###### Abstract  
The U.S. Environmental Protection Agency (USEPA) provides databases that agglomerate data provided by companies or states reporting emissions, releases, wastes generated, and other activities to meet statutory requirements. These databases, often referred to as inventories, can be used for a wide variety of environmental reporting and modeling purposes to characterize conditions in the United States. Yet, users are often challenged to find, retrieve, and interpret these data due to the unique schemes employed for data management, which could result in erroneous estimations or double-counting of emissions. To address these challenges, a system called Standardized Emission and Waste Inventories (SHEVI) has been created. The system consists of four python modules that provide rapid access to USEPA inventory data in standard formats and permit filtering and combination of these inventory data. When accessed through SHEVI, reported emissions of carbon dioxide to air and ammonia to water are reduced approximately two- and four-fold, respectively, to avoid duplicate reporting. SHEVI will greatly facilitate the use of USEPA inventory data in chemical release and exposure modeling and life cycle assessment tools, among other things. To date, SHEVI has been used to build the recent USEEIO model and the baseline electricity life cycle inventory database for the Federal LCA Commons. National Emissions Inventory; Toxics Release Inventory; substance registry service; facility registry service; eGRID; RCRAInfo; bennial hazardous waste report; discharge monitoring report; EPA data; greenhouse gas reporting program; python; tool ecosystem +
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facility qualifies as a Type A or Type B source under the AERR, it will be incorporated in the NEI as a point source. The NEI contains specific reporting thresholds for Type A and Type B sources (details can be found in the supporting information). Reporting of hazardous air pollutants (HAPs) (e.g., acetaldehyde) is optional in the NEI. The reporting process in the NEI varies by state due to budget and by category of facility. The NEI is different from other inventories such as the TRI as the emissions are not necessarily reported directly by facilities. Emissions in the NEI can also be compiled by states, tribes, or the USEPA. The TRI covers facilities that manufacture, processes, or otherwise use any of the Emergency Planning and Community Right-to-Know Act (EPCRA) Section 313 chemicals. Facilities that have 10 or more full-time employees (as defined in 40 CFR SS372.3) and are in a TRI-covered sector, as defined by the North American Industry Classification System (NAICS) code, or are a federal facility must report TRI chemical releases. Almost all HAPs reported within the NEI are also TRI chemicals. However, the TRI also includes toxic chemicals that may not be considered HAPs, and therefore are not assessed in the NEI. Unlike the NEI, TRI data are based on facility self-reporting, and facilities report on an annual basis. While there may be overlap in TRI and NEI air emissions, the TRI also reports chemical releases to other media such as land and water. In some cases, the NEI may use the TRI to supplement HAP information. However, the common air emission values between the NEI and the TRI may not always match due to differences in the reporting such as threshold values and the reporting process itself. States, tribes, and the USEPA have more discretion to modify NEI facility-level data during the reporting process as compared with the TRI reporting process. While each inventory adheres to relevant regulations, the differences in the coverage and reporting process can lead to complexities when using the databases together. Public versions of these inventories are housed in various locations, are encoded in various data formats, and use various vocabularies to describe their contents.