Page 262 - Fundamentals of Air Pollution
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IV. Quality Assurance 223
Fig. 15-4. Ethylene concentrations measured by the DIAL system along a 5-km path
length near Menlo Park, California. The open circles are ethylene concentrations of samples
taken at three ground-level locations near the line of sight and analyzed by gas chromatogra-
phy. Source: Murray, E. A., and Van der Laan, }. E., Appl. Opt. 17, 814-817 (1978).
stringent regulations requiring well-documented quality assurance pro-
grams for air quality monitoring activities (13).
Quality assurance programs are designed to serve two functions:
(1) assessment of collected air quality data and (2) improvement of the data
collection process. These two functions form a loop; as air quality data are
collected, procedures are implemented to determine whether the data are
of acceptable precision and accuracy. If they are not, increased quality
control procedures are implemented to improve the data collection process.
The components of a quality assurance program are designed to serve
the two functions just mentioned—control and assessment. Quality control
operations are defined by operational procedures, specifications, calibration
procedures, and standards and contain the following components:
1. Description of the methods used for sampling and analysis
2. Sampling manifold and instrument configuration
3. Appropriate multipoint calibration procedures
4. Zero/span checks and record of adjustments
5. Control specification checks and their frequency
6. Control limits for zero, span, and other control limits
7. The corrective actions to be taken when control limits are exceeded
8. Preventative maintenance
9. Recording and validation of data
10. Documentation of quality assurance activities