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Technology Transfer Network - OAR Policy and Guidance






  • On June 30, 2005 the Environmental Protection Agency (EPA) issued a proposed rule supplementing a 1998 proposal to control hazardous air pollutant emissions from oil and natural gas production facilities. Hazardous air pollutants (HAP), also known as air toxics, are pollutants known or suspected of causing cancer or other serious health problems. The June 30, 2005 proposal is posted at https://www3.epa.gov/ttn/oarpg/t3pfpr.html.

  • This supplemental proposal would apply to smaller sources of HAP, known as area sources. The 1998 proposal specified that area source triethylene glycol dehydration units (TEG units) would have to reduce emissions in counties designated as urban areas. The additional option being proposed in this notice would require TEG units in any U.S. location to reduce emissions. TEG units are used to remove excess water vapor from natural gas before it enters transmission pipelines.

  • This proposal would require emission controls for a single emission point: process vents at TEG units. These process vents will be required to do one of the following:

    • vent emissions to a control device.

    • make process changes to achieve emission reductions comparable to a control device.

    • document that the unit’s emissions are low enough that controls are not needed.


  • EPA estimates that the proposed two options being considered would have the following emission reduction and cost impacts:

Emission Reductions (Mg/yr)

No. of Affected Sources



Total Annual Compliance Cost (Million $/yr)






Urban County Only





  • The VOC reductions shown represent a 33% reduction for the national option and a 16% reduction for the urban county option, from current levels. VOC contribute to the formation of ground-level ozone, the primary constituent of smog. When inhaled, even at very low levels, ground-level ozone can cause acute respiratory problems, aggravate asthma, reduce lung capacity, inflame lung tissue, and impair the body’s immune system.



  • The Clean Air Act Amendments of 1990 (CAA), require EPA to regulate sources of 188 listed toxic air pollutants. The CAA also requires EPA to identify industrial or “source” categories that emit one or more of these pollutants.

  • The oil and natural gas production source category extends from the oil and natural gas well head through various facilities used to recover products, such as a tank battery or a natural gas processing plant, up to the oil and natural gas distribution systems.

  • For major sources within each source category, the CAA required EPA to develop standards that restrict emissions to levels consistent with the lowest-emitting (also called best-performing) plants. Major sources are those that emit 10 tons a year or more of a single toxic air pollutant or 25 tons a year or more of a combination of air toxics. Facilities emitting below the major source threshold are considered “area sources.”

  • The CAA further required EPA to develop a strategy to identify and reduce emissions of these toxic air pollutants in urban areas. To meet that requirement, EPA published its Integrated Urban Air Toxics Strategy (Strategy) on July 19, 1999 in the Federal Register.

  • As part of the Strategy, EPA identified a list of the 33 air toxics that present the greatest threat to public health in the largest number of urban areas (see attached table for list of urban air toxics). Of these 33 urban air toxics, EPA has identified the 30 with the greatest contribution from smaller commercial and industrial operations or so-called “area” sources.

  • In the Strategy published July 19, 1999, EPA also identified 29 area source categories that contribute to the emissions of these 30 listed air toxics. Oil and Natural Gas Production was one of the area source categories listed in the Strategy. Subsequent notices published on June 26 and November 22, 2002 added 41 source categories to the list of area sources.

  • EPA proposed a rule to reduce air toxics from oil and natural gas production facilities considered to be both major and area sources in February 1998. The Agency issued a final rule regulating major sources only on June 17, 1999.

  • EPA is proposing this rule by June 30, 2005 as agreed upon with the Sierra Club and will take final action by December 30, 2006.


  • The proposed rule is posted at: https://www3.epa.gov/ttn/oarpg/t3pfpr.html.

  • Today's proposed rule and other background information are also available either electronically in EDOCKET, EPA's electronic public docket and comment system, or in hardcopy at EPA's Air and Radiation Docket and Information Center, Environmental Protection Agency, Room B102, 1301 Constitution Avenue, NW, Washington, DC (Docket ID No. OAR-2004-0238 (Legacy Docket ID No. A-94-04)). 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 and Radiation Docket and Information Center is (202) 566-1742.

  • HOW TO COMMENT. Comments should be identified by Docket ID No. OAR-2004-0238 (Legacy Docket ID No. A-94-04) and submitted by one of the following methods:

    • online through the Federal eRulemaking Portal ( http://www.regulations.gov );

    • by e-mail ( a-and-r-docket@epa.gov );

    • by fax to (202) 566-1741;

    • by mail (Air and Radiation Docket and Information Center, Environmental Protection Agency, Mailcode: 6102T, 1200 Pennsylvania Avenue, NW, Washington, DC 20460); or

    • by hand-delivery to (Air and Radiation Docket and Information Center, Environmental Protection Agency, Room B102, 1301 Constitution Avenue, NW, Washington, DC).

  • For further information about the final rule, contact Mr. Greg Nizich of the EPA’s Office of Air Quality Planning and Standards by phone (919) 541-3078 or by e-mail at nizich.greg@epa.gov.

  • EPA's Office of Air and Radiation (OAR) home page on the Internet contains a wide range of information on the air toxics program, as well as many other air pollution programs and issues. The OAR home page address is: https://www.epa.gov/oar.

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