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###### Environmental Protection Agency

          - 40 CFR Parts 60, 61, and 63
          - [EPA-HQ-OAR-2009-0174; FRL-8968-8]
          - RIN 2060-AP63

# AGENCY:

Environmental Protection Agency (EPA).

# ACTION:

Advanced notice of proposed rulemaking.

# SUMMARY:

The purpose of this Advanced Notice of Proposed Rulemaking (ANPRM) is to convey issues raised by stakeholders about EPA's emissions factors program, inform the public of our initial ideas on how to address these issues, and solicit comments on our current thinking to resolve these issues. Our goal is to develop a self-sustaining emissions factors program that produces high quality, timely emissions factors, better indicates the precision and accuracy of emissions factors, encourages the appropriate use of emissions factors, and ultimately improves emissions quantification.

Although initially developed for emissions inventory purposes only, use of emissions factors has been expanded to a variety of air pollution control activities including permitting, enforcement, modeling, control strategy development, and risk analysis. This ANPRM discusses the appropriateness of using emissions factors for these activities.

# DATES:

Comments must be received on or before November 13, 2009.

# ADDRESSES:

                        EPA has established a docket for this action under Docket ID No. EPA-HQ-OAR-2009-0174. All documents in the docket are listed in the Federal Docket Management System index at                         *http://www.regulations.gov*. Publicly available docket materials are available either electronically through                         *http://www.regulations.gov*                         or in hard copy at the EPA Docket Center, Public Reading Room,                         *ANPRM Docket,*                         EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the Air Docket is (202) 566-1742.                    

*Instructions:*                         Direct your comments to Docket ID No. EPA-HQ-OAR-2009-0174. The U.S. Environmental Protection Agency's (EPA's) policy is that all comments received will be included in the public docket without change and may be made available online at                         *http://www.regulations.gov,*                         including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through                         *http://www.regulations.gov*                         or e-mail. The                         *http://www.regulations.gov*                         Web site is an “anonymous access” system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e-mail comment directly to EPA without going through                         *http://www.regulations.gov,*                         your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional information about EPA's public docket, visit the EPA Docket Center homepage at                         *http://www.epa.gov/​epahome/​dockets.htm*.                    

*Docket:*                         All documents in the docket are listed in the                         *http://www.regulations.gov*                         index. Although listed in the index, some information is not publicly available,                         *e.g.,*                         CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically in                         *http://www.regulations.gov*                         or in hard copy at the Public Reading Room.                    

# FOR FURTHER INFORMATION CONTACT:

                        Mr. Thomas A. Driscoll, Measurement Policy Group (MPG), Office of Air Quality Planning and Standards (D243-05), Environmental Protection Agency, Research Triangle Park, North Carolina 27711, telephone number: (919) 541-5135; fax number: (919) 541-1039; e-mail address:                         *driscoll.tom@epa.gov.*

# SUPPLEMENTARY INFORMATION:

*Outline.*                     The information in this preamble is organized as follows:                

I. General Information

A. Does this action apply to me?

B. What should I consider as I prepare my comments for EPA?

C. Where can I get a copy of this document and other related information?

II. Background Information

A. The Role of Emissions Factors and Stakeholder Comments

B. Overview of the Emissions Factors Improvement Program

C. Goals for the Emissions Factors Improvement Program

III. Emissions Factors Development Process and Tools

A. WebFIRE

B. Electronic Reporting Tool (ERT)

C. Emissions Factors Development Guidance

IV. Changes to the Emissions Factors Program, Emissions Factors Development, and Associated Tools

A. Potential Revisions to the Emissions Factors Development Process: Overview and Issues

B. Test Data Submittal Requirements

C. Emissions Factors Content and Format

                        D. Interacting with the SPECIATE Database                              ( print page 52724)    

V. Request for Comment and Next Steps

VI. Statutory and Executive Order Reviews

## I. General Information

### A. Does this action apply to me?

                    This notice is likely to be of interest to a variety of parties, including owners and operators of stationary sources who use emissions factors and, in particular, those that are subject to source testing requirements under EPA air rules (                    *i.e.,*                     New Source Performance Standards (NSPS), National Emissions Standards for Hazardous Air Pollutants (NESHAP), and Maximum Achievable Control Technology (MACT) standards); industry sectors that believe that the emissions factors currently used to characterize their emission sources could be updated and improved; industry sectors that currently lack emissions factors; State, local, and tribal air pollution control agencies (S/L/Ts) and other individuals and organizations with an interest in emissions factors. In that the use of emissions factors has expanded beyond developing emissions inventories to other uses (                    *e.g.,*                     developing emissions limits for incorporation into New Source Review (NSR) and Title V operating permits, determining applicability to air pollution regulations, determining compliance with emissions standards, conducting air quality impact analyses, developing control strategies, and performing risk analyses (                    *i.e.,*                     section 112(f) residual risk requirements)), S/L/Ts, industry representatives, environmental action groups, individuals and other organizations may have a vested interest in this notice.                

All of these parties are encouraged to read this notice and to submit comments for EPA's consideration. We realize that in many cases organizations other than EPA develop emissions factors for a variety of purposes, and, in most cases, we do not require the use of EPA emissions factors. However, because the EPA factors are so broadly used and accepted, we are soliciting information and feedback on how they are developed, currently used, and how they can be improved.

### B. What should I consider as I prepare my comments for EPA?

                    Do not submit CBI to EPA through                     *http://www.regulations.gov*                     or e-mail. Clearly mark the part or all of the information that you claim to be CBI. For CBI information in a disk or CD-ROM that you mail to EPA, mark the outside of the disk or CD-ROM as CBI and then identify electronically within the disk or CD-ROM the specific information that is claimed as CBI. In addition to one complete version of the comment that includes information claimed as CBI, a copy of the comment that does not contain the information claimed as CBI must be submitted for inclusion in the public docket. Information so marked will not be disclosed except in accordance with procedures set forth in 40 CFR part 2.                

### C. Where can I get a copy of this document and other related information?

                    In addition to being available in the docket, an electronic copy of this notice will be available on the Worldwide Web through the Technology Transfer Network (TTN). The TTN provides information and technology exchange in various areas of air pollution control. Following signature, an electronic version of this document will be posted at                     *http://www.epa.gov/​ttn/​oarpg*                     under “Recent Additions.”                

## II. Background Information

### A. The Role of Emissions Factors and Stakeholder Comments

                    An emissions factor is a representative value that attempts to relate the quantity of a pollutant released to the atmosphere with an activity associated with the release of that pollutant. These factors are usually expressed as the mass of pollutant divided by a unit mass, volume, distance, or duration of the activity emitting the pollutant (                    *e.g.,*                     kilograms of particulate emitted per megagram of coal burned). Such factors facilitate estimation of emissions from various sources of air pollution. In most cases, these factors are simply averages of all available data of acceptable quality that were collected through source performance testing, and are generally assumed to be representative of population averages for all facilities in the source category.                

