major” or “minor” 

source. In making any change to a minor NSR program, the State or local agency needs to 

address air quality impact considerations in addition to those discussed here. For example, an 

agency limit to ensure that a source is minor for sulfur dioxide (SO2) may involve fuel sulfur 
7 

limits. Because those same fuel sulfur limits could possibly lead to short-term exceedances of the 

SO2 standards, and the agency could not categorically exempt such a source from minor NSR 

without addressing those air quality impacts; it is important to note that the annual limits 

contained in the guidance, while ensuring that the source is not a “major source,” may not ensure 

that the source meets all short-term NAAQS. 

Does this Policy Create Any Rights or Obligations? 

The policies set forth in this memorandum are intended solely as guidance, do not represent final 

Agency action, are not binding on any party, and cannot be relied upon to create any rights 

enforceable by any party. 

How Is This Guidance Being Distributed? 

The Regional Offices should send this memorandum to State and local agencies within 

their jurisdiction. This memorandum and the accompanying technical support document are 

accessible from the Internet. The Internet location is the “Office of Air and Radiation (OAR) 

Policy Guidance” portion of EPA’s “technology transfer network (TTNWeb),” bulletin board, 

that is, http://www.epa.gov/ttn/oarpg. 

If There Is Something I Do Not Understand, Who Will Answer My Questions? 

Questions concerning specific issues and cases should be directed to the appropriate EPA 

Regional Office. If you are a source owner and have questions about this policy, you should 

direct questions concerning specific issues and source-specific cases to the appropriate State or 

local agency. The Regional Office staff with questions may contact Timothy Smith of the 

Integrated Implementation Group at (919) 541-4718, or Carol Holmes of the Office of 

Regulatory Enforcement at (202) 564-8709. 

Attachments 

cc: C. Holmes (2242A) 

T. Kelly (2131) 

J. Ketcham-Colwill (6103) 

T. Smith (MD-12) 

J. Walke (2344) 
Addressees:

Director, Office of Ecosystem Protection, Region I 

Director, Environmental Planning and Protection Division, Region II

Director, Air Protection Division, Region III

Director, Air, Pesticides, and Toxics Management Division, Region IV

Director, Air and Radiation Division, Region V 

Director, Multimedia Planning and Permitting Division, Region VI

Director, Air, RCRA and Toxics Division, Region VII

Assistant Regional Administrator, Office of Pollution Prevention, State, and Tribal Assistance,

Region VIII

Director, Air and Toxics Division, Region IX 

Director, Office of Air Quality, Region X 

Regional Counsels, Regions I-X

Director, Office of Environmental Stewardship, Region I

Director, Division of Enforcement and Compliance Assurance, Region II

Director, Enforcement Coordination Office, Region III

Director, Compliance Assurance and Enforcement Division, Region VI

Director, Enforcement Coordination Office, Region VII

Assistant Regional Administrator, Office of Enforcement, Compliance

and Environmental Justice, Region VIII

Enforcement Coordinator, Office of Regional Enforcement Coordination, Region IX
GUIDANCE FOR STATES AND LOCAL AGENCIES TO USE FOR 

GENERAL PERMITS AND PROHIBITORY RULES 

Table 1. Guidance For Gasoline Service Stations 

If your regulations 

require these types of 

controls . . . 

. . . and the 

major source 

cutoff in tons 

per year is . . . 

. . . then the EPA guideline for a 

prohibitory rule or general permit 

cutoff in gallons per month is: 

Uncontrolled 

Stage I vapor recovery 

Stage I and Stage II 

vapor recovery 

100 tpy VOC 

50 tpy VOC 

25 tpy VOC 

10 tpy VOC 

100 tpy VOC 

50 tpy VOC 

25 tpy VOC 

10 tpy VOC 

100 tpy VOC 

50 tpy VOC 

25 tpy VOC 

10 tpy VOC 

380,000 

190,000 

95,000 

38,000 

630,000 

310,000 

160,000 

63,000 

2,900,000 

1,500,000 

740,000 

290,000 

Table 1 applies to facilities for which 90 percent or more of volatile organic compounds (VOC) 

emissions come from gasoline service station operations. 

