The concept of the scan MDC is especially important in MARSSIM. A scan MDC is an MDC calculated for an instrument that takes continuous or "scanning" measurements. A scanning instrument can often take more measurements more cheaply and in less time than a non-scanning instrument. However, it is important that the scan MDC obtained by the scanning procedures used will actually detect the required DCGL in the field.
If the scan MDC is adequate to detect the DCGLEMC, it can be used to greatly reduce or eliminate the possibility of missing an area of elevated concentration.
For more information on the MARSSIM process, visit MARSSIM on EPA.gov.