Jump to main content or area navigation.

Contact Us

Technology Transfer Network - OAR Policy and Guidance





  • On December 21, 2006, the Environmental Protection Agency (EPA) proposed to amend the General Provisions to the air toxics standards. The proposed amendment would clarify how and when an industrial facility can switch its status from "major source" to "area source."
  • Major sources are those that have the potential to emit more than 10 tons per year of a single toxic air pollutant or 25 tons per year of any combination of toxic air pollutants. If sources emit less than these amounts, they are called area sources.
  • The proposed amendment would allow a major source to become an area source at any time by limiting its potential to emit toxic air pollutants to below the major source thresholds. The limit would be enforced through a permit. The amendment would allow this change either before a standard is in place or after a standard is already in place.
  • Once a major source becomes an areas source, it would no longer need to comply with the major source standards. The source would be required to comply with any area source standards for that industry.
  • The amendment would replace EPA's so-called "once in, always in" policy established in May, 1995. The once in always in policy stated that once a source was subject to a major source standard, it would always be subject, regardless of the source's subsequent toxic air pollutant emissions.
  • EPA is proposing this change to provide an incentive for industry to reduce emissions below major source threshold.
  • EPA will accept comments for 60 days after the proposal is published in the Federal Register.

  • Under the Clean Air Act, EPA is required to regulate sources of 187 listed toxic air pollutants. On July 16, 1992, EPA published a list of industrial source categories that emit one or more of these air toxics.
  • EPA originally promulgated General Provisions for air toxics rules in 1994. The General Provisions contain general requirements regarding applicability, compliance, testing, monitoring, reporting, recordkeeping that apply to most or all of the Maximum Achievable Control Technology (MACT) Standards.
  • For listed categories of major sources the Act requires EPA to develop standards that require the application of MACT, or maximum achievable control technology standards. MACT Standards are based on emissions levels that are already being achieved by the better-controlled and lower-emitting sources in an industry.
  • For listed categories of area sources the Act requires EPA to develop generally available control technologies (GACT) or management practices rather than the maximum achievable control technology (MACT) required for major sources.
  • To download the proposal from EPA's website, go to the following address: https://www3.epa.gov/ttn/oarpg/new.html.
  • Today's proposed rule and other background information are also available either electronically at http://www.regulations.gov/, EPA's electronic public docket and comment system, or in hardcopy at the EPA Docket Center's Public Reading Room.
    • The Reading Room is located in the EPA Headquarters Library, Room Number 3334 in the EPA West Building, located at 1301 Constitution Ave., NW, Washington, DC. Hours of operation are 8:30 AM to 4:30 PM Eastern Standard Time (EST), Monday through Friday, excluding Federal holidays.
    • Visitors are required to show photographic identification, pass through a metal detector, and sign the EPA visitor log. All visitor materials will be processed through an X-ray machine as well. Visitors will be provided a badge that must be visible at all times.
    • Materials for this proposed action can be accessed using Docket ID No. OAR-2004-0094.
  • HOW TO COMMENT: Comments should be identified by Docket ID No. EPA-HQ- OAR-2004-0094 and submitted by one of the following methods:
    • Federal eRulemaking Portal (http://www.regulations.gov),
    • e-mail (a-and-r-docket@epa.gov),
    • Mail (EPA Docket Center, Environmental Protection Agency, Mailcode 6102T, 1200 Pennsylvania Avenue, NW, Washington, DC 20460), or
    • Hand delivery (EPA Docket Center, Environmental Protection Agency, Room 3334, 1301 Constitution Avenue, NW, Washington, DC).
    • We request that a separate copy of each comment also be sent to the contact person listed below:

top of page

Jump to main content.