NOTES ON TABLE 1: 

1. There are probably very few uncontrolled gas stations in areas where the cutoff is 10, 25, and 

50 tons per year VOC because Stage I and Stage II vapor recovery is required by the Act. The EPA 

made the calculations for “uncontrolled” in these areas to address any small stations that may be 

exempted by State regulations. 

2. The EPA calculated the cutoff at 50 percent of major source threshold. The calculations are 

discussed in the technical support document. 
Table 1 Continued Page 2 

3. State and local prohibitory rules and general permits must require records sufficient to ensure that 

the cutoff can be enforced. The EPA guidelines on “practical enforceability” considerations are 

contained in a January 25, 1995 memorandum from EPA’s Office of Enforcement and Compliance 

Assurance (OECA) entitled “Guidance on Enforceability Requirements for Limiting Potential to Emit 

Through SIP and Section 112 Rules and General Permits.” 

4. Where the cutoffs are contingent on stage I and/or stage II vapor recovery, the EPA recommends 

that general permit and prohibitory rule limits include a cross-reference to the applicable stage I and 

stage II regulations. 
Table 1A. Guidance For Gasoline Stations Not Requiring Notifications 

Under General Permits and Prohibitory Rules 

If you own or 

operate a 

gasoline service 

station . . . 

. . . and the type of 

vapor recovery 

required by SIP 

regulations is . . . 

. . . and you are a 

State or local area 

whose major source 

cutoff for VOC in tons 

per year is: 

...then no formal 

notification is required by 

a State or local agency’s 

prohibitory rule or general 

permit, if the number of 

refueling positions is no 

more than: 

No controls 100 17 

No controls 50 9 

No controls 25 4 

No controls 10 2 

Stage I 100 29 

Stage I 50 14 

Stage I 25 7 

Stage I 10 3 

Stage I and Stage II 100 134 

Stage I and Stage II 50 67 

Stage I and Stage II 25 34 

Stage I and Stage II 10 13 
Table 1A Continued Page 2 

NOTES ON TABLE 1A: 

1. The EPA calculations (see attached technical support document) concluded that it is a reasonable 

likelihood that sources meeting the size cutoffs in table 1A would not exceed the suggested 

throughput limits in table 1. In addition, sources meeting this description already keep records on 

gasoline sales that agencies can use to confirm that the limits are not exceeded. The EPA, States and 

localities have readily available sources of information to identify existing gas stations. Based upon 

these considerations, the EPA considers sources meeting the size cutoffs in table 1A as a lower 

regulatory priority. Accordingly, the EPA suggests those gas stations meeting these size cutoffs may 

be exempted from notification requirements by State prohibitory rules and general permits. (If 

exempted, owners of these stations would not be required to submit a written notification accepting a 

throughput limit). 

2. The number of “refueling positions” means the number of cars that could refuel at the same time. 

For example, a typical service station island with two dispensers has three nozzles on each side of both 

dispensers. Such a two-dispenser design has four “refueling positions” because a maximum of four 

vehicles could be refueling at any given time. If the island had three dispensers with three nozzles on 

each side of each dispenser, this would be six refueling positions because six vehicles could refuel at 

once. 

3. The calculations for this table assume that the location where the gasoline refueling is a service 

station with only trivial emissions from other sources and does not contain other significant sources of 

emissions. Do not rely on this table unless gasoline loading and refueling emissions cause 90 percent 

or more of your VOC emissions. 
Table 2. Guidance For Bulk Gasoline Plants 

For bulk 

gasoline plants 

. . . 

If the major 

source cutoff is 

. . . 

. . . then the EPA guideline for a prohibitory 

rule or general permit cutoff is . . . 

[All areas] the basic definition of a bulk plant. That is, a 

source owner agreeing to limit the amount of 

gasoline loaded to no more than 20,000 gallons 

per day is a minor source. 

Table 2 applies to bulk distribution facilities for which 90 percent or more of VOC emissions come 

from bulk loading and unloading of gasoline. 

