Guidance on Removing Stage II Gasoline Vapor 

Control Programs from State Implementation 

Plans and Assessing Comparable Measures
EPA-457/B-12-001

August 7, 2012

Guidance on Removing Stage II Gasoline Vapor Control Programs from State 

Implementation Plans and Assessing Comparable Measures

Prepared By:

H. Lynn Dail, Environmental Scientist

State and Local Programs Group

Air Quality Policy Division

Glenn W. Passavant, Senior Mechanical Environmental Engineer

Assessment and Standards Division

Office of Transportation and Air Quality

U. S. Environmental Protection Agency

Office of Air Quality Planning and Standards

Research Triangle Park, NC 27711
ii

List of Selected Acronyms and Abbreviations

A/L air to liquid ratio

ARB Air Resources Board (California)

CAA Clean Air Act

CAPCOA California Air Pollution Control Officers Association

CF Compatibility Factor

EE Excess Vent Emissions

EPA Environmental Protection Agency

EVR California enhanced vapor recovery program

FR Federal Register

GDF gasoline dispensing facility

GPM gallons per month

GVWR gross vehicle weight rating

IUVP Input Use Verification Program

MOVES Motor Vehicle Emissions Simulator

NAAQS National Ambient Air Quality Standards

NESHAP National Emissions Standards for Hazardous Air Pollutants

NOX nitrogen oxides

OBD onboard diagnostics

ORVR onboard refueling vapor recovery

OTR Ozone Transport Region

RFP reasonable further progress

RFG reformulated gasoline

RVP Reid vapor pressure

SIP state implementation plan

VOC volatile organic compound

UST underground storage tank

VMT vehicle miles traveled

VRS vapor recovery systems
iii

Preface

On May 9, 2012, the EPA Administrator signed a notice of final rulemaking determining that 

onboard refueling vapor recovery (ORVR) systems are in widespread use throughout the motor 

vehicle fleet which was published in the Federal Register on May 16, 2012 (77 FR 28772). In 

that notice the Administrator also exercised her authority to waive the statutory requirement that 

Serious, Severe, and Extreme ozone nonattainment areas adopt and implement EPA programs 

requiring Stage II gasoline vapor recovery systems (VRS) at certain gasoline dispensing facilities 

(GDFs). Many states and local areas have previously adopted Stage II programs into their state 

implementation plans (SIPs). This guidance document provides both technical and policy 

recommendations to states and local areas on how to develop and submit an approvable SIP 

revision seeking to remove or phase-out an existing Stage II program. This guidance introduces 

methods and equations that could be used to calculate the emissions consequences of 

discontinuing Stage II control programs for purposes of demonstrating compliance with specific

CAA provisions in sections 110(l) and 193 governing EPA approval of SIP revisions. This 

document also includes new technical and policy guidance, updating that previously issued by 

EPA in 1995, for areas of the Ozone Transport Region (OTR) on implementing measures 

capable of achieving emissions reductions comparable to those achievable by ongoing 

implementation of Stage II controls.

Table of Contents

1. Introduction..............................................................................................................................................1

2. When can a state or a GDF stop implementing existing Stage II programs? ....................................3

2.1 What are the CAA requirements that govern EPA approval of a Stage II removal SIP revision? ....3

2.2 Complying with the “noninterference” clause (CAA section 110(l)) ................................................3

2.3 Complying with the OTR “comparable measures” requirement (CAA section 184(b)(2))...............5

2.4 Complying with the “general savings clause” for pre-1990 Stage II control programs (CAA section 

193)...........................................................................................................................................................7

3. Assessing Area-Wide Impacts on Vehicle Refueling Emissions.............................................................7

3.1 Discussion of Terms ..........................................................................................................................8

3.2 Parameters and Variables Related to Implementing Stage II VRS and ORVR...............................10

3.2.1 Terms for Estimating Area-Wide Stage II VRS Control Efficiency.........................................10

3.2.2 Terms for Estimating Area-Wide ORVR Control Efficiency...................................................13

3.3 Calculating Impacts on the Refueling Emission Inventory..............................................................13

3.3.1 Key Equation for Assessing and Demonstrating Compliance with the Noninterference 

Provisions of CAA Section 110(l) and the Comparable Measures Requirement of CAA Section 

184(b)(2) .............................................................................................................................................13

3.3.2 Key Equation for Assessing and Demonstrating Compliance with CAA Section 193.............14

3.3.3 Developing Area-Specific Values for the Terms Used in Equations 1 and 2 ...........................14

3.4 Example Calculations for Equations 1 and 2 ...................................................................................16

3.4.1 Example Scenario #1 ................................................................................................................16
iv

3.4.2 Example Scenario #2 ................................................................................................................17

3.4.3 Example Scenario #3 ................................................................................................................17

3.5 Calculating the Impact on the Area-Wide VOC Inventory..............................................................19

3.5.1 Terms for Calculating Tons VOC.............................................................................................19

3.6 States/Areas with Stage II but not Affected by 182(b)(3) or 184(b)(2)............................................21

4. Strategies and Considerations for Phasing Out Stage II Controls.........................................................22

4.2 Cost Considerations.........................................................................................................................22

4.3 Decommissioning issues..................................................................................................................23

4.4 Potential Emission Reduction Programs for GDFs..........................................................................23

5. Submission, Review and Approval of SIP Revisions............................................................................24

5.1 Elements of SIP Revision Package ..................................................................................................24

5.2 EPA SIP Review Process.................................................................................................................24

Table A-1 - Projected Penetration of ORVR in the National Gasoline Fueled Vehicle Fleet by Year ......25

Table A-2 - Monthly Average Dispensed Liquid Temperature ..................................................................26

Table A-3 - Seasonal Variation In Temperature Difference Between Vehicle Fuel Tank and Dispensed 

Fuel ...........................................................................................................................................................27

Table A-4 - Percent of 50 State Gasoline Consumption for Areas Covered by CAA Sections 182(b)(3) or 

184(b)(2).....................................................................................................................................................28

Table A-5 - Applicability of Clean Air Act Requirements to Areas Implementing Stage II Gasoline Vapor 

Recovery Programs for the Ozone NAAQS ...............................................................................................30

Table A-6 - Percent of State/Area GDF Dispensers Using Vacuum Assist Stage II Technology (June 

2012)...........................................................................................................................................................32

Table A-7 - Five –Month (May-September) Uncontrolled Displacement (non-ORVR) Refueling Emission 

Factors (g/gal).............................................................................................................................................33

Table A-8 - Input Data for States/Areas with Stage II but not Affected by 182(b)(3) or 184(b)(2) (July 

2012)...........................................................................................................................................................34

Table A-9 – MOVES 2012 Vehicle Class Age Distribution ......................................................................35
1. Introduction

Stage II VRS were adopted by some states beginning in the 1980s to meet the ozone 

National Ambient Air Quality Standards (NAAQS). Stage II and ORVR are two types of 

emission control systems that capture fuel vapors from vehicle gas tanks during refueling. Stage 

II and vehicle ORVR were initially both required by the 1990 Amendments to the CAA under 

sections 182(b)(3) and 202(a)(6), respectively. In some areas Stage II VRS has been in place for 

over 25 years, but was not widely implemented by the states until the early to mid-1990s as a 

result of the CAA requirements for Moderate, Serious, Severe, and Extreme ozone 

nonattainment areas and for states in the Northeast Ozone Transport Region (OTR) under CAA

section 184(b)(2). CAA section 202(a)(6) required EPA to promulgate regulations for ORVR for 

light-duty vehicles (passenger cars). The EPA adopted these requirements in 1994; at which 

point Moderate ozone nonattainment areas were no longer subject to the section 182(b)(3) Stage 

II requirement. However, some Moderate areas retained Stage II VRS requirements to provide a 

control method to comply with rate-of-progress emission reduction targets.1 ORVR equipment 

has been phased in for new passenger vehicles beginning with model year 1998, and starting in 

2001 for light-duty trucks and most heavy-duty gasoline-powered vehicles. ORVR equipment 

has been installed on nearly all (~99%) new gasoline-powered light-duty vehicles, light-duty 

trucks and heavy-duty vehicles since 2006.

During the phase-in of ORVR controls, which began in 1997, Stage II vapor recovery has 

provided volatile organic compound (VOC) reductions in ozone nonattainment areas and certain 

attainment areas of the OTR. Congress recognized that ORVR and Stage II would eventually 

become largely redundant technologies, and provided authority to the EPA to allow states to 

remove Stage II from their SIPs after EPA finds that ORVR is in widespread use. Effective May 

16, 2012, the date the final rule was published in the Federal Register (77 FR 28772), the EPA 

determined that ORVR is in widespread nationwide use for control of gasoline emissions during 

refueling of vehicles at gasoline dispensing facilities (GDFs). Currently, more than 75 percent of 

gasoline refueling nationwide occurs with ORVR-equipped vehicles, so Stage II programs have 

become largely redundant control systems and Stage II VRS achieve an ever-declining emissions 

benefit as more ORVR-equipped vehicles continue to enter the on-road motor vehicle fleet. In 

fact, in areas where certain types of vacuum-assist Stage II control systems are used, the limited 

compatibility between ORVR and some configurations of this Stage II hardware may ultimately

result in an area-wide emissions disbenefit. Therefore, EPA also exercised its authority under 

CAA section 202(a)(6) to waive certain federal statutory requirements for Stage II gasoline 

vapor recovery at GDFs.2 This decision exempts all new ozone nonattainment areas classified 

Serious or above from the requirement to adopt Stage II control programs. Similarly, any state 

currently implementing Stage II programs may decide to seek SIP revisions that, once approved 

by EPA, would allow them to phase out Stage II control systems. Appendix Table A-5 provides 

a list of states currently implementing Stage II programs under sections 182(b)(3) and 184(b)(2).

 

1 Kentucky, Tennessee, Michigan, Ohio, Virginia, West Virginia, Nevada, California, Oregon and Washington have 

implemented Stage II for some areas. If these states/areas included Stage II vapor control programs in their SIPs, 

they will have to amend their SIPs if Stage II is no longer required, and will have to address the provisions of CAA 

section 110(l).

2

77 FR 28772, May 16, 2012. Widespread Use for Onboard Refueling Vapor Recovery and Stage II Waiver.
2

Ozone nonattainment areas previously required under the CAA to have Stage II gasoline 

VRS on GDFs may choose to remove the requirement from their SIPs, but states may also retain 

their Stage II requirements if they wish. A small fraction of the on-road vehicle fleet is not 

covered by EPA’s ORVR regulations, so Stage II controls would not be redundant for such 

vehicles refueling in areas subject to existing Stage II programs. Even though Stage II controls 

are capable of achieving some small level of area-wide benefit for non-ORVR refueling events, 

they may become a less cost-effective method than other alternatives for addressing area-wide 

VOC emissions and, as noted above, may ultimately result in a disbenefit to air quality in the 

areas.

In order to phase out existing Stage II programs in SIPs, states would need to submit SIP 

revisions to EPA meeting applicable CAA requirements and receive approval from the EPA. 

States in the OTR remain obligated under CAA section 184(b)(2) to implement either a Stage II 

program or other measures capable of achieving emissions reductions comparable to those 

achievable by Stage II. The EPA issued guidance on this latter requirement in 1995, and is now 

updating that guidance to account for ORVR’s widespread use in the motor vehicle fleet and its 

increasing displacement of Stage II as the primary means of controlling refueling emissions

This guidance document contains the information needed for a state to conduct an

emissions inventory analysis related to phasing out an existing Stage II program and is designed 

to facilitate this assessment. The ORVR phase-in and fuel consumption data presented here are 

derived from the same core approach as used in EPA’s MOVES model and incorporates all 

major elements of that work. Furthermore, it relies on the latest technical information and data 

available to EPA on both ORVR and Stage II, and in some cases incorporates information not 

yet in MOVES models. Given these differences, even though the ORVR phase-in and fuel 

consumption data presented here are derived from the same core approach as used in MOVES, it 

is expected that the results from using MOVES to assess the inventory impact would be different 

than the approach suggested below. This is further discussed in Section 3.

