Page 263 - Fundamentals of Air Pollution

224 15. Air Pollution Monitoring and Surveillance

Table 15-2 contains a specific example of these components for ambient
monitoring for ozone.
In addition to fulfilling the in-house requirements for quality control, state
and local air monitoring networks which are collecting data for compliance
purposes are required to have an external performance audit on an annual
basis. Under this program, an independent organization supplies externally
calibrated sources of air pollutant gases to be measured by the instrumenta-
tion undergoing audit. An audit report summarizes the performance of the
instruments. If necessary, further action must be taken to eliminate any
major discrepancies between the internal and external calibration results.
Data quality assessment requirements are related to precision and accu-
racy. Precision control limits are established, i.e., +10% of span value, as
calculated from Eq. (15-1). The actual results of the may be used to calculate
an average deviation (Eq. 15-3):

where d t is the percentage difference, y, the analyzer's indicated concentra-
tion of the test gas for the zth precision check, and x f the known concentra-
tion of the test gas for the fth precision check.

TABLE 15-2
Quality Control Components for Ambient Ozone Monitoring
Component Description

Method Chemiluminescent O 3 monitor
Calibration method by certified ozone UV transfer method
Manifold/instrument Instrument connected to sampling manifold which draws ambient
configuration air at 3 m into instrument shelter
Calibration Multipoint calibration on 0.5-ppm scale at 0.0, 0.1, 0.2, and
0.4 ppm weekly
Zero/ span check Zero check ± 0.005 ppm
Span check 0.08-0.10 on a 1.0-ppm full scale daily
Control specification Ethylene flow
checks Sample flow, daily
Corrective limits ± 0.005 ppm zero and span
Corrective action Do multipoint calibration; invalidate data collection since last zero/
span check within control limits
Preventive maintenance Manufacturer's procedures to be followed
Recording and Data reported weekly to quality assurance coordinator, with invalid
validating data data flagged
Documentation Data volume includes all quality control forms, e.g., zero/span
control charts and multipoint calibration results