Ambient Air quality Monitoring Guidlines. - Maharashtra Pollution ...

5.0 QUALITY ASSURANCE AND QUALITY CONTROL
IN AIR QUALITY MONITORING
An analytical quality control program develops information which can be used to,
evaluate the accuracy and precision of analytical data in order to establish the quality of
the data; provide an indication of the need for corrective actions and to determine the
effects of corrective actions.
5.1 Analytical Quality Control
Analytical quality control (AQC) scheme is taken up at two levels as mentioned below:
Within- laboratory AQC,
It is necessary to check the accuracy of analytical results within laboratory. The various
sequential stages involved are:
1. Choosing an analytical method suitably free from bias, and ensuring the
complete and unambiguous description of that method.
2. Checking that satisfactory precision is obtained with the method.
3. Establishing a control chart as a continuing check on precision and some
sources of bias.
4. Ensuring accuracy of standard solution.
2. Between laboratory ( or Inter- laboratory) AQC
In between laboratory ( or Inter- laboratory) AQC a group of laboratories has to achieve
comparability of results by controlling the accuracy of each laboratory. Usually between-
laboratory AQC should be conducted as soon as all laboratories have satisfactorily
completed the within laboratory AQC tests.
AQC tests between laboratories are necessary for the following two reasons:
1. To test for possible bias caused by sources not already checked in within
laboratory AQC.
2. To provide direct evidence that the required comparability of results between
laboratories has been achieved.
Accuracy may deteriorate with time and hence subsequently regular tests are
required as a continuing check on between laboratories bias. Interlaboratory
proficiency testing of ambient air quality measurement methods is described below.
A flow chart for approach to achieving accuracy of analytical results is shown in
Figure 5.1.
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