MACT Hammer

Requirements under Section 112(j) of the federal Clean Air Act presently affect facilities that are major stationary sources of hazardous air pollutants (HAP). A facility that emits or has the potential to emit at least 10 tons per year of a single HAP or at least 25 tons per year of any combination of HAPs is considered to be a major stationary source.

Under Section 112(j), also known as the "MACT Hammer, "affected sources are required to implement emission standards equivalent to the maximum achievable control technology (MACT) standards that EPA should have established in the event that EPA fails to promulgate a scheduled MACT standard by the regulatory deadline.

A list of the remaining MACT standards for source categories that were not promulgated in time to meet the regulatory deadline is provided below. 

Subpart Title

  • Subpart AAAA Municipal Solid Waste Landfills

  • Subpart DDDD Plywood & Composite Wood Products

  • Subpart J Polyvinyl Chloride & Co-Polymers Production

The rather extensive listing previously shown here has been reduced to these remaining three standards. Here is a link to the EPA website page with a table showing the most current status of the MACT StandardsLink to external website. (Exit to EPA website). This link provides a table listing those MACT standards that have been promulgated along with the associated Federal Register Dates and citation, and the Compliance Date set by EPA.

A facility that is a major source of HAPs must notify both SCAQMD and EPA if the facility operates equipment subject to these standards, regardless of the magnitude of emissions from that equipment. Under Section 112(j), affected facilities were required to comply with the notification requirement by May 15, 2002. The current list of HAPs can be downloaded from 188 HAPS (DOC, 88.5kb). Compliance with the notification requirement may be achieved by completing the Form 500-MACT(PDF). It is recommended that the affected facilities consult the status of the proposed MACT standards using the EPA web site at to external website..

Background [For those requiring additional information, read on.]

The federal Clean Air Act (Act) Amendments of 1990 required EPA to identify source categories that emit one or more of 188 listed HAPs. For major sources of HAPs within each source category, EPA would develop national standards that restrict emissions to levels consistent with the lowest emitting standards, referred to as maximum achievable control technology (MACT) standards. The Act Amendments required EPA to promulgate all the MACT standards for these source categories by November 15, 2000. In addition, the Act required EPA to adopt a rule pursuant to Section 112(j), also known as the "MACT Hammer," to establish a mechanism for states and local agencies to regulate emissions of HAPs in the event EPA failed to promulgate standards for one or more of these source categories. In 1994, EPA adopted a rule to address this requirement.

Recently, EPA failed to promulgate MACT standards for a number of source categories by the applicable deadlines. On April 5, 2002, EPA promulgated a rule to implement Section 112(j). Unless stayed by ongoing legal action, this rule will require affected facilities to comply with the notification, application, and emission control requirements discussed below.

Implementation of the MACT Hammer is accomplished in two parts:

Part 1: Notification by Affected Facility for Existing Sources

To comply with the Part 1 requirement of Section 112(j), major sources of HAPs must notify both SCAQMD and EPA by May 15, 2002. EPA refers to the notification as "Part 1 Air Toxic Control Permit Application." The notification must include: (1) the name, address, and a brief description of the business, (2) identification of the relevant source category, (3) identification of emission points associated with the relevant source category, and (4) identification of any Section 112(g) (for new major HAP sources) determinations that have been made. SCAQMD Form 500-MACT (PDF) may be used to comply with the Part 1 requirement.

Part 2: Subsequent Requirements for Existing Sources

The April 5, 2002 version of the Section 112(j) rule required an affected facility to submit a Title V permit application to comply with Part 2 requirements within 24 months of the Part 1 deadline. EPA refers to this application as "Part 2 Air Toxic Control Permit Application." The Part 2 application includes the relevant process, pollutant and control information to allow SCAQMD to develop MACT for the facility equivalent to what EPA would have developed. The Section 112(j) rule was amended on May 12, 2003. The amendments tied the Part 2 deadline to EPA’s schedule for issuing MACT standards; specifically, the Part 2 application is due 60 days after the scheduled date for promulgating a given standard. Based on the schedule provided in Table 1 of 40 CFR 63 Subpart B, there are currently no Part 2 applications required for any source category.

If the facility has a valid Title V permit, compliance with the Part 2 requirement entails a revision to the existing Title V permit. Facilities that have not previously applied for a Title V permit must submit an application for an initial Title V permit to comply with the Part 2 requirement.

Upon submittal of the Part 2 application, if any, SCAQMD will conduct a completeness review and determination within 60 days of application submittal. SCAQMD will then issue a revised Title V permit (or initial Title V permit as the case may be) incorporating the MACT standards. If EPA subsequently issues a MACT standard, the facility will have additional time to revise its Title V permit, as necessary, to incorporate the EPA issued MACT standards to their permit.

Requirements for New Sources

For new major HAP emissions sources the facility must provide notification 30 days after startup or, in cases where Section 112(g) of the Clean Air Act applies, 30 days after issuance of the Title V permit. Facilities would then have two years from this date to submit the required Part 2 Application. However, this does not relieve the facility from the requirements under SCAQMD Rule 201 to apply for and obtain an SCAQMD Permit to Construct before commencing construction, and a temporary or permanent Permit to Operate before commencing operation.

For more information, the EPA rule is available from their website at: to external website. 

Additional information is also available at the following link:

Air Toxics Website: to external website. 

California Air Resources Board website: to external website.