United States

Environmental Protection

Agency

Air and Radiation EPA420-F-01-031

October 2001

Mobile Source Air

Toxics (MSAT) Rule

Questions And Answers

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EPA420-F-01-031

October 2001

Mobile Source Air Toxics (MSAT) Rule

Questions And Answers

June 20, 2001

Assessment and Standards Division

Office of Transportation and Air Quality

U.S. Environmental Protection Agency

NOTICE

This technical report does not necessarily represent final EPA decisions or positions.

It is intended to present technical analysis of issues using data that are currently available.

The purpose in the release of such reports is to facilitate the exchange of

technical information and to inform the public of technical developments which

may form the basis for a final EPA decision, position, or regulatory action.
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Assessment and Standards Division

Office of Transportation and Air Quality

U.S. Environmental Protection Agency

Mobile Source Air Toxics (MSAT) Rule Questions And Answers

June 20, 2001

The following are responses to questions received by the Environmental Protection Agency

(“EPA” or the “Agency”) concerning the Mobile Source Air Toxics (“MSAT”or “Toxics”) Rule

published in the Federal Register on March 29, 2001 (66 FR 17230).

Regulated parties may use this document to aid in achieving compliance with the MSAT

regulations. However, this document does not in any way alter the requirements of these

regulations. While the answers provided in this document represent the Agency’s interpretation

and general plans for implementation of the regulations at this time, some of the responses may

change as additional information becomes available or as the Agency further considers certain

issues.

This guidance document does not establish or change legal rights or obligations. It does not

establish binding rules or requirements and is not fully determinative of the issues addressed. 

Agency decisions in any particular case will be made by applying the law and regulations on the

basis of specific facts and actual action.

While we have attempted to include answers to all questions received, the necessity for policy

decisions and/or resource constraints may have prevented the inclusion of certain questions. 

Questions not answered in this document may be answered in a subsequent document.

MSAT Rule Questions and Answers

1. Question: The toxics standard in the anti-dumping program for conventional gasoline (CG) is

an exhaust toxics standard, not a total toxics standard. The reformulated gasoline (RFG)

program includes a total toxics standard. Based on several statements in the Preamble for the

MSAT final rule, it appears that the Agency clearly intends the Subpart J toxics standard for CG

to remain an exhaust toxics standard. The regulations, however, do not clearly specify that the

Subpart J CG toxics standard is an exhaust toxics standard.

Answer: Throughout the regulations at Subpart J, we used the term “toxics” in the generic sense,

and refer separately to the requirements for conventional gasoline and to the requirements for

reformulated gasoline and RBOB, combined. The anti-backsliding provisions are intended to

apply to the toxics performance standards applicable to the specific type of gasoline. Thus, the

standard for conventional gasoline applies to exhaust toxics emissions, in mg/mile, and the

standard for reformulated gasoline and RBOB applies to total toxics, in percent reduction.
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2. Question: In § 80.915(a)(3), what does “All consecutive and non-consecutive batch toxics

measurements” mean?

Answer: The intent of the phrase “All consecutive and non-consecutive batch toxics

measurements” at § 80.915(a)(3) was to instruct the refiner or importer that all data during the

baseline period must be included in the baseline determination.

3. Question: On page 17250 of the preamble, EPA states: “Because this data is already required

to demonstrate compliance with RFG and anti-dumping requirements, a refiner must simply

submit the same information found in its original submittals of its RFG and anti-dumping

reports.” The 1998 and 1999 toxics calculations were reported based on Phase I of the Complex

Model. The regulations require that Phase II of the Complex Model be used.

Answer: The procedure listed in the regulations should be followed. See 40 CFR § 80.915(d).

All 1998 and 1999 batch toxics values (as applicable for RFG or CG) should be determined using

the Phase II Complex Model.

4. Question: Should Gasoline Treated as Blendstock (GTAB) be included in the baseline

determination?

Answer: Yes, GTAB should be included in the baseline determination to the same extent it was

used in determining compliance with the RFG or anti-dumping requirements.

5. Question: Should Oxygenated Fuels Program Reformulated Gasoline (OPRG) be included in

the baseline determination?

Answer: Yes, OPRG should be included in the baseline determination because it is considered

RFG.

6. Question: In one of the baseline years, we were not in compliance with our anti-dumping

baseline requirement. How do we handle this in calculating our individual baseline?

Answer: If a refinery’s or importer’s anti-dumping standard was not met during one (or more) of

the baseline years under this rule (i.e., 1998, 1999, 2000), then the refinery’s or importer’s antidumping toxics standard should be used as the toxics value for all batches produced in the year(s)

the anti-dumping standard was not met.

7. Question: How should the compliance margin be used in calculating the baseline toxics

value?

