MACT Update and the Often Overlooked General Provisions

The Clean Air Act requires the US EPA to regulate emissions of hazardous air pollutants (HAPs) under regulations know as Maximum Achievable Control Technologies (MACTs). These MACTs are embodied in National Emission Standards for Hazardous Air Pollutants (NESHAPs). MACT standards are developed for individual source categories, such as Publicly Owned Treatment Works (POTWs) and Industrial, Commercial, and Institutional Boilers and Process Heaters. EPA initially listed 174 source categories for regulation under MACT standards, and is required to evaluate the list every 8 years. The majority of the MACT standards can be found in Title 40 Code of Federal Regulations Part 63 (40 CFR 63); the MACT standard for each source category is located in a separate subpart of 40 CFR 63. In addition to the source category specific requirements found in each subpart there are General Provisions that apply to each source that is regulated by a MACT standard. These General Provisions are found in 40 CFR 63 Subpart A. Applicable MACT requirements are generally included in each facility's air quality operation permit and become an important element in facility compliance. This paper provides a brief overview of the MACT rules, a discussion of the General Provisions, and an update on two recent changes to the MACT rules.