This report documents an assessment of Generic Issue 43, "Contamination of Instrument Air Lines," and Generic Letter 88-14, "Instrument Air Supply System Problems Affecting Safety-Related Equipment." This assessment is part of an ongoing initiative through which the U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Regulatory Research, is reviewing selected agency regulations and decisions to determine whether they are achieving the desired results. For this assessment, the staff compared expectations with outcomes. Whenever outcomes fell short of expectations, the staff attempted to identify ways to enhance the effectiveness, efficiency, and realism of the NRC's regulatory process.