How is this guidance document organized? Section 2 discusses the statutory and 

regulatory framework governing removal of Stage II control programs from SIPs. Section 3

provides technical information that states may consider using to calculate the impact of phasing 

out Stage II control programs. Section 4 discusses general strategies and considerations for 

phasing out Stage II control programs. Section 5 presents information on developing SIP 

revisions for submission to EPA for review and approval. The appendix contains look up tables 

associated with the equations presented in this guidance and a chart indicating the specific CAA 

requirement applicable to each state.
3

2. When can a state or a GDF stop implementing existing Stage II 

programs?

The CAA section 182(b)(3) requirements for Stage II have been waived as a result of 

EPA’s exercise of waiver authority under CAA section 202(a)(6). This waiver extends to areas 

classified as Serious or above for the 1997 or 2008 8-hour ozone NAAQS, and to those that were 

classified Serious or above for the 1-hour ozone NAAQS at the time that the 1-hour NAAQS was 

revoked.3 However, areas where a Stage II program is part of an EPA-approved SIP need to 

continue implementing Stage II until EPA approves a SIP revision that removes the requirement 

from the SIP.

The EPA is aware that new GDF construction undertaken prior to the approved phase-out

date may incur capital costs for installing Stage II that may only be required for a short time. It 

is evident from the public comments on the EPA’s proposed waiver rule and other materials that 

states and members of the regulated industry are seeking to curtail Stage II installations at newly 

constructed GDFs. Changing Stage II applicability requirements contained in state rules that 

have been approved into SIPs is ultimately an issue that each state would need to address. The 

EPA cannot unilaterally change existing state regulations or lawfully-adopted SIPs containing

Stage II requirements, and the May 16, 2012, waiver does not directly alter those state 

regulations or revise SIPs. 

2.1 What are the CAA requirements that govern EPA approval of a Stage II removal SIP 

revision?

There are three main CAA provisions that affect EPA’s ability to propose approval of any 

SIP revision seeking to discontinue an existing SIP-approved Stage II control program. Section 

110(l) governs EPA approval of all SIP revisions, including SIP revisions involving phase out of 

Stage II controls. Section 193 applies to any current nonattainment area that adopted a Stage II 

control program into its SIP prior to November 15, 1990. Section 184(b)(2) applies to any area 

of the northeast OTR.

2.2 Complying with the “noninterference” clause (CAA section 110(l))

Under CAA section 110(l), the EPA cannot approve a SIP revision if it would interfere

with attainment of the NAAQS, reasonable further progress toward attainment, or any other 

applicable requirement of the Clean Air Act. Therefore, the EPA could propose to approve a SIP 

revision that removes or modifies Stage II gasoline refueling vapor control measure(s) in the SIP 

only if there is a basis in the state’s submittal for concluding that approval of the revision would 

 

3 The EPA codified anti-backsliding provisions governing the transition from the revoked 1-hour ozone NAAQS to 

the 1997 8-hour ozone NAAQS in 40 CFR part 51.905(a). These provisions indicate that some control measures 

may not be removed from a SIP even if their removal would not interfere with air quality goals. These measures are 

listed as “applicable requirements” because the CAA requires that they be included in a SIP for an area based on the 

area’s designation status and classification. The authority in CAA section 202(a)(6) makes it possible for EPA to 

waive Stage II control programs such that they are no longer an “applicable requirement” or a required contingency 

measure.
4

not interfere with attainment of the NAAQS, reasonable further progress (RFP) or any other 

applicable requirement of the CAA.

Specifically, section 110(l) states:

Each revision to an implementation plan submitted by a State under this Act shall be 

adopted by such State after reasonable notice and public hearing. The Administrator 

shall not approve a revision of a plan if the revision would interfere with any applicable 

requirement concerning attainment and reasonable further progress (as defined in 

section 171), or any other applicable requirement of this Act.

A Federally approved SIP is viewed as the state’s blueprint for maintaining clean air, and

from time to time a state may choose to revise its SIP and demonstrate that the revision would 

not interfere with air quality goals. Accordingly, states should explain how the SIP revision that 

modifies an existing SIP-approved Stage II control program does not interfere with attainment of 

all applicable ozone NAAQS, including the 2008 NAAQS, and any applicable reasonable further 

progress requirements. In evaluating whether a given SIP revision would interfere with

attainment or maintenance, as required by section 110(l), the EPA generally considers whether 

the SIP revision will allow for an increase in actual emissions into the air over what is allowed 

under the existing EPA-approved SIP. The EPA has not required that a state produce a new

complete attainment demonstration for every SIP revision, provided that the status quo air 

quality is preserved. See, e.g., Kentucky Resources Council, Inc., v. EPA, 467 F.3d 986 (6th Cir. 

2006); see also, 61 FR 16,050, 16,051 (April 11, 1996) (actions on which the Kentucky

Resources Council case were based). Section 3 of this guidance document provides information 

that states may consider using to develop noninterference demonstrations, including methods to 

assess the VOC emissions impact in the affected area during the Stage II phase-out period.

As one considers this non-interference assessment, it should be noted that the potential 

emission control losses from removing Stage II VRS are transitional and relatively small. 

ORVR-equipped vehicles will continue to phase in to the fleet over the coming years and will 

exceed 80 percent of all highway gasoline vehicles and 85 percent of all gasoline dispensed 

during 2015. As the number of these ORVR-equipped vehicles increase, the control attributed to 

Stage II VRS will decrease even further, and the potential foregone Stage II VOC emission 

reductions are generally expected to be no more than one percent of the VOC inventory in the 

area.

Substituting new control measures. The EPA believes that a planned Stage II phase-out 

that is shown not to result in an increase in area-wide VOC emissions would be consistent with 

the conditions of CAA section 110(l). A planned Stage II phase-out that would otherwise result 

in an area-wide VOC emissions increase could also be consistent with the conditions of CAA 

section 110(l) if the state offsets the increase in emissions by adopting and implementing 

additional emissions controls into the SIP. One example of substitution is where a state or area 

may substitute refueling emissions at GDFs with stationary source controls or area source 

controls, including additional controls on other gasoline vapor emissions points at GDFs (See

section 4.4). States have wide latitude to select additional emissions controls to make up for the 

absence of Stage II VRS, including substituting NOx controls. The offsetting emissions controls 

should be generally contemporaneous with the Stage II VRS phase-out period. 
5

Offset of emissions due to excess emission reductions not accounted for in the current 

SIP. An additional factor that may be relevant in evaluating whether a SIP revision removing 

Stage II vapor recovery programs is consistent with the provisions of section 110(l) is the 

consideration of emission reductions not otherwise included in the current SIP. Changes in an

area’s stationary or area source inventories resulting from changes in industrial population or 

activity in that area could result in a decrease in VOC emissions compared to that the emissions

considered in the SIP. There are too many potential examples to list, but this could include a 

plant closure or the continued decline in GDF population. Also, there may be changes in the 

motor vehicle fleet VMT or fleet populations that provide VOC and NOx emission reductions not 

accounted for in the SIP. With an increased penetration of newer model year ORVR-equipped 

vehicles, the amount of additional emission reduction achieved by Stage II over time is smaller 

in comparison to areas with lower percentages of ORVR penetration into the fleet. In these 

circumstances it may also be true that the lower exhaust and evaporative emission rates from 

these newer vehicles in the fleet relative to those being scrapped will offset any transitional VOC 

emission increases from phasing out Stage II VRS. Furthermore, there may be additional VOC 

and NOx emission reductions from non-road sources that could be considered if states have not 

already sought SIP credit for them.

Emissions increases that do not interfere with attainment. Under the circumstances 

created by the CAA's widespread use waiver, a planned Stage II phase-out that is shown to result 

in an area-wide VOC emissions increase may also be consistent with the conditions of CAA 

section 110(l). A phase-out plan that would result in very small foregone emissions reductions 

in the near term that continue to diminish rapidly over time as ORVR phase-in continues, may 

result in temporary increases that are too small to interfere with attainment or progress toward 

attainment. This may be particularly evident in areas that are already attaining the ozone 

NAAQS or where emissions and/or air quality projections already demonstrate that an area is 

likely to maintain the NAAQS into the future. Similarly, in areas where ozone formation is 

limited by the availability of NOx emissions, a small (and ever-declining) increase in VOC 

emissions may have little or no effect on future ozone levels. The EPA would consider any air 

quality analyses and supporting information provided by a state to show that a proposed SIP 

revision would not interfere with attainment and maintenance of the NAAQS.

2.3 Complying with the OTR “comparable measures” requirement (CAA section 

184(b)(2))

All areas of the Northeast OTR, both attainment and nonattainment, are subject to the 

requirements of CAA section 184(b)(2), commonly referred to as the “comparable measures 

requirement.”4 Section 184(b)(2) directs these areas to adopt and implement either Stage II 

controls meeting the general requirements for Stage II gasoline vapor recovery programs under 

CAA section 182(b)(3), or “control measures capable of achieving emissions reductions

comparable to those achievable” by Stage II. Section 3 of this guidance document provides 

information that states may consider in developing a comparability analysis that includes an 

estimate of lost Stage II reductions incremental to ORVR during the Stage II phase out period. 

 

4

The States of Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, 

Pennsylvania, Rhode Island, Vermont, Virginia and the District of Columbia are in the OTR and are subject to these 

provisions.
6

States in the OTR can conduct comparability analyses on a state-wide basis, or separately for 

nonattainment and attainment areas within the state. 

Demonstrating Comparability. The CAA does not require OTR states to implement 

measures that would achieve reductions “equivalent” to a Stage II control program; the CAA 

requires that the reductions be “comparable.” Now that ORVR is in widespread use in the motor 

vehicle fleet, the EPA believes it may be appropriate for states to demonstrate that the 

comparable measures requirement is satisfied if phasing out a Stage II control program in a 

particular area is estimated to have no, or a de minimis, incremental loss of area-wide emissions 

control– i.e., when no alternative reductions are needed to achieve reductions comparable to 

those achievable in the area by the Stage II control program stipulated in CAA section 182(b)(3). 

As the fraction of total gasoline dispensed into ORVR-equipped vehicles continues each 

year to increase in relation to the fraction of total gasoline dispensed into non-ORVR vehicles, 

the incremental emission reduction benefit achieved by Stage II controls over ORVR controls 

declines. Accordingly, in the specific context of the comparable measures requirement, EPA 

believes it is reasonable to conclude that the incremental emissions control that Stage II achieves

beyond ORVR is de minimis if it is less than 10 percent of the area-wide emissions inventory 

associated with refueling highway motor vehicles. This is because the Stage II control program 

stipulated by Congress in CAA section 182(b)(3) exempts some GDFs from Stage II controls, 

such that even where Stage II was required approximately 10 percent of the gasoline throughput 

was not subject to the statutory requirement. Specifically, GDFs that sell 10,000 gallons or less 

per month, and GDFs identified as independent small business marketers that sell 50,000 gallons 

or less per month, are exempt from the statutory Stage II control requirements. For a typical area 

implementing the CAA-based exemption program EPA estimates that about 10 percent of 

highway motor vehicle fleet gasoline consumption was therefore exempted from the statutory 

requirement for Stage II controls.

5

In light of the Congressional judgement that Stage II controls 

need only apply to 90 percent of gasoline sales, no new control measure may be necessary to 

demonstrate comparability to Stage II when the difference between retaining Stage II and 

removing Stage II affects less than 10 percent of the refueling emissions from area-wide gasoline 

consumption.

Agencies can consider using the calculations explained in this guidance document to 

determine the point in time at which de minimis incremental benefits are reached in a specific 

area, based on the area’s fleet profile and Stage II control program parameters. The EPA is 

aware that some states are implementing Stage II control programs that are nominally more 

stringent than the minimum program requirements in CAA section 182(b)(3). For example, in 

some states exemptions are provided only for GDFs dispensing 10,000 gallons or less per month. 

