“Response Correlation Audit (RCA)” means the series of tests procedure that you conduct to ensure the continued validity of your PM CEMS correlation. RCA procedures, including sampling and analysis methods, sampling strategy, and structuring test conditions over the prescribed range of PM concentrations. In the context of CEMS or air quality monitoring, an RCA would involve investigating and analyzing the root causes of issues or discrepancies in the monitoring system’s performance. This could include issues related to data accuracy, instrument malfunctions, calibration problems, or other factors that may impact the reliability of the emissions data collected by the CEMS.