                    Quantifying air emissions is a vital aspect of all air pollution programs. Emissions factors have long been a fundamental tool in developing national, regional, state, and local emissions inventories for air quality management decisions and in developing emissions control strategies. More recently, emissions factors have been applied in determining site-specific applicability and emissions limitations in operating permits by federal agencies, S/L/Ts, consultants, and industry. These users have requested guidance on the use of emissions factors and other emissions quantification tools (                    *e.g.,*                     emissions testing and monitoring, mass balance techniques) in developing permits that are more practical in their enforcement.                

Under ideal circumstances, all emissions data users would quantify emissions from ongoing operations with continuous emissions monitoring, periodic emissions performance testing, or frequent calculation using well-accepted engineering principles, such as mass balances or other detailed engineering calculations. Because these methods can be time and resource intensive, users sometimes do not have or are unable to secure data sufficient to allow detailed site-specific emissions determinations. In some cases, measurement via instruments or long-term performance testing, which would provide such data, is not feasible or too costly. Without such data, emissions factors, which are assumed to be representative of population-average values, are frequently used, along with production information as a quick, low-cost method to estimate emissions.

                    EPA's Office of Air Quality Planning and Standards (OAQPS) has long recognized the importance of emissions factors and has focused effort and resources on developing and documenting emissions factors. The EPA-approved emissions factors are contained in an online document called the “AP-42 Compilation of Air Pollutant Emissions Factors” (hereafter referred to as “AP-42”) available at                     *http://www.epa.gov/​ttn/​chief/​ap42/​index.html*. The document is organized into 15 chapters that describe industrial emission sources and the derivation of industry-specific emissions factors. Many of the individual sections of this document are supported by an associated background report providing summaries of the individual test data and a corresponding assigned quality rating, the rationale for grouping and using individual data, and the assignment of the factor and factor quality.                

Emissions factors were originally established only for use in estimating emissions for developing national emissions inventories. However, as mentioned earlier, emissions factors are used for many other air pollution control activities for which they were not designed.

                    AP-42, which was developed by OAQPS, is not the only repository of emissions factors. Emissions factors have been developed for a number of other programs and there are other databases that contain emissions factors. For example, EPA's Office of Atmospheric Programs has recently proposed a greenhouse gas reporting rule and provided many emissions factors for sources to use in assessing their emissions. In addition, EPA's Office of Research and Development                           ( print page 52725)                        administers the SPECIATE database that contains many emissions factors. Because the applications, uses, and requirements of these other emissions factors databases are different than AP-42, these databases have operated in a fairly autonomous manner. However, we are seeking comment on whether there should be more interaction among these databases. For a discussion of SPECIATE, see section IV.D.                

                    As part of a reevaluation of the emissions factors program, EPA interviewed and surveyed various emissions factors users and held a series of workshops in 2003 and 2004 with stakeholders to solicit their input on what is needed to update and improve the emissions factors program.[1]                                          First and foremost, stakeholders (industry, S/L/Ts, EPA program offices, environmental action groups, and others) indicated that EPA needs to continue to maintain the AP-42 factors information compilation and retrieval system. In addition, they indicated that it takes EPA too long to develop emissions factors, that data submitted for regulatory development have not been used to develop new emissions factors, that there have been several inappropriate uses for emissions factors, and that, in general, EPA is not developing new emissions factors. The stakeholders said that EPA should develop criteria to address the development and uses of emissions factors for purposes other than just emissions inventory development, such as for use as screening tools for compliance determinations, applicability purposes, and preparing air program permit applications. They also said that the current program is unresponsive to their needs, too complex for their active participation, and lacks transparency concerning data manipulation. More recently, the National Academy of Sciences (NAS) (see National Research Council of the National Academies, 2004, Air Quality Management in the United States, Washington, DC: The National Academies Press) and EPA's Office of Inspector General (OIG) (see U.S. EPA, Office of Inspector General Evaluation Report: EPA Can Improve Emissions Factors Development and Management, Report No. 2006-P-00017, March 22, 2006) also reviewed and commented on the emissions factors program. Their comments echoed those of all other stakeholders in that the EPA must continue to maintain the emissions factors program, but it must be improved to support EPA and stakeholder uses. They also noted that EPA should quantify uncertainty to improve emissions factors and that EPA should be developing and updating emissions factors regularly.                

### B.  Overview of the Emissions Factors Improvement Program

Based on the results of the emissions factors reevaluation process that included collecting stakeholder input, preparing an improvement plan, and an internal effort to review and reexamine our efforts, we have identified four focus areas for improvement that are the basis for this action:
    - Designing a process for developing and improving emissions factors to allow easier and more effective participation by interested parties, to be open and transparent, to accommodate the continuing (self-sustaining) development and improvement of factors rather than being a large, one-time effort to address the current needs, and to provide an electronic mechanism for test report submittal and review. We want to develop a process that, at the end of the emissions factors development, will result in high quality emissions factors.
    - Improving methods for compiling and providing emissions factors data and other pertinent information to users, including complete and easy access to all available test data.
    - Developing guidance on the application of EPA's default emissions factor or the selection of a more appropriate emissions factor for specific applications, calculating emissions factors from available test data or other information, conducting emissions tests to facilitate the development of emissions factors, and evaluating and considering data quality.
    - Updating existing emissions factors and developing more factors where gaps currently exist.

EPA intends to implement a multi-part process to improve the emissions factors program. The first part involves further development of the existing electronic reporting tool (ERT) to make it easier for S/L/Ts, industry, and other stakeholders to plan, document, accept, assess, and transmit emissions test data. The second part involves upgrading the AP-42 factors information system into WebFIRE. WebFIRE is an Internet-based application that compiles and retrieves emissions factors and performance test data and information; making it an interactive, up-to-date, and easy to expand and enhance replacement for the current AP-42. Additionally, to make the emissions factors development process easier and more transparent, EPA plans to rewrite the existing emissions factors development procedures and reissue the revised document following a public review and comment process. Finally, in order to acquire adequate data for the development or improvement of the emissions factors, we are considering requiring the submission of certain performance testing information by industry to EPA's OAQPS via electronic reporting. Implementing this multi-part effort will result in a self-sustaining emissions factors program receiving ongoing data submittals to improve emissions estimation for regulatory authorities and others to use in: (1) Developing emissions inventories, (2) updating emissions standards, (3) identifying and evaluating control strategies, (4) determining applicability of permit and regulatory requirements, (5) assessing risks, and (6) conducting other air pollution control activities. We believe this effort will reduce the burden of handling test data, while improving access to and the utility of the data.