NOTES ON TABLE 2: 

1. This guideline is based upon calculations that presume that reasonably available control technology 

(RACT) controls are required in all ozone nonattainment areas (see attached technical support 

document). 

2. The calculations assume that the RACT regulations follow the control technique guideline (CTG), 

under which vapor balance is required for outgoing trucks when the bulk plant has a throughput 

greater than 4000 gallons per day. For areas with 10, 25, and 50 tons per year VOC major source 

cutoffs, the above guideline is sensitive to this assumption. If vapor balance is not required for 

outgoing trucks when the bulk plant has a throughput greater than 4000 gallons per day, prohibitory 

rules and general permits should contain a different cutoff that takes this into account. In any case, 

general permit and prohibitory rule limits at the 20,000 gallon limit should include a cross-reference to 

the applicable RACT regulation where such regulations are in place. 

3. State and local prohibitory rules and general permits must require records sufficient to ensure that 

the cutoff can be enforced. The EPA guidelines on “practical enforceability” considerations are 

contained in a January 25, 1995 memorandum from EPA’s OECA entitled “Guidance on 

Enforceability Requirements for Limiting Potential to Emit Through SIP and Section 112 Rules and 

General Permits.” 
Table 3. Guidance For Printing, Publishing And Packaging Operations 

For this type of 

printing, 

publishing and 

packaging 

operation . . . 

. . . and for this 

major source cutoff 

. . . 

. . . EPA’s guideline for a simplified screening approach 

in a general permit or prohibitory rule would limit usage 

to the following amounts in any 12-month rolling 

period*: 

Sheetfed 

(nonheatset) 

offset 

lithography 

100 tpy VOC 

50 tpy VOC 

25 tpy VOC 

10 tpy VOC 

25 tpy total HAP 

10 tpy single HAP 

14,275 gallons of cleaning solvent and fountain solution 

additives 

7125 gallons of cleaning solvent and fountain solution 

additives 

3550 gallons of cleaning solvent and fountain solution 

additives 

1425 gallons of cleaning solvent and fountain solution 

additives 

3333 gallons of all hazardous air pollutant (HAP) containing 

materials 

1333 gallons of material containing any one HAP 

Nonheatset web 

offset 

lithography 

100 tpy VOC 

50 tpy VOC 

25 tpy VOC 

10 tpy VOC 

25 tpy total HAP 

10 tpy single HAP 

14,275 gallons of cleaning solvent and fountain solution 

additives 

7125 gallons of cleaning solvent and fountain solution 

additives 

3550 gallons of cleaning solvent and fountain solution 

additives 

1425 gallons of cleaning solvent and fountain solution 

additives 

3333 gallons of all HAP containing materials 

1333 gallons of material containing any one HAP 
For this type of 

printing, 

publishing and 

packaging 

operation . . . 

. . . and for this 

major source cutoff 

. . . 

. . . EPA’s guideline for a simplified screening approach 

in a general permit or prohibitory rule would limit usage 

to the following amounts in any 12-month rolling 

period*: 

Heatset web 

offset 

lithography --

uncontrolled 

100 tpy VOC 

50 tpy VOC 

25 tpy VOC 

10 tpy VOC 

25 tpy total HAP 

10 tpy single HAP 

100,000 lbs of ink, cleaning solvent, and fountain solution 

additives 

50,000 lbs of ink, cleaning solvent, and fountain solution 

additives 

25,000 lbs of ink, cleaning solvent, and fountain solution 

additives 

10,000 lbs of ink, cleaning solvent, and fountain solution 

additives 

3333 gallons of all HAP containing materials 

1333 gallons of materials containing any one HAP 

Screen printers 100 tpy VOC 

50 tpy VOC 

25 tpy VOC 

10 tpy VOC 

25 tpy total HAP 

10 tpy single HAP 

14,275 gallons of the sum of: (a) solvent based inks; (b) 

cleaning solvent; (c) adhesives; and (d) coatings 

7,125 gallons of the sum of: (a) solvent based inks; (b) 

cleaning solvent; (c) adhesives; and (d) coatings 

3,550 gallons of the sum of: (a) solvent based inks; (b) 

cleaning solvent; (c) adhesives; and (d) coatings 

1,425 gallons of the sum of: (a) solvent based inks; (b) 

cleaning solvent; (c) adhesives; and (d) coatings 

3,333 gallons of all HAP-containing materials 

1,333 gallons of materials containing any one HAP 
For this type of 

printing, 

publishing and 

packaging 

operation . . . 

