Pursuant to requirements concerning enhanced monitoring and compliance certification under the Clean Air Act (the Act), EPA is promulgating new regulations and revised regulations to implement compliance assurance monitoring (CAM) for major stationary sources of air pollution that are required to obtain operating permits under title V of the Act. Subject to certain exemptions, the new regulations require owners or operators of such sources to conduct monitoring that satisfies particular criteria established in the rule to provide a reasonable assurance of compliance with applicable requirements under the Act. Monitoring will focus on emissions units that rely on pollution control device equipment to achieve compliance with applicable standards. The regulations also provide procedures for coordinating these new requirements with EPA's operating permits program regulations. Revisions to the operating permits program regulations clarify the relationship between the 64 requirements and periodic monitoring and compliance certification requirements. The rulemaking is estimated to improve compliance with existing regulations which will potentially reduce the need for further regulation to achieve clean air goals at a cost significantly less than that of the 1993 proposed rule.