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The Combined Air Emissions Reporting (CAER) project seeks to streamline the way industry reports air emissions to meet EPA, state, local, and tribal program requirements. The CAER System (CAERS) is an electronic reporting application that allows facilities to report to more than one program via a single data submission.


Various federal, state, local, and tribal programs require industry to report air pollutant emissions to separate systems at different times of the year to meet requirements for the National Emissions Inventory (NEI), the Toxics Release Inventory (TRI), the Greenhouse Gas Reporting Program (GHGRP), the Compliance and Emissions Data Reporting Interface (CEDRI), and partner-specific systems. This leads to duplication of effort for both industry and government. While each program collects different data, shared data could be reported just once for use across multiple programs.


Combined emissions reporting will reduce redundancy in reporting air emissions and associated facility data, as well as review time for EPA, state, local, and tribal (SLT) programs on data quality assurance and data reconciliation among programs.

  • Regulated Community: CAER will decrease the reporting burden for facilities by reducing duplicative data entry across programs and improving both the reporting experience and efficiencies.
  • Public: CAER will improve data availability, timeliness, transparency, consistency, and quality for users.
  • Regulators: EPA, States, Tribes, and local governments will spend less time reviewing, compiling, and reconciling data, and the most timely and high-quality data will be available to decision makers.


CAERS Version 5 deployed in February 2024 for the NEI 2023 reporting cycle and is being used by SLT programs in the District of Columbia, Georgia, Idaho, Maine, Mississippi, and Pima, Arizona. More programs are scheduled to onboard next year and/or have requested test accounts to evaluate CAERS, giving them the opportunity to provide feedback on their specific needs to the CAERS development team.

Updates in CAERS include the ability for SLT users to retrieve data reported by their industry via the CAERS application programming interface (API) for use in their own tools for advanced quality assurance and other specific purposes.


  • Build additional CAERS functionality to refine the data that can be made available to TRI.   
  • Add specific data fields to sub-facility data in CAERS to allow users to identify which facility components report to specific rules, and thus begin harmonizing the Emissions Inventory System and CEDRI facility inventory.
  • Explore additional use cases between CAERS and SLTs that may allow additional States to onboard in CAERS. 
  • New SLTs are always welcome to provide input for CAERS continuous improvement by signing up for the CAER Product Design Team (PDT) or reaching out to the project contacts.


State/Local/Tribal (SLT), National Emission Inventory (NEI), Toxic Release Inventory (TRI) Mapping

Research consistency and possible workflows for sharing of emissions data between TRI, SLTs and NEI. This will include creating a crosswalk for pollutants between programs, figuring out how to handle each program’s terminology (e.g. facility, unit) and emission sources covered by reporting, and identifying where guidance needs to be harmonized, among other things.

Quality Assurance / Quality Control (QA/QC)

Identification and evaluation of a common set of emissions data QA/QC procedures for potential use in a shared emission reporting system.

Data Model for the Common Emissions Form (CEF)

Document a data model with the emissions-related data elements needed to support a common emission form (CEF) reporting structure in a shared emissions platform. Identify and include state-specific data elements sufficient to allow for broad usage by states and EPA CAER

SCC-WebFIRE for the Common Emissions Form (CEF)

Scoping study for identifying problems and solutions with SCCs and WebFIRE that will meet SLT, NEI, NATA, and CEDRI/ERT requirements under the CAER project.

State Greenhouse Gas Reporting Program (GHGRP) to National GHGRP Mapping

This will be a pilot study to map emission data in the national GHGRP to state GHGRP programs. The goal of the study is to understand which data elements state mandatory reporting programs have in common with GHGRP required data elements. This will help us understand what would be necessary to share data between the programs.