. . . and for this 

major source cutoff 

. . . 

. . . EPA’s guideline for a simplified screening approach 

in a general permit or prohibitory rule would limit usage 

to the following amounts in any 12-month rolling 

period*: 

Flexography and 

rotogravure --

water-based or 

UV-cured inks, 

coatings and 

adhesives 

100 tpy VOC 

50 tpy VOC 

25 tpy VOC 

10 tpy VOC 

25 tpy total HAP 

10 tpy single HAP 

400,000 lbs of the sum of: (a) inks; (b) coatings; and (c) 

adhesives 

200,000 lbs of the sum of: (a) inks; (b) coatings; and (c) 

adhesives 

100,000 lbs of the sum of: (a) inks; (b) coatings; and (c) 

adhesives 

40,000 lbs of the sum of: (a) inks; (b) coatings; and (c) 

adhesives 

3,333 gallons of all HAP-containing materials 

1,333 gallons of materials containing any one HAP 

Flexography and 

rotogravure --

solvent inks --

uncontrolled 

100 tpy VOC 

50 tpy VOC 

25 tpy VOC 

10 tpy VOC 

25 tpy total HAP 

10 tpy 

single HAP 

100,000 lbs of the sum of: (a) ink; (b) coatings; (c) 

adhesives; (d) dilution solvents; and (e) cleaning solvents 

50,000 lbs of the sum of: (a) ink; (b) coatings; (c) adhesives; 

(d) dilution solvents; and (e) cleaning solvents 

25,000 lbs of the sum of: (a) ink; (b) coatings; (c) adhesives; 

(d) dilution solvents; and (e) cleaning solvents 

10,000 lbs of the sum of: (a) ink; (b) coatings; (c) adhesives; 

(d) dilution solvents; and (e) cleaning solvents 

3,333 gallons of all HAP-containing materials 

1,333 gallons of materials containing any one HAP 

* Table 3 applies to facilities for which 90 percent or more of VOC and HAP emissions come from the 

listed type of printing, publishing, and packaging operation, and from the materials indicated in the 

right-hand column. In determining whether this screening approach can be used, be careful to ensure 

that VOC and HAP emissions from materials not listed in the right-hand column (or other VOC or 

HAP sources present at the facility) do not exceed 10 percent of the total facility emissions. 
If any of the screening levels is exceeded or if there is a combination of printing technologies (e.g., 

lithography and flexography, or water-based and solvent-based flexography operations) used in the 

same facility, then a more detailed approach is needed (see note 2). 

NOTES ON TABLE 3: 

1. These guidelines represent a simplified screening approach. This means that these cutoffs represent

conservative calculations that would ensure that printers accepting these screening cutoffs as limits

would be considered minor sources if records are kept of material usage. 

2. A more sophisticated system of prohibitory rule or general permit limit is possible for sources

exceeding these levels, but for which emissions remain well below the major source threshold. For

such sources, who are willing to keep records of not only material usage but also the content of those

materials, prohibitory rules may establish a 50 percent emissions cap. The technical support document

includes equations to use in establishing that sources would remain below the

50 percent limitation. Note that emission calculations under this approach would use the actual

density of each material used, rather than the “default” densities assumed in the technical support

document. This more detailed approach must be used where any of the screening levels are exceeded,

or there is a combination of printing technologies (e.g., lithographic and flexographic or water-based

and solvent-based flexographic) present in the same facility. 

3. The EPA is working on software that could be used by printers to demonstrate that emissions are

below the screening cutoffs, or below the 50 percent cap. 

4. State and local prohibitory rules and general permits must require records sufficient to ensure that

the cutoff can be enforced. The EPA guidelines on “practical enforceability” considerations are

contained in a January 25, 1995 memorandum from EPA’s OECA entitled “Guidance on

Enforceability Requirements for Limiting Potential to Emit through SIP and Section 112 Rules and

General Permits.” 

