This user's manual was prepared for and funded by the New Source Review RACT/BACT/LAER Clearinghouse (RBLC),1 U.S. Environmental Protection Agency (EPA). The RBLC has been established and is maintained by the Clean Air Technology Center (CATC) to assist State and local air pollution control personnel in making control technology determinations and in sharing technology information. The RBLC provides data on prevention and control technology determinations made primarily by State and local permitting agencies. The Clearinghouse contains over 4,000 determinations that can help the user to identify appropriate technologies to mitigate or treat most air pollutant emission streams. The RBLC was designed to help permit applicants and reviewers make pollution prevention and control technology decisions for stationary air pollution sources and includes data submitted by 50 states and territories in the U.S. on over 200 different air pollutants and 1,000 industrial processes. The Clearinghouse also has a rule data base that summarizes all emission standards issued by EPAs Office of Air Quality Planning and Standards (OAQPS). This includes New Source Performance Standards (NSPS), National Emission Standards for Hazardous Air Pollutants (NESHAP), and Maximum Achievable Control Technology (MACT) standards. The rule data base also includes prevention and control technology cost information related to each rule and references to supporting documentation.