### C. Goals for the Emissions Factors Improvement Program

                    We believe the critical element in improving the emissions factors program is changing the role of OAQPS from sole developer of emissions factors to a facilitator who provides stakeholders with the tools to participate in all aspects of the process, generates tools that capture the existing work performed by stakeholders and enhance consistency across the program, audits and oversees the program, and develops policies for the appropriate use of emissions factors in non-inventory applications where there are no policies or where existing policies are inadequate. To this end, we encourage collection and submission of critical site-specific process and testing information that will allow stakeholders to improve the predictive accuracy of emissions factors and characterize the associated uncertainties. We also want to encourage and facilitate the electronic documentation and transfer of source test information to reduce stakeholder workload, ease assessment, increase communications, establish consistency (content and assessment), increase the transparency of the entire program, and provide information transfer to critical air programs (emissions factors development, compliance verification, emissions inventory, permitting,                     *etc.*).                

                    Finally, we currently are considering replacing the highly subjective manual method of updating all emissions factors                           ( print page 52726)                        for a source category with a more consistent, objective, and automated system that better delineates source descriptions so that emissions factors' source categories are more meaningful and useful. Guidance is a critical part of developing emissions factors. As such, we are updating guidance of procedures for preparing emissions factors to make the procedures clearer, improve the predictive accuracy of the resulting emissions factors, improve stakeholders' confidence in the revised process, and help us achieve our overall goals of improving the emissions factors program.                

## III. Emissions Factors Development Process and Tools

We seek to replace the manual emissions factor development process, which is shown in Figure 1. The manual emissions factors development process begins with the performance and documentation of source tests at individual facilities. After obtaining the report of the source test, the emissions factors developer (EPA) assesses the documentation with respect to its representativeness to the source category and its precision and accuracy of quantifying the facility's emissions. Test reports are then grouped by process (using the source classification code, or SCC), control device employed, and pollutant. These groupings are reviewed to combine related processes and control technologies that will result in comparable data being used to establish or revise emissions factors. After making determinations about the use of data with differing test report quality ratings, the emissions factors are calculated (or recalculated) with an associated factor quality rating. The public is notified of the availability of the draft factors and is given an opportunity to comment on them. After consideration of the public comments, EPA publishes the new or revised factors in AP-42.

As will be discussed in more detail in section IV, we propose to move from this subjective resource intensive system where EPA relies on a relatively open-ended set of criteria to make major decisions such as the test data and factor quality ratings to one that is objective (more science based) and designed to reduce the variability associated with manual emissions factor development. The new system will provide an objective evaluation scheme for grading the quality of each emissions test, as well.

We are in the process of updating and revising three key existing tools (WebFIRE, ERT, and the emissions factors guidance document) to help us improve the current system. Note that the revised emissions factors guidance document will provide information for implementing both WebFIRE and ERT. The existing tools are described in the remainder of this section. Section IV describes how we plan to augment and update these tools to develop the improved emissions factors development program.

### A.  WebFIRE

                    WebFIRE, on the EPA Web site at                     *http://cfpub.epa.gov/​oarweb/​index.cfm?​action=​fire.main,*                     is the Internet version of the Factor Information Retrieval (FIRE) Data System software application (in a Microsoft Access format) database. WebFIRE contains EPA's recommended emission estimation factors for criteria and hazardous air pollutants obtained from AP-42, Locating and Estimating (L&E) documents, and other documents. The WebFIRE database usually contains a single value (factor) for source classification code (SCC),[2]                                          control, and pollutant combination. Users can conduct simple or detailed searches for emissions factors by process, control device, and/or pollutant. There is a separate database (                    *http://www.epa.gov/​ttn/​chief/​database/​search.html*) that is available to access the complete test reports and other references cited in the section and background report. Also, for many AP-42 sections there is a background report containing summaries of the contents of the supporting test reports, assessments of the quality of these test reports, judgments on the combining and separation of reports for averaging, and the final assessment of the quality rating assigned to the final factor. We are modifying WebFIRE to connect these three components and provide stakeholders with improved access and management capabilities.                

### B.  Electronic Reporting Tool (ERT)

                    In order to streamline the collection of source test data and ensure the completeness of data collection for the development of emissions factors, we created the ERT. The current version of the ERT is available at                     *http://www.epa.gov/​ttn/​chief/​ert/​ert_​tool.html.*                     The ERT is a Microsoft Access desktop application that is currently an electronic alternative to the submittal of paper test plans, reports, and                           ( print page 52727)                        evaluations. Currently, data collected using 19 of EPA's emissions measurement methods for stationary sources can be handled by the ERT. The ERT supplements the time-intensive manual preparation and transcription of stationary source emissions test plans and reports for emissions sources testing with an electronic alternative where the resulting data can be transmitted more easily and quickly to the Agency and S/L/Ts who choose to use this system.                

The ERT provides a format and a process that: (1) Documents the key information and procedures required by the existing EPA Federal Test Methods; (2) facilitates coordination among the source, the test contractor, and the regulatory agency in planning and preparing for the emissions test; (3) provides for consistent criteria to characterize quantitatively the quality of the data collected during the emissions test; (4) standardizes the form and content of test reports; and (5) calculates the emissions factor, and exports the emissions factor and associated data to WebFIRE. We expect the ERT to significantly reduce the monitoring and testing burden for testers, source owners or operators, S/L/Ts, EPA, and other interested stakeholders in collecting, reviewing, storing, and accessing test data and reports.

### C.  Emissions Factors Development Guidance

                    We have developed guidance to assist in the emissions factors development process titled, “Procedures for Preparing Emissions Factors” (EPA-454/R-95-015).[3]                                          This document is intended for use by EPA employees, EPA contractors, and external stakeholders. It describes the procedures, technical criteria, and standards and specifications for developing and reporting air pollutant emissions factors or equations for publication in AP-42. The document also includes background on emission factors and their uses and limitations. It describes the pollutant terminology used in AP-42 and discusses some of the emissions test methods used to measure these pollutants. The reasons and procedures for initiating revisions to emissions factors are also discussed. In addition, public participation procedures are discussed. Many of the changes discussed in the proposed emissions factor development process will be reflected in a revised procedures document.                

## IV. Changes to the Emissions Factors Program, Emissions Factors Development, and Associated Tools

### A.  Potential Revisions to the Emissions Factors Development Process: Overview and Issues

As described in this notice, our current plans are to move from the relatively static format for emissions factors development to one that is more flexible, current, and transparent. We will strive for a balanced process that may be more prescriptive in many aspects of the program while providing users with the flexibility to derive factors that are more suitable for their specific intended purpose. Figure 2 provides an overview of how this process could work. We believe this process can provide source owners or operators with the tools they need to develop emissions factors and provide environmental authorities with the tools they can use to assess the quality and uncertainty of emissions test data. These tools should reduce real or perceived barriers to emissions factors development and result in a substantially improved emissions factors development process.