For the purposes of addressing comparability under CAA section 184(b)(2), states only need to 

consider the reductions achievable by the minimum program required by CAA section 182(b)(3), 

as section 182(b)(3) defined the scope of applicability of Stage II within the GDF source 

category – and therefore the scope of expected emissions reductions from Stage II – against 

which alternative control measures were to be compared under section 184(b)(2).

 

5

See “Technical Guidance – Stage II Vapor Recovery Systems for Control of Gasoline Refueling Emissions at 

Gasoline Dispensing Facilities Vol. 1,” EPA-450/3-91-022a, November 1991.
7

2.4 Complying with the “general savings clause” for pre-1990 Stage II control programs 

(CAA section 193)

Section 193 prohibits modification of any control requirement in effect before November 

15, 1990 in a current nonattainment area, unless modification “insures equivalent or greater 

emissions reductions.” This means that, in areas currently designated nonattainment for ozone, 

any Stage II control program implemented under a SIP prior to November 15, 1990 could not be 

removed from the SIP until the ORVR control requirement (or some other requirement or set of 

requirements) is shown to achieve equal or greater emissions reductions compared to the 

emissions reductions attributable to Stage II vapor recovery. Alternatively, States can show that 

removing the area’s pre-1990 Stage II control program would have no impact on area-wide 

emissions reductions. The EPA anticipates that the later showing is inherently more 

conservative than the former.

Agencies can consider using the assessment method described in Section 3 to determine 

the point in time the ORVR control requirement achieves equivalent emissions reductions to the 

reductions credited to the pre-1990 Stage II vapor recovery program. The assessment method is 

similar to the method the EPA used for establishing the national ORVR widespread use finding 

and waiver of the section 182(b)(3) requirement, except that here it would be applied on a state 

or local area level rather than a national level.

3. Assessing Area-Wide Impacts on Vehicle Refueling Emissions

This section covers many of the technical issues states may need to address in developing 

SIP revisions to phase out existing Stage II programs. Note that the analyses for purposes of 

section 110(l) and section 193 may not be identical. However, in some cases, an area may be 

able to show that, due to disbenefits from simultaneous implementation of Stage II and ORVR, 

phasing out Stage II will result in a net improvement in emissions reductions, satisfying the 

provisions of both section 110(l) and section 193.

Section 3.1 describes some key terms. Section 3.2 identifies and describes a series of 

parameters and variables related to the implementation of Stage II and ORVR. Section 3.3

combines these parameters and variables into two equations that states can consider using to 

evaluate and compare the emission reduction impacts of various combinations of Stage II and 

ORVR control technologies in the context of the provisions of CAA sections 110(l), 184(b)(2), 

and 193. Section 3.4 provides guidance on selecting parameter values and ways to determine the 

variables in the equations. Section 3.5 presents a series of examples of how this information can 

be used to conduct SIP-related analyses.

States may be accustomed to running the MOVES model in support of SIP revisions. 

And, while the use of the MOVES model is certainly allowed, without additional analyses and 

inputs from outside the model, it may not yield outcomes similar to those obtained using 

Equations 1, 2 and 3 that are presented in this section. For these reasons, and the fact that all 

previous EPA ORVR/Stage II inventory comparison analyses have been conducted in a similar 
8

manner, EPA believes the approach discussed in this document would be preferable for these 

assessments.6

3.1 Discussion of Terms

The EPA’s emission factors document divides vehicle refueling emissions into three 

broad categories.7These include vehicle fuel tank displacement emissions, gasoline spillage, 

and underground storage tank (UST) breathing and empting losses.8 In a previous analysis EPA 

concluded that removing Stage II vapor recovery would potentially impact overall vehicle fuel 

tank displacement emissions and breathing/emptying losses from UST vent pipes where Stage II 

vacuum assist technology is used. The analysis further concluded that removing Stage II would 

neither increase nor decrease gasoline spillage during refueling and that with appropriate 

measures such as the pressure/vacuum valves now widely employed on UST vent pipes, 

breathing/emptying losses from non-Stage II nozzles and balance type Stage II nozzles would be 

similar.9,10 Thus, this guidance need only address impacts on vehicle fuel tank displacement 

emissions and impacts on UST vent pipe emission rates from non-ORVR compatible Stage II 

nozzles.11

Described below are key terms used in the calculations and discussions which follow. 

Gasoline dispensing facility (GDF): A location which dispenses gasoline to highway 

motor vehicles and serves as a fueling point for nonroad engines and equipment. It includes all 

retail outlets such as traditional service stations, convenience stores, truck stops, and 

hypermarkets (e.g., warehouse clubs and big box stores) as well as private and commercial 

outlets such as those for centrally-fueled fleets, government operations, and private businesses as 

well as private outlets such as centrally-fueled fleet and government operations. For these 

purposes, it generally does not include marinas and general aviation airports dispensing aviation 

gasoline. Note that some lower throughput GDFs are exempt from Stage II vapor recovery by 

state regulations.

 

6

In previous publications, (footnote 9 below) EPA concluded that for these purposes factors such as spillage 

emission rates and traditional breathing/emptying loss emision rates would not be affected by removing Stage II 

vapor recovery. MOVES runs should not include spillage. Also, it is important to note that the gasoline 

consumption data in Appendix Table A-1 includes ORVR for Class III HDGVs beginning in 2006. When the last 

version of the MOVES model was released, EPA was not aware that manufacturers had voluntarily incorporated 

ORVR on these vehicle models. This guidance document does not include every potential minor emission impact 

that has been identified for either Stage II or ORVR. For example, vacuum assist Stage II may capture a fraction of 

the refueling emissions released from an ORVR vehicle fillpipe during a refueling event (~0.05g/gal) and through 

testing, API has identified that emissions released from the fillpipe immediately after the fuel cap is removed are 

lower for ORVR vehicles than non-ORVR vehicles. The delta in emissions (about 0.10 g/gal) depends on RVP and 

fuel tank temperature. These offsetting minor differences are not included in the calculations in this guidance.

7 AP-42, Fifth Edition, “Compilation of Air Pollutant Emission Factors – Volume 1, Stationary Point and Area 

Sources” January 1995. The EPA’s emission factors document, identifies three sources of refueling emissions: 

displacement, spillage, and breathing losses..

8

See Chapter 5 of AP-42, http://www.epa.gov/ttn/chief/ap42/ch05/final/c05s02.pdf

9

See EPA memorandum, “Onboard Refueling Vapor Recovery Widespread Use Assessment,” June 9, 2011. 

10 There would still be breathing and emptying losses from some systems at various times. These could be addressed 

by one of the post-processor technologies now being marketed for addition to the GDF UST vent pipes

11 Dispensers using traditional gasoline nozzles, balance-type Stage II nozzles, and specially certified ORVR 

compatible vacuum-assist type nozzles would not be expected to increase UST vent emissions.
9

Stage II Vapor Recovery System (VRS): A system designed to capture displaced vapors 

that emerge from inside a vehicle’s fuel tank, when gasoline is dispensed into the tank. There

are two basic types of Stage II systems, the balance type and the vacuum assist type.

Balance-type Stage II system: The balance system transfers vapors from the vehicle tank 

to the GDF UST based on pressure differential. A key feature in the balance system is a hose 

nozzle that makes a tight connection with the fill pipe on the vehicle fuel tank. The nozzle spout 

is fitted with an accordion-like bellows that presses snugly against the fill pipe lip. The vapors 

flow into the port, through the nozzle bellows, through a coaxial hose that connects the nozzle to 

the dispenser, and finally on through a vapor-return pipe back into the UST.

Vacuum assist-type Stage II system: This system relies on a vacuum source to help move 

the vapors out of the vehicle tank and into the UST. Current designs do not rely on a tight-fitting 

seal at the nozzle-fillpipe interface. Traditional vacuum systems are of two types: passive and 

active. In a passive vacuum-assist system, which is the dominant approach today, an electrically 

driven vacuum pump, typically in the dispenser cabinet, provides the vacuum power. An active 

system maintains a vacuum on the entire Stage II vapor recovery system through a central pump 

(jet pump) to recover vapors from the entire system to the tank. A key feature of vacuum assist 

system design and operation is the design air/liquid (A/L) volume ratio which is a measure of the 

volume of air returned to the tank to the volume of liquid dispensed. (When refueling a nonORVR vehicle this “air” also contains gasoline vapor.) The larger the design A/L ratio the 

greater the amount of fresh air returned to the UST. Some passive vacuum assist systems 

employ loose-fitting mini-bellows to help reduce the design A/L ratio. Sometimes these are 

called hybrid systems. Active vacuum assist systems often have A/L ratios somewhat greater 

than unity and employ a post-processor to reduce excess vent pipe emissions created by the 

higher A/L ratio with these systems.

Vent pipe: A pipe from the UST to the atmosphere which allows the tank to “breathe”

during normal operation. This allows the tank to bring in fresh air to relieve negative pressure or 

release vapor to reduce positive pressure in the UST as needed. Vent pipes are generally 12 feet 

in height and two inches in diameter.

Pressure vacuum vent valve: A device, usually referred to as a "P/V vent valve," 

installed at the discharge end of a vent pipe connected to a gasoline storage tank, to regulate the 

pressure at which vapor is allowed to escape from the tank, and the vacuum at which outside air 

is allowed to enter the tank. The inflow/outflow of air through the vent pipe is controlled at 

specified pressures. These vent valves generally inhibit vapor release and are used to ensure the 

proper operation of Stage II balance systems. These P/V vent valves are now widely required as 

a result of EPA’s GDF “Stage I” NESHAP regulation (40 CFR 63 CCCCCC).

Onboard Refueling Vapor Recovery (ORVR): A system employed on gasoline-powered 

highway motor vehicles to capture gasoline vapors displaced from a vehicle fuel tank during 

refueling events. These systems are required under section 202(a)(6) of the CAA and 

implementation of these requirements began in the 1998 model year. Currently they are now 

used on all gasoline-powered passenger cars, light trucks, and complete heavy trucks of less than 

14,000 lbs GVWR. ORVR systems typically employ a liquid fill neck seal to block vapor escape 

to the atmosphere and otherwise share many components with the vehicle’s evaporative emission 

control system including the onboard diagnostic system (OBD) sensors.
10

ORVR/Stage II Compatibility: Compatibility problems can result in an increase in 

emissions from the UST vent pipe and other system fugitive emissions related to the refueling of 

ORVR vehicles with some types of vacuum assist-type Stage II systems. This occurs during

refueling an ORVR vehicle when the vacuum assist system draws fresh air into the UST rather

than an air vapor mixture from the vehicle fuel tank. Vapor flow from the vehicle fuel tank is 

blocked by the liquid seal in the fill pipe which forms at a level deeper in the fill pipe than can be 

reached by the end of the nozzle spout. The fresh air drawn into the UST enhances gasoline 

evaporation in the UST which increases pressure in the UST. Unless it is lost as a fugitive 

emission, any tank pressure in excess of the rating of the pressure/vacuum valve is vented to the 

atmosphere over the course of a day. The magnitude of these emissions at a specific GDF is 

primarily a function of the fraction of total gasoline throughput dispensed to the ORVR vehicles 

and the A/L ratio of the dispensers.

The compatibility factor is an especially important consideration in calculating the 

emissions impacts of Stage II controls. Even if a state/local area wishes to keep Stage II controls 

to address non-ORVR equipped vehicles being refueled at Stage II GDFs, for non-ORVR 

compatible Stage II vacuum assist systems there will come a point where the emissions impact of 

the compatibility factor surpasses any gain from controlling non-ORVR vehicles. After that 

point, Stage II would lead to a net area-wide loss in emissions control. The point in time when 

this occurs depends on the nature of the Stage II program and the rate of ORVR penetration into 

the fleet. 

