This action promulgates national emission standards for hazardous air pollutants (NESHAP) for new and existing publicly owned treatment works (POTW). The primary hazardous air pollutants (HAP) emitted by these sources include xylenes, methylene chloride, toluene, ethyl benzene, chloroform, tetrachloroethylene, benzene, and naphthalene. Each of these HAP can cause adverse health effects provided sufficient exposure. For example, exposure to methylene chloride can adversely affect the central nervous system and has been shown to cause liver and lung cancers in animals, while benzene is known to cause cancer in humans. With this final rule, the EPA is requiring air pollution controls on a new or reconstructed treatment plant at a POTW that is a major source of HAP. The standards also require that new and existing POTW treating regulated waste streams from an industrial user, for the purpose of allowing that industrial user to comply with another NESHAP, meet the treatment and control requirements of the other relevant NESHAP.