                    Under the proposed system, source test data would be compiled electronically via the ERT or another electronic format by the source submitting the data. Because the ERT does not yet support all test methods and because some users may prefer to use a different format, we have provided a spreadsheet template that is to be used to submit source test reports that do not use the ERT. See                     *http://www.epa.gov/​ttn/​chief/​ert/​ert_​tool.html*                     for a copy of                           ( print page 52728)                        the current version of the spreadsheet. We are also seeking comment on the availability of other electronic formats that currently may be used by sources to report source test information to their S/L/Ts and whether these formats could be used or adapted to fit into this proposed process.                

In general, we believe that standardization of the test report's form and content will enhance the emission factor development process, while at the same time increase accuracy of the emissions factors. Performance test data compiled in the ERT will also provide value to the enforcement and compliance monitoring community through the readily-available information from the tests in an electronic format. The ERT will provide other items of information from stack tests that may be used for evaluation that EPA's stationary source compliance monitoring/enforcement system, the Air Facility System (AFS), does not currently house such as method test used, process being tested, emissions levels and stack test review date. However, we recognize that such report standardization could have an impact on S/L/T data systems and how they electronically store such information. Some sources might still be required to submit paper or other reports to satisfy S/L/T requirements. We request comment on how the design of the ERT might mitigate these concerns.

We expect that our improved emissions factors' development process, including the ERT, will facilitate the submittal of new test data from a number of sources. As explained later in this notice, we are considering requiring certain facilities to submit electronically their performance test data to WebFIRE. In addition, it is possible that sources or groups with an interest in adding or revising emissions factors for certain categories might be motivated to submit data from previous tests or tests conducted for other purposes than complying with a Federal standard. To the extent that these data are representative of current practices in the category, they could and should be considered in emissions factor development.

We believe that the field evaluations and source test assessments performed by S/L/Ts improve the reliability of the test data. For example, such assessments will help to ensure testing requirements are met, the test plan was followed, and results were accurately recorded while also minimizing sample recovery/handling errors and equipment errors. We want to encourage this type of third party review of all source tests. Ideally the S/L/T would use the tools and criteria we provide to conduct this review, but in some cases acceptable reviews might be provided by independent contractors or others with an interest in developing or revising certain emissions factors. Well conducted and documented source tests that have been subject to such review can potentially receive a higher quality rating than tests that have not been reviewed.

We seek comment on other ways that we could encourage independent “third party” reviews and the weight we should give them in assigning a quality rating. Even in the absence of quality reviews for a test, there will be broader quality assurance provisions in the proposed process. EPA plans to conduct audits of selected tests to ensure their quality as part of the overall program. In addition, we will retain the public review and comment features of the existing system to provide additional assurance that tests submitted to the system are assigned an appropriate quality rating. However, at this time, it is not our intent to make this process a formal rulemaking process.

                    Under the current performance test evaluation system, test data quality is rated A through D, with A-ratings assigned to well documented tests performed by using an EPA reference test method, or when not applicable, a sound methodology that is well-documented. At the other end of the spectrum, a D-rated test is based on test reports with minimal documentation or where a generally unacceptable method was employed. The test quality is reported in enough detail for adequate validation, and raw data are provided that can be used to duplicate the emission results presented in the test report. In the absence of better test reports, lower-rated tests may provide an order-of-magnitude value for a source category emission factor. Specific criteria that are considered in assigning the test report quality ratings include source operation (                    *e.g.,*                     whether the source was conducting the test under representative operating conditions), test method and sampling procedures, process information (extent to which process variation explains variation in test runs), and documentation of the analysis and calculations. After assigning a preliminary emission data quality rating based on these criteria, the quality of production data is considered. Test data that include the collection of production or process data during the test are rated at a higher level than tests that do not include production data.                

Under the process being considered, the ERT or alternative electronic format would be modified to provide a rating for the quality of the individual test based on specified algorithms and data quality objectives. The very process of using the ERT will address many of the rating issues described above by encouraging submittal of the information needed for an A rating. We are not seeking comment on specific changes to the ERT and associated procedures document. However, we are interested in comments on the general features we should incorporate to move us to an automated system for compiling test data and calculating or assigning corresponding test ratings. We are also seeking comments on whether the use of different formats for the ratings might be helpful for stakeholders. For example, would a more prescriptive numerical test report assessment rating focus more attention on the quality of the test reports, thereby improving the information in these reports and provide more information to the stakeholders on the quality of the data? As described above, should a well-documented performance test conducted according to the Federal Reference Method that has been reviewed by an independent third party receive a rating adjustment to reflect the results of the third party verification? Also, we are seeking comment on whether the third party reviewer should have the authority to reduce the quality rating of a test report (such as noting poor documentation or test performance deficiencies).

                    Under our conceptual approach, the source test data would be transferred from ERT to EPA's Central Data Exchange [4]                                          (CDX), which is the point of entry on the Environmental Information Exchange Network (Exchange Network) for environmental data exchanges to the Agency. In the future, we may consider using the capabilities of the CDX to provide for future exchanges of information in these reports electronically with facility, state, or federal data systems. For example, as mentioned earlier, it is possible that there might be other audiences for the ERT data such as the AFS. This EPA database contains compliance monitoring and enforcement data for stationary sources of air pollution regulated by EPA and S/L/Ts. The environmental regulatory community uses this information to track the compliance status of point sources with various programs regulated under the Clean Air Act. With certain modifications, the ERT could be designed to collect information used by AFS. We believe that by providing stack                           ( print page 52729)                        test and facility data electronically through the ERT in a format for S/L/Ts to update AFS would result in a decrease of some existing reporting requirements' burden for S/L/Ts. We seek comments on whether the ERT information should be used to provide input to the AFS (and whether this would decrease S/L/T reporting burden). Transfers to other data systems such as the National Emissions Inventory, Toxics Release Inventory, and Title V reporting also may be desirable. We request comments on how and whether the ERT could be expanded to address other program needs.                

                    The Cross-Media Electronic Reporting Regulation (CROMERR) [5]                                          has been recently promulgated to provide the legal framework for electronic reporting of information and data to EPA and others who administer EPA programs. CROMERR is intended to reduce the cost and burden of electronic reporting while maintaining the level of corporate, legal, and individual responsibility and accountability that exists in the traditional paper format. At this time, we intend to develop ERT to fully comply with CROMERR.                

Once received through CDX, the source test data would be stored in WebFIRE. We currently plan to update WebFIRE to collate and integrate the data into emissions factors calculations for similar processes, pollutants, and control devices. For example, our current plan is to upgrade WebFIRE to calculate automatically the arithmetic mean of the data in individual source test reports to provide updated emissions factors on a periodic schedule. Please note that we do not envision that this approach would be used to update emissions factors as each source test is received. Source test data will not be used for new or amended emissions factors until the data have been vetted through our public review process. Additional features such as calculations of other statistical and distribution characteristics, including the standard deviation and range of data values, could also be added. We seek comments on what kinds of statistical information would be helpful for stakeholders.

