Maximum Achievable Control Technology (MACT) Standards

U.S. EPA has established the new "Boiler MACT" rules (40 CFR 63, Subpart DDDDD and 40 CFR 63, Subpart JJJJJJ).  Please check U.S. EPA's website concerning the Industrial/Commercial/Institutional Boilers and Process Heaters MACT for more information.

Section 112 (c) of the Clean Air Act (CAA) requires the U.S. EPA to publish a list of industry group (major source and area source) categories and subcategories that employ, manufacture, or emit hazardous air pollutants (HAP). The 1990 CAA Amendments require the U.S.EPA to promulgate technology-based emission standards and allows for the possible supplementation of health based standards. The regulatory standard, for the HAP sources, is the Maximum Achievable Control Technology (MACT) standard. Prior to the1990 CAA Amendments, the regulatory standards for the HAP sources were health based standards. The 1970 CAA Amendments had established the National Emission Standards for Hazardous Air Pollutants (NESHAP) program, establishing standards and providing national conformity. A NESHAP based on Maximum Achievable Control Technology is called a MACT standard or simply a MACT.

Permitting and Compliance Assessment of Area Source Maximum Achievable Control Technology

The Division of Air Pollution Control (DAPC) has created a memo to provide permitting staff DAPC’s position concerning the permitting and compliance assessment of area source Maximum Achievable Control Technology (MACT) standards (also known as Generally Available Control Technologies (GACTs)). Over the past decade, a significant number of new rules have been adopted that specifically apply to area sources. For area sources within each source category, the Clean Air Act allows U.S. EPA to develop standards or requirements which provide for the use of generally available control technologies (GACT) or management practices rather than the maximum achievable control technology (MACT) required for major sources. MACT requirements apply to major sources of HAPs or area sources, and these standards are congressionally mandated. GACT standards apply to some area sources, and they are considered to be an optional alternative approach to MACT. You can access this memo by clicking HERE {PDF].

What is a MACT Standard?

The Maximum Achievable Control Technology standard is a level of control that was introduced by Title III of the 1990 Clean Air Act Amendments. The purpose of these Amendments was to expedite the development of standards that would reduce HAP emissions.

When developing a MACT standard for a particular source category, U.S. EPA looks at the level of emission control currently being achieved by the best-performing similar sources through various control methods, such as clean processes, control devices and work practices. These emission levels set a baseline, often referred to as the "MACT floor", for the MACT standard.

The "MACT floor" is the initial determination of the MACT standard for each industry source category. It provides the minimum level of HAP emission control requirement for new and existing sources. The MACT floor for new sources is equivalent to the level of HAP emission control achieved by the best-controlled similar source, and the "MACT floor" for existing sources is the average level of HAP emission control achieved by the top 12% of that industry group's currently operating sources. At a minimum, a MACT standard must achieve, throughout the industry, a level of emissions control that is at least equivalent to the MACT floor. Under 1990 CAA Amendments, U.S. EPA can establish a more stringent standard when this makes economic, environmental, and public health sense

Who is regulated by the MACT standards?

All source categories that include major sources and area sources of HAPs are listed within section 112(c) of the Clean Air Act. This list has been divided into three groups, or "bins" of MACT standards. The two- and four-year standards were required to be promulgated within four years of the passage of the Clean Air Act Amendment of 1990, which was in 1994. The seven-year standards were required to be promulgated in 1997, and the ten-year standards are required to be promulgated in the year 2000. The determination whether or not area sources in any given source category should be regulated is based upon the health risk those sources present to the public.

What MACT standard applies to my company?

All source categories and subcategories that include major sources and area sources of HAP are listed within Section 112(c) of the CAA. To find which MACT standards apply to your company, first select the best matched source category from the MACT promulgated standard list source description. Then, from this list, an industry can obtain further information about what processes are regulated by the MACT standard, and what are the compliance deadlines in the standard.

The compliance deadlines according to 112 (e)(1)(A), for MACT standard promulgation for an industry source, are to be within 10 years of the enactment of the CAA Amendments, or within 2 years from the date the categories or subcategories were listed for an industry source, whichever is later. The completion schedule for this list includes 40 categories to be completed within 2 years of the 1990 Amendments, with 25% of the remaining entries on the list to be completed within 4 years of the 1990 Amendments, another 25% within 7 years, and the remainder before the 10 year deadline.

Other Related Sites

For more information, please contact Briana Hilton, MACT Coordinator