5. Note that the cutoffs for non-heatset sheetfeed and web-offset lithography do not require tracking

of ink usage. As noted in the attached technical support document, only a small portion of the VOC

content in ink is emitted for this type of printing, publishing, and packaging operation. Consequently,

the EPA expects that more than 90 percent of emissions will be covered even if ink usage was not

tracked. (Note that the screening approach can only be used if the materials in the right-hand column

constitute more than 90 percent of emissions). In addition, the screening levels in the right-hand

column are calculated at 50 percent of the major source threshold, and therefore provide a sufficient

“cushion” to account for ink emissions. 

6. Coatings use in printing and packaging operations are subject to the above table 3 cutoffs, rather

than those in table 4. 
7. The following industry trade groups have offered to provide their members with further 

information on this table: Gary Jones, Graphic Arts Technical Foundation (412) 741-6860; Marcia 

Kinter, Screenprinting and Graphic Imaging Association International (703) 359-1313; Dr. Doreen 

Monteleone, Flexographic Technical Association (516) 737-6020; Kelley Clark, Newspaper 

Association of America (703) 902-1833; Ben Cooper, Printing Industries of America (703) 519-8115; 

Monica McCabe, National Association of Printers and Lithographers (201) 444-6804. 
Table 4. Guidelines For Surface Coating 

For surface coating, 

the “limiting case 

pollutant” is . . . 

. . . and the EPA guideline for a simplified screening cutoff for 

prohibitory rules and general permits would limit usage of 

coatings to: 

10 TPY single HAP 250 gallons of coatings per month or 

3000 gallons of coatings per 12-month period 

[See note 4 for description of more detailed approach] 

Table 4 applies to facilities for which 90 percent or more of HAP emissions come from surface 

coatings. 

NOTES ON TABLE 4: 

1. These guidelines represent a simplified screening approach. This means that these cutoffs represent 

conservative calculations that would ensure that surface coaters accepting these screening cutoffs as 

limits would be considered minor sources, and would only need to keep records of material usage. 

2. The guidelines are derived in part from an assumption that 6 pounds per gallon as the worst-case 

value for any individual HAP. These guidelines should not be relied upon if the State or local agency 

or source has data indicating that coatings used could exceed this level. The EPA recommends 

including 6 pound per gallon individual HAP limit in general permits and prohibitory rules. 

3. “Coatings” means coatings plus diluents plus cleanup solvents. 

4. A more sophisticated system of prohibitory rule or general permit limits is possible for sources 

exceeding these levels, but for which emissions remain well below the major source threshold. For 

such sources, who are willing to keep records of not only material usage but also the content of those 

materials, prohibitory rules may establish a 50 percent emissions cap. 

5. State and local prohibitory rules and general permits must require records sufficient to ensure that 

the cutoff can be enforced. The EPA guidelines on “practical enforceability” considerations are 

contained in a January 25, 1995 memorandum from EPA’s OECA entitled “Guidance on 

Enforceability Requirements for Limiting Potential to Emit Through SIP and Section 112 Rules and 

General Permits.” 
Table 4A. Guidance For Auto Body Shops Not Requiring Notifications Under 

General Permits And Prohibitory Rules 

If you own this type of auto body 

shop . . . 

. . . then no formal notification is 

required by a State or local agency’s 

prohibitory rule or general permit, 

if: 

Business entirely, or almost 

entirely, for collision repairs 

. . . your shop has two or fewer bays 

devoted to painting. 

Substantial portions of business 

devoted to repainting entire 

vehicles 

. . . your shop has only one bay 

devoted to painting. 

All auto body shops .... your shop does not have the 

physical or operational capacity to do 

more than 50 jobs per week 

NOTES ON TABLE 4A: 

1. The values in this table are for facilities involved in automobile repair and are not appropriate for 

facilities capable of painting much larger surfaces, such as buses or earthmoving equipment. 