The frequency of emissions factors updates is an issue for which we are seeking comment. As noted above, while WebFIRE might theoretically be structured to calculate a new or revised emissions factor whenever a qualified test is submitted, we understand that updating emissions factors very frequently may be disruptive to emissions factors users because it could create a rapidly moving target that could add significant uncertainty to users. Instead, we think a better approach is to schedule periodic updates. Such updates might be based on a specified calendar schedule to allow interested parties to understand when an update might be expected. Because updating emissions factors impacts many other programs, such as operating and new source review permitting, modeling, risk and technology analysis, control strategy development, enforcement, and others, we believe that updating specific emissions factors more than once per year would complicate activities of these other programs. Other triggers could be when a certain volume of new data is submitted in certain categories, or when the newly submitted data results in significant changes to the emissions factor. There also might be value in making supplementary updates whenever there is an associated review of an existing standard (every 8 to 10 years). We are seeking comments on the frequency and scheduling of emissions factors updates.

                    Some stakeholders have expressed concern that new data would be used to automatically update emissions factors and that there would be no opportunity afforded to comment on the accuracy, representativeness, and completeness of the new data. We believe this is a valid concern and are planning, as discussed above, to only update emissions factors on a periodic schedule. In addition, we are planning on incorporating a full public review and comment period into WebFIRE, similar to the existing system for updating emissions factors. When all data for a specific source category, control device, and pollutant are compiled and resultant emissions factors are drafted, we currently notify all subscribers to the CHIEF list serve                     *(http://www.epa.gov/​ttn/​chief/​listserv.html)*                     that new draft emissions factors are available for public review. We plan to add a feature into WebFIRE that will automatically notify subscribers of the availability of new proposed emissions factors for review and comment.                

We plan to add flexibility to WebFIRE so that the user may calculate their own emissions factor using a different mix of test reports than those used for the existing emissions factor. Sources already have the ability to suggest alternative factors, but this change to WebFIRE could help make the development process more transparent. This capability might lessen the need for extremely frequent updates and would allow the calculation of emissions factors for specific applications for which the average emissions factor is inappropriate. However, the resulting “user calculated” emissions factors would not be considered “official” EPA factors and we do not plan to retain these emissions factors in WebFIRE.

We currently plan to build into WebFIRE decision criteria that would be used to select the test data to be used in an emissions factor update. For example, one of the current decision criteria includes the exclusion of C- and D-rated data whenever A- or B-rated test data are available. We seek comment on this approach and other criteria we should consider. We anticipate that the changes to the data reporting system will generally result in higher quality and significantly more data than may have been available in the past for developing some emissions factors. At what point and under what conditions do we drop lower quality data from the emissions factor calculation? If we allow the use of lower quality data, how should it be incorporated? For example, if we have an existing emissions factor that is based upon several “C” rated tests and we receive a new high quality performance test, should we average together all of the data or only use the most recent high quality test? Would a numerical quality rating that would allow automated selection criteria be more useful than the current letter rating system?

                    WebFIRE will be revised to assign an emissions factor quality rating based on specified criteria. We presently assign an emissions factor rating to indicate the ability of the overall average factor to represent a national annual average emissions rate for the source category. The emission factor rating is an overall assessment of how good a factor is, based on both the quality of the test(s) or information that is the source of the factor and on how well the factor represents the emission source. Higher ratings are for emission factors based on many unbiased observations, or on widely accepted test procedures. In the current procedures guidance document, we state as an example that an emissions factor based on 20 or more source tests on different randomly selected plants would likely be assigned an “A” rating if all tests are conducted using a single valid federal reference measurement method. Likewise, the guidance indicates that a single observation based on questionable methods of testing would be assigned an “E” rating. Should the current EPA approach for WebFIRE incorporate more standardized and consistent criteria for                           ( print page 52730)                        assigning emissions factor quality ratings? Should the criteria be predicated upon an estimated predictive accuracy of the national average emissions factor? How should the quality rating of the supporting test data be incorporated into the emissions factor quality rating?                

As we revise WebFIRE, a key issue will be how it groups emissions data into related clusters for which the average emissions factors will be developed. What groupings could be performed automatically and which ones would require external manual assessment and management? Who should be responsible and what additional level of peer review should be introduced? Examples of some of the groupings we consider in the present system include the source category, process type, representativeness of source, emission source, equipment design, operating conditions, raw material or fuel characteristics, control devices, and test method used. We request comment on the ways we should incorporate these groupings into WebFIRE and whether there are additional criteria that should be added. For example, what is the best way to characterize facilities for emissions factor development purposes? Currently we are using SCC and pollutant codes with control device type. Is the current characterization system robust enough?

Once the SCC for the facility is tested, the specific pollutant measured, and the control device is determined, the existing procedures should guide the developer through a process of grouping the data. One type of grouping may result in combining data from several SCCs (for example Utility, Industrial, Commercial and Institutional combustion, or the four types of Portland Cement Manufacturing processes). Another type of grouping could result in data from different types of control devices being combined. In the emissions factor development process, these characteristics (and others) are evaluated to determine whether there is a significant difference in the factors when different SCC and/or controls are represented. We traditionally combine data from different SCC and controls for some pollutants, if the factors are not significantly different. The criteria used to determine whether to combine data have varied. Should a more standardized assessment and decision criteria be developed? Should these criteria be based upon a statistical approach? Would a combination of statistical and non-statistical approaches be reasonable? If so, when would one approach be preferred over the other approach?

In some cases, a grouping of SCC and control device type has what appears to be a bimodal distribution of emissions. When detailed information is available in the test reports, these differences could be attributed to differences in the raw material, the production method, the end product specification, or one or more production or control device parameters. What methods should be used to assess and address these situations? Should the same assessment approach used to cluster data be used? Should there be a more rigorous approach adopted? In addressing situations where there are significant differences, how should they be addressed? In the past, these situations have been addressed through the expansion of the available SCCs. In some cases this has led to increased confusion for the user of emissions factors. In lieu of expanding the available SCCs, should we develop additional criteria in WebFIRE to allow for broader differentiation of the emissions factors?

How do we determine whether a specific source has significantly changed such that the existing emissions factor is no longer appropriate? There are many examples of significant changes, including variance in control device performance over time or process changes that alter emissions. We are seeking comment on how to determine whether a process change is significant enough to warrant a new or revised emissions factor. We are also seeking comment on how to account for control device performance in establishing emissions factors.

