Figure 2‐6 CEM systems and enforcement policy.

      Periodic Monitoring

      The position of EPA has been that sources are obligated to comply with all permit emission limits and standards at all times. With regard to this position of EPA, in §§70.6(a)(3) and 71.6(a)(3) of 40 CFR 70 and 71, State and Federal Operating Permit Programs require that a source operating permit include a monitoring program. As stated in Section 70.6:

      Where the applicable requirement does not require periodic testing or instrumental or noninstrumental monitoring, [the permit must still include] periodic monitoring [requirements] sufficient to yield reliable data from the relevant time period, that are representative of the source's compliance with the permit.

      Also, a responsible official from the company must certify that the source is in compliance with all applicable requirements. The periodic monitoring should be of sufficient quality to provide a basis for the official to certify the compliance status of the source under all operating conditions.

      Epilogue

      Environmental control agencies have found CEM systems to be valuable tools in their regulatory programs. Whether used as control equipment operation and maintenance indicators, compliance monitors, or the basis for allowance trades, CEM systems today have become integral to achieving environmental goals. Requirements to install CEM systems at stationary sources arise from both federal and state regulatory programs. Whether state or federal, these programs specify pollutants that are to be monitored, emission limits, CEM system performance criteria, CEM quality assurance requirements, and reporting requirements. However, they are still incomplete if they do not include some mechanism for independently validating the data (Duflo et al. 2013).

      Even with the best of intentions, CEM systems can be unsuccessful in supporting emission control programs. Analyzers, controls, computers, and associated equipment make up a CEM system, but just as an automobile’s odometer can be compromised, data from a CEM system can be falsified. If the environmental control agency has incentives to reduce emissions but no disincentives to prevent deliberate adjustments to data, the likelihood of data corruption is higher than if procedures are instituted to discourage such behavior. Especially problematical is the case when ethical personnel are requested by management to make adjustments they know to be wrong. It then often becomes a matter of either acceding to the request or being terminated. Although ultimately becoming a whistleblower may offer some sense of retribution, employees should never be put in such a position.

It is relatively easy to adjust and report CEM data to any value desired. It is also relatively easy to detect such adjustments. Given the daily calibration verification values, the emissions data record, maintenance logbook, and other records, an astute inspector can readily identify questionable data. Jumps in emission values, miscalibrated instruments, frequent instrument recalibrations, the introduction of correction factors, or CEM downtime during emission excursions are all situations that invite further investigation. A review of both calibration verification quality control charts and the analog emissions data are particularly useful in such an investigation. The problem is that someone has to do this. However, all too often, both the regulated facilities and/or the environmental control agencies either lack the foresight or lack the resources to institute procedures to make reality checks.

      As an example of one solution to these issues, in the U.S. acid rain program, all calibration, emissions data, and performance evaluation results as well as plant operating data are submitted to EPA’s Clean Air Markets database. The data are checked for format and cross checked using various algorithms to evaluate whether they are internally consistent and whether they are consistent with plant operating conditions and past performance. Inconsistent data are flagged and requests are made to clarify and correct the data, as appropriate. In another example, the Canadian CEM Guidelines, EPS 1/PG/7, require that a facility’s CEM QA/QC program be evaluated annually by an independent inspector. In the United States, in the rare case that CEM data have been falsified, legal proceedings often ensue. In these proceedings, penalties are not civil penalties such as those incurred for having excess emissions, but criminal penalties – a significant disincentive.

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