ORVR-compatible vacuum assist-type Stage II system: A vacuum assist type Stage II 

system that is designed to sense when an ORVR vehicle is being refueled and reduces the A/L 

ratio to near zero to avoid compatibility emission effects. Current ORVR compatible nozzles are 

certified to meet ARB requirements for Stage II enhanced vapor recovery (EVR) efficiency with 

up to 80 percent ORVR vehicles in the fleet mix. Balance type nozzles are ORVR compatible as 

well.

3.2 Parameters and Variables Related to Implementing Stage II VRS and ORVR 

To conduct analyses of the impact of phasing out Stage II VRS, several key pieces of 

information and data are needed for the equations used in the assessments, which are presented 

in section 3.3. Each of these is described below, first for Stage II VRS, and then for ORVR.

3.2.1 Terms for Estimating Area-Wide Stage II VRS Control Efficiency

ηiuSII - Stage II VRS in-use control efficiency: This is the current best estimate of the 

average in-use control efficiency for Stage II VRS in the state/area when applied to vehicles that 

are not equipped with ORVR. It is expressed as a fraction of 1. This value considers not only 

vapor capture at the vehicle fillpipe opening but also its transmittal to and storage in the UST. 

This value likely varies somewhat by state/area depending on how well GDF operators follow 

the inspection, testing, and maintenance activities specified in the state’s implementing 

regulations and the frequency of inspection and follow-on enforcement actions by state/local 

authorities in implementing the regulations. This judgment should be informed by test data if 

available either from within the state/area or from other sources if no local data is available. 

Publicly available data suggests typical current values are in the range of 60-75 percent (0.60 –
11

0.75).

12,13,14,15 As a result, it may be appropriate to identify significantly lower Stage II in-use 

control efficiencies than were identified in EPA’s 1991 technical guidance on Stage II systems 

(see footnote 5).

QSII - Fraction of highway gasoline throughput covered by Stage II VRS: The fraction of 

gasoline that is sold through dispensers equipped with Stage II VRS equipment expressed as a 

fraction of 1. This likely varies somewhat by state/area and can be derived from state data. 

Typical default values are 0.9 for states/areas that adopted the CAA allowed exemption value of 

10,000 gallons per month (gpm) for private GDFs and 50,000 gpm for independent small 

business marketers and 0.95-0.97 for states/areas that adopted 10,000 gpm exemption criteria for 

all GDFs.

QSIIva – Fraction of highway gasoline throughput dispensed through vacuum-assist type 

Stage II VRS: The fraction of annual gasoline consumption in the state/area dispensed through 

vacuum assist type Stage II VRS expressed as a fraction of 1. This would not include gasoline 

dispensed through dispensers with traditional nozzles, balance-type Stage II VRS nozzles, or 

ORVR-compatible Stage II nozzles. If the fraction dispensed through traditional vacuum assist 

VRS is not known, then the fraction of GDFs with traditional vacuum assist Stage II VRS may 

be substituted based on the assumption that throughput is evenly distributed across the various 

GDFs that are not exempt from Stage II requirements.

VMTORVRi - ORVR Vehicle Miles Traveled: The fraction of annual area-wide VMT 

traveled by ORVR-equipped vehicles. The subscript i denotes that this term varies by calendar 

year.

CFi - Compatibility Factor: This is an increase in UST vent pipe emissions over the 

normal breathing/emptying loss emissions. As discussed above, this is a function of the fraction 

of gasoline dispensed to ORVR vehicles in any given year (using VMT of ORVR vehicles as a 

surrogate), the design features of the traditional vacuum assist Stage II nozzles, and the 

proportion of vacuum assist Stage II stations with various A/L ratios. This term may be 

calculated as the product of VMTORVRi and a constant term 0.07645.

 It should be noted that for a 

state/area with all balance systems or with a requirement for ORVR compatible nozzles, the CF 

term is zero because there is no compatibility problem by definition.

 

12 “Stage II Vapor Recovery Systems Issues Paper,” U.S. EPA, Office of Air Quality Planning and Standards, 

August, 2004.

13 “Analysis of Future Option’s for Connecticut’s Gasoline Dispensing Facility Vapor Control Program,” 

Connecticut Department of Energy and Environmental Protection, December 2011.

14 “Draft Vapor Recovery Test Report,” CARB and CAPCOA, April, 1999. This data was used in CARB’s analyses 

of their Enhanced Vapor Recovery rules. See, “Enhanced Vapor Recovery Emissions Reduction Calculations” 

(available at http://www.arb.ca.gov/regact/march2000evr/march2000evr.htm), Appendix D to “Enhanced Vapor 

Recovery: Initial Statement of Reasons for Proposed Amendments to the Vapor Recovery Certification and Test 

Procedures for Gasoline Loading and Motor Vehicle Gasoline Refueling at Service Stations,” February 4, 2000; and 

CARB, “Updated ISD Emission Reductions” (available from http://www.arb.ca.gov/regact/evrtech/isor4d.pdf), 

Appendix 3 to “Enhanced Vapor Recovery Technology Review”, Staff Report, October 2002.

15 “Performance of Balance Vapor Recovery Systems at Gasoline Dispensing Facilities,” San Diego Air Pollution 

Control District, May 18, 2000.

CFi = (0.07645)(VMTORVRi)
12

The constant term 0.07645 is an estimate of the control efficiency loss with vacuum assist 

systems derived by weighting two technologies tested in a California ARB study.

16 This testing 

was conducted with the P/V valve in place on the vent pipe and with frequent monitoring of the 

A/L ratio to be certain that it stayed close to the design values. The technologies are weighted by 

about 65 percent for the higher A/L ratio dispenser and 35 percent for the lower A/L ratio 

dispenser.17,18,19 The results in lbs/1000 gallons are divided by the uncontrolled emission factor 

for the area where and when this testing occurred (7.6 lbs/1000 gal). The equation yields a term 

expressed as a fraction of the displacement emission factor (dimensionless) thus allowing it to be 

used in calculations with the other fractions above.20 The subscript i denotes that this term varies 

by calendar year.

The compatibility factor can also be calculated as a function of annual gallons of highway 

motor gasoline dispensed to ORVR-equipped vehicles, where the constant term 0.0777 is derived 

based on the national average gasoline throughput that corresponds to the ORVR VMT data.

For completeness sake, it should be noted that the excess vent emissions (EE) on a 

lb/1000 gal basis can be estimated using the equations: 

 

16 EPA Memorandum “Calculating Stage II Vacuum Assist Stage II VRS and ORVR Excess Emissions,” Glenn W. 

Passavant, May 2012.

17 California ARB, Preliminary Draft Test Report, Total Hydrocarbon Emissions from Two Phase II Vacuum Assist 

Vapor Recovery Systems During Baseline Operations and Simulated Refueling of Onboard Refueling Vapor 

Recovery (ORVR) Equipped Vehicles, Project Number ST-98-XX, June 1999.

18 See Letter from William Loscutoff, Chief, Monitoring and Laboratory Division ARB to Prentiss Searles, Senior 

Marketing Issues Associate, American Petroleum Institute, “Comments on Enhanced Vapor Recovery (EVR) 

Technology Review.” August 5, 2002, p.6.

19 Keeping the in-use A/L ratio close to the design value is very important. A significant variation upward in the 

A/L ratio would increase CF because more air would be ingested while a significant decrease could decrease capture 

efficiency and send less vapor to the UST and thus perhaps also increase CF.

20 This approach gives a different value than that presented in a previous EPA report titled “Stage II Vapor Recovery 

Systems - Option Paper,” February 2006, because this methodology allows for an estimation of the compatibility 

factor as a function of the fraction of gasoline dispensed to ORVR vehicles rather than at full fleet turnover, and 

because the results for the two technologies tested in California are weighted by an estimate of their relative fraction 

of use in the GDF population rather than using only the higher value. Finally, the result is divided by the 

displacement refueling emission factor in the area of California where and when this testing was conducted to get a 

factor expressed in the same terms as control efficiency. (see California ARB, Uncontrolled Vapor Emission Factor 

at Gasoline Dispensing Facilities, January 5, 2000).

EEi = 0.581(VMTORVRi) or 

EEi = 0.591(QORVRi)

CFi = (0.0777)(QORVRi) . . .defined below
13

3.2.2 Terms for Estimating Area-Wide ORVR Control Efficiency

QORVRi - Fraction of annual gallons of highway motor gasoline dispensed to ORVRequipped vehicles: This is likely to vary by state/area depending on the fleet turnover/scrappage 

rate, annual VMT, and fuel economy of the vehicles involved in the analysis. The subscript i

denotes that this term varies by calendar year. Table A-1, column 4 in the Appendix shows 

national average values that a state could use or adapt by extrapolation or interpolation as 

appropriate. For example, if the fleet in the state was one year newer than the national average 

then the analysis would use the data for the next calendar year (e.g., 2014 for 2013). Conversely, 

for example, if the fleet in the state was on average six months older than the national average 

then the analysis would interpolate between the current and past year (e.g., halfway between 

2012 and 2013). Data on the fleet average age distributions by vehicle class for 2012 used in 

these calculations is provided in Appendix Table A-9.

ηORVR - In-use control efficiency for ORVR: EPA recommends a value of 0.98.21 States 

may use a lower or higher value, if justified. This value is based on testing of over 1,600 in-use 

vehicles with mileages ranging from about 6,000 – 135,000. This value does not reflect other 

adjustments found in the MOVES emissions model. The current MOVES model does not fully 

consider the in-use verification program (IUVP) test results as mentioned above. Other MOVES 

model efficiency adjustments are based on data from older vintage evaporative emission control 

systems and do not fully reflect the benefits derived from OBD, I/M, or improved durability 

resulting from the integrated ORVR/evaporative control systems used in vehicles meeting the 

progressively more stringent evaporative emission standards which were implemented in the 

mid-1990s and later. 

3.3 Calculating Impacts on the Refueling Emission Inventory

This section presents the two main equations that use the terms discussed in section 3.2 as 

inputs to calculate area-wide control efficiency impacts of Stage II VRS and ORVR. States can 

consider using the results of these equations to support SIP actions phasing out Stage II control 

programs.

3.3.1 Key Equation for Assessing and Demonstrating Compliance with the Noninterference 

Provisions of CAA Section 110(l) and the Comparable Measures Requirement of CAA Section 

184(b)(2)

Overall Stage II-ORVR increment: The overall increment identifies the annual area-wide 

emission control gain from Stage II installations at GDFs as ORVR technology phases in. Thus, 

it also indicates the emission reduction potential loss (in year i) from removing Stage II. 

 

21 EPA Memorandum, “Updated ORVR In-Use Efficiency,” Glenn W. Passavant. February, 2012.

Equation 1

incrementi = (QSII)(1-QORVRi)(ηiuSII) - (QSIIva)(CFi)
14

Under the current regulatory construct for ORVR, there is a small and declining number 

of non-ORVR equipped vehicles and thus a small level of future emission reduction achievable 

from Stage II. However, due to the vacuum assist compatibility factor, this emission reduction 

will eventually go to zero and become negative for states/areas that do not use properly 

calibrated ORVR-compatible nozzles because the incompatibility effect will be larger than the 

Stage II increment. If the value is greater than zero for the year under consideration there is still 

a remaining emission reduction benefit for Stage II for the year relative to ORVR. If it is zero 

there is no net difference in the inventory. If it is zero or negative, this would indicate that 

removing Stage II would not increase the refueling emissions inventory because the higher 

efficiency from ORVR and the incompatibility emissions offset the increment due to non-ORVR 

vehicles being refueled at Stage II GDFs. It should be noted that for a state/area with all balance 

systems or with a requirement for ORVR compatible nozzles, the CF term is zero.

3.3.2 Key Equation for Assessing and Demonstrating Compliance with CAA Section 193

Overall Stage II - ORVR delta: The overall delta is the comparison between the Stage II 

efficiency and the ORVR efficiency with both technologies in place.

