Quality Assurance for Continuous Methods for Particulate Monitoring
These are some of the measures APCD staff take to ensure the quality of data from the continuous sampling/weighing systems used to monitor particulate matter (PM10 and a href="/APCD/AboutAirPollution/glossary.htm#aPM2_5">PM2.5). A monitoring system of this type usually consists of a single instrument that samples and weighs particulate matter as often as every two seconds and a data acquisition system (which may be connected to other instruments or may be built into the sampler) and possibly a strip chart recorder.
- Traceability of standards:
- flow: orifices certified against a NIST-traceable displacement meter
- flow calibrators (bubble meters and/or dry flow calibrators) certified NIST-traceable
- temperature, pressure, etc. certified NIST-traceable
- Calibrations: The operator performs a multi-point flow calibration of each particulate sampler/analyzer using an orifice unit (quarterly, after maintenance or repairs and when indicated).
- Precision checks through collocation: A second sampler is placed at 25% (but at least one) of all state and local air monitoring stations (SLAMS). For PM10, the second sampler can use the federal reference method (FRM) or a federal equivalent method (FEM). For PM2.5, 50% of the second samplers should be FRM samplers and 50% should use the same method as the main sampler/analyzer.
- Performance audits: An APCD auditor (normally not the regular operator) does a one-point flow audit quarterly on at least 25% of all samplers, using a different orifice unit than the one used to calibrate the sampler.
- Data audit: An APCD auditor (not the operator of the monitoring system in question) verifies the highest and one random hourly reading each day for each parameter, and reviews all the data for anomalies. APCD does this for all data every month; KyDAQ does it for one month's data per quarter.