Answer: The compliance margin value should be included in a toxics baseline determination in

such a manner that its inclusion provides an additional margin of flexibility to comply with the

standard. The technique of including the compliance margin value can vary depending on the
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sign convention applied to the toxics standard, especially in the case of RFG, where toxics

emissions are determined as “percent reductions”. For example, the compliance margin value for

RFG is given as -0.7% (§ 80.915(h)(1)). For a refiner or importer whose batch calculations result

in a toxics value of -32% (also known as a 32% reduction), proper inclusion of the compliance

margin would result in a toxics baseline value (per § 80.915 (b)(1)) of -31.3%.

8. Question: Would an equivalent method for calculating the baseline be to use a volume

weighted average of the compliance performance for 1998, 1999 and 2000?

Answer: No, the toxics value of each batch (determined according to the RFG or anti-dumping

requirements, as applicable) must be determined using the appropriate Phase II seasonal

Complex Model, and then the toxics values of all of the batches (separately for RFG/RBOB and

CG) must be volume-weighted together. 

9. Question: Under § 80.855 (a) and (b) a refiner or importer must use the default values “if it

cannot determine an applicable toxics value for every batch of gasoline produced or imported for

12 or more consecutive months during January 1, 1998 through December 31, 2000.” So if a

refiner produced only one batch over the three-year period and is able to determine the toxics

value, would its baseline be based on that one value, or would the refiner need to have batches

with a toxics determination in each month of a 12 month period in order to use the calculated

baseline? 

Answer: Our intent in establishing the default compliance baseline was that it apply to those

refiners or importers with minimal or inconsistent production or importation of gasoline during

the baseline period. By providing threshold criteria in § 80.855 for when a default baseline will

apply, we sought to ensure that individual baselines are developed rigorously, considering

volume, batch frequency, etc. The default compliance baseline provision was not intended to

apply to refiners or importers with continuous gasoline production or supply (import) during the

baseline period. Most refiners will have produced gasoline during every month of a 12-month

period and will have data for every batch of gasoline produced over that period. Thus, the 12-

month requirement in § 80.855 is easily met by these refiners no matter how EPA interprets the

requirement. Importers on the other hand, supply gasoline in many patterns. Some importers

bring in gasoline only seasonally, but they do it every season, and in significant quantity. Other

importers bring in batches regularly throughout the year. Particularly for importers, we were

wary of the possibility of a very small number of batches during the baseline period constituting

a baseline.

We interpret § 80.855 to apply to a refiner or importer which does not have data spanning a 12-

month period between 1998 and 2000 (that is, any 12-month period between 1998 and 2000). 

For example, § 80.855 would not apply to an importer that imported two batches – a batch in

January 1999 and a batch in December 1999. Nor would § 80.855 apply if the two batches were

imported in June 1998 and May 1999. However, if the only two batches imported by the

importer were in January 1999 and June 1999, the importer would not have data for batches over
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a 12-month period and would be subject to the default baseline. Likewise, if the two batches are

spread out by more than 12 months (e.g., a batch in January 1999 followed by a January 2000

batch), this would not be considered sufficient to support an individual baseline and the importer

would be subject to the default compliance baseline.

It is important to note that this 12-month requirement is simply a threshold. Once a refiner or

importer satisfies this requirement and determines it is eligible for an individual baseline, it must

include all data on any gasoline produced or imported (for use in the United States, excluding

California gasoline per § 80.845)) during the baseline period (1998-2000).

It is also important to note that a baseline adjustment under § 80.915(g) is only available to those

eligible for an individual baseline; refiners or importers subject to the default compliance

baseline are not eligible for such an adjustment.

10. Question: A party could have activity in every calendar month but not in both RFG and CG. 

Does the default baseline apply separately?

Answer: Yes. The baselines should be determined separately. In other words, you should look

only at the CG data in determining whether the minimum data requirements in § 80.915(a)(1) are

satisfied for the CG baseline and only at the sufficiency of the RFG data for the RFG baseline. 

Refer to Question 9 for additional discussion on the minimum data requirements of

§ 80.915(a)(1).

11. Question: If the default compliance baseline (under § 80.855) is applicable due to

insufficient data, must the batch information required under § 80.910(c)(5) be submitted?

Answer: Yes. Section 80.910 applies to all refiners and importers, whether or not they are

subject to the default compliance baseline provided in § 80.855. Section § 80.910(c)(2), for

example, specifically addresses the information to be submitted under that paragraph in the event

that a refinery or importer is subject to § 80.855. The information required to be submitted under

§ 80.910(c)(5) will help us to verify that such facilities have correctly determined that the default

baseline is the appropriate baseline for that facility.

