This action finalizes the residual risk and technology review (RTR) conducted for the Ferroalloys Production source category regulated under national emission standards for hazardous air pollutants (NESHAP). These final amendments include revisions to particulate matter (PM) standards for electric arc furnaces, metal oxygen refining processes, and crushing and screening operations, and expand and revise the requirements to control process fugitive emissions from furnace operations, tapping, casting, and other processes. We are also finalizing opacity limits, as proposed in 2014. However, regarding opacity monitoring, in lieu of Method 9, we are requiring monitoring with the digital camera opacity technique (DCOT). Furthermore, we are finalizing emissions standards for four previously unregulated hazardous air pollutants (HAP): Formaldehyde, hydrogen chloride (HCl), mercury (Hg) and polycyclic aromatic hydrocarbons (PAH). Other requirements related to testing, monitoring, notification, recordkeeping, and reporting are included. This rule is health protective due to the revised emissions limits for the stacks and the requirement of enhanced fugitive emissions controls that will achieve significant reductions of process fugitive emissions, especially manganese.