EPA's Applicability Determination Index (ADI) Database Includes Agency Memorandum and Letters of Interpretations

Each year, EPA issues hundreds of letters or memoranda on Clean Air Act (CAA) applicability or monitoring issues under the New Source Performance Standards (NSPS, 40 CFR Part 60) and the National Emission Standards for Hazardous Air Pollutants (NESHAP, 40 CFR Parts 61 and 63) programs. The general provisions of 40 CFR Parts 60 and 61 provide that a source owner or operator may request a determination of whether certain intended actions constitute the commencement of construction, reconstruction, or modification ("applicability determinations"); or seek permission to use monitoring or record keeping which is different from the promulgated NSPS and NESHAP standards ("alternative monitoring"). EPA also issues applicability determinations to a particular source pursuant to 40 CFR Part 63, even though the general provisions do not contain a specific provision under which source owners or operators may request determinations.

These letters and memoranda are compiled on the agency's Applicability Determination Index (ADI) database Web site. The ADI database allows users to search by date, office of issuance, subpart, citation, control number, or string word searches. The Office of Enforcement and Compliance Assurance (OECA), Compliance Assessment and Media Programs Division (CAMPD) maintains the ADI database and provides on how to review and issue CAA applicability determinations.
The link to the ADI database can be found at http://cfpub.epa.gov/adi/.