Another question is how WebFIRE will assess data collected by non-EPA reference methods, such as those developed by the California Air Resources Board or the American Society for Testing and Materials (ASTM). We believe that, in many cases, these “other” methods may not be significantly different from EPA-reference methods and, as is the case of some ASTM methods, can be used as alternatives to EPA reference methods or are referenced in some of EPA's reference methods. To the extent the method is a close replica of the EPA method, we believe that WebFIRE should be able to note the different, but similar, method when using its data to develop emissions factors. We currently accept performance test data collected from non-EPA reference methods to develop or revise emissions factors and we are inclined to continue this practice. We are seeking comment on whether the use of methods other than EPA-reference methods should be noted when used to develop emissions factors. Another similar issue is where multiple methods can be employed to test a pollutant. For example, there are several federal reference methods for testing particulate matter. The particulate matter methods were usually designed for a specific source category or process, but now have been used for other sources. One approach we have been considering is a cross walk in WebFIRE and/or the ERT to explain the differences between the various methods and pollutants being tested and when such methods are appropriate. Are there some methods that should be excluded from WebFIRE? For example, EPA Method 25A can be used to develop a mass emissions factor. However, it does not measure all the components of hydrocarbons. We also request comment on how the quality rating might be adjusted to account for methods that are less easy to compare directly.

There are issues associated with the process for developing draft factors. We request comment on how new test data should be presented (prior to WebFIRE calculating the emissions factor), when a commenter believes there are errors in the test data. Some stakeholders have suggested that we should make all data available as they are submitted (for public review and comment), but not to be used to update the emissions factors until all available data are compiled and evaluated. Should the commenter provide a third party review or update, should the test be returned to the facility for correction, or should EPA perform the third party review? Should the draft emissions factor be presented (along with the new test data) and should the draft factor quality be presented? In general, what should be the responsibilities of the commenters, EPA, and the tested source? We are also seeking comment on whether there should be a specified time for submitting comments? Should data be posted to the site when it is submitted or during some specified period prior to the update of the emission factor in WebFIRE?

                    There are several data handling criteria associated with preparing draft emission factors. These criteria are addressed in the current procedures document and include data averaging, rounding, outliers, detection limits, use of blanks, and format and unit of measure of the factor. We are requesting comment on whether any changes or additions are needed regarding these criteria as we develop changes to WebFIRE. We are especially interested in your comments on how to average                           ( print page 52731)                        test data that is below the detection limits of the analyzer. Similarly, we currently provide the arithmetic mean as the best measure of an emissions factor to provide a tool for estimating emissions where there are gaps in emissions inventories. However, other descriptive statistics such as median, mode, range, percentiles, and standard deviation may also be useful in characterizing emissions for other purposes. How the precision of the supporting data is characterized is a related issue. In general, we believe that the impact associated with the emissions variability between sources will be reduced when we obtain improved test reports via the ERT or alternative electronic format and as we obtain a larger number of higher quality tests. We expect that more high quality data will yield more accurate emissions factors. In addition, improved process information will allow for developing a process based factor which will improve the predictive accuracy of the resulting emissions estimate. We request comment on our plans to provide additional information on the precision and accuracy of the emissions factors in the new emissions factors development process. This additional information would include the median, mode, range, and standard deviation of the data set used to develop the emissions factor. What methodologies and criteria should be used to achieve more and better factors? Should WebFIRE be limited only to factors that have documented supporting source test data? Should we continue to allow the expansion of emissions factors based upon unsupported assessments (                    *i.e.,*                     assumed control efficiencies applied to average controlled factors to arrive at an uncontrolled factor, and then a subsequent assumed control efficiency applied to that uncontrolled factor to arrive at a controlled factor)?                

Some stakeholders have requested development of emissions factors for uncontrolled processes. It is not surprising that the existing emissions factors characterize emissions for controlled processes, because these are the emissions sources that typically are subject to regulation and required to conduct performance tests to demonstrate compliance. However, should a source desire to test uncontrolled processes and enter the information into the ERT, we would accept such data. A broader issue might be how we could encourage stakeholders to provide any data (controlled or uncontrolled) and/or to adopt the use of the ERT for reporting of testing programs not required for federal regulatory purposes.

Some industry groups and trade associations independently have developed industry-specific emissions factors. In some cases, these stakeholders have asked us to include their emissions factors in WebFIRE without a critical review of the source testing and resultant data. Should these groups choose to submit their data through the ERT or an alternative electronic format and result in highly rated tests, we believe their data should be considered the same as any other data for calculating emissions factors. However, some of these tests may involve information that the sources being tested consider proprietary or the test reports may lack critical details because they were conducted for different purposes. Where do we draw the line in accepting such data for use in developing emissions factors? If we accept some lesser quality tests and data, would others be encouraged to do the same which may result in less transparency in the process and poorer quality emissions factors? If CBI data are considered by us, how can we assure the other stakeholders of the reliability of the supporting data without incurring a workload on ourselves that would result in substantial slowing of the process? A similar issue is whether we should accept assessment of their source test data by stakeholders. We believe one way to address this concern is to have an independent third party review. We have discussed third party review to ensure objectivity of the data elsewhere in this notice.

                    We intend for the revised emissions factors development process guidance to retain the opportunity for public review of the individual test data, the emissions factor calculations, and associated quality rating prior to finalizing any new or revised emissions factor. However, as previously discussed our current thinking is to modify some of the aspects of the review process. For example, we currently plan to change from revising entire sections in AP-42 at one time to a review of recently added source test data. We are also considering conducting a periodic review of the entire WebFIRE (limited to data that had been submitted since the last review) at a single time. We request comment on these changes and suggestions for alternative approaches to updating emissions factors and handling data before they are used to update emissions factors. We also recognize the potential impact that changing emissions factors can have on sources (                    *e.g.,*                     a higher revised emissions factor could mean that the source may be out of compliance, or the source may become subject to newly applicable requirements such as Title V or Toxics Release Inventory reporting). Should we limit reviews to the additional source tests or should we allow reviewers to address the implications of these additions? We request comment on any steps that could enhance public review of the emissions factor development process and outcome and will contribute to the timely development of new and revised factors.                

### B. Test Data Submittal Requirements

We believe that an additional enhancement to the current emissions system is for us to take steps to increase the quality and quantity of performance test data submittals. With the ERT, we believe we have a tool to encourage the submission of higher quality test data. However, the quantity of data submittals has to be increased to ensure continuous development of better emissions factors. Unfortunately, while the ERT has been available for several years, we are not seeing widespread use of it to submit data to EPA for use in emissions factors development. There could be several reasons that test data submittals to EPA are not more widespread.
    - There is no regulatory driver requiring submission of data.
    - Stakeholders are worried that data submitted this way will result in emissions factors being updated too quickly, making the verification of appropriate emissions factors a more difficult process.
    - The ERT is perceived as requiring too much data or more data are required than what is normally required by S/L/Ts for performance testing.
    - There are electronic compatibility issues for agencies with electronic reporting systems that are similar to ERT in scope. Some agencies may have their own electronic reporting systems, but these may be limited to the reporting of the test results only.
    - There is a perception that using the ERT costs more than the traditional paper formats or that using the ERT will increase the costs of performance testing to collect the information required by the ERT.
    - Agencies still require paper reports or a signed copy of the report.