2. The values in this table assume that nearly all of the VOC and HAP emissions from your shop come 

from coatings (including diluents and cleanup solvents). Do not rely on this table if more than 90 

percent of your VOC and HAP emissions do not come from coatings, diluents and cleanup solvents. 

3. The EPA calculations (see attached technical support document) concluded that facilities meeting 

the above descriptions would have a reasonable likelihood of complying with the limits contained in 

table 4. Accordingly, the EPA suggests that these sources are a relatively low regulatory priority, and 

that sources meeting these guidelines may be exempted from notification requirements in State 

prohibitory rules or general permits. 

4. Facilities should not rely on these values in cases where the shop is capable of handling 

substantially more jobs per week than a typical facility. Caution should be given especially in using 

these values for facilities that routinely perform more than 50 jobs per week. 
Table 5. Guidelines For Degreasing Operations 

For degreasing 

operations . . . 

. . . for the following 

major source cutoff 

. . . 

. . . the EPA guideline for a simplified 

screening cutoff for prohibitory rules and 

general permits would limit usage of 

degreasing solvent (from the entire plant) 

in any 12-month rolling period to . . . 

10 TPY single HAP 

25 TPY total HAPs 

2200 gallons of any one solvent-containing 

material (if no halogenated solvents) 

1200 gallons (if contains perchloroethylene, 

1,1,1-TCA, methylene chloride, or TCE) 

AND 

5400 gallons of any combination of solventcontaining materials (if no halogenated 

solvents) 

2900 gallons (if halogenated included) 

Table 5 (except as noted in note 2 below) applies to facilities for which 90 percent or more of VOC 

and HAP emissions come from degreasing. 

NOTES FOR TABLE 5: 

1. These values were calculated originally by California agencies for the California model prohibitory 

rule (see attached technical support document). 

2. These cutoffs provide a simplified method for sources for which degreasing constitutes nearly all of 

the emissions from a given site. A more sophisticated approach to prohibitory rules or general permits 

is possible for sites having significant contributions from both coating and degreasing sources. Such 

an approach would involve a 50 percent “cap” on emissions with documentation of material content 

and usage. An example approach for documenting that emissions are under such a 
Table 5 continued Page 2 

“cap” is contained in an EPA policy memorandum of October 15, 1993 entitled "Guidance for State 

Rules for Optional Federally-Enforceable Emissions Limits Based on Volatile Organic Compound 

Use," issued by D. Kent Berry, Acting Director, Air Quality Management Division. 

3. State and local prohibitory rules and general permits must require records sufficient to ensure that 

the cutoff can be enforced. The EPA guidelines on “practical enforceability” considerations are 

contained in a January 25, 1995 memorandum from EPA’s OECA entitled “Guidance on 

Enforceability Requirements for Limiting Potential to Emit Through SIP and Section 112 Rules and 

General Permits.” 
Table 6. Guidance For Cotton Gins 

For cotton gins with 

the following 

configuration . . . 

... if the major cutoff 

for PM-10 is . . . 

. . . then the EPA prohibitory rule 

and general permit guideline for 

throughput, in bales of cotton 

ginned over a cotton ginning season, 

is . . . 

Cyclones on all 

exhaust points 

Screened drums or 

cages on battery 

condenser and lint 

cleaner, cyclones on 

all other exhausts 

100 tpy PM-10 

70 tpy PM-10 

100 tpy PM-10 

70 tpy PM-10 

90,000 bales 

63,000 bales 

72,000 bales 

50,000 bales 

Table 6 applies to facilities for which 90 percent or more of particles with an aerodynamic diameter 

less than or equal to a nominal 10 micrometers (PM-10) emissions come from cotton ginning 

operations. 

NOTES FOR TABLE 6: 

1. For a more detailed description of the two configurations listed above, please refer to EPA’s 

AP-42 document, section 9.7. 

2. State and local prohibitory rules and general permits must require records sufficient to ensure that 

the cutoff can be enforced. EPA guidelines on “practical enforceability” considerations are contained 

in a January 25, 1995 memorandum from EPA’s OECA entitled “Guidance on Enforceability 

Requirements for Limiting Potential to Emit Through SIP and Section 112 Rules and General 

Permits.” 

3. The EPA calculated the 72,000 and 90,000 ton cutoffs based upon the upper end of the range from 

available tests. EPA believes these numbers are very conservative (worse than the typical “worstcase”) and should ensure that there is a very low probability that a cotton gin limited to these levels 

would have a potential to emit major amounts. To reduce this probability even further, State and local 

agency prohibitory rules should ensure that the cutoff is not relied upon by the source in cases where: 

(1) the source owner, or a State or local agency has data for an individual source indicating major 

emissions at the cutoff; or (2) there are unique circumstances that would lead to greater emissions than 

for a typical plant design. 
Table 7. Guidance For Oil And Natural Gas-Fired Boilers With Capacity 

That Is No More Than 100 million BTUs per hour 

For boilers capable 

of burning . . . 

. . . if the major 

source cutoffs are . . . 

... then EPA’s guidelines for 

prohibitory rule and general permit 

cutoffs are the following 12-month 

rolling limits: 

NATURAL GAS 

ONLY 

100 tpy NOX 

100 tpy SO2 

50 tpy NOX 

100 tpy SO2 

25 tpy NOX 

100 tpy SO2 

10 tpy NOX 

100 tpy SO2 

710 million cubic feet 

360 million cubic feet 

180 million cubic feet 

71 million cubic feet 

DISTILLATE OIL 

ONLY 

100 tpy NOX 

100 tpy SO2 

50 tpy NOX 

100 tpy SO2 

25 tpy NOX 

100 tpy SO2 

10 tpy NOX 

100 tpy SO2 

700,000 gallons 

700,000 gallons 

700,000 gallons 

500,000 gallons 

RESIDUAL OIL 

ONLY 

100 tpy NOX 

100 tpy SO2 

50 tpy NOX 

100 tpy SO2 

25 tpy NOX 

100 tpy SO2 

10 tpy NOX 

100 tpy SO2 

160,000 gallons 

160,000 gallons 

160,000 gallons 

160,000 gallons 
For boilers capable 

of burning . . . 

. . . if the major 

source cutoffs are . . . 

... then EPA’s guidelines for 

prohibitory rule and general permit 

cutoffs are the following 12-month 

rolling limits: 

NATURAL GAS 

AND DISTILLATE 

OIL ONLY 

100 tpy NOX 

100 tpy SO2 

50 tpy NOX 

100 tpy SO2 

25 tpy NOX 

100 tpy SO2 

10 tpy NOX 

100 tpy SO2 

630 million cubic feet AND 

600,000 gallons distillate 

320 million cubic feet and 

260,000 gallons distillate 

160 million cubic feet and 

130,000 gallons distillate 

65 million cubic feet and 52,000 

gallons distillate 

NATURAL GAS 

AND RESIDUAL 

OIL ONLY 

100 tpy NOX 

100 tpy SO2 

50 tpy NOX 

100 tpy SO2 

25 tpy NOX 

100 tpy SO2 

10 tpy NOX 

100 tpy SO2 

650 million cubic feet and 

160,000 gallons residual 

300 million cubic feet and 

160,000 gallons residual 

150 million cubic feet and 

160,000 gallons residual 

51 million cubic feet and 

51,000 gallons residual 

NATURAL GAS, 

RESIDUAL AND 

DISTILLATE 

100 tpy NOX 

100 tpy SO2 

50 tpy NOX 

100 tpy SO2 

25 tpy NOX 

100 tpy SO2 

10 tpy NOX 

100 tpy SO2 

650 million cubic feet and 

160,000 gallons residual 

300 million cubic feet and 

160,000 gallons residual 

150 million cubic feet and 

160,000 gallons residual 

51 million cubic feet and 

51,000 gallons residual 

Table 7 applies to facilities where 90 percent of air emissions come from oil and natural gas-fired 

boilers with a capacity less than 100 million BTUs per hour. 

NOTES FOR TABLE 7: 
1. For the combustion source categories listed above, please note that the tables cover limits for 

boilers only and the fuels listed only. These fuel use limits are not applicable to other types of 

combustion devices such as engines and gas turbines, and are not applicable to facilities combusting 

waste oil. 

2. The values listed in italics may be adjusted by States to take into account State and local fuel sulfur 

regulations. As explained in further detail in the technical support document, EPA calculated these 

values based upon worst-case sulfur content. Typically allowed sulfur-in-fuel values are less than 

those used in these calculations. 

3. State and local prohibitory rules and general permits must require records sufficient to ensure that 

the cutoff can be enforced. The EPA guidelines on “practical enforceability” considerations are 

contained in a January 25, 1995 memorandum from EPA’s OECA entitled “Guidance on 

Enforceability Requirements for Limiting Potential to Emit Through SIP and Section 112 Rules and 

General Permits.” 

4. The guidelines are for the combined fuel use for all boilers at a given facility. 
Table 7A. Boilers Not Needing Legal Limits On The Amount Of Fuel Burned 

If you own or operate a 

boiler or group of boilers, 

and are capable of burning 

the following . . . 

... and you are located in an 

area whose major source 

cutoff for NOX is the 

following . . . 

. . . then you are a minor 

source if the TOTAL 

COMBINED boiler 

capacity, in million BTUs 

per hour is no more than: 

Natural gas only 25, 50, or 100 tons per year 25 

Natural gas only 10 tons per year 10 

Distillate oil, or a 

combination of distillate fuel 

and natural gas 

[All areas] 10 

Residual oil, or a combination 

of residual oil 

[All areas] 5 

NOTES ON TABLE 7A: 

The calculations for this table are based upon calculations of nitrogen oxides (NOX) and SO2 

emissions. The calculations assume that most of the emissions of these pollutants from your plant 

come from boilers. Do not rely on this table unless boilers cause 90 percent or more of your NOX and 

SO2 emissions. 
Table 8. Guidance For Hot Mix Asphalt Plants 

For asphalt plants, 

the following 

pollutants are the 

“limiting case” and . . 

. 

...the EPA guideline for general 

permits and prohibitory rules is the 

following annual limit: 

100 tpy CO 

100 tpy SO2 

100 tpy PM10 

70 tpy PM10 

250,000 tons hot mix asphalt 

produced per 12-month rolling period 

Table 8 applies to facilities for which 90 percent or more of air emissions come from hot mix asphalt 

production, including associated fugitives. 

NOTES FOR TABLE 8: 

1. For asphalt plants, States must determine on a case-by-case basis whether the guidelines are 

appropriate for their situation because it is possible that particulates are the limiting pollutant for 

sources constructed before the 1973 applicability date for the new source performance standard 

(NSPS). The EPA could not, in developing this guidance, address the effect of each particulate SIP 

regulation for asphalt plants that may exist. Although EPA does not expect that there are many States 

or sources for which this is the case, these guidelines only cover sources subject to the NSPS unless 

the State has made a demonstration that the 250,000 ton cutoff assures minor source levels for preNSPS sources. 

2. State and local prohibitory rules and general permits must require records sufficient to ensure that 

the cutoff can be enforced. The EPA guidelines on “practical enforceability” considerations are 

contained in a January 25, 1995 memorandum from EPA’s OECA entitled “Guidance on 

Enforceability Requirements for Limiting Potential to Emit Through SIP and Section 112 Rules and 

General Permits.” 

3. The EPA calculated the 250,000 ton cutoff based upon AP-42 factors. Because the AP-42 factors 

are the averages of available tests, EPA included a margin to address sources whose emissions are 

greater than the average. State and local agency prohibitory rules should ensure that the cutoff is not 

relied upon by the source in cases where: (1) the source owner, or a State or local agency has data for 

an individual source indicating major emissions at the cutoff; or (2) there are unique circumstances 
Table 8 Continued Page 2 

(for example, the presence of a large on-site generator) that would lead to greater emissions than for a 

typical plant design. 

4. Do not interpret this table as having any implications for minor source permitting. For example, as 

noted in the technical support document, sources meeting the above limit have the possibility to cause 

2 short-term violations of the ambient air quality standards for SO .