This is not the same as the increment calculation in Equation 1 above because it 

considers the greater efficiency of ORVR relative to non-ORVR vehicles refueling at Stage II 

equipped GDFs.

3.3.3 Developing Area-Specific Values for the Terms Used in Equations 1 and 2

To conduct analyses using Equations 1 and 2, a state would first select a base year or date 

for the analysis. The base year or date would correspond to the date the state is considering for 

starting to allow decommissioning for affected GDFs. Alternatively, this could be a set of base 

years/dates if a state is considering phasing-out Stage II in a specific area over a longer time 

period such as two or more years.

Second, the state would develop the values needed for the equations. The information 

and values in Table 2 are provided for consideration.

Equation 2

deltai = (QSII)(ηiuSII) - (QSIIva)(CFi) - (QORVRi)(ηORVR)
15

Table 2

Values and Information Sources for Analysis Terms

Term Values/Sources Other Comments

ηiuSII

In-use Stage II control efficiency

This refers to the in-use efficiency of 

the Stage II vapor recovery system 

when refueling a non-ORVR 

equipped vehicle. State/area specific 

value based on best estimate of inuse efficiency when Stage II 

decommissioning begins. Consider 

available test data.22

Prior EPA guidance links in-use 

efficiency to the level of inspection, 

testing, and maintenance by the 

GDF and follow up by the state.23 

We recommend an efficiency value 

consistent with field test data and the

expected future investment of state 

inspection and enforcement 

resources during the base year and 

any subsequent year if a phase-out is 

used. We advise against relying

solely on prior EPA guidance, new 

system certification efficiency, or 

what your state regulations claim 

regarding efficiency.

QSII

Fraction of gasoline throughput 

covered by Stage II VRS

Appropriate default values are 0.90 

if the state adopted the CAA 

exemption provisions and 0.95-0.97 

if the state used 10,000 gpm for all 

GDFs

Other values may be justified based 

on state data. This fraction has the 

effect of excluding throughput at 

exempt GDFs. 

QSIIva

Fraction of gasoline throughput 

covered by traditional vacuum assist 

Stage II VRS

State/area specific value; state could 

use GDF survey data for throughput 

or GDF population by dispenser 

type. Estimated default values are 

provided in Appendix Table A-6

Zero if all GDFs use the balance 

type approach or dispenser nozzles 

are required to be ORVR 

compatible.

VMTORVR 

Fraction of annual VMT of gasolinepowered highway motor vehicles by 

ORVR equipped vehicles

See Appendix Table A-1, Column 3. May use state/area specific data or 

adjust Appendix Table A-1 as 

appropriate (interpolation) if fleet 

characteristics are different. Does 

not include diesels or any off road 

vehicles.

CF

Compatibility factor term

EPA recognizes a value for this 

constant of 0.07645 associated with 

the VMTORVR value, or 0.0777 

associated with QORVR value. CF is 

zero by definition for balance and 

ORVR compatible dispensers.

May calculate using data derived 

from traditional vacuum assist Stage 

II dispensers based on knowledge of 

the distribution of the different types 

of Stage II vacuum-assisted 

equipment designs (e.g., high A/L 

vs. low A/L ratio) and field test 

data.

24

QORVR

Fraction of annual gallons of 

highway motor gasoline dispensed 

to ORVR-equipped vehicles

See Appendix Table A-1, Column 4. 

Note that QORVRi = 

0.9826(VMTORVRi)

May use state/area specific data or 

adjust Appendix Table A-1 as 

appropriate (interpolation) if fleet is 

older or newer, or more or less fuel 

efficient. Does not include diesels or 

any off road vehicles.

 

22 See reference in footnotes 12-15 above.

23 EPA report, “Enforcement Guidance for Stage II Vehicle Refueling Control Programs,” U.S. EPA, Office of Air 

and Radiation, Office of Mobile Sources, December 1991.

24 See reference 16 for an example of how this work could be done.
16

Table 2

Values and Information Sources for Analysis Terms

Term Values/Sources Other Comments

ηORVR

ORVR in-use control efficiency

EPA recommends 0.98. May use a locally derived value if 

state/local authority believes EPA 

in-use testing data is 

unrepresentative.

3.4 Example Calculations for Equations 1 and 2

3.4.1 Example Scenario #1

Calculate the increment for a potential deactivation of Stage II requirements in mid-2013

assuming 70 percent in-use Stage II control efficiency, a relatively low Stage II GDF exemption 

level of 10,000 gpm, a relatively high use of vacuum assist-type dispensers of 90 percent, 

national fleet ORVR penetration values (interpolated between 2012 and 2013 from columns 3 

and 4 of Appendix Table A-1), and EPA’s recommended 98 percent ORVR control efficiency. 

The inputs are as follows:

ηiuSII = 0.70; QSII = 0.97; QSIIva = 0.9; VMTORVRmid2013 = 0.8169; QORVRmid2013 = 0.7935; ηORVR= 

0.98

Compatibility factor calculation:

CFmid2013 = (0.07645)(VMTORVRmid2013) = (0.07645)(0.8169) = 0.0625

Increment calculation using Equation 1: 

Incrementmid2013 = (QSII)(1 - QORVRmid2013)(ηiuSII) - (QSIIva)(CFmid2013) 

= (0.97)(1 - 0.7935)(0.70) - (0.9)(0.0625) 

= 0.084

In this example the Stage II - ORVR increment is 8.4 percentage points at the midpoint of 

2013 and would decrease over time. 

For comparison, it is interesting to look at the overall delta using the same input values as 

above in Equation 2:

Deltamid2013 = (QSII)(ηiuSII) - (QSIIva)(CFmid2013) - (QORVRmid2013)(ηORVR)

= (0.97)(0.70) - (0.9)(0.0625) - (0.7935)(0.98) 

= - 0.155

In this case the ORVR control program provides 15.5 percent greater emission reduction 

benefits than the Stage II control program alone.
17

3.4.2 Example Scenario #2

Calculate the increment for a potential deactivation of Stage II requirements beginning in 

2013 assuming a 75 percent in-use Stage II control efficiency, a relatively low Stage II GDF 

exemption level of 10,000 gpm, no traditional vacuum assist-type pumps, and ORVR penetration 

in the fleet lags the national average by one year (using end of 2011 values from columns 3 and 4 

of Appendix Table A-1). The inputs are as follows:

ηiuSII = 0.75; QSII = 0.97; QSIIva = 0.0; VMTORVR2013 = 0.76; QORVR2013= 0.7385; ηORVR = 0.98

Compatibility factor calculation:

CF2013 = (0.07645)(VMTORVR2013) = (0.07645)(0.76) = 0.0581

Increment calculation using Equation 1:

Increment2013 = (Q SII)(1 - QORVR2013)(ηiuSII) - (QSIIva)(CF2013) 

= (0.97)(1 - 0.7385)(0.75) - (0)(0.0581) 

= 0.1902

In this example the Stage II - ORVR increment is 19.02 percentage points at the 

beginning of 2013 (end of 2012). For comparison, it is interesting to look at the overall delta

using the same input values as above in Equation 2:

Delta2013 = (QSII)(ηiuSII) - (QSIIva)(CF2013) - (QORVR2013)(ηORVR)

= (0.97)(0.75) - (0.0)(0.0581) - (0.7385)(0.98) 

= 0.0038

In this case the Stage II program provides 0.38 percentage points greater emission 

reduction benefits than Stage II at the beginning of 2013 (end of 2012). The programs are 

essentially equivalent.

Using the same scenario for the beginning of 2014, (Q SII)(ηiuSII) would stay the same 

while (QORVRi)(ηORVR) would increase from 0.7237 to 0.7611. Thus, Delta2014 indicates 3.36 

percentage points more reduction from ORVR than Stage II. Similarly, for 2015, Delta2015

indicates 6.67 percentage points more reduction from ORVR than Stage II. This difference in 

effectiveness would be larger if a CF effect from traditional vacuum assist Stage II nozzles was 

included. 

3.4.3 Example Scenario #3

Calculate the increment for a potential deactivation of Stage II requirement beginning in 

2013 for GDFs dispensing less than 100,000 gpm, beginning in 2014 for GDFs dispensing 

between 100,000 and 200,000 gpm, and beginning in 2015 for all larger throughput GDFs. In 

this scenario, the state/area must also know the fraction of covered throughput in these three 

segments and conduct the analysis for each of the three years. For the sake of this example, 

assume that the less than 100,000 gpm segment is 40 percent of throughput, the over 100,000 

gpm but less than 200,000 gpm segment is 30 percent of throughput, and the over 200,000 gpm 

segment is 30 percent of throughput. Thus, beginning in 2013 Stage II would be deactivated at 
18

GDFs representing 40 percent of throughput, beginning in 2014 Stage II would be deactivated at 

GDFs representing an additional 30 percent of throughput, and beginning in 2015 at the 

remaining GDFs. In this example, assume the ORVR fleet in the state/area is typical of the 

national average and 75 percent in-use Stage II control efficiency.

For the beginning of 2013 segment of the analysis use the following values:

ηiuSII = 0.75; QSII = 0.97; QSIIva = 0.6; VMTORVR2013 = 0.7997; QORVR2013= 0.7766; ηORVR = 0.98

Compatibility factor calculation:

CF2013 = (0.07645)(VMTORVR2013) = (0.07645)(0.7997) = 0.0611

Increment calculations for 2013 using Equation 1, in two parts:

2013, Part A: Stage II removed in 2013 at GDFs representing 40 percent of consumption:

Increment2013 = (0.4)[(Q SII)(1 - QORVR2013)( ηiuSII) - (QSIIva)(CF2013)]

= (0.4)[(0.75)(0.97)(1 - 0.7766) - (0.6)(0.0611)] 

= (0.40)[(.7275)(0.2234 - 0.0366)]

= 0.054

2013, Part B: Stage II is not removed in 2013 for GDFs over 100,000 gpm, so the 

increment would be zero.

In this example the Stage II - ORVR increment is 5.4 percentage points for 2013. For 

comparison, note that the increment would be 12.59 percent if all Stage II VRS were removed in 

2013.

For the beginning of 2014 segment of the analysis use the following values:

ηiuSII = 0.75; QSII = 0.97; QSIIva = 0.6; VMTORVR2014 = 0.8341; QORVR2014= 0.8104; ηORVR = 0.98

Compatibility factor calculation:

CF2014 = (0.07645)(VMTORVR2014) = (0.07645)(0.8341) = 0.0638

Increment calculations for 2014 using Equation 1, in two parts:

2014, Part A: Stage II removed in 2014 at GDFs representing 70 percent of consumption:

Increment2014 = (0.7)[(Q SII)(1 - QORVR2014)(ηiuSII) - (QSIIva)(CF2014)] 

= (0.7)[(0.75)(0.97)(1 - 0.8104) - (0.6)(0.0638)] 

= (0.7)[(0.1379) - (0.0383)]

= 0.070

2014, Part B: Stage II is not removed in 2014 for GDFs over 200,000 gpm so the increment 

would be zero.

In this example the Stage II - ORVR increment is 7.0 percentage points for 2014.
19

For the beginning of 2015 segment of the analysis use the following values:

ηiuSII = 0.75; QSII = 0.97; QSIIva = 0.6; VMTORVR2015 = 0.8633; QORVR2015= 0.8397; ηORVR = 0.98

Compatibility factor calculation:

CF2015 = (0.07645)(VMTORVR2015) = (0.07645)(0.8633) = 0.066

Increment calculations for 2015 using Equation 1:

Increment2015 = (Q SII)(1 - QORVR2015)(ηiuSII) - (QSIIva)(CF2015)

= (0.75)(0.97)(1 - 0.8397) - (0.6)(0.066)

= [(0.1166) - (0.0288)]

= 0.0878

In this example the Stage II - ORVR increment is 8.8 percentage points for 2015 and 

would continue to decrease over time. To summarize, the increment values for scenario #3 are:

2013 – 0.054 2014 – 0.070 2015 – 0.088

The cumulative Stage II-ORVR increment for the three years would be 0.21 for the 

gradual phase-out scenario which is lower than an increment of 0.30 for the same three year 

period if the controls were fully removed in 2013.

