Air Emissions Factors and Quantification

AP-42: Compilation of Air Emission Factors

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Compilation of Air Pollutant Emission Factors (AP-42)

AP-42, Compilation of Air Pollutant Emission Factors, has been published since 1972 as the primary compilation of EPA's emission factor information. It contains emission factors and process information for more than 200 air pollution source categories. A source category is a specific industry sector or group of similar emitting sources. The emission factors have been developed and compiled from source test data, material balance studies, and engineering estimates. The Fifth Edition of AP-42 was published in January 1995. Since then EPA has published supplements and updates to the fifteen chapters available in Volume I, Stationary Point and Area Sources. The latest emissions factors are available below on this website. Use the AP 42 Chapter webpage links below to access the document by chapter.

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Proposed/Revised/New Emissions Factors

Documentation Supporting Proposed and New Emissions Factors

AP-42 Proposed Emissions Factors, But Not Finalized

After the comment period, can I use a draft section? (TXT) (1 p, 1 K)

Chapter & Section Description Comments Requested by:
Section 2.4 Municipal Solid Waste Landfills May 5, 2009
Section 4.12 Manufacture of Rubber Products February 2, 2009
Chapter 15 Ordnance Detonation December 7, 2009

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AP 42, Fifth Edition Compilation of Air Pollutant Emission Factors, Volume 1: Stationary Point and Area Sources

Chapter Title
Cover page and Table of Contents Cover page, detailed Table of Contents, Publications in Series, Insertion Instructions, and Key Word Index (PDF)(26 pp, 128 K, About PDF). This is current through the Fifth Edition, Supplement C of AP 42. For sections and chapters added after November 1997, see the chapter web pages below.
Introduction Introduction to AP 42, Volume I, Fifth Edition ( PDF) - January 1995 (10 pp, 70 K, About PDF)
Chapter 1 External Combustion Sources
Chapter 2 Solid Waste Disposal
Chapter 3 Stationary Internal Combustion Sources
Chapter 4 Evaporation Loss Sources
Chapter 5 Petroleum Industry
Chapter 6 Organic Chemical Process Industry
Chapter 7 Liquid Storage Tanks
Chapter 8 Inorganic Chemical Industry
Chapter 9 Food and Agricultural Industries
Chapter 10 Wood Products Industry
Chapter 11 Mineral Products Industry
Chapter 12 Metallurgical Industry
Chapter 13 Miscellaneous Sources
Chapter 14 Greenhouse Gas Biogenic Sources
Chapter 15 Ordnance Detonation
Appendix A Miscellaneous Data and Conversion Factors -- September 1985 (32 pp, 103 K, About PDF)
Appendix B.1 Particle Size Distribution Data and Sized Emission Factors for Selected Sources -- October 1986(103 pp, 2 M, About PDF)
Appendix B.2 Generalized Particle Size Distributions -- September 1996(103 pp, 137 K, About PDF)
Appendix C.1 Procedures for Sampling Surface/Bulk Dust Loading -- July 1993(13 pp, 65 K, About PDF)
Appendix C.2 Procedures for Laboratory Analysis of Surface/Bulk Dust Loading Samples -- July 1993(9 pp, 42 K, About PDF)

Historical AP-42 Information

Proposed and final rules related to emissions factors
October 14, 2009 - The Emissions Factors Program Improvements - Advanced notice of proposed rulemaking is available on the website. The comment period ended December 14, 2009.

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AP 42 FAQs

Answers to frequent questions about AP 42.

Drafts Under Review

There are currently no drafts sections under review.

AP 42 listing of supplements and updates.

Supplements A through F (1996 - 2000)(PDF)(3 pp, 148 K, About PDF)
Updates 2001 to 2011 (PDF)(2 pp, 241 K, About PDF)

Older editions of AP-42, Volume 1

This information is available for historical purposes only. For the most recent emissions factors, supported by the EPA, please see the table of contents above.