As illustrated in Table IV, the Aerospace NESHAP, originally slated as a 4-year MACT, is still pending final rulemaking. Currently, the only MACT standards applicable to aerospace spraybooth operations are those promulgated in the September 1, 1995, final rule (Table II); however, if the proposed October 29, 1996, amendment goes through the standards reflected in Table III will be the rule. Paint shop forepersons, maintenance managers, environmental coordinators, and those responsible for procuring filters and equipping booths must decide which system to select (EPA did grandfather those new and reconstructed booths for which construction commenced after September 1, 1996, but before December 29, 1996, but that window is now closed) and still ensure regulatory compliance given the limited number of filter manufacturers offering certified systems and probable high, short-term demand. Also the EPA is set to evaluate the environmental benefits attained through the use of MACT by the source categories after 8 years of service (2003 for the aerospace industry). At that time EPA may promulgate new MACT standards based on improved control technology then available or instead may institute health-based performance standards. Table IV provides the sequence of events for this NESHAP that have taken place since the Clean Air Act Amendments of 1990 were first written into law by Congress.