Area Source Standard Updates

The Environmental Protection Agency published approximately 96 major hazardous air pollutants, or HAP, source standards to regulate 174 industrial source categories that emit one or more hazardous air pollutant. Both the major source standards and the area source standards are located in 40 CFR Part 63. The area source standards are collectively known as Generally Available Control Technology, or GACT, standards and the major source standards are known as Maximum Achievable Control Technology, or MACT, standards.

Area HAP sources are those that emit less than 10 tons per year of any individual HAP or less than 25 tons per year of any combination of HAPs.  Area HAP sources that use or emit any of the regulated HAPs are expected to be impacted by one or more of the 70 area source GACTs. The Air Pollution Control Program and the local air agencies are tasked with identifying potentially affected sources for MACTs, GACTs, and residual risk requirements, as well as offering compliance assistance and other outreach as needed.  Although there are exceptions, existing sources typically have three years after the federal rule is finalized to demonstrate full compliance with MACT and GACT regulatory requirements.

The Clean Air Act also requires EPA to conduct residual risk assessments for all MACT standards to determine, after the requirements of each MACT are implemented, if additional regulatory requirements are necessary to further protect public health and the environment with respect to HAP emissions.

As of September 2008, EPA completed residual risk assessments for eight MACT source categories and is currently evaluating the residual risk of 30 additional source categories. EPA plans to propose residual risk assessments for nine MACT source categories and finalize assessments for eight more source categories by summer 2009. Those that have already been finalized are in the table below. They are listed in reverse chronological order with more recently published source category requirements listed at the top.

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