2. Quality assurance

When measuring the concentration of a compound in the air, the aim is obviously always to obtain a value that represents environmental reality as accurately as possible. What's more, beyond the absolute value of the concentration, we are often interested in its variation in space and time, which often leads us to compare measurements made by many different devices. This calls for strict procedures to control the protocols used, to ensure the quality and comparability of the values obtained: these are known as quality assurance/quality control (QA/QC) procedures.

This section deals with the important case of quality assurance in an air quality monitoring network. Procedures for any other situation can easily be derived from it.