3.5 Calculating the Impact on the Area-Wide VOC Inventory

Calculating the impact on the VOC inventory is important in the context of assessing a 

SIP action against the provisions of CAA section 110(l), though the methodology in this section 

can be applied equally to the outputs of either Equation 1 or Equation 2. The methodology 

involves multiplying three different terms, which are area/state specific, as well as appropriate 

unit conversion factors, and is shown in Equation 3.

3.5.1 Terms for Calculating Tons VOC

Increment: This is the increment percentage impact on the refueling inventory of 

removing Stage II as discussed above, and is the output from Equation 1. The delta percentage 

from Equation 2 can also be substituted here.

EF: The uncontrolled displacement refueling emission factor (g/gal). This depends on 

the Reid vapor pressure (RVP), dispensed fuel temperature (Td), and the difference between tank 

fuel temperature and the dispensed fuel temperature (ΔT). While there are various forms of 

equations used to calculate these values we recommend using the equation presented in EPA’s 

Equation 3

Tonsi = (Incrementi)(GCi)(EF)
20

ORVR widespread use determination final rule.25 This equation reflects a wider variety of 

vehicle models than used in the data set to develop the equation in AP-42.

26

EF (g/gal) = exp[-1.2798 - 0.0049(ΔT) + 0.0203(Td) + 0.1315(RVP)] 

where RVP is in psi and temperatures are in °F 

There are three terms needed for this calculation. These terms vary by region/state by 

month or season. Values used by the EPA for ΔT and Td are contained in the Appendix Tables

A-2 and A-3.

27

 The RVP value is derived from 40 CFR 80.27 unless there are more specific 

state requirements or lower RVP values such as the 7.0 psi RVP gasoline needed to meet the 

RFG VOC performance standard. While there is normally some in-use compliance margin for 

RVP, to be conservative we recommend that modeling of emissions assume that the in-use RVP 

is at the level of the standard. Information on EPA volatility standards and RFG can be found at 

the referenced websites.

28 States should refer to and rely on any governing federal and state 

regulations in lieu of these websites. Default emission factors based on the latest available RVP 

information from footnote 28 and temperature information in Tables A-2 and A-3 are provided in 

Table A-7 in the Appendix. These were calculated using the equation provided.

GC: The projected gasoline consumption (gal) for the time period(s) and state/area of 

interest in gallons. A good publicly available source for information on recent consumption is

the Federal Highway Administration.29 This source provides past gasoline consumption by state 

and by month. Information may also be available from other authorities within the state. 

Forecast information may be derived from the U.S. Department of Energy’s national annual 

forecasts of future gasoline consumption in millions of barrels per day, however, this forecast is

not disaggregated to the state/area level.30 (Note that 1 barrel equals 42 gallons.) A simple 

approach for projecting state/area-level consumption would be to apply the national average 

growth rate to the latest state-level reported values. States may develop their own approach for 

disaggregation or use the state/area gasoline consumption breakouts provided in Table A-4 in the 

Appendix. The values in Appendix Table A-4 are EPA estimates based on the ratio of countylevel highway gasoline consumption to national consumption generated from national MOVES 

2010b runs based on Department of Energy Annual Energy Outlook 2011 VMT.

 

25 See EPA Memorandum Onboard Refueling Vapor Recovery Widespread Use Assessment, Glenn W. Passavant, 

June 2011. This equation was also used in EPA’s RIA for the original ORVR Final Rule 77 FR 28772, May 16, 

2012.

26 Exp is the root of the natural logarithm e, it has a value of 2.71828. In this case it is e raised to the power of the 

term in the brackets.

27 See pp. 3-16 to 3-18 of, “Technical Guidance – Stage II Vapor Recovery Systems for Control of Vehicle 

Refueling at Gasoline Dispensing Facilities Volume I: Chapters” EPA-450/3-91-022a, November 1991, for basic 

information. Additional references are listed in this document.

28

 http://www.epa.gov/otaq/fuels/gasolinefuels/volatility/standards.htm

29 Use the latest version available of the DoT FHWA Highway Statistics; see the table entitled “Monthly gasoline 

reported by States – MF33GA.” The 2010 version of “Highway Statistics” is found at: 

http://www.fhwa.dot.gov/policyinformation/statistics/2010/33ga.cfm

30 Use the motor gasoline projection from the latest version available of the Department of Energy EIA Annual 

Energy Outlook (AEO); see the table entitled “Liquid Fuels Supply and Distribution - Reference Case.” The 2011 

AEO is found at: http://www.eia.gov/oiaf/aeo/tablebrowser/#release=AEO2011&subject=0-AEO2011&table=11-

AEO2011®ion=0-0&cases=ref2011-d020911a
21

Example 1: Assume we are conducting this calculation for a State in Region 1 of the 

EPA fuels temperature matrix for the five-month ozone season May-September, and assume we 

are using the Incrementmid2013 value from Example Scenario #1 above, which is 8.4 percentage 

points in mid-2013. Since this is an area in Region 1 of the EPA fuels temperature matrix with an 

ozone season gasoline RVP of 7.0 psi, the EF calculates to 3.0 g/gal (Td=74°F and ΔT=11.4°F). 

Using Table MF-33GA from the 2010 Highway Statistics report, determine Massachusetts’

annual gasoline consumption (i.e., 2,795,148,000 gallons per year). For the five month ozone 

season the monthly data in the table indicates that about 43 percent of gasoline is being 

consumed during May-September. Growth from 2010-2013 is about 3.44 percent. So, GCmid2013

= 2,795,148,000 * 0.43 * 1.0344 = 1,243,259,400 gal/ozone season.

For the five month ozone season selected here the overall emissions effect of removing 

Stage II would be:

 Tonsmid2013 = Incrementmid2013 * GCmid2013 * EF * (conversion factors)

= (0.084)(1,243,259,400 gal/season)(3.0 g/gal)[(1 lb/453.59 g)(1 ton/2000 lbs)] 

= 341.9 tons/ozone season

In the above equation, in order to obtain an answer in tons per ozone season, we have 

introduced conversion factors into the equation where 453.59 grams equal 1 pound, and 2,000 

pounds equal 1 ton. These conversion factors are also used in the equation below.

On a daily basis this would be about 2.23 tons per day on average for the 153 days in this 

five-month ozone season. There are approximately 3,200 GDFs in Massachusetts with Stage II 

VRS. On a daily basis this represents about 1.4 lbs/day per GDF.

States can further disaggregate these calculations to individual ozone nonattainment areas 

in the state using the estimates in Appendix Table A-4. The effect would be proportional to 

gasoline consumption.

Example 2: Looking at this same Example Scenario #1 above for Deltamid2013, the 

emissions impact calculation shows a net gain of tons reduction per ozone season for ORVR 

over Stage II alone:

 Tonsmid2013 = (0.155)(1,243,259,400 gal/season)(2.97 g/gal)[(1 lb/453.59 g)(1 ton/2000 lbs)] 

= 630.9 tons/ozone season 

On a daily basis this net difference would be about 4.12 tons per day on average for the 

153 days in this five-month ozone season.

3.6 States/Areas with Stage II but not Affected by 182(b)(3) or 184(b)(2)

Portions of six states have implemented Stage II for some areas even though they were 

not required to do so under the CAA to meet a requirement under sections 182(b)(3) or 

184(b)(2). These include Kentucky, Tennessee, Nevada, California, Oregon, and Washington. 

If these states/areas included Stage II-related emission reductions in their SIPs, they will have to 

amend their SIPs if Stage II is no longer required, and will have to address the provisions of 
22

CAA section 110(l). To facilitate any assessments for SIP revisions (as discussed above), we 

have included the relevant input parameters in Table A-8 in the Appendix.

4. Strategies and Considerations for Phasing Out Stage II Controls

Even though EPA has determined that ORVR is in widespread use in the motor vehicle 

fleet, and has waived the statutory requirement to implement Stage II programs in ozone 

nonattainment areas, states are not obligated to remove the programs. States and local areas may 

elect to retain Stage II because it provides VOC and hazardous air pollutant emission reductions 

for non-ORVR equipped vehicles. States that wish to phase out Stage II controls do not 

necessarily need to wait until the foregone emissions control approaches zero before seeking a 

SIP revision. There may come a point where retaining Stage II controls is otherwise unattractive 

for cost and cost-effectiveness reasons and, as discussed above, the foregone emission reductions 

are small enough that the loss of control would not affect compliance with the NAAQS. This is 

especially relevant here since the increment in the first year of Stage II removal will not remain 

constant in the future but will continue to decrease going forward in time. This will provide 

added assurance that any potential impact on air quality would also diminish. The state would 

need to maintain its Stage II program until it is fully phased out and until the state has begun 

implementing any needed new measures to ensure there will not be a harmful gap in area-wide 

emissions control.

4.1 Gradual Phase-out Strategy

If a state determines that decommissioning all Stage II control in an area all at one time 

or by a date certain would result in an unacceptable area-wide emissions increase, then states 

might consider a gradual phase-out strategy. A strategy of this nature is illustrated in Example 

Scenario #3 above. Using this approach a state might design a phase-out strategy that first 

exempts new GDFs from Stage II controls starting in 2013, and provides for subsequent 

decommissioning of existing Stage II-equipped GDFs starting with the lowest throughput 

stations in 2014 and ending with the highest throughput stations in 2017. An example phase-out 

strategy might also use some of the original Stage II program phase-in parameters in CAA 

section 182(b)(3) (e.g., new facilities exempted first, then GDFs that dispense less than 100,000 

gallons per month, and then all remaining GDFs). 

4.2 Cost Considerations

To support their decision making, states may wish to conduct an economic analysis of 

their Stage II control program to evaluate the ongoing annualized cost per ton of VOC removed. 

The EPA conducted this type of assessment to support the final widespread use determination

rule.

31

 The EPA estimates that for an average size GDF the annual cost to maintain existing 

Stage II systems is about $3,000per year. These total costs would be incurred by GDF operators 

each year to cover ever decreasing annual emission reduction benefits as measured by the 

increment calculation (Equation 1) described above. The EPA also estimates that the additional 

 

31 See Final Regulatory Support Document - Widespread Use for Onboard Refueling Vapor Recovery and Stage II 

Waiver: Decommissioning Stage II Vapor Recovery, Financial Benefits and Costs, March 2012.
23

costs of installing Stage II vapor recovery equipment at new GDFs, which typically include 

USTs, associated piping, pumps and ancillary equipment, ranges from $20,000 to $60,000. If 

this cost is amortized over a short period of time as ORVR continues to phase-in (e.g., 3 years)

the new control may not be attractive from a cost effectiveness view point.

4.3 Decommissioning Issues

Whatever approach a state decides upon for phasing out Stage II controls, consideration 

should be given to proper decommissioning of Stage II-related equipment, including the 

underground vapor piping, and to ensuring that consistent procedures are in place to address 

liquid and vapor leak issues associated with decommissioning. The EPA recommends that 

currently available industry association codes and standards be followed (where applicable) to 

ensure that Stage II systems are properly designed, constructed, installed, and, in this case, 

dismantled or decommissioned. These codes and standards of practice provide a means for 

states to monitor methods of Stage II system decommissioning and we encourage state and local 

agencies to reference these codes. The EPA realizes that industry codes and standards may be 

updated periodically, and the EPA also recognizes that state and local requirements may 

supersede industry codes and standards or be inherently more stringent. The EPA regulations do 

not require the use of a particular issue of code. The Petroleum Equipment Institute (PEI) and at 

least four states have recommended practices or specific requirements for decommissioning 

Stage II systems. The PEI guidance, “Recommended Practices for Installation and Testing of 

Vapor Recovery Systems at Vehicle Fueling Sites, PEI/RP300-09,” is especially instructive as it 

was developed by industry experts with a focus on regulatory compliance and safety. It contains 

the steps involved in dismantling Stage II hardware and applies to both balance and vacuum 

assist type systems. Please be aware that there may be other codes or standards not listed here 

that may also be appropriate to ensure proper Stage II decommissioning.

