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The Environmental Protection Agency (EPA) performs limited oversight of states' processes for verifying the accuracy of large industrial facilities' emissions reports. EPA's data show that most emissions determinations from large sources are based on generic emissions factors. Although EPA allows facilities to estimate their emissions in this manner, EPA officials generally consider direct methods to be more reliable. The accuracy of these reports is important because they influence (1) the financing of states' regulatory programs through fees and (2) the development of emissions inventories, which, in turn, help regulators to develop control strategies and establish permit limits. Furthermore, steps taken to assess the accuracy of these reports, such as more thoroughly reviewing the supporting information, could improve compliance with Clean Air Act requirements. For example, a more thorough review of the information underlying a facility's emission reports, or a more systematic comparison of these reports over time, could identify increased emissions. Such indications could, in turn, trigger a review of compliance with new source review requirements, an area in which EPA found widespread noncompliance in four industries. In the four states that GAO reviewed, the states that had done the most detailed reviews found widespread inaccuracies. Although it is taking steps to improve its overall compliance monitoring strategy, EPA does not plan to evaluate states' processes for verifying emissions reports from large facilities.

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Recommendations for Executive Action

Agency Affected Recommendation Status
Environmental Protection Agency 1. To help ensure the accuracy of facilities' emissions reports, the Administrator of EPA should evaluate states' programs to determine whether they have adequate mechanisms in place for verifying the accuracy of the reports. If the results of these reviews identify inadequacies, the Administrator should work with the states to improve their processes in order to provide reasonable assurance that facility reports are subject to thorough review.
Closed - Implemented
According to EPA data, emissions factors (average emissions rates that have been calculated for various combinations of industrial processes, raw materials, and other factors) are used, nationally, for about 80 percent of emissions reports, instead of direct measurements of emissions. EPA has revised the emissions factor program (1) to better account for the uncertainty inherent in using emissions factors, (2) to expedite the data transfer necessary to develop and approve emissions factors, and (3) to consolidate and facilitate the retrieval of information on emissions factors. These steps will make emissions factors, and thereby emissions reports, more accurate.

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