The AP 42 Compilation of Air Pollutant Emission Factors, was first published by the U.S. Public Health Service in 1968. In 1972, it was revised and issued as the second edition by the U.S. Environmental Protection Agency (EPA). In 1985, the subsequent fourth edition was split into two volumes. Volume I includes stationary point and area source emission factors, and Volume II includes mobile source emission factors. Volume I is currently in its fifth edition and its main table of contents is available online at www.epa.gov/ttn/chief/ap42/index.html. Volume II is no longer maintained as such, but roadway air dispersion models for estimating emissions from onroad vehicles and from non-road vehicles and mobile equipment are available at www.epa.gov/otaq/models.htm. This power plant in New Mexico releases sulfur dioxide and particulate matter into the air. ... Introduction to Emission Factors The following discussion of emission factors is taken from the introduction to the Emission Factor Ratings Public Review Of Emission Factors Other Ways To Obtain AP-42 Information And Updates Introduction Emission factors and emission inventories have long been fundamental tools for air quality management. ...

In routine common usage, Volume I of the emission factor compilation is very often referred to as simply AP 42.

Introduction

Air pollutant emission factors are representative values that attempts to relate the quantity of a pollutant released to the ambient air with an activity associated with the release of that pollutant. These factors are usually expressed as the weight of pollutant divided by a unit weight, 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, and are generally assumed to be representative of long-term averages. Pollutants are substances which directly or indirectly damage us or the environment. ... This power plant in New Mexico releases sulfur dioxide and particulate matter into the air. ...

The equation for the estimation of emissions before emission reduction controls are applied is: This power plant in New Mexico releases sulfur dioxide and particulate matter into the air. ...

E = A × EF

and for emissions after reduction controls are applied:

E = A × EF × (1-ER/100)

Emission factors are used by atmospheric dispersion modelers and others to determine the amount of air pollutants being emitted from sources within industrial facilities. Atmospheric dispersion modeling is performed with computer programs that use mathematical equations and algorithms to simulate how pollutants in the ambient atmosphere disperse in the atmosphere. ...

Chapters in AP 42, Volume I, Fifth Edition

Chapter 5, Section 5.1 "Petroleum Refining" discusses the air pollutant emissions from the equipment in the various refinery processing units as well as from the auxiliary steam-generating boilers, furnaces and engines, and Table 5.1.1 includes the pertinent emission factors. Table 5.1.2 includes the emission factors for the fugitive air pollutant emissions from the large wet cooling towers in refineries and from the oil/water separators used in treating refinery wastewaters. Cooling towers are structures for cooling water or other working medium to near-ambient temperature. ... View of Shell Oil Refinery in Martinez, California. ... Wastewater is any water that has been adversely affected in quality by any anthropogenic influence. ...

The fugitive air pollutant emission factors from relief valves, piping valves, open-ended piping lines or drains, piping flanges, sample connections, and seals on pump and compressor shafts are discussed and included the report EPA-458/R-95-017, "Protocol for Equipment Leak Emission Estimates" which is included in the Chapter 5 section of AP 42. That report includes the emission factors developed by the EPA for petroleum refineries and for the synthetic organic chemical industry (SOCMI). A safety valve is an automatic valve mechanism for the release of a gas from a boiler or other system when the pressure or temperature exceeds preset limits. ... A valve is a mechanical device that regulates the flow of fluids (either gases, fluidised solids, slurries or liquids) by opening, closing, or partially obstructing various passageways. ... Prov Room 9A Flange A flange is an external or internal rib, or rim, for strength, as the flange of an iron beam; or for a guide, as the flange of a train wheel; or for attachment to another object, as the flange on the end of a pipe, steam... A mechanical seal is a type of seal utilised in rotating equipment, such as pumps and compressors. ... Manual pump used to obtain water A pump is a mechanical device used to move liquids or gases. ... Compressor has several meanings: A gas compressor is a mechanical device that takes in a gas and increases its pressure by squeezing a volume of it into a smaller volume. ...

In most cases, the emission factors in Chapter 5 are included for both uncontrolled conditions before emission reduction controls are implemented and controlled conditions after specified emission reduction methods are implemented.

Chapter 7 "Liquid Storage Tanks" is devoted to the methodology for calculating the emissions losses from the six basic tank designs used for organic liquid storage: fixed roof (vertical and horizontal), external floating roof, domed external (or covered) floating roof, internal floating roof, variable vapor space, and pressure (low and high). The methodology in Chapter 7 was developed by the American Petroleum Institute in collaboration with the EPA. The American Petroleum Institute, commonly referred to as API, is the main professional organization for the petroleum and chemical industry. ...

The EPA has developed a software program named "TANKS" which performs the Chapter 7 methodology for calculating emission losses from storage tanks. The program's installer file along with a user manual, and the source code may be downloaded from the TANK download site.

Chapters 5 and 7 discussed above are illustrative of the type of information contained in the other chapters of AP 42. It should also be noted that many of the fugitive emission factors in Chapter 5 and the emissions calculation methodology in Chapter 7 and the TANKS program also apply to many other industrial categories besides the petroleum industry.

Other sources of emission factors

• Fugitive emissions leaks from ethylene and other chemical plants.
• United Kingdom's emission factor database.
• European Environment Agency's 2005 Emission Inventory Guidebook.

External links

• AP 42 online