In-situ stack monitoring measures emissions directly in the stack without removing a sample, avoiding problems from moisture in the sampling system that can affect extractive systems by potentially removing water-soluble compounds and impacting the accuracy of measurements. In-situ monitoring does not need to remove moisture from samples taken.

1. In EXTRACTIVE systems the measurement is
only as good as the sample. Moisture in the sampling system can be a
significant problem.
IN-SITU VS. EXTRACTIVE
STACK MONITORING:
IN-SITU need not remove
moisture from the sample, reducing the
risk of removing water-soluble compounds
affecting the “true measurement.”