                    In order to ensure we receive timely submittal of data necessary for a robust emissions factors program, we are considering using the authority under section 114 of the Clean Air Act to require the electronic submission to EPA of performance test reports conducted for compliance certifications or other regulatory purposes. Specifically, we are considering                           ( print page 52732)                        amending the reporting provisions of the 40 CFR parts 60 (New Source Performance Standards (NSPS)), 61 (National Emission Standards for Hazardous Air Pollutants (NESHAP)), and 63 (Maximum Achievable Control Technology (MACT standards)) General Provisions to require electronic submittal of performance tests that are already required by standards in these parts. The General Provisions contain requirements, such as monitoring, recordkeeping, and reporting that are common to all NSPS, NESHAP, and MACT rules. We want to emphasize that this approach would not add any additional performance testing. Nor do we anticipate that this requirement would significantly increase the reporting and recordkeeping burden of sources that are already required to submit their performance test data. As described below, we think that using the ERT will likely result in reducing the overall burden of submitting test data by standardizing the reporting form and automating many of the quality assurance and calculation features associated with paper reporting. We are seeking comments on the concept of requiring electronic submittal of performance reports. We are also seeking comments on any perceived reduction (or other benefits) or addition in costs to stakeholders should we require the submittal of performance tests required by parts 60, 61, and 63. Should we propose such requirements in a future rulemaking, we will assess this potential burden reduction.                

We also request comment on whether we should specify specific required elements to be contained in source test reports. The components would include not only the documentation of the conduct of the stack sampling activities, but also the process parameters, such as, process operations, control device design, and monitoring parameters that are indicative of the emissions performance of the process and control device. We believe that requiring these components should not increase performance test burdens, because this kind of information is required in the existing methods and are necessary to evaluate the conformance to the test method or for compliance with applicable parts 60, 61, or 63 provisions. The advantage of the ERT, which was developed with input from stack testing companies, is that it would provide a standardized method and template to collect and store all the documentation required.

We believe that obtaining these test data already collected for other purposes and using them in the emissions factors development program will save industry, S/L/Ts, and EPA time and money. A benefit of submitting these data to WebFIRE electronically is that these data will greatly improve the overall quality of the existing and new emissions factors by supplementing the pool of emissions tests data upon which the emission factor is based and by ensuring that data are more representative of current industry operational procedures. Submitting these data to EPA will address a common complaint we hear from industry and regulators that emissions factors are out-dated and/or not representative of a particular source category. We also believe that having these data will enable EPA to conduct more effective residual risk analyses (required under section 112(f) of the Clean Air Act Amendments of 1990) and periodical technology reviews for parts 60 and 63 NESHAP and MACTs respectively, without requiring industry to submit additional data. Moreover, as each source category emissions' factors are populated with more high-quality tests, the accuracy of the emissions factors will increase. The regulations at 40 CFR parts 60, 61, and 63, the NSPS, NESHAP, and MACTs already have performance test requirements and, again, this rule would not add additional testing. However, we will need to revise the reporting requirements for these rules. One option we are contemplating is to amend the reporting requirements of the general provisions for 40 CFR parts 60, 61, and 63 to require submittal of required performance testing to EPA. Hundreds of these performance tests are conducted each year and the resultant test reports and pertinent data reside in S/L/Ts' filing cabinets. EPA does not receive these tests routinely, and does not have funding to travel to the S/L/T offices to copy and/or scan these tests to obtain the data. Subsequently emissions factors remain static.

We are seeking comment on the scope of required data submittals. For example, there are some source categories with numerous sources and frequent testing requirements. In some cases, this might result in hundreds of submittals for the same category. Should there be a process to limit the number of reports in these situations? Also, should there eventually be a cutoff in the submittal requirement after several years of data have been submitted? Statistic analyses show that data from more than 30 source tests normally do not appreciably impact the mean value of the emissions factor. On the other hand, if we limit the number of source test reports, then how would we determine that there had been significant changes in processes and/or controls that might influence the existing emissions factors, suggest the need for new emissions factors, or the need for new source classification codes?

Requiring submission of performance test data will require coordination with respect to changes to ERT and WebFIRE. For example, ERT will need to be updated to accommodate other pollutant measurements that may be required in 40 CFR parts 60, 61, and 63. The ERT also needs to be modified to transmit data to a centralized point (EPA's Central Data Exchange), so that it could be stored in WebFIRE for future use.

We believe that ERT, or an alternate system (such as some existing S/L/T electronic performance test submittal software), should be the preferred method of submitting test data that ensures the quality of the data that are used in emissions factors development. In addition to providing an easy way to submit performance tests and more consistency in these submissions, the ERT addresses some source test reporting deficiencies we have observed over the years. For example, not all source tests received from S/L/Ts include the documentation necessary to verify that the procedures established in the applicable test method are being performed. Test reports also may fail to include reports and the requisite documentation from laboratories describing the analyses performed.

                    Documentation is sometimes lacking regarding the facility's production level, process flow rate, secondary products, final products, or other integral information. Information regarding the facility's performance,                     *i.e.*                     at normal or near maximum production levels at the time of testing, may also be needed. Critical design and operational information on the equipment used to control the pollutants being tested also may be missing. Given our objective to improve the quality of data used to develop emissions factors, we think this detailed information may be needed. The absence of any of this information will be considered in rating the quality of the performance test data.                

                    In summary, we request comment on whether additional source and testing information should be required to be submitted to the ERT to enhance the emissions factor development process. To what extent should background information, like a process flow data, on the source be required to be provided? Finally, additional data may be needed to develop algorithms (based on emissions factors), such as those used in                           ( print page 52733)                        the TANKS [6]                                          program. In cases where we seek information on process conditions, we may find that a few sources may consider this information or data to be CBI. There are several issues with requiring CBI, and we are seeking comment on the receipt of CBI to develop more accurate emissions factors.                

### C. Emissions Factors Content and Format

The existing AP-42 currently expresses emissions factors as the arithmetic mean, which generally is an expeditious choice for use in traditional applications such as emissions inventories gap filling. However, our current thinking is to identify ways to expand the scope of emissions factors' application into areas where the existing format of the factors may not satisfy the new application. For example, it may be helpful to provide the range of the test data to users, so that they can understand the variability of the source tests used to develop a particular emissions factor. Also, WebFIRE could be modified to calculate and provide other relevant statistical and distribution characteristics, including the standard deviation, in order to provide users with a more complete description of the data. Such a description, whether tabular or graphical, could help educate users and allow them to make better informed decisions. We seek comment on the type and format of emission factor information beyond the mean value that would be useful for stakeholders.