12. Question: Two of our refineries produced a few batches of RBOB/RFG over the baseline

period. Is this considered sufficient data for calculating a toxics baseline?

Answer: See Question 9 regarding minimum data requirements.

13. Question: A refinery that had not previously produced RFG may choose to do so in the

future. Its 1998-2000 baseline RFG volume will be zero. Will future RFG production be based

on an incremental volume production basis (i.e., the new RFG production is subject to existing

RFG standards) or is the refinery judged as incapable of establishing a 1998-2000 RFG baseline

and therefore subject to the new default RFG standard (not based on environmental need nor
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cost-effectiveness)?

Answer: Refineries in operation during 1998-2000 that did not make one or the other type of

gasoline (reformulated or conventional) are subject to the default baseline for the type of gasoline

they did not produce. As we explained in the preamble to the final rule, “For those refineries or

importers that are unable to establish a volume baseline for 1998 to 2000 either because they

were not operating during that period, or did not exist as a refining or importing facility, the

applicable standard shall be the 1998-2000 national average toxics performance for RFG and

CG.” 66 FR 17230, 17249 (March 29, 2001). We explained further that, “[A] refiner or

importer which did not produce or import one or more types of gasoline (either RFG or CG)

during the baseline period but who produces or imports that type of gasoline after December 31,

2000 will have the applicable default toxics anti-backsliding baseline . . . .” 66 FR at 17521.

Thus, a refinery which, during 1998-2000, produced RFG and/or RBOB but insufficiently per the

requirements at § 80.855 (see Question 9)) or begins the production of reformulated gasoline

after December 31, 2000, will be subject to the default RFG toxics baseline for its reformulated

gasoline.

14. Question: § 80.815(c)(2) calls for complying with subpart J on an aggregate basis consistent

with subpart E. Does this then apply to RFG as well as conventional gasoline?

Answer: No. The regulations at Subpart E (Anti-Dumping), including the provisions in 40 CFR

§ 80.101(h) allowing refiners to comply on an aggregate basis, apply only to conventional

gasoline, unless otherwise referenced. During the period 1995-1997, when refiners and

importers could opt to use the “simple model” to determine compliance with the reformulated

gasoline requirements, the annual average standards applicable to reformulated gasoline for

sulfur, olefins and T90 were required to be met on the same basis as the aggregate chosen for

conventional gasoline. 40 CFR § 80.41(h)(2)(iii). This option to comply with the simple model

RFG standards on an aggregate basis, however, is no longer available. RFG must now meet the

Phase II complex model standards and there are no aggregation provisions applicable to these

standards.

15. Question: A refinery that had not previously produced RFG may choose to do so in the

future. If the refinery was part of an aggregation group wherein other refineries produced RFG in

1998-2000 and therefore are capable of determining a refinery-specific RFG standard, is the

refinery that produced only conventional gasoline in 1998-2000 now subject to the RFG standard

set by other refineries in its aggregate, by the existing RFG standards, or by the new default RFG

standard?

Answer: As indicated in Question 14, aggregation provisions do not apply to reformulated

gasoline. As a result, if a refinery is part of an aggregate for anti-dumping purposes, it will not

change the baseline applicable to RFG produced at the refinery whether the refinery produced

RFG during the baseline period or not.
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16. Question: My company chose to aggregate all refineries for the purposes of Subpart E. One

of these refineries was permanently shutdown in January of 2001. How should this refinery be

factored into the toxics baseline?

Answer: Every facility of a company must have its own individual baseline (be it a unique

individual baseline or the default baseline). For this rule, as for the anti-dumping program, to

determine the aggregated standard for your refineries, the individual facility baselines are

volume-weighted together to form the aggregate baseline. Also, as required for the anti-dumping

program, when a facility is sold or shutdown, its contribution to the aggregate compliance

standard is removed. Thus, in this case, the aggregate baseline would exclude the shutdown

refinery’s baseline.

17. Question: What is the process for getting a baseline adjustment?

Answer: The baseline adjustment provision at § 80.915(g) specifies the procedure and general 

requirements for submitting a toxics baseline adjustment petition. A refinery or importer which

is eligible for an individual baseline under this rule must submit the petition with its baseline

submittal. The petition must include the unadjusted and adjusted baseline fuel parameters,

applicable toxics values and volumes. The petition must also include “[a] narrative describing

how the circumstances during 1998-2000 materially affected the baseline toxics value . . . .” 40

CFR § 80.915(g)(2)(ii). The narrative must include an appropriate description, including the

reasoning underlying the adjustment, and the calculations used to determine the adjusted values.

Because the reasons a refiner or importer may petition for a baseline adjustment under this rule

may vary widely, we will evaluate all petitions for a toxics baseline adjustment on a case-by-case

basis, with significant interaction between EPA and the petitioner.