Truth or Dare: Data Augmentation in the Point Source 2002 NEI

The Environmental Protection Agency (EPA) compiles the National Emission Inventory (NEI) for hazardous air pollutants (HAPs) and criteria air pollutants (CAPs). The NEI plays an important role in air quality management activities such as emission trends, rule and policy development and risk assessment. To support many of the these functions, the NEI must contain the data necessary for air quality modeling. The NEI contains estimates of facility-specific HAP and CAP emissions and their source-specific parameters necessary for modeling such as location and facility characteristics (stack height, exit velocity, temperature, etc.). Complete source category coverage is needed, and the NEI contains estimates of emissions from stationary point and nonpoint (i.e., stationary sources such as residential heating that are inventoried at the county level) and mobile source categories. This paper focuses on a particular aspect of the development of the point source inventory. Point source categories include major and area sources as defined in section 112 of the CAA. Key processing activities for point source data include submittal of 2002 inventory data by state and local agencies, tribes, EPA, and industry; blending/merging of data from multiple data sources; augmentation of data for missing data elements; QC/QA of the data; preparation of draft NEI for external review; incorporation of external review comments; and preparation of final NEI. An important step in preparing point source files is augmentation of data. The EPA conducts a variety of QA steps to identify any missing or out-of-range parameters which are needed for air quality and exposure modeling. After conducting QA, the EPA augments data using a published methodology. The NEI data files identify all records that have defaulted parameters and the methodology used to default data fields.