### D. Interacting With the SPECIATE Database

SPECIATE is the EPA repository of total organic compound (TOC) and particulate matter (PM) speciation profiles for emissions from stationary and mobile air pollution sources. The profiles are key inputs to air quality modeling and source-receptor modeling applications. SPECIATE essentially provides emissions factors and information for pollutants, from both controlled and uncontrolled processes, at a level of detail that is not adequately or traditionally presented in AP-42. The emissions factors developed for SPECIATE are gleaned from available sources, such as test data, literature searches or academic studies. References and data quality ratings are provided to guide the user. We are seeking comment on whether SPECIATE (or any other source of emissions factors) should be linked to or contained in WebFIRE.

## V. Request for Comment and Next Steps

As described throughout this notice, EPA is soliciting comments to help in improving the way emissions factors are developed and used. We also encourage readers to submit other general comments and supporting data that could help us further improve the emissions factors program. In order to ensure a well balanced response and develop the best possible product, we encourage the submittal of both comments offering suggestions and changes and those supporting our current thinking on potential emissions factors program improvements.

For the convenience of the reader, the following list summarizes the major areas for which we are seeking comment:
    - Is it appropriate to amend the reporting provisions of the 40 CFR parts 60 ,  61 , and  63  General Provisions to require electronic submittal of performance tests that are already required by standards in these parts?
    - As acknowledged earlier, emissions factors are used for many air pollution control activities that were not envisioned when this program was established. We are seeking comment on the appropriateness of using emissions factors for these other purposes and, if they are to be used for other purposes, should there be any other requirements for these emissions factors (such as using only high rated emissions factors for permitting) or more information required for these emissions factors (such as greater precision and accuracy).
    - Are third party reviews of performance tests needed and, if so, then how could we encourage third party reviews of test reports and what weight should we give reviews in assigning a quality rating?
    - Should we require electronic submittal of performance tests via the ERT or some similar electronic submittal software (such as existing S/L/T submittal software)? What is the availability of other electronic formats that currently may be used by sources to report source test information to their S/L/Ts? Could these formats be used or adapted to fit into our proposed process?
    - Would a different format for the ratings of test data be useful? For example, would a numerical system provide more information on the quality of the test rating?
    - If needed, should additional information be required as part of ERT to enhance the emissions factors development process? Should we obtain continuous emissions monitoring data in a fashion that could be used for emissions factors development in the next versions of ERT and WebFIRE?
    - We plan to build into WebFIRE decision criteria that would be used to select the test data to be used in an emissions factors update. For example, we may have four performance tests conducted in 1979 and four performance tests conducted in 1995 where the source made a slightly different product. What tests should we use to develop the emissions factors and what criteria should we consider to select the performance tests?
    - How should emissions data be grouped into related clusters for which the average emissions factors will be developed? Examples of some of the criteria we consider in the present system include the source category, process type, representativeness of source, emission source, equipment design, operating conditions, raw material or fuel characteristics, control devices, and test method used.
    - How should WebFIRE assess data collected by non-EPA reference methods (such as those developed by the California Air Resources Board) or data from two different methods that are averaged to develop an emissions factor? How might the quality rating be adjusted to account for methods that are less easy to compare directly?
    - At what frequency or schedule should emissions factors in WebFIRE be updated?
    - There are several data handling criteria associated with preparing draft emission factors. These criteria include data averaging, rounding, outliers, detection limits, use of blanks, and format and unit of measure of the factor. How should we account for these potential variables in emissions factors?
    - Besides calculating the arithmetic mean to be used as the traditional emissions factor, what other statistical characteristics should additional features such as calculations of median and mode factors or other information from the data sets also be provided and in what format, i.e.,                      tabular or graphical, should they be provided?                
    - Should there be a process to limit the number of performance test reports from a particular source category submitted to EPA? For example, should we establish a threshold in the submittal requirement after 50 or 100 performance tests have been submitted? If so, then how would EPA know when source categories significantly change process or controls, such that we would want       ( print page 52734)                          additional performance tests for emissions factors revisions?                
    - What steps could enhance public review of the emissions factors development process and outcome and contribute to the timely development of new and revised factors?

When finalized, the Emissions Factors Guidance will address many of these issues.

We will consider the comments submitted in response to this ANPRM as we proceed to implement an improved emissions factors program.

## VI. Statutory and Executive Order Reviews

### Executive Order 12866: Regulatory Planning and Review

Under Executive Order 12866, entitled Regulatory Planning and Review (58 FR 51735, October 4, 1993), this is a “significant regulatory action” because we expect this action to raise novel legal or policy issues. Accordingly, EPA submitted this action to the Office of Management and Budget (OMB) for review under Executive Order 12866 and any changes made in response to OMB recommendations have been documented in the docket for this action. Because this action does not propose or impose any requirements, and instead seeks comments and suggestions for the Agency to consider in possibly developing a subsequent proposed rule, the various statutes and Executive Orders that normally apply to rulemaking do not apply in this case. Should EPA subsequently determine to pursue a rulemaking, EPA will address the statutes and Executive Orders as applicable to that rulemaking.

# List of Subjects in 40 CFR Parts 60, 61, and 63

      - Environmental protection
      - Air pollution control
      - Hazardous substances
      - Reporting and recordkeeping requirements
      - Emissions factors
      - Performance testing

Dated: October 7, 2009.

Lisa P. Jackson,

Administrator.

# Footnotes

1.                             A copy of the draft report, Emissions Factors Program Improvement Efforts (September 2005), is available on EPA's Web site at:                         *http://www.epa.gov/​ttn/​chief/​efpac/​workshops/​efp_​improvement_​efforts_​draft.pdf.*
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2.                             There are currently a few emissions factors in AP-42 with duplicate values (factors). EPA is working to correct these emissions factors so that there are no duplicates.                    
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3.                             We have previously prepared a revised procedures document (2006 draft) for public review. Based on the comments we received, that document was withdrawn and never finalized.                    
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4.                             For more information on the CDX, see                         *http://www.epa.gov/​cdx/​.*
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5.                             For more information on CROMERR, see EPA's Web site at:                         *http://www.epa.gov/​CROMERR/​index.html.*
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6.                             TANKS is a Windows-based computer software program that estimates volatile organic compound (VOC) and hazardous air pollutant (HAP) emissions from fixed- and floating-roof storage tanks.                        *TANKS*                         is based on the emission estimation procedures from Chapter 7 of AP-42.                    
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[FR Doc. E9-24684 Filed 10-13-09; 8:45 am]

BILLING CODE 6560-50-P