As mentioned, however, § 111 (d) exempts existing facilities in source categories regulated under § 112 — an exemption covering power plants thanks to EPA's nonsensical MATS rule. (globalwarming.org)
In other words, in 1990, Congress gave EPA the discretion to determine that listing power plants as a HAP source category subject to MACT standards is not «necessary and appropriate.» (globalwarming.org)
The EPA also believes that section 108 (g) is the correct amendment because the Clean Air Act Amendments revised section 112 to include regulation of source categories in addition to regulation of listed hazardous air pollutants, and section 108 (g) thus conforms to other amendments of section 112. (globalwarming.org)