4.4 Potential Emission Reduction Programs for GDFs

By viewing the GDF in its entirety as a fuel storage and dispensing system, existing GDF

emissions control systems can be enhanced to achieve a higher level of in-use efficiency, and to 

deliver more environmental benefit. Of course, additional system design, maintenance, and 

enforcement provisions add cost to the installation and ongoing operation of the systems. 

Examples of extra design and monitoring features include: 1) ORVR compatible Stage II 

nozzles; 2) systems to help better manage UST pressure and control emissions lost from the UST

through vent lines and fugitive leak sources during normal operations; 3) post processors to 

control or eliminate normal UST breathing/emptying loss emissions; 4) standards for specially 

designed nozzles that reduce emissions from liquid retention, drips, and spills; and 5) low 

permeation fuel hoses. 
24

5. Submission, Review and Approval of SIP Revisions

When submitting a SIP revision seeking removal of an existing Stage II vapor recovery 

program, the SIP revision package should include the information necessary for the EPA to 

determine that the action complies with all relevant CAA provisions, including, as applicable,

sections 110(l), 193, and 184(b)(2). States are encouraged to work closely with EPA Regional 

Offices to develop SIP revision packages. 

5.1 Elements of SIP Revision Package

The state should coordinate with the appropriate EPA Regional Office on the necessary 

format and procedures for submitting a SIP revision. Submittal and cover letters should be 

addressed to the EPA Regional Administrator (RA) or the Regional Air Division Director (ADD) 

if the RA has delegated that authority to the ADD to accept SIP revisions submittals. The SIP 

revision should clearly identify the portion of the state regulation pertaining to the Stage II 

regulatory program that the state is requesting to revise. If following this guidance document, 

the state could include the results of area-wide emissions and emissions control calculations 

based on Equation 1 (increment) and/or Equation 2 (delta). The submittal should also include 

analysis, discussion, and any other relevant materials supporting a request for SIP approval with 

regards to sections 110(l), 184 (b)(2) and 193, as applicable. If new emissions control 

regulations are being adopted to offset emissions controls forgone by the phasing out of a Stage 

II program, an analysis of the expected net area-wide emissions change would be appropriate.

5.2 EPA SIP Review Process

The EPA expects that state submission to revise the SIP should show how the revision 

satisfies the requirement in section 110(l) not to interfere with attainment or maintenance of the 

NAAQS or any other applicable requirement. First, the EPA must determine that the submittal is 

complete within 6 months of the submission date. If deemed complete, the EPA must either 

approve or disapprove the submittal within one year of the determination of completeness. The 

EPA will act on SIP revisions through notice and comment rulemaking. 

The EPA is not limited to only considering the calculations presented in this 

memorandum when considering a SIP revision seeking to remove Stage II control requirements. 

There is no specific value in terms of percentage control or tons of emissions that a state must 

meet before EPA can propose to approve a SIP revision. Each SIP revision will be reviewed on 

a case-by-case basis against the criteria of CAA section 110(l), and if applicable, sections 193

and/or 184(b)(2), with due consideration to the basis for the values used in supporting 

calculations and any related emissions inventory and/or air quality analyses. 
25

Appendix

Table A-1 - Projected Penetration of ORVR in the National Gasoline Fueled Vehicle Fleet 

by Year

[Based on MOVES 2010(a)]

1 2 3 4

End of Calendar 

Year

Vehicle Population 

Percentage VMT Percentage Gasoline Dispensed Percentage

2006 42.6% 51.2% 49.2%

2007 48.4% 57.3% 55.5%

2008 53.3% 62.3% 60.5%

2009 57.7% 66.8% 64.8%

2010 62.4% 71.6% 69.5%

2011 67.1% 76.0% 73.9%

2012 71.4% 80.0% 77.7%

2013 75.3% 83.4% 81.0%

2014 78.7% 86.3% 84.0%

2015 81.8% 88.8% 86.5%

2016 84.5% 90.9% 88.6%

2017 86.8% 92.5% 90.3%

2018 88.8% 93.9% 91.9%

2019 90.5% 95.0% 93.2%

2020 92.0% 95.9% 94.3%

See EPA Memorandum “Updated data for ORVR Widespread Use Assessment” February 29, 

2012, in docket (number EPA-HQ-OAR-2010-1076) addressing details on values in this table

and providing more calendar years.

Note: In this table, the columns have the following meaning.

1. Calendar year that corresponds to the percentages in the row associated with the year.

2. Percentage of the gasoline-powered highway vehicle fleet that have ORVR.

3. Percentage of gasoline-fueled vehicle miles traveled (VMT) by vehicles equipped with 

ORVR.

4. Amount of gasoline dispensed into ORVR-equipped vehicles as a percentage of all gasoline 

dispensed to highway motor vehicles.
26

Table A-2 - Monthly Average Dispensed Liquid Temperature

Dispensed liquid temperature (°F)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Weighted Average

Summer

(Apr–Sep)

Winter

(Oct-Mar)

Annual 

Average

National 

Average 51 54 54 58 69 76 82 81 76 70 62 54 74 58 66

Region 1 43 45 48 53 66 74 78 78 72 66 59 46 70 51 61

Region 2 69 74 73 80 84 87 90 91 78 85 83 73 85 76 81

Region 3 54 57 61 67 76 82 83 84 79 76 67 54 79 62 70

Region 4 50 51 41 47 63 74 88 85 83 75 63 52 74 56 65

Region 5 54 NA NA NA 72 77 83 83 79 74 67 58 79 63 72

Region 6 NA 48 49 53 59 63 NA 73 71 60 49 42 64 50 57

Regional Boundaries

Region 1: ME, VT, NH, MA, CT, RI, NY, NJ, PA, DE, MD,VA,WV,DC, KY, OH, IN, IL, MI, WI

Region 2: NC, SC, GA, FL, AL, MS, AR, LA, TN

Region 3: OK, TX, NM, AZ

Region 4: MN, IA, MO, ND, SD, NE, KS, MT, WY, CO

Region 5: CA, NV, UT

Region 6: WA, OR, ID

Source: McNally Michael and Dickerman J.C., "Summary and Analysis of Data from Gasoline 

Temperature Survey," conducted by API, Radian Corporation, May, 1976.
27

Table A-3 - Seasonal Variation In Temperature Difference Between Vehicle Fuel Tank and

Dispensed Fuel

(

Temperature Difference (

Average 

Annual

Summer

(Apr – Sep)

Winter

(Oct – Mar)

5-Month 

Ozone Season

(May – Sep)

2-Month 

Ozone Season

(Jul – Aug)

National 

Average 4.4 8.8 -0.8 9.44 9.9

Region 1 5.7 10.7 -0.3 11.5 12.5

Region 2 4.0 6.8 0.9 7.5 8.2

Region 3 3.7 7.6 -0.4 7.1 7.0

Region 4 5.5 11.7 -2.4 12.1 13.3

Region 5 0.1 3.9 -4.4 5.1 3.2

Region 6 Use Region 4 data

Regional Boundaries

Region 1: ME, VT, NH, MA, CT, RI, NY, NJ, PA, DE, MD,VA,WV,DC, KY, OH, IN, IL, MI, WI

Region 2: NC, SC, GA, FL, AL, MS, AR, LA, TN

Region 3: OK, TX, NM, AZ

Region 4: MN, IA, MO, ND, SD, NE, KS, MT, WY, CO

Region 5: CA, NV, UT

Region 6: WA, OR, ID

Source: Rothman, Dale and Johnson, Robert, Technical Report, “Refueling Emissions from 

Uncontrolled Vehicles,” EPA.OMS, EPA-AA-SDSB-85-6. June 1985.
28

Table A-4 - Percent of 50 State Gasoline Consumption for Areas Covered by CAA Sections 

182(b)(3) or 184(b)(2)

State Counties

Historical 

Ozone 

Nonattainment

Areas

Area Name

% of 50 State 

Gasoline 

Consumption

AZ 3 1 Phoenix 1.079%

CA 21 8

Sacramento 0.7181%

San Joaquin 1.140%

East Kern 0.0532%

LA - South Coast 4.545%

Southeast Desert 0.6764%

San Diego 1.096%

Santa Barbara 0.1270%

Ventura 0.2201%

CT 8 1

All CT 1.061%

Greater CT 1.041%

NY-NJ-CT 0.0196%

DC 1 1 DC 0.1270%

DE 3 2

All DE 0.3079%

Philadelphia-WilmingtonTrenton 0.2345%

Sussex 0.0763%

GA 13 1 Atlanta 1.677%

IL 8 1 Chicago-Gary-Lake 1.678%

IN 4 1 Chicago-Gary-Lake 0.2906%

LA 6 1 Baton Rouge 0.2221%

MA 14 2

All MA 1.922%

Boston (Eastern MA) 1.960%

Springfield (Western MA) 0.2314%

MD 12 3

Baltimore 0.85859%

DC/MD/VA 0.7161%

Philadelphia-WilmingtonTrenton 0.043%

ME 3 0 Portland 0.1943%

MO 5 1 St. Louis 0.7764%

NH 4 1 Portsmouth-Dover-Rochester 0.2950%
29

State Counties

Historical 

Ozone 

Nonattainment

Areas

Area Name

% of 50 State 

Gasoline 

Consumption

NJ 21 2

All NJ 2.598%

New York-New Jersey-Long 

Island 1.736%

Philadelphia-WilmingtonTrenton 0.8621%

NY 10 1

New York-New Jersey-Long 

Island 2.427%

PA 12 2

Philadelphia-WilmingtonTrenton 0.8480%

Pittsburgh-Beaver Valley 0.652%

RI 5 1 All RI 0.307%

TX 16 4

Houston-Galveston-Brazoria 1.646%

El Paso 0.1841%

Dallas-Ft. Worth 1.786%

Beaumont-Port Arthur 0.1230%

VA 17 2

DC/MD/VA 0.7082%

Richmond 0.3390%

VT 14 0 All VT 0.362%

WI

6

4

Milwaukee-Racine & Kenosha 0.5779%

1 Sheboygan 0.0383%

1 Manitowoc 0.0349%

1 Kewaunee 0.0084%
30

Table A-5 - Applicability of Clean Air Act Requirements to Areas Implementing Stage II 

Gasoline Vapor Recovery Programs for the Ozone NAAQS

State Nonattainment Areas §110(l)

Only1

§184(b)(2)

(OTR 

Comparable 

Measures)

§193

(Pre-1990 

Savings 

Provision)

Attaining

Ozone NAAQS2

1-hour3 1997

8-hour4 

2011

DV

2008 8-

hour5

AZ Phoenix X Yes Yes 0.077 No

CA

LA-South Coast X No No 0.107 No

LA-San Bernardino Co 

(West Mojave Desert)

6 X No No 0.097 No

Sacramento Metro X Yes No 0.095 No

San Joaquin Valley6 X No No 0.094 No

Riverside Co (Coachella 

Valley)6 X Yes No 0.093 No

Ventura Co X Yes Yes 0.083 No

San Diego X Yes Yes 0.082 No

Santa Barbara-Santa 

Maria-Lompoc X Yes Yes 0.076 No

CT NYC-Long Is., NY-NJ-CT X Yes Yes 0.084 No

Greater CT Area X Yes Yes 0.076 No

DE

Philadelphia-WilmingtonAtlantic City, PA-NJ-MDDE

X Yes Yes 0.083 No

Sussex County, DE OTR 

Area X Yes Yes 0.077 No

GA Atlanta X Yes Yes 0.080 No

IL

Chicago-Gary, IL-IN X Yes Yes 0.077 No

St. Louis, MO-IL X Yes Yes 0.077 No

IN Chicago-Gary, IL-IN X Yes Yes 0.077 No

LA Baton Rouge X Yes Yes 0.082 No

ME ME OTR Area X

Implementing Stage II in 3 

Southern ME Counties.

Yes

MD

Baltimore X Yes No 0.092 No

Philadelphia-WilmingtonAtlantic City, PA-NJ-MDDE

X Yes Yes 0.083 No

Washington DC-MD-VA X Yes Yes 0.082 No

MA7

Boston-LawrenceWorcester (E. MA) X Yes Yes 0.075 Yes

Springfield (W. MA) X Yes Yes 0.074 Yes

MO St. Louis, MO-IL X Yes Yes 0.079 No

NH

Boston-LawrenceWorcester (E. MA) X Yes Yes 0.075 Yes

Portsmouth-DoverRochester X Yes Yes 0.063 Yes

Rest of NH OTR Area X

Implementing Stage II and 

RFG to meet comparable 

measures. 

Yes
31

State Nonattainment Areas §110(l)

Only1

§184(b)(2)

(OTR 

Comparable 

Measures)

§193

(Pre-1990 

Savings 

Provision)

Attaining

Ozone NAAQS2

1-hour3 1997

8-hour4 

2011

DV

2008 8-

hour5

NJ

NYC-Long Is., NY-NJ-CT X X Yes Yes 0.084 No

Philadelphia-WilmingtonAtlantic City, PA-NJ-MDDE

X Yes Yes 0.083 No

Rest of NJ OTR Areas X

Implementing Stage II in all 

counties. Yes

NY NYC-Long Is., NY-NJ-CT X X Yes Yes 0.084 No

PA

Philadelphia-WilmingtonAtlantic City, PA-NJ-MDDE

X Yes Yes 0.083 No

Pittsburgh-Beaver Valley, 

PA (1-hour Moderate area 

under §182(b)(3))

X Yes Yes 0.080 No

RI Providence and all RI

Areas X Yes Yes 0.073 Yes

TX

Houston X No No 0.089 No

Dallas-Ft. Worth X Yes No 0.090 No

Beaumont-Port Arthur X Yes Yes 0.074 Yes

El Paso X Yes Yes 0.071 Yes

VT All of VT (OTR) X

Implementing Stage II in all 

counties. Yes

VA

Washington DC-MD-VA

(Northern VA) X Yes Yes 0.082 No

Richmond, VA X Yes Yes 0.075 Yes

WI Milwaukee-Racine X Yes Yes 0.077 No

1

All states and all areas are required to comply with CAA section 110(l), chart shows states/areas where 110(l) is the only constraint. 

2 Based on air quality data from 2009-2011.3 The 1-hour ozone NAAQS was promulgated in 1979 and was 0.12 ppm.

4 The first 8-hour ozone NAAQS was promulgated in 1997 and is 0.08 ppm and is attained if the area design value is less that or equal to 0.084 

ppm. Once an area was designated under the 1997 ozone standard, the 1-hour standard was revoked for that area. As of April 15, 2008, all areas 

were designated under the 1997 ozone standard.

5 The 2008 8-0hour Ozone NAAQS is 0.075 ppm. 

6 History of redistricting and boundary changes between air districts with pre-1990 requirements. District may have Stage II gasoline dispensing 

rules in some parts of district prior to 1990.

7 The MA Stage II program was adopted prior to 11/15/1990 but was not approved into the SIP until 12/14/1992.
32

Table A-6 - Percent of State/Area GDF Dispensers Using Vacuum Assist Stage II 

Technology (June 2012)

State Number

Counties Area name % GDFs usingVacuum Assist

ARIZONA 3 Phoenix 85%

CALIFORNIA32 21

Average QSIIva 70%

Sacramento ORVR Compatible

San Joaquin ORVR Compatible

East Kern ORVR Compatible

LA - South Coast ORVR Compatible

Southeast Desert ORVR Compatible

San Diego ORVR Compatible

Santa Barbara ORVR Compatible

Ventura ORVR Compatible

CONNECTICUT 8 All CT 88%

DELAWARE 3 All DE 88%

DC 1 DC 97%

GEORGIA 13 Atlanta 95%

ILLINOIS 8 Chicago metro 92%

INDIANA 4 Chicago-Gary metro 95%

LOUISIANA 6 Baton Rouge 90%

MAINE 3 Portland 95%

MARYLAND 12 Baltimore and Wash DC areas 94%

MASSACHUSETTS 14 All MA 90%

MISSOURI 5 St. Louis 0%

NEW HAMPSHIRE 4 Portsmouth Dover Rochester 93%

NEW JERSEY 21 All NJ 48%

NEW YORK 10 NYC metro 73%

PENNSYLVANIA 12 Philadelphia metro 80%

Pittsburgh -Beaver Valley 96%

RHODE ISLAND 5 All RI 93%

TEXAS33 16

Average QSIIva 90%

Houston-Galveston-Brazoria ORVR Compatible

El Paso ORVR Compatible

Dallas-Fort Worth ORVR Compatible

Beaumont -Port Arthur ORVR Compatible

VIRGINIA 17 Wash DC metro area 93%

Richmond 85%

VERMONT 14 All VT 95%

WISCONSIN 9 All Counties 85%

 

32 Estimates for California provided by state sources, all vacuum assist must be ORVR compatible.

33 Estimates for Texas provided by state sources, all vacuum assist must be ORVR compatible.
33

Table A-7 - Five –Month (May-September) Uncontrolled Displacement (non-ORVR) 

Refueling Emission Factors (g/gal)

State Number

Counties Area name RVP (psi)

Emission 

Factor

ARIZONA 3 Phoenix 7.8 3.5

CALIFORNIA 58 All CA 7.0 3.4

CONNECTICUT 8 All CT 7.0 3.0

DELAWARE 3 All DE 7.0 3.0

DC 1 DC 7.0 3.0

GEORGIA 13 Atlanta 7.0 4.6

ILLINOIS 8 Chicago metro 7.0 3.0

INDIANA 4 Chicago-Gary metro 7.0 3.0

LOUISIANA 6 Baton Rouge 7.8 5.1

MAINE 3 Portland 7.8 3.3

MARYLAND 12 Baltimore and Wash DC areas 7.0 3.0

MASSACHUSETTS 14 All MA 7.0 3.0

MISSOURI 5 St. Louis 7.0 3.3

NEW HAMPSHIRE 4 Portsmouth Dover Rochester 7.0 3.0

NEW JERSEY 21 All NJ 7.0 3.0

NEW YORK 10 NYC metro 7.0 3.0

PENNSYLVANIA 12 Philadelphia metro 7.8 3.0

Pittsburgh -Beaver Valley 7.0 3.3

RHODE ISLAND 5 All RI 7.0 3.0

TEXAS 16 All TX 7.0 3.5

VIRGINIA 17 All VA 7.0 3.0

VERMONT 14 All VT 9.0 3.9

WISCONSIN 6

Milwaukee-Racine 7.0 3.0

Sheboygan, Manitowoc, 

Kewaunee 9.0 3.9
34

Table A-8 - Input Data for States/Areas with Stage II but not Affected by 182(b)(3) or 

184(b)(2) (July 2012)

State

Number

Counties Area name

Percent of 50 

State Gasoline 

Consumption

% GDFs 

using

Vacuum 

Assist34

RVP 

(psi)

Five –

Month 

(MaySeptember 

Refueling 

Emission 

Factors 

(g/gal)

CALIFORNIA35 37

All AQMDs

& APCDs 

not listed in 

tables above

2.565% 70% ORVR 

Compatible 7.0 3.4

KENTUCKY 3

Jefferson 0.2498% 98% 7.0 3.0

N KY 0.1299% 98% 7.0 3.0

NEVADA 2

Washoe 

County 0.1087% 40% 7.8 3.9

Clark 

County 0.430% 70% 9.0 4.4

OHIO 16

ClevelandAkron 0.8076% 97% 9.0 3.9

Cincinnati 0.4775% 96% 7.8 3.4

Dayton 0.2884% 94% 7.8 3.4

OREGON 3 Portland 0.426% 50% 7.8 3.7

TENNESSEE

1 Davidson 0.2409% 98% 7.8 4.6

4

Nashville 

Metro 1.1687% 95% 7.8 4.6

WASHINGTON

5 Seattle 1.088% 80% 9.0 4.3

2 Vancouver 0.1542% 80% 9.0 4.3

 

34 Estimates for California provided by state sources; all vacuum assist must be ORVR compatible.

35 This data provided by the Petroleum Equipment Institute.
35

Table A-9 – MOVES 2012 Vehicle Class Age Distribution

Calendar Model Gasoline

Year Age Year ID Motorcycle Pass Car LDT1 LDT2 HDGV

2012 30 1982 0.001966 0.000668 0.002037 0.002037 0.005699

2012 29 1983 0.001689 0.000718 0.002178 0.002178 0.005426

2012 28 1984 0.002310 0.001094 0.003234 0.003234 0.006327

2012 27 1985 0.002585 0.001559 0.004318 0.004318 0.008814

2012 26 1986 0.003071 0.002170 0.004989 0.004989 0.011413

2012 25 1987 0.003696 0.002585 0.006043 0.006043 0.009350

2012 24 1988 0.003741 0.003538 0.007146 0.007146 0.011049

2012 23 1989 0.004419 0.004355 0.007774 0.007774 0.011843

2012 22 1990 0.005962 0.005407 0.008745 0.008745 0.010388

2012 21 1991 0.007355 0.006255 0.008972 0.008972 0.009462

2012 20 1992 0.009290 0.008232 0.011363 0.011363 0.011102

2012 19 1993 0.011102 0.011132 0.014774 0.014774 0.014453

2012 18 1994 0.013623 0.015221 0.018422 0.018422 0.020989

2012 17 1995 0.011840 0.018786 0.020574 0.020574 0.023061

2012 16 1996 0.015718 0.023545 0.024745 0.024745 0.025302

2012 15 1997 0.017935 0.028620 0.028422 0.028422 0.027497

2012 14 1998 0.018745 0.034619 0.034691 0.034691 0.032089

2012 13 1999 0.021968 0.044520 0.039503 0.039503 0.045460

2012 12 2000 0.029065 0.054649 0.047137 0.047137 0.048348

2012 11 2001 0.036410 0.056862 0.051960 0.051960 0.052218

2012 10 2002 0.042963 0.057388 0.056257 0.056257 0.047379

2012 9 2003 0.048226 0.056194 0.061399 0.061399 0.052367

2012 8 2004 0.056980 0.057747 0.066770 0.066770 0.058223

2012 7 2005 0.067163 0.060876 0.070393 0.070393 0.064607

2012 6 2006 0.076695 0.063183 0.068310 0.068310 0.063641

2012 5 2007 0.080950 0.062722 0.068566 0.068566 0.063843

2012 4 2008 0.089568 0.056968 0.046968 0.046968 0.048232

2012 3 2009 0.047643 0.051356 0.037902 0.037902 0.040547

2012 2 2010 0.067916 0.061669 0.054558 0.054558 0.052774

2012 1 2011 0.089591 0.070362 0.059917 0.059918 0.057786

2012 0 2012 0.109815 0.076999 0.061931 0.061930 0.060313

Total 1.000000 1.000000 1.000000 1.000000 1.000000

Avg Age 6.9 8.0 8.9 8.9 9.6

LDT1: <6000 lbs GVWR

LDT2 : >6000 but <8500 lbs GVWR

HDGV: > 8500lbs GVWR
36

United States

Environmental Protection

Agency

Office of Air Quality Planning and 

Standards

Research Triangle Park, NC

Publication No. EPAEPA-457/B-12-001

August 7, 2012