In 1994, EPA promulgated national emission standards for hazardous air pollutants (NESHAP) for the synthetic organic chemical manufacturing industry. This rule is commonly known as the hazardous organic NESHAP (HON) and established maximum achievable control technology standards to regulate the emissions of hazardous air pollutants from production processes that are located at major sources. The Clean Air Act directs EPA to assess the risk remaining (residual risk) after the application of the maximum achievable control technology standards and to promulgate additional standards if required to provide an ample margin of safety to protect public health or prevent an adverse environmental effect. The Clean Air Act also requires us to review and revise maximum achievable control technology standards, as necessary, every 8 years, taking into account developments in practices, processes, and control technologies that have occurred during that time. On June 14, 2006, EPA proposed two options regarding whether to amend the current emission standards for synthetic organic chemical manufacturing industry units. This action finalizes one of those options, and reflects our decision not to impose further controls and not to revise the existing standards based on the residual risk and technology review. It also